OCaml Changelog

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Read the latest releases and updates from the OCaml ecosystem.

Two months after the release of OCaml 5.1.1, the set of new features for the future version 5.2.0 of OCaml has been frozen. We are thus happy to announce the first alpha release for OCaml 5.2.0.

This alpha version is here to help fellow hackers join us early in our bug hunting and opam ecosystem fixing fun (see below for the installation instructions).

The progresses on stabilising the ecosystem are tracked on the opam readiness for 5.2.0 meta-issue. The full release is expected around April.

If you find any bugs, please report them on OCaml's issue tracker.

If you are interested in the ongoing list of new features and bug fixes, the updated change log for OCaml 5.2.0 is available on GitHub.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1 and later:

opam update
opam switch create 5.2.0~alpha1

For previous version of opam, the switch creation command line is slightly more verbose:

opam update
opam switch create 5.2.0~alpha1 --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

The source code for the alpha is also available at these addresses:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.2.0~alpha1+options <option_list>

where option_list is a space separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.2.0~alpha1+flambda+nffa ocaml-variants.5.2.0~alpha1+options ocaml-option-flambda ocaml-option-no-flat-float-array

The command line above is slightly more complicated for opam version anterior to 2.1:

opam update
opam switch create <switch_name> --packages=ocaml-variants.5.2.0~alpha1+options,<option_list> --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

In both cases, all available options can be listed with opam search ocaml-option.

In the last three months after the release of OCaml 5.1.0, three significant regressions have been discovered in OCaml 5.1.0. Those regressions concern the packaging of executables, the typechecking of OCaml programs, and the performance of numerical codes.

Since those regressions affect many users and could have lasting effects, we have published patch release OCaml 5.1.1 fixing those issues.

As a major exception to our policy for patch releases, OCaml 5.1.1 will contain one breaking change in the standard library: the Compression flag has been removed from the Marshal module.

This drastic measure was taken because supporting ZSTD compression in the standard library made ZSTD a dependency of all OCaml executables. Since the compiler should not impose its dependency on end users, the support for compressed marshaling has been moved to a compiler internal library in 5.1.1.

Accounting for the still-experimental nature of the Multicore runtime, this patch release 5.1.1 also contains safe fixes for subtle concurrency issues in the OCaml runtime.

The full list of changes is available below for more details.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands:

opam update
opam switch create 5.1.1

The source code for the release is also directly available on:

See full changelog

Standard library:

  • (breaking change) #12562, #12734, #12783: Remove the Marshal.Compression flag to the Marshal.to_* functions introduced in 5.1 by #12006, as it cannot be implemented without risking to link -lzstd with all ocamlopt-generated executables. The compilers are still able to use ZSTD compression for compilation artefacts. (Xavier Leroy and David Allsopp, report by Kate Deplaix, review by Nicolás Ojeda Bär, Kate Deplaix, and Damien Doligez).

Runtime Bug Fixes:

  • #11800, #12707: Fix an assertion race condition in install_backup_thread (Jan Midtgaard, review by Gabriel Scherer)

  • #12486, #12535: Fix delivery of unhandled effect exceptions on AMD64 with --enable-frame-pointers (Miod Vallat, report by Jan Midtgaard, review by Gabriel Scherer)

  • #12712, #12742: Fix an assertion boundary case in caml_reset_young_limit (Jan Midtgaard, review by Guillaume Munch-Maccagnoni)

  • #12713, #12715: Disable common subexpression elimination for atomic loads (Gabriel Scherer and Vincent Laviron, review by Vincent Laviron, KC Sivaramakrishnan and Xavier Leroy, report by Vesa Karvonen and Carine Morel)

GC Performance Regression Bug Fixes:

  • #12318: GC: simplify the meaning of custom_minor_max_size: blocks with out-of-heap memory above this limit are now allocated directly in the major heap. (Damien Doligez, report by Stephen Dolan, review by Gabriel Scherer)

  • #12439: Finalise and collect dead custom blocks during minor collection (Damien Doligez, review by Xavier Leroy, Gabriel Scherer and KC Sivaramakrishnan)

  • #12590, #12595: Move caml_collect_gc_stats_sample in caml_empty_minor_heap_promote before barrier arrival. (B. Szilvasy, review by Gabriel Scherer)

  • #12491, #12493, #12500, #12754: Do not change GC pace when creating subarrays of bigarrays (Xavier Leroy, report by Ido Yariv, analysis by Gabriel Scherer, review by Gabriel Scherer and Fabrice Buoro)

Bug Fixes

  • #12581, #12609: Fix error on uses of packed modules outside their pack to correctly handle nested packs (Vincent Laviron, report by Javier Chávarri, review by Pierre Chambart)

  • #12623: Fix the computation of variance composition (Florian Angeletti, report by Vesa Karvonen, review by Gabriel Scherer)

  • #12645, #12649: Fix error messages for cyclic type definitions in presence of the -short-paths flag. (Florian Angeletti, report by Vesa Karvonen, review by Gabriel Scherer)

  • #12757: Fix ocamlnat (native toplevel) by registering frametables correctly (Stephen Dolan, Nick Barnes and Mark Shinwell, review by Vincent Laviron and Sébastien Hinderer)

  • #12791: extern is applied to definitions of caml_builtin_cprim and caml_names_of_builtin_cprim when linking bytecode -custom executables with a C++ linker. (Shayne Fletcher, review by Antonin Décimo and Xavier Leroy)

Two months (and half) after the release of OCaml 5.1.0, we have discovered three significant regressions in OCaml 5.1.0, affecting the packaging of executables, the typechecking of OCaml programs, and the performance of numerical codes.

Since those regressions affect many users and could have lasting effects, we have decided to cut a patch release of OCaml 5.1 with fixes for those issues next week.

To give time for opam packages to test this patch version, we have just published a first release candidate for OCaml 5.1.1 . The full list of changes in this release candidate is available below.

As a major exception to our policy for patch releases, OCaml 5.1.1 will contain one breaking change in the standard library: the Compression flag has been removed from the Marshal module. This drastic measure was taken because supporting zstd compression in the standard library made zstd a dependency of all OCaml executables. Since the compiler should not impose its dependency on end-users, the support for compressed marshaling has been moved to a compiler internal library in 5.1.1. This internally library might be released as an independent library in later releases of OCaml but not in OCaml 5.1.1 to give us time to polish the library integration and packaging.

Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1 and later:

opam update
opam switch create 5.1.1~rc1

The source code for the release candidate is also directly available on:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.1.1~rc1+options <option_list>

where option_list is a space-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.1.1~rc1+flambda+nffa ocaml-variants.5.1.1~rc1+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with opam search ocaml-option.

See full changelog

Changes in OCaml 5.1.1

Standard Library Dependency Fix:

  • (breaking change) #12562, #12734, #12783: Remove the Marshal.Compression flag to the Marshal.to_* functions introduced in 5.1 by #12006, as it cannot be implemented without risking to link -lzstd with all ocamlopt-generated executables. The compilers are still able to use ZSTD compression for compilation artefacts. (Xavier Leroy and David Allsopp, report by Kate Deplaix, review by Nicolás Ojeda Bär, Kate Deplaix, and Damien Doligez).

Type System Bug Fix:

  • #12623, fix the computation of variance composition (Florian Angeletti, report by Vesa Karvonen, review by Gabriel Scherer)

GC Performance Regression Fixes

  • #12590, #12595: Move caml_collect_gc_stats_sample in caml_empty_minor_heap_promote before barrier arrival. (B. Szilvasy, review by Gabriel Scherer)

  • #12318: GC: simplify the meaning of custom_minor_max_size: blocks with out-of-heap memory above this limit are now allocated directly in the major heap. (Damien Doligez, report by Stephen Dolan, review by Gabriel Scherer)

  • #12439: Finalize and collect dead custom blocks during minor collection (Damien Doligez, review by Xavier Leroy, Gabriel Scherer and KC Sivaramakrishnan)

  • #12491, #12493, #12500, #12754: Do not change GC pace when creating sub-arrays of bigarrays (Xavier Leroy, report by Ido Yariv, analysis by Gabriel Scherer,

Miscellaneous Bug Fixes

  • #12581, #12609: Fix error on uses of packed modules outside their pack to correctly handle nested packs (Vincent Laviron, report by Javier Chávarri, review by Pierre Chambart)

  • #12757: Fix ocamlnat (native toplevel) by registering frametables correctly (Stephen Dolan, Nick Barnes and Mark Shinwell, review by Vincent Laviron and Sébastien Hinderer)

  • #12645, #12649 fix error messages for cyclic type definitions in presence of the -short-paths flag. (Florian Angeletti, report by Vesa Karvonen, review by Gabriel Scherer)

We have the pleasure of celebrating the anniversary of Olympe de Gouges' "Declaration of the Rights of Woman and of the Female Citizen" by announcing the release of OCaml version 5.1.0.

Some of the highlights in OCaml 5.1.0 are:

  • Many runtime performance regression and memory-leaks fixes (dynlinking, weak array, weak hash sets, GC with idle domains, GC prefetching)
  • Restored support for native code generation on RISC-V and s390x architectures
  • Restored Cygwin port
  • Reduced installation size (50% reduction)
  • Compressed compilation artefacts (.cmi, .cmt, .cmti, .cmo, .cma files)
  • 19 error message improvements
  • 14 standard library functions made tail-recursive with Tail-Recursion-Modulo-Cons (TRMC), such as List.append and List.map
  • 57 new standard library functions
  • More examples in the standard library documentation
  • 42 bug fixes

OCaml 5.1.0 is still a relatively experimental release compared to the OCaml 4.14 branch. In particular:

  • The POWER port is being tested in the dev version of the compiler.
  • The Windows MSVC port is still unavailable.
  • Ephemeron performances need to be investigated.
  • GC compaction is a work in progress.
  • statmemprof is a work in progress.
  • There are a number of known runtime concurrency bugs (that trigger under rare circumstances).

We are planning to address those regressions, hopefully in time for the OCaml 5.2.0 release for some of them. Meanwhile, the OCaml 4.14 branch will be maintained, and the next release on the OCaml 4.14 branch, OCaml 4.14.2, should follow this release in the upcoming months.

Please report any unexpected behaviours on the OCaml issue tracker and post any questions or comments you might have on our discussion forums.

The full list of changes can be found in the changelog below.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands:

opam update
opam switch create 5.1.0

The source code for the release candidate is also directly available on:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.1.0+options <option_list>

where <option_list> is a comma-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.1.0+flambda+nffa ocaml-variants.5.0.0+options ocaml-option-flambda ocaml-option-no-flat-float-array
See full changelog

Restored backends

  • #11418, #11708: RISC-V multicore support. (Nicolás Ojeda Bär, review by KC Sivaramakrishnan)

  • #11712, #12258, #12261: s390x / IBM Z multicore support: OCaml & C stack separation; dynamic stack size checks; fiber and effects support. (Aleksei Nikiforov, with help from Vincent Laviron and Xavier Leroy, additional suggestions by Luc Maranget, review by the same and KC Sivaramakrishnan)

  • #11642: Restore Cygwin port. Add GC messages for address space reservations when OCAMLRUNPARAM option v includes 0x1000. (David Allsopp, review by Xavier Leroy, Guillaume Munch-Maccagnoni and Gabriel Scherer)

Standard library:

  • #12006, #12064: Add Marshal.Compression flag to Marshal.to_* functions. When this flag is explicitly set, marshaled data is compressed using ZSTD. On some practical examples, the marshalled output became three times smaller at no noticeable cost on the marshalling time. (Xavier Leroy, review by Edwin Török and Gabriel Scherer, fix by Damien Doligez)

  • #10464: Add List.is_empty. (Craig Ferguson, review by David Allsopp)

  • #11848: Add List.find_mapi, List.find_index: ('a -> bool) -> 'a list -> int option, Seq.find_mapi, Seq.find_index, Array.find_mapi, Array.find_index, Float.Array.find_opt, Float.Array.find_index, Float.Array.find_map, Float.Array.find_mapi. (Sima Kinsart, review by Daniel Bünzli and Nicolás Ojeda Bär)

  • #11410: Add Set.to_list, Map.to_list, Map.of_list, Map.add_to_list: key -> 'a -> 'a list t -> 'a list t. (Daniel Bünzli, review by Nicolás Ojeda Bär and Gabriel Scherer)

  • #11836, #11837: Add Array.map_inplace, Array.mapi_inplace, Float.Array.mapi_inplace and Float.Array.mapi_inplace. (Léo Andrès, review by Gabriel Scherer, KC Sivaramakrishnan and Nicolás Ojeda Bär)

  • #10967: Add Filename.temp_dir. (David Turner, review by Anil Madhavapeddy, Valentin Gatien-Baron, Nicolás Ojeda Bär, Gabriel Scherer, and Daniel Bünzli)

  • #11246: Add "hash" and "seeded_hash" functions to Bool, Int, Char, Float, Int32, Int64, and Nativeint. (Nicolás Ojeda Bär, review by Xavier Leroy and Gabriel Scherer)

  • #11488: Add Mutex.protect: Mutex.t -> (unit -> 'a) -> 'a for resource-safe critical sections protected by a mutex. (Simon Cruanes, review by Gabriel Scherer, Xavier Leroy, Guillaume Munch-Maccagnoni)

  • #11581: Add type equality witness type (_, _) eq = Equal: ('a, 'a) eq in a new module Stdlib.Type. (Nicolás Ojeda Bär, review by Daniel Bünzli, Jacques Garrigue, Florian Angeletti, Alain Frisch, Gabriel Scherer, Jeremy Yallop and Xavier Leroy)

  • #11843: Add In_channel.input_lines and In_channel.fold_lines. (Xavier Leroy, review by Nicolás Ojeda Bär and Wiktor Kuchta).

  • #11856, #11859: Using TRMC, the following Stdlib functions are now tail-recursive: Stdlib.(@), List.append, List.concat_map. (Jeremy Yallop, review by Daniel Bünzli, Anil Madhavapeddy, Nicolás Ojeda Bär, Gabriel Scherer, and Bannerets)

  • #11362, #11402: Using TRMC, the following Stdlib functions are now tail-recursive: List.map, List.mapi, List.map2, List.filter, List.filteri, List.filter_map, List.init, List.of_seq. (Nicolás Ojeda Bär, review by Xavier Leroy and Gabriel Scherer)

  • #11878, #11965: Prevent seek_in from marking buffer data as valid after closing the channel. This could lead to inputting uninitialized bytes. (Samuel Hym, review by Xavier Leroy and Olivier Nicole)

  • #11128: Add In_channel.isatty, Out_channel.isatty. (Nicolás Ojeda Bär, review by Gabriel Scherer and Florian Angeletti)

  • #10859: Add Format.pp_print_iter and Format.pp_print_array. (Léo Andrès and Daniel Bünzli, review by David Allsopp and Hugo Heuzard)

  • #10789: Add Stack.drop (Léo Andrès, review by Gabriel Scherer)

  • (breaking change) #10899: Change Stdlib.nan from signaling NaN to quiet NaN. (Greta Yorsh, review by Xavier Leroy, Guillaume Melquiond and Gabriel Scherer)
  • #11026, #11667, #11858: Rename the type of the accumulator of fold functions to 'acc: fold_left : ('acc -> 'a -> 'acc) -> 'acc -> 'a list -> 'acc fold_right : ('a -> 'acc -> 'acc) -> 'a list -> 'acc -> 'acc fold_left_map : ('acc -> 'a -> 'acc * 'b) -> 'acc -> 'a list -> 'acc * 'b list ... (Valentin Gatien-Baron and Francois Berenger, review by Gabriel Scherer and Nicolás Ojeda Bär)

  • #11354: Hashtbl.find_all is now tail-recursive. (Fermín Reig, review by Gabriel Scherer)

  • #11500: Make Hashtbl.mem non-allocating. (Simmo Saan, review by Nicolás Ojeda Bär)

  • #11412: Add Sys.is_regular_file (Xavier Leroy, review by Anil Madhavapeddy, Nicolás Ojeda Bär, David Allsopp)

  • #11322, #11329: serialization functions Random.State.{of,to}_binary_string between Random.State.t and string (Gabriel Scherer, report by Yotam Barnoy, review by Daniel Bünzli, Damien Doligez, Hugo Heuzard and Xavier Leroy)

  • #11830: Add Type.Id with val provably_equal : 'a Type.Id.t -> 'b Type.Id.t -> ('a, 'b) Type.eq option (Daniel Bünzli, review by Jeremy Yallop, Gabriel Scherer, Wiktor Kuchta, Nicolás Ojeda Bär)

  • #12184, #12320: Sys.rename Windows fixes on directory corner cases. (Jan Midtgaard, review by Anil Madhavapeddy)

  • (breaking change) #11565: Enable -strict-formats by default. Some incorrect format specifications (for printf) where silently ignored and now fail. Those new failures occur at compile-time, except if you use advanced format features like %(...%) that parse format strings dynamically. Pass -no-strict-formats to revert to the previous lenient behavior. (Nicolás Ojeda Bär, review by David Allsopp)

Installation size

Specific efforts have been made during this release to reduce the filesystem size of installed artifacts of the compiler distribution. The installation size of 5.1 is 272 MiB compared to 521 MiB for 5.0. Some of those changes will benefit all OCaml packages.

  • ocaml/RFCs#23, #12006: use compressed marshaled format from #12006 for .cmi, .cmt, .cmti files, and for debug info in .cmo and .cma files, resulting in major reduction in size. (Xavier Leroy, review by Edwin Török and Gabriel Scherer, RFC by Simon Cruanes)

  • #11981: Reduce size of OCaml installations by removing debugging information from installed bytecode executables. It is no longer possible to run ocamldebug over these installed bytecode executables, nor to get exception backtraces for them. (Xavier Leroy, review by David Allsopp, report by Fabrice Le Fessant)

  • (breaking change) #11993: install only bytecode executables for the ocamlmklib, ocamlcmt, ocamlprof, ocamlcp, ocamloptp, and ocamlmktop tools, but no native-code executables. A tool like ocamlmklib for example is now installed directly to $BINDIR/ocamlmklib; ocamlmklib.byte and ocamlmklib.opt are no longer installed to $BINDIR. (Xavier Leroy, review by Gabriel Scherer)

Runtime system:

  • #11589, #11903: Modify the GC pacing code to make sure the GC keeps up with allocations in the presence of idle domains. (Damien Doligez and Stephen Dolan, report by Florian Angeletti, review by KC Sivaramakrishnan and Sadiq Jaffer)

  • #11743: Speed up weak array operations (KC Sivaramakrishnan, review by François Bobot and Sadiq Jaffer)

  • #12131: Simplify implementation of weak hash sets, fixing a performance regression. (Nick Barnes, review by François Bobot, Alain Frisch and Damien Doligez).

  • #11474, #11998, #12065: Add support for user-defined events in the runtime event tracing system. (Lucas Pluvinage, review by Sadiq Jaffer, Guillaume Munch-Maccagnoni, Enguerrand Decorne, Gabriel Scherer and Anil Madhavapeddy)

  • #11827, #12249: Restore prefetching for GC marking (Fabrice Buoro and Stephen Dolan, review by Gabriel Scherer and Sadiq Jaffer)

  • #11144: Restore frame-pointers support for amd64 (Fabrice Buoro, review by Frederic Bour and KC Sivaramakrishnan)

  • #11935: Load frametables of dynlink'd modules in batch (Stephen Dolan, review by David Allsopp and Guillaume Munch-Maccagnoni)

  • #11284, #12525: Use compression of entries scheme when pruning mark stack. Can decrease memory usage for some workloads, otherwise should be unobservable. (Tom Kelly, review by Sabine Schmaltz, Sadiq Jaffer and Damien Doligez)

  • (breaking change) #11865, #11868, #11876: Clarify that the operations of a custom block must never access the OCaml runtime. The previous documentation only mentioned the main illicit usages. In particular, since OCaml 5.0, it is no longer safe to call caml_remove_global_root or caml_remove_generational_global_root from within the C finalizer of a custom block, or within the finalization function passed to caml_alloc_final. As a workaround, such a finalization operation can be registered with Gc.finalize instead, which guarantees to run the finalizer at a safe point. (Report by Timothy Bourke, discussion by Yotam Barnoy, Timothy Bourke, Sadiq Jaffer, Xavier Leroy, Guillaume Munch-Maccagnoni, and Gabriel Scherer)
  • #12130: Fix multicore crashes with weak hash sets. Fixes #11934. (Nick Barnes, review by François Bobot)

  • #12099: Add ocamlrund option, -events, to produce a trace of debug events during bytecode interpretation. Fixes #12098. (Richard L Ford, review by Gabriel Scherer)

  • #12001: Fix book keeping for last finalisers during the minor cycle (KC Sivaramakrishnan and Enguerrand Decorne, report by Guillaume Bury and Vincent Laviron, review by Sadiq Jaffer and KC Sivaramakrishnan)

  • #11919: New runtime events counters for major heap stats and minor heap resizing. (Sadiq Jaffer, review by Gabriel Scherer and David Allsopp)

  • #11287, #11872, #11955: Clean up reserved header bits (once used for Spacetime profiling). (Nick Barnes, review by Gabriel Scherer and Damien Doligez)

  • #11750: Decouple major slice from minor GC. (KC Sivaramakrishnan, review by Sadiq Jaffer, Guillaume Munch-Maccagnoni and Damien Doligez)

  • #11796: protect lazy computation of code fragment digest by a mutex. This makes the thread sanitizer happier, and avoids duplicating the hashing work. (Gabriel Scherer, review by Xavier Leroy, report by Olivier Nicole)

  • #11137: new Unsafe_store_tag(val, new_tag) macro to stop using Tag_val(val) as lvalue. (Gabriel Scherer, review by Xavier Leroy, Guillaume Munch-Maccagnoni and Nicolás Ojeda Bär)

  • #11880: Restore the correct sigmask in systhreads. (Christiano Haesbaert, review by Guillaume Munch-Maccagnoni and Sébastien Hinderer)

  • #11881: Fix thread-unsafety of registration of operations for "custom" values. (Guillaume Munch-Maccagnoni, review by Gabriel Scherer and KC Sivaramakrishnan)

  • #11980: fix quadratic behavior in natdynlink by using a STW section for frame-descriptor updates. (Gabriel Scherer, review by Sadiq Jaffer, report by André Maroneze for Frama-C and Guillaume Melquiond for Coq)

  • #12121: unrooted implementations of caml_callback*_exn (Gabriel Scherer, review by KC Sivaramakrishnan and Xavier Leroy)

  • #3921, #12039, #12128: poll for signals in long-running polymorphic comparisons. (B. Szilvasy, Gabriel Scherer and Xavier Leroy, review by Stefan Muenzel, Guillaume Munch-Maccagnoni and Damien Doligez)

  • #12231: Support MinGW-w64 11.0 winpthreads library, where the macro to set up to get flexdll working changed (David Allsopp and Samuel Hym, light review by Xavier Leroy)

Language features:

  • (breaking change) #11694: Add short syntax for generative functor types () -> ... (Jeremy Yallop, review by Gabriel Scherer, Nicolás Ojeda Bär, Jacques Garrigue)

  • (breaking change) #11457: Remove old polymorphic variant syntax. With type t = [ `A | `B ], one could use the syntax #t in types, where it means the same thing as [< t], and in patterns, where it means (`A | `B). The use of #t in types for polymorphic variants was deprecated since 2001, and is now removed. The syntax remains available in patterns, or for objects -- when t is a class type. (Stefan Muenzel, review by Gabriel Scherer and Jacques Garrigue)

  • (breaking change) #11984: Add dedicated syntax for generative functor application. Previously, OCaml did not distinguish between F () and F (struct end), even though the latter looks applicative. Instead, the decision between generative and applicative functor application was made based on the type of F. With this patch, we now distinguish these two application forms; writing F (struct end) for a generative functor leads to new warning 73. (Frederic Bour and Richard Eisenberg, review by Florian Angeletti)

  • #9975, #11365: Make empty types (type t = |) immediate. (Antal Spector-Zabusky, review by Gabriel Scherer)

Type system:

  • (breaking change) #6941, #11187, #12483: prohibit using classes through recursive modules inheriting or including a class belonging to a mutually-recursive module would previous behave incorrectly, and now results in a clean error. (Leo White, review by Gabriel Scherer and Florian Angeletti)

  • (breaking change) #12189, #12211: anonymous row variables in explicitly polymorphic type annotation, e.g. 'a. [< X of 'a ] -> 'a, are now implicitly universally quantified (in other words, the example above is now read as 'a 'r. ([< X of 'a ] as 'r) -> 'a). (Florian Angeletti and Gabriel Scherer, review by Jacques Garrigue)

Code generation and optimizations:

  • #11967: Remove traces of Obj.truncate, which allows some mutable loads to become immutable. (Nick Barnes, review by Vincent Laviron and KC Sivaramakrishnan)

  • #9945, #10883: Turn boolean-result float comparisons into primitive operations Uses the architecture's elementary operations for float comparisons, when available, rather than branching and then setting the return value. (Stefan Muenzel, review by Stephen Dolan, Alain Frisch and Vincent Laviron)

  • #8998, #11321, #11430: change mangling of OCaml long identifiers from camlModule__name_NNN to camlModule.name_NNN. The previous mangling schema, using __, was ambiguous. (Xavier Leroy, report by sliquister and Michael Bacarella, review by Gabriel Scherer)

  • #10834: The -safer-matching option disables type-based optimizations of pattern-matching compilation. This allows to produce a match failure if a pattern-matching was wrongly assumed to be exhaustive. Since the exhaustiveness check for GADTs has had bugs in the past, it may be useful if you need extra security with GADTs. (Jacques Garrigue, review by Gabriel Scherer)

  • #11102: Speed up register allocation by permanently spilling registers (Stephen Dolan, review by Xavier Leroy)

  • #11383: Restrict the local function optimisation to forbid moving code inside a sub-function (Vincent Laviron, review by Gabriel Scherer)

  • #11686: Better spilling heuristic for the Linear Scan allocator for more efficient stack usage. (Nicolás Ojeda Bär, Gabriel Scherer, Alain Frisch, review by Gabriel Scherer, Alain Frisch and Nathanaëlle Courant)

  • #11904: Remove arm, i386 native-code backends that were already disabled at configuration time. (Nicolás Ojeda Bär, review by Stephen Dolan, Anil Madhavapeddy, and Xavier Leroy)

  • #11134: Optimise 'include struct' in more cases (Stephen Dolan, review by Leo White and Vincent Laviron)

Other libraries:

  • #11374: Remove pointer cast to a type with stricter alignment requirements in Windows implementation of Unix.gettimeofday. Windows implementations of caml_unix_map_file, caml_unix_lseek and caml_unix_lseek_64 now release the runtime lock. Windows implementation of caml_unix_lockf modernised and simplified. Where possible, 64 bit integers are used instead of LARGE_INTEGER structs. (David Allsopp, review by Jonah Beckford and Xavier Leroy)

  • #11475: Make Unix terminal interface bindings domain-safe (Olivier Nicole and Xavier Leroy, review by Xavier Leroy)

  • #11775: Unix.write on a non-blocking socket under Windows will return normally if the write blocks after some data has already been written (as otherwise there is no way of knowing how much data has been written before blocking). The same behaviour was already present under Unix. (Nicolás Ojeda Bär, review by David Allsopp)

  • (breaking change) #11991: Unix on Windows: map ERROR_TOO_MANY_LINKS to EMLINK. (Nicolás Ojeda Bär)
  • #12067: Document Windows specific meanings of Unix.process_status type (Samuel Hym, review by David Allsopp)

  • #12072: Document and test that Sys.rename works over directories too (Jan Midtgaard, review by Anil Madhavapeddy and Xavier Leroy)

Tools:

  • #11889, #11978: ocamldoc: handle injectivity annotations and wildcards in type parameters. (Florian Angeletti, report by Wiktor Kuchta, review by Jules Aguillon)

  • #11787: Fix GDB scripts to work with OCaml 5's heap layout. (Nick Barnes)

  • #11772: fix ocamlyacc's handling of raw string literals (Demi Marie Obenour)

  • #9290: Add a directive to switch off debugging in toplevel. This allows to see optimized bytecode with -dlambda. (Jacques Garrigue, review by Gabriel Scherer)

  • #11166: ocamllex: the union of two character sets "cset1 | cset2" can now be used in any context where a character set is expected. (Nicolás Ojeda Bär, Martin Jambon, review by Sébastien Hinderer)

  • #11718: ocamlyacc: OCaml-style comments are now supported, in addition to the C-style comments already supported. The syntax is the same as that used in OCaml code. (Demi Marie Obenour, review by Damien Doligez)

  • #11728: ocamlyacc: generate line directives for %type declarations (Demi Marie Obenour, review by Damien Doligez)

  • #11773: ocamlyacc: Do not allow quoted literals (such as 'a' or "bc") in a token name or %type declaration. Previously such literals were accepted by ocamlyacc, but produced malformed OCaml that was rejected by the compiler. (Demi Marie Obenour, review by Gabriel Scherer)

  • #11774: ocamlyacc: fail if there is an I/O error (Demi Marie Obenour, review by Gabriel Scherer)

  • #11973: Add support for postfixed mingw host triplets (Romain Beauxis)

  • #12165: ocamldoc, use standard doctype to avoid quirk mode. (Florian Angeletti, review by Gabriel Scherer)

Manual and documentation:

  • #11476: Add examples in documentation of Hashtbl, Queue, Atomic, Format (Simon Cruanes, review by Yotam Barnoy, Gabriel Scherer, Daniel Bünzli, Ulugbek Abdullaev, and Nicolás Ojeda Bär)

  • #11883, #11884: Update documentation for In_channel and Out_channel with examples and sections to group related functions. (Kiran Gopinathan, review by Daniel Bünzli and Xavier Leroy)

  • #12095, #12097: Put the sample code of the user's manual and reference documentation of the standard library under the CC0 1.0 Universal (CC0 1.0) Public Domain Dedication license.

  • #11892: Document the semantic differences of Unix.exec* between Unix and Windows. (Boris Yakobowski, review by Daniel Bünzli, Gabriel Scherer and Nicolás Ojeda Bär)

  • #9430, #11291: Document the general desugaring rules for binding operators. (Gabriel Scherer, review by Nicolás Ojeda Bär)

  • #11481: Fix the type of Unix.umask to Unix.file_perm -> Unix.file_perm (Favonia, review by Sébastien Hinderer)

  • #11514: Document ocamltest builtin variables and actions (Olivier Nicole, review by Sébastien Hinderer)

  • #11676: Fix missing since annotation in the Sys and Format modules (Github user Bukolab99, review by Florian Angeletti)

  • #12028: Update format documentation to make it clearer that pp_print_newline flushes its newline (Florian Angeletti, review by Gabriel Scherer)

  • #12201: in the tutorial on modules, replace priority queue example by a simpler example based on FIFO queues. (Xavier Leroy, review by Anil Madhavapeddy and Nicolás Ojeda Bär).

  • #12352: Fix a typo in the documentation of Arg.write_arg (Christophe Raffalli, review by Florian Angeletti)

  • #7179, #11894: correct the description of CAMLreturn and CAMLreturn0 in the Interfacing C page and memory.h file. (Dong An, review by Guillaume Munch-Maccagnoni and Olivier Nicole )

Compiler user-interface and warnings:

  • #10647: Show hints for the "undefined global" error in the toplevel (Wiktor Kuchta, review by Gabriel Scherer)

  • #12116: Don't suggest to insert a semicolon when the type is not unit (Jules Aguillon, review by Florian Angeletti)

  • #11679: Improve the error message about too many arguments to a function (Jules Aguillon, review by Gabriel Scherer and Florian Angeletti)

  • #10009: Improve the error reported by mismatched struct/sig and =/: in module and module type bindings. (Jules Aguillon, review by Gabriel Scherer)

  • #11530: Include kinds in kind mismatch error message. "Error: This variant or record definition does not match that of type M.t The original is abstract, but this is a record". (Leonhard Markert, review by Gabriel Scherer and Florian Angeletti)

  • #11646: Add colors to error message hints. (Christiana Anthony, review by Florian Angeletti)

  • #11235, #11864: usage warnings for constructors and fields can now be disabled on field-by-field or constructor-by-constructor basis (Florian Angeletti, review by Gabriel Scherer)

  • #11888: Improve the error message when type variables cannot be deduced from the type parameters: Before: "Error: In this definition, a type variable cannot be deduced from the type parameters." After: "Error: In the GADT constructor T : 'a -> 'a s t the type variable 'a cannot be deduced from the type parameters." (Stefan Muenzel, review by Florian Angeletti and Gabriel Scherer)

  • #10818: Preserve integer literal formatting in type hint. (Leonhard Markert, review by Gabriel Scherer and Florian Angeletti)

  • #11338: Turn some partial application warnings into hints. (Leo White, review by Stephen Dolan)

  • #10931: Improve warning 14 (illegal backslash) with a better explanation of the causes and how to fix it. (David Allsopp, Florian Angeletti, Lucas De Angelis, Gabriel Scherer, review by Nicolás Ojeda Bär, Florian Angeletti, David Allsopp and Gabriel Scherer)

  • #10911: Improve the location reported by parenthesized assert expressions (Fabian Hemmer, review by Gabriel Scherer)

  • #1391, #7645, #3922: Add an early error when compiling different modules with mismatching -for-pack (Pierre Chambart and Vincent Laviron, review by Mark Shinwell)

  • #11297: Report "unclosed" error when "done" is missing in a "do .. done" construct. (Nicolás Ojeda Bär, review by Gabriel Scherer)

  • #11635, #5461, #10564: turn warning 31 (Module_linked_twice) into a hard error for ocamlc — this was already an error with ocamlopt. (Hugo Heuzard, review by Valentin Gatien-Baron and Gabriel Scherer)

  • #11653: Add the -no-absname option to ocamlc, ocamlopt and ocamldep. (Abiola Abdulsalam, review by Sébastien Hinderer and Florian Angeletti)

  • #11696: Add the -no-g option to ocamlc and ocamlopt. (Abiola Abdulsalam, review by Sébastien Hinderer, Nicolás Ojeda Bär and Florian Angeletti)

  • #11722: clearer error messages on non-well-founded type definitions (Gabriel Scherer, review by Jacques Garrigue)

  • #11819: make the native_compiler and native_dynlink configuration variables available through ocamlc -config. (Sébastien Hinderer, review by Gabriel Scherer and David Allsopp)

  • #8602, #11863: Add -stop-after lambda flag option (Douglas Smith and Dmitrii Kosarev, review by Gabriel Scherer)

  • #11910: Simplify naming convention for shadowed or ephemeral identifiers in error messages (eg: Illegal shadowing of included type t/2 by t) (Florian Angeletti, review by Jules Aguillon)

  • #12024: insert a blank line between separate compiler messages (Gabriel Scherer, review by Florian Angeletti, report by David Wong)

  • #12088, #9265, #11949: ocamldebug: fix confusing repeating behavior on blank lines within source scripts (Damien Doligez, review by Gabriel Scherer, report by Gaëtan Gilbert)

  • #12107: use aliases to mark weak row variables: _[< ... ], < _..>, _#ct are now rendered as [< ...] as '_weak1, < .. > as '_weak1, and #ct as '_weak1. (Florian Angeletti, suggestion by Stefan Muenzel, review by Gabriel Scherer)

  • #12051: Improve the error messages when type variables cannot be generalized (Stefan Muenzel, review by Florian Angeletti)

  • (breaking change) #12094: Trigger warning 5 (ignored-partial-application) when the scrutinee of a pattern matching is of arrow type and all cases match wildcard or exception patterns. (Nicolás Ojeda Bär, review by Gabriel Scherer)

Internal/compiler-libs changes:

  • #11018, #11869: Clean up Types.Variance, adding a description of the lattice used, and defining explicitly composition. (Jacques Garrigue, review by Gabriel Scherer and Jeremy Yallop)

  • #11536: Introduce wrapper functions for level management ([Ctype.with_level], etc) and for type variable scoping ([Typetexp.with_local_type_variable_scope]). The older API ([Ctype.(begin_def,end_def)], [Typetexp.(narrow,widen)], etc.) is now removed. (Jacques Garrigue and Takafumi Saikawa, review by Gabriel Scherer)

  • #11601, #11612, #11628, #11613, #11623, #12120 : Clean up some global state handling in emitcode, bytepackager, bytegen, bytesections, spill. (Hugo Heuzard, Stefan Muenzel, review by Vincent Laviron, Gabriel Scherer and Nathanaëlle Courant)

  • #12119, #12188, #12191: mirror type constraints on value binding in the parsetree: the constraint typ in let pat : typ = exp is now directly stored in the value binding node in the parsetree. (Florian Angeletti, review by Richard Eisenberg)

  • #11912: Refactoring handling of scoped type variables (Richard Eisenberg, review by Gabriel Scherer and Florian Angeletti)

  • #11691, #11706: use asm instead of asm for strict ISO C conformance (Xavier Leroy, report by Gregg Reynolds , review by Sadiq Jaffer)

  • #11764: add prototypes to old-style C function definitions and declarations (Antonin Décimo, review by Xavier Leroy)

  • #11693: Remove use of C99 Variable Length Arrays (VLAs) in the runtime. (David Allsopp, review by Xavier Leroy, Guillaume Munch-Maccagnoni, Stefan Muenzel and Gabriel Scherer)

  • #12138: Generalise interface for BUILD_PATH_PREFIX_MAP mapping. Absolute paths are now rewritten too. (Richard L Ford, suggestions and review by Gabriel Scherer)

  • #10512: explain the compilation strategy for switches on constructors (Gabriel Scherer, review by Vincent Laviron)

  • #11990: Improve comments and macros around frame descriptors. (Nick Barnes, review by Gabriel Scherer)

  • #11847, #11849, #11851, #11898: small refactorings in the type checker (Gabriel Scherer, review by Nicolás Ojeda Bär)

  • #11027: Separate typing counter-examples from type_pat into retype_pat; type_pat is no longer in CPS. (Jacques Garrigue and Takafumi Saikawa, review by Gabriel Scherer)

  • #11286, #11515: disambiguate identifiers by using how recently they have been bound in the current environment (Florian Angeletti, review by Gabriel Scherer)

  • #11364: Allow make -C testsuite promote to take TEST and LIST variables (Antal Spector-Zabusky, review by Gabriel Scherer and David Allsopp)

  • #11446: document switch compilation (lambda/switch.ml) (Gabriel Scherer, review by Luc Maranget and Vincent Laviron)

  • #11568: Encode inline record types in Path.t (Leo White and Hyunggyu Jang, review by Gabriel Scherer)

  • #11569: Remove hash type encoding (Hyunggyu Jang, review by Gabriel Scherer and Florian Angeletti)

  • #11627: use return values instead of globals for linear scan intervals (Stefan Muenzel, review by Nicolás Ojeda Bär)

  • #11634: Dll.open_dll now properly handles opening for execution while already opened for checking (Hugo Heuzard, review by Nicolás Ojeda Bär)

  • (breaking change) #11745, #12358: Debugger and toplevels: embed printer types rather than reading their representations from topdirs.cmi at runtime. This change also removes the ocamlmktop initialization module introduced in #11382 which was no longer useful. This change breaks toplevel scripts relying on the visibility of Topdirs in the initial toplevel environment without loading topfind. Since the opam default .ocamlinit file loads topfind, it is expected that only scripts run with ocaml -noinit are affected. For those scripts, accessing Topdirs now requires the compiler-libs directory to be added to the toplevel search path with
      #directory "+compiler-libs";;
    
    as was already the case for the other modules in the toplevel interface library. (Sébastien Hinderer, review by Florian Angeletti, Nicolás Ojeda Bär and Gabriel Scherer)
  • #11615: remove global variables form asmcomp/linearize.ml (Stefan Muenzel, review by Nicolás Ojeda Bär

  • #10856: Add location, attribute(s) visitors to Tast_mapper/Tast_iterator (Yan Dong, review by Nicolás Ojeda Bär and Gabriel Scherer)

  • #11763, #11759, #11861: Enable stricter C compilation warnings, use strict prototypes on primitives. (Antonin Décimo, review by Xavier Leroy, David Allsopp and Sébastien Hinderer)

  • #11933: Use the correct machtype when reading the code pointer from closures (Nathanaëlle Courant, review by Gabriel Scherer and Vincent Laviron)

  • #11972: refactor runtime/frame_descriptors.c in preparation for quadratic-time fix (Gabriel Scherer, review by Enguerrand Decorne)

  • #11997: translate structured constants into their Obj.t representation at compile time rather than link time. Changes the way dumpobj prints these constants because their representation becomes untyped. (Sébastien Hinderer, review by Xavier Leroy, Nicolás Ojeda Bär and Hugo Heuzard)

  • #12011: remove Ctype.reified_var_counter (Takafumi Saikawa and Jacques Garrigue, review by Gabriel Scherer)

  • #12012: move calls to Typetexp.TyVarEnv.reset inside with_local_level etc. (Jacques Garrigue and Takafumi Saikawa, review by Gabriel Scherer)

  • #12034: a logarithmic algorithm to find the next free variable (Gabriel Scherer, review by Stefan Muenzel)

  • #12092: remove Lev_module_definition from lambda (Nick Roberts, review by Gabriel Scherer)

  • #12117: Remove arity-interrupting elaboration of module unpacks (Nick Roberts, review by Richard Eisenberg and Jacques Garrigue)

  • #12118: stop storing names of predefined exceptions in the cu_required_globals field of compilation unit descriptors. (Sébastien Hinderer, review by Vincent Laviron)

  • #12125: Add Misc.print_see_manual and modify [@manual_ref] to accept lists for simpler printing of manual references (Stefan Muenzel, review by Florian Angeletti)

  • #12509: Use strict prototypes on primitives when generating a standalone bytecode executable (ocamlc -custom). (Antonin Décimo, review by Xavier Leroy)

Build system:

  • #11844: Reduce verbosity of make logs by printing program invocations in shorthand (eg OCAMLC foo.cmo). Setting V=1 recovers the old style (with full command-lines). (Xavier Leroy, Nicolás Ojeda Bär, review by Sébastien Hinderer)

  • #11590: Allow installing to a destination path containing spaces. (Élie Brami, review by Sébastien Hinderer and David Allsopp)

  • #11243, #11248, #11268, #11420, #11675: merge the sub-makefiles into the root Makefile. (Sébastien Hinderer, review by David Allsopp and Florian Angeletti)

  • #11828: Compile otherlibs/ C stubs in two version for native and bytecode (Olivier Nicole, review by Sébastien Hinderer and Xavier Leroy)

  • #12265: Stop adding -lexecinfo to cclibs (leftover debugging code from the multicore project). Harden the feature probe for -lm in configure so -lm is only added if strictly necessary. configure.ac now correctly propagates library flags for the Windows ports, allowing Windows OCaml to be configured with ZSTD support. (David Allsopp, review by Sébastien Hinderer)

  • #12372: Pass option -no-execute-only to the linker for OpenBSD >= 7.3 so that code sections remain readable, as needed for closure marshaling. (Xavier Leroy and Anil Madhavapeddy, review by Anil Madhavapeddy and Sébastien Hinderer)

Bug fixes:

  • #12062: fix runtime events consumer: when events are dropped they shouldn't be parsed. (Lucas Pluvinage)

  • #12132: Fix overcounting of minor collections in GC stats. (Damien Doligez, review by Gabriel Scherer)

  • #12017: Re-register finaliser only after calling user alarm in Gc.create_alarm (Fabrice Buoro, report by Sam Goldman, review by Guillaume Munch-Maccagnoni)

  • #11887, #11893: Code duplication in pattern-matching compilation (Vincent Laviron, report par Greta Yorsh, review by Luc Maranget and Gabriel Scherer)

  • #10664, #11600: Unsoundness in the typing of polymorphic methods involving polymorphic variants (Jacques Garrigue, report by Mike Shulman, review by Gabriel Scherer)

  • #11302, #11412: ocamlc and ocamlopt should not remove generated files when they are not regular files. (Xavier Leroy, report by Thierry Martinez, review by Anil Madhavapeddy, Nicolás Ojeda Bär, David Allsopp)

  • #10348, #10560, #11561: Expand GADT equations lazily during unification to avoid ambiguity (Jacques Garrigue, review by Leo White)

  • #11436: Fix wrong stack backtrace for out-of-bound exceptions raised by leaf functions. (Tom Kelly and Xavier Leroy, review by Mark Shinwell)

  • #11450, #12018: Fix erroneous functor error messages that were too eager to cast struct end functor arguments as unit modules in F(struct end). (Florian Angetti, review by Gabriel Scherer)

  • #11643: Add missing test declaration to float_compare test, so that it will run. (Stefan Muenzel, review by David Allsopp)

  • #11630: Use correct location when reporting record labels with non-existent paths. (Nicolás Ojeda Bär, report by Jason Gross, review by Gabriel Scherer)

  • #11727: Ensure push_defaults can push past module patterns, fixing an currying optimisation accidentally disabled by #10340. (Stephen Dolan, review by Gabriel Scherer)

  • #11771: Use a more relaxed mode for unification in Ctype.subst (Leo White, review by Jacques Garrigue and Gabriel Scherer)

  • #11803, #11808: on x86, the destination of an integer comparison must be a register, it cannot be a stack slot. (Vincent Laviron, review by Xavier Leroy, report by Emilio Jesús Gallego Arias)

  • #11809: Protect Parmatch.pats_of_type from missing cmis (Jacques Garrigue, review by Stephen Dolan and Gabriel Scherer)

  • #11824: Fix a crash when calling ocamlrun -b (Florian Angeletti, review by Sébastien Hinderer)

  • #11815: Marshalling continuations raises invalid argument exception. (Jérôme Vouillon, review by Nicolás Ojeda Bär, Stephen Dolan and Hugo Heuzard)

  • #11846: Mark rbx as destroyed at C call for Win64 (mingw-w64 and Cygwin64). Reserve the shadow store for the ABI in the c_stack_link struct instead of explictly when calling C functions. This simultaneously reduces the number of stack pointer manipulations and also fixes a bug when calling noalloc functions where the shadow store was not being reserved. (David Allsopp, report by Vesa Karvonen, review by Xavier Leroy and KC Sivaramakrishnan)

  • #11850: When stopping before the emit phase (using -stop-after), an empty temporary assembly file is no longer left in the file system. (Nicolás Ojeda Bär, review by Gabriel Scherer and Xavier Leroy)

  • #11866: Fix the result of caml_read_directory() on non-existent paths. (Andrei Paskevich and Charlène Gros, review by David Allsopp and Nicolás Ojeda Bär)

  • #11879: Bugfix for Ctype.nondep_type (Stephen Dolan, review by Gabriel Scherer)

  • #12004: Don't ignore function attributes on lambdas with locally abstract types. (Chris Casinghino, review by Gabriel Scherer)

  • #12037: Fix some data races by using volatile when necessary (Fabrice Buoro and Olivier Nicole, review by Guillaume Munch-Maccagnoni, Gabriel Scherer and Luc Maranget)

  • #12046: Flush stderr when tracing the parser (Hugo Heuzard, review by David Allsopp and Nicolás Ojeda Bär)

  • #12061, #12063: don't add inconsistent equalities when computing high-level error messages for functor applications and inclusions. (Florian Angeletti, review by Gabriel Scherer)

  • #12075: auto-detect whether ar support @FILE arguments at configure-time to avoid using this feature with toolchains that do not support it (eg FreeBSD/Darwin). (Nicolás Ojeda Bär, review by Xavier Leroy, David Allsop, Javier Chávarri, Anil Madhavapeddy)

  • #12103, 12104: fix a concurrency memory-safety bug in Buffer (Gabriel Scherer, review by Florian Angeletti, report by Samuel Hym)

  • #12112: Fix caml_callback{2,3}_exn when used with effect handlers. (Lucas Pluvinage, review by Gabriel Scherer, David Allsopp and Xavier Leroy)

  • #12134: Use ghost location for nodes created when handling defaults in optional arguments. (Paul-Elliot Anglès d'Auriac, review by Gabriel Scherer)

  • #12153: Fix segfault in bytecode programs involving recursive value definitions of values of size 0 (Vincent Laviron, Xavier Leroy, Gabriel Scherer, review by Xavier Leroy, report by Nick Roberts)

  • #12162: Fix miscompilation on amd64 backends involving integer overflows (Vincent Laviron and Greta Yorsh, review by Stefan Muenzel)

  • #12170: fix pthread_geaffinity_np configure check for android (David Allsopp, review by Sébastien Hinderer)

  • #12178: Fix runtime events consumer poll function returning an invalid value instead of an OCaml integer value. (Lucas Pluvinage)

  • #12252: Fix shared library build error on RISC-V. (Edwin Török, review by Nicolás Ojeda Bär and Xavier Leroy)

  • #12255, #12256: Handle large signal numbers correctly (Nick Barnes, review by David Allsopp).

  • #12277: ARM64, fix a potential assembler error for very large functions by emitting stack reallocation code before the body of the function. (Xavier Leroy, review by KC Sivaramakrishnan)

  • #12253, #12342: Fix infinite loop in signal handling. (Guillaume Munch-Maccagnoni, report by Thomas Leonard, review by KC Sivaramakrishnan and Sadiq Jaffer)

  • #12445: missing GC root registrations in runtime/io.c (Gabriel Scherer, review by Xavier Leroy and Jeremy Yallop)

  • #12481, #12505: Fix incorrect initialization of array expressions [|e1;...;eN|] when N is large enough to require major heap allocation. (Xavier Leroy, report by Andrey Popp, analysis by KC Sivaramakrishnan and Vincent Laviron, review by Gabriel Scherer)

  • #11150, #11207, #11936: Avoid recomputation in Typedecl.check_wellfounded (Jacques Garrigue, report by Boris Yakobowski, review by Gabriel Scherer)

  • #11186, #11188: Fix composition of coercions with aliases (Vincent Laviron, report and review by Leo White)

  • #12486: Fix delivery of unhandled effect exceptions on s390x (Miod Vallat, report by Jan Midtgaard, review by Vincent Laviron and Xavier Leroy)

Since last week, there were two significant bugs fixed in the OCaml 5.1.0 runtime (one overflow bug and a stack corruption bug in the s390x port). Since those bug fixes are as small as they are subtle, they were deemed worthy of a release of a third release candidate for OCaml 5.1.0.

If there are no more surprises this week, the release of OCaml 5.1.0 shall happen next week.

If you find any bugs, please report them on OCaml's issue tracker.

The full changelog for OCaml 5.1.0 is available on GitHub

A short summary of the two fixed bugs in this release candidate is also available below.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1 and later:

opam update
opam switch create 5.1.0~rc3

The source code for the release candidate is also directly available on:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.1.0~rc3+options <option_list>

where <option_list> is a comma-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.1.0~rc3+flambda+nffa ocaml-variants.5.1.0~rc3+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with opam search ocaml-option.

See full changelog

Last Second Bug Fixes

  • #11284, +#12525: Use compression of entries scheme when pruning mark stack. Can decrease memory usage for some workloads, otherwise should be unobservable. (Tom Kelly, review by Sabine Schmaltz, Sadiq Jaffer, and Damien Doligez)

  • #12486: Fix delivery of unhandled effect exceptions on s390x (Miod Vallat, report by Jan Midtgaard, review by Vincent Laviron and Xavier Leroy)

In the last two weeks, two significant bugs have been discovered in the release candidate for OCaml 5.1.0 (one affecting the type system, another in the runtime).

Those bugs are now fixed and we are publishing a second release candidate to check that everything is in order before the release in the upcoming week.

If you find any bugs, please report them on OCaml's issue tracker.

The full changelog for OCaml 5.1.0 is available on GitHub. A short summary of the two fixed bugs in this release candidate is also available below.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1 and later:

opam update
opam switch create 5.1.0~rc2

The source code for the release candidate is also directly available on:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.1.0~rc2+options <option_list>

where <option_list> is a comma-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.1.0~rc2+flambda+nffa ocaml-variants.5.1.0~rc2+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with opam search ocaml-option.

See full changelog

Last Minute Bug Fixes

Type System:

  • (breaking change) #6941, #11187, +#12483: prohibit using classes through recursive modules inheriting or including a class belonging to a mutually-recursive module would previous behave incorrectly, and now results in a clean error. (Leo White, review by Gabriel Scherer and Florian Angeletti)

Runtime

  • #12481, #12505: Fix incorrect initialization of array expressions [|e1;...;eN|] when N is large enough to require major heap allocation. (Xavier Leroy, report by Andrey Popp, analysis by KC Sivaramakrishnan and Vincent Laviron, review by Gabriel Scherer)

The release of OCaml 5.1.0 is imminent. As a final step, we are publishing a release candidate to check that everything is in order before the release in the upcoming week(s).

If you find any bugs, please report them on OCaml's issue tracker.

Compared to the beta release, this release contains one safe runtime fix and two configuration tweaks.

The full change log for OCaml 5.1.0 is available on GitHub A short summary of the changes since the beta release is also available below.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1 and later:

opam update
opam switch create 5.1.0~rc1

The source code for the release candidate is also directly available on:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.1.0~rc1+options <option_list>

where <option_list> is a comma-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.1.0~rc1+flambda+nffa ocaml-variants.5.1.0~rc1+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with opam search ocaml-option.

See full changelog

Changes Since the Beta

Bug Fix

  • #12445: missing GC root registrations in runtime/io.c (Gabriel Scherer, review by Xavier Leroy and Jeremy Yallop)

Configuration Fix (openBSD)

  • #12372: Pass option -no-execute-only to the linker for OpenBSD >= 7.3 so that code sections remain readable, as needed for closure marshaling. (Xavier Leroy and Anil Madhavapeddy, review by Anil Madhavapeddy and Sébastien Hinderer)

Tool Fix (ocamlmktop)

  • #11745, #12358: Debugger and toplevels: embed printer types rather than reading their representations from topdirs.cmi at runtime. This change also removes the ocamlmktop initialisation module introduced in #11382 which was no longer useful. This change breaks toplevel scripts relying on the visibility of Topdirs in the initial toplevel environment without loading topfind. Since the opam default .ocamlinit file loads topfind, it is expected that only scripts run with ocaml -noinit are affected. For those scripts, accessing Topdirs now requires the compiler-libs directory to be added to the toplevel search path with
      #directory "+compiler-libs";;
    

as was already the case for the other modules in the toplevel interface library. (Sébastien Hinderer, review by Florian Angeletti, Nicolás Ojeda Bär, and Gabriel Scherer)

Documentation Changes

  • #12201: in the tutorial on modules, replace priority queue example by a simpler example based on FIFO queues. (Xavier Leroy, review by Anil Madhavapeddy and Nicolás Ojeda Bär).

  • #12352: Fix a typo in the documentation of Arg.write_arg (Christophe Raffalli, review by Florian Angeletti)

After two alpha releases, the release of OCaml 5.1.0 is drawing near. We have thus released a first beta version of OCaml 5.1.0 to help you update your softwares and libraries ahead of the release (see below for the installation instructions). Compared to the last alpha release, this beta contains two subtle internal runtime fixes and one Windows fix. Overall, the opam ecosystem looks in a good shape for the first beta release.

If you find any bugs, please report them on OCaml's issue tracker.

Nearly all core development tools support OCaml 5.1.0, and you can follow the last remaining wrinkles on the opam readiness for 5.1.0 meta-issue.

Currently, the release is planned for the end of July or the beginning of August.

If you are interested in full list of features and bug fixes of the new OCaml version, the updated change log for OCaml 5.1.0 is available on GitHub.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1:

opam update
opam switch create 5.1.0~beta1

The source code for the alpha is also available at these addresses:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.1.0~beta1+options <option_list>

where option_list is a space-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.1.0~beta1+flambda+nffa ocaml-variants.5.1.0~beta1+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with opam search ocaml-option.

See full changelog

Runtime System Bugfix

  • #12037: Fix some data races by using volatile when necessary (Fabrice Buoro and Olivier Nicole, review by Guillaume Munch-Maccagnoni, Gabriel Scherer and Luc Maranget)

  • #12253, #12342: Fix infinite loop in signal handling. (Guillaume Munch-Maccagnoni, report by Thomas Leonard, review by KC Sivaramakrishnan and Sadiq Jaffer)

Windows Bugfix

  • #12184, #12320: Sys.rename Windows fixes on directory corner cases. (Jan Midtgaard, review by Anil Madhavapeddy)

With the progress of the ongoing stabilisation effort for OCaml 5.1.0, I am happy to announce a second alpha release for OCaml 5.1.0.

This second alpha release contains many noteworthy fixes:

  • a long-awaited GC fix
  • a Windows ABI fix

as announced in the first alpha but also

  • a compiler-libs (parsetree) fix
  • a type system compatibility enhancement change
  • a restored backed for s390x/IBM Z

The full list of changes since the first alpha is available below.

Once most major OCaml tools are updated to the last compiler-libs changes, we will switch to beta releases. Hopefully, this will happen in the upcoming weeks. The progress on stabilising the ecosystem is tracked on the opam readiness for 5.1.0 meta-issue.

Currently, the release is still planned for around July.

If you find any bugs, please report them on OCaml's issue tracker.

If you are interested in the ongoing list of new features and bug fixes, the updated change log for OCaml 5.1.0 is available on GitHub.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1:

opam update
opam switch create 5.1.0~alpha2

The source code for the alpha is also available at these addresses:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.1.0~alpha2+options <option_list>

where option_list is a space-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.1.0~alpha2+flambda+nffa ocaml-variants.5.1.0~alpha2+options ocaml-option-flambda ocaml-option-no-flat-float-array

All available options can be listed with opam search ocaml-option.

See full changelog

Runtime System

  • #11589, #11903: Modify the GC pacing code to make sure the GC keeps up with allocations in the presence of idle domains. (Damien Doligez and Stephen Dolan, report by Florian Angeletti, review by KC Sivaramakrishnan and Sadiq Jaffer)
  • (breaking change) #11865, #11868, #11876: Clarify that the operations of a custom block must never access the OCaml runtime. The previous documentation only mentioned the main illicit usages. In particular, since OCaml 5.0, it is no longer safe to call caml_remove_global_root or caml_remove_generational_global_root from within the C finalizer of a custom block, or within the finalization function passed to caml_alloc_final. As a workaround, such a finalization operation can be registered with Gc.finalize instead, which guarantees to run the finalizer at a safe point. (Report by Timothy Bourke, discussion by Yotam Barnoy, Timothy Bourke, Sadiq Jaffer, Xavier Leroy, Guillaume Munch-Maccagnoni, and Gabriel Scherer)
  • #11827, +#12249: Restore prefetching for GC marking (Fabrice Buoro and Stephen Dolan, review by Gabriel Scherer and Sadiq Jaffer)
  • #12131: Simplify implementation of weak hash sets, fixing a performance regression. (Nick Barnes, review by François Bobot, Alain Frisch and Damien Doligez).

  • #12231: Support MinGW-w64 11.0 winpthreads library, where the macro to set up to get flexdll working changed (David Allsopp and Samuel Hym, light review by Xavier Leroy)

Type System

  • (breaking change) #12189, #12211: anonymous row variables in explicitly polymorphic type annotation, e.g. 'a. [< X of 'a ] -> 'a, are now implicitly universally quantified (in other words, the example above is now read as 'a 'r. ([< X of 'a ] as 'r) -> 'a). (Florian Angeletti and Gabriel Scherer, review by Jacques Garrigue)

Code Generation And Optimizations

  • #11712, #12258, #12261: s390x / IBM Z multicore support: OCaml & C stack separation; dynamic stack size checks; fiber and effects support. (Aleksei Nikiforov, with help from Vincent Laviron and Xavier Leroy, additional suggestions by Luc Maranget, review by the same and KC Sivaramakrishnan)

Internal/compiler-libs Changes

  • #12119, +#12188, +#12191: mirror type constraints on value binding in the parsetree: the constraint typ in let pat : typ = exp is now directly stored in the value binding node in the parsetree. (Florian Angeletti, review by Richard Eisenberg)

Bug Fixes

  • #11846: Mark rbx as destroyed at C call for Win64 (mingw-w64 and Cygwin64). Reserve the shadow store for the ABI in the c_stack_link struct instead of explictly when calling C functions. This simultaneously reduces the number of stack pointer manipulations and also fixes a bug when calling noalloc functions where the shadow store was not being reserved. (David Allsopp, report by Vesa Karvonen, review by Xavier Leroy and KC Sivaramakrishnan)

  • #12170: fix pthread_geaffinity_np configure check for android (David Allsopp, review by Sébastien Hinderer)

  • #12252: Fix shared library build error on RISC-V. (Edwin Török, review by Nicolás Ojeda Bär and Xavier Leroy)

  • #12255, #12256: Handle large signal numbers correctly (Nick Barnes, review by David Allsopp).

  • #12277: ARM64, fix a potential assembler error for very large functions by emitting stack reallocation code before the body of the function. (Xavier Leroy, review by KC Sivaramakrishnan)

Four months after the release of OCaml 5.0.0, the set of new features for the future version 5.1.0 of OCaml has been frozen. We are thus happy to announce the first alpha release for OCaml 5.1.0.

This alpha version is here to help fellow hackers join us early in our bug hunting and opam ecosystem fixing fun (see below for the installation instructions). The progresses on stabilising the ecosystem are tracked on the opam readiness for 5.1.0 meta-issue.

If you find any bugs, please report them on OCaml's issue tracker.

Note that this early alpha version is missing two important fixes for the garbage collector and Windows support. Those fixes will be available before the beta. The full release is expected in July.

If you are interested in the ongoing list of new features and bug fixes, the updated change log for OCaml 5.1.0 is available on GitHub.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1:

opam update
opam switch create 5.1.0~alpha1

For previous version of opam, the switch creation command line is slightly more verbose:

opam update
opam switch create 5.1.0~alpha1 --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

The source code for the alpha is also available at these addresses:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.1.0~alpha1+options <option_list>

where option_list is a space separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.1.0~alpha1+flambda+nffa ocaml-variants.5.1.0~alpha1+options ocaml-option-flambda ocaml-option-no-flat-float-array

The command line above is slightly more complicated for opam version anterior to 2.1:

opam update
opam switch create <switch_name> --packages=ocaml-variants.5.1.0~alpha1+options,<option_list> --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

In both cases, all available options can be listed with opam search ocaml-option.

We have the pleasure of celebrating the birthday of Oronce Finé by announcing the release of OCaml version 4.14.1.

This release is a collection of safe bug fixes, cherry-picked from the OCaml 5.0.0 release. If you were using OCaml 4.14.0 and cannot yet upgrade to OCaml 5, this release is for you.

The 4.14 branch is expected to receive more backported fixes during the maturation of OCaml 5. Thus don't hesitate to report any bugs on the OCaml issue tracker.

See the list of changes below for more details.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands:

opam update
opam switch create 4.14.1

The source code for the release candidate is also directly available on:

See full changelog

Changes in OCaml 4.14.1 (20 December 2022)

Compiler User-Interface and Warnings:

  • #11184, #11670: Stop calling ranlib on created / installed libraries (Sébastien Hinderer and Xavier Leroy, review by the same)

Build System:

  • #11370, #11373: Don't pass CFLAGS to flexlink during configure. (David Allsopp, report by William Hu, review by Xavier Leroy and Sébastien Hinderer)

  • #11487: Thwart FMA test optimisation during configure (William Hu, review by David Allsopp and Sébastien Hinderer)

Bug Fixes:

  • #10768, #11340: Fix typechecking regression when combining first class modules and GADTs. (Jacques Garrigue, report by François Thiré, review by Matthew Ryan)

  • #11204: Fix regression introduced in 4.14.0 that would trigger Warning 17 when calling virtual methods introduced by constraining the self type from within the class definition. (Nicolás Ojeda Bär, review by Leo White)

  • #11263, #11267: caml/{memory,misc}.h: Check whether _MSC_VER is defined before using it to ensure that the headers can always be used in code which turns on -Wundef (or equivalent). (David Allsopp and Nicolás Ojeda Bär, review by Nicolás Ojeda Bär and Sébastien Hinderer)

  • #11314, #11416: Fix non-informative error message for module inclusion (Florian Angeletti, report by Thierry Martinez, review by Gabriel Scherer)

  • #11358, #11379: Refactor the initialisation of bytecode threading, This avoids a "dangling pointer" warning of GCC 12.1. (Xavier Leroy, report by Armaël Guéneau, review by Gabriel Scherer)

  • #11387: Module type with constraints no longer crash the compiler in presence of both shadowing warnings and the -bin-annot compiler flag. (Florian Angeletti, report by Christophe Raffalli, review by Gabriel Scherer)

  • #11392, #11392: Assertion failure with -rectypes and external definitions (Gabriel Scherer, review by Florian Angeletti, report by Dmitrii Kosarev)

  • #11417: Fix a regression which allowed virtual methods in non-virtual classes. (Leo White, review by Florian Angeletti)

  • #11468: Fix regression from #10186 (OCaml 4.13) detecting IPv6 on Windows for Mingw-w64 i686 port. (David Allsopp, review by Xavier Leroy and Sébastien Hinderer)

  • #11489, #11496: More prudent deallocation of alternate signal stack (Xavier Leroy, report by @rajdakin, review by Florian Angeletti)

  • #11516, #11524: Fix the deprecated_mutable attribute. (Chris Casinghino, review by Nicolás Ojeda Bär and Florian Angeletti)

  • #11194, #11609: Fix inconsistent type variable names in "unbound type var" messages (Ulysse Gérard and Florian Angeletti, review Florian Angeletti and Gabriel Scherer)

  • #11622: Prevent stack overflow when printing a constructor or record mismatch error involving recursive types. (Florian Angeletti, review by Gabriel Scherer)

  • #11732: Ensure that types from packed modules are always generalised (Stephen Dolan and Leo White, review by Jacques Garrigue)

  • #11737: Fix segfault condition in Unix.stat under Windows in the presence of multiple threads. (Marc Lasson, Nicolás Ojeda Bär, review by Gabriel Scherer and David Allsopp)

  • #11776: Extend environment with functor parameters in strengthen_lazy. (Chris Casinghino and Luke Maurer, review by Gabriel Scherer)

  • #11533, #11534: Follow synonyms again in #show_module_type (this had stopped working in 4.14.0) (Gabriel Scherer, review by Jacques Garrigue, report by Yaron Minsky)

  • #11768, #11788: Fix crash at start-up of bytecode programs in no-naked-pointers mode caused by wrong initialisation of caml_global_data (Xavier Leroy, report by Etienne Millon, review by Gabriel Scherer)

  • #11803, #11808: On x86, the destination of an integer comparison must be a register; it cannot be a stack slot. (Vincent Laviron, review by Xavier Leroy, report by Emilio Jesús Gallego Arias)

We have the pleasure of celebrating the birthdays of Jane Austen and Arthur C. Clarke by announcing the release of OCaml version 5.0.0.

The highlight of this new major version of OCaml is the long-awaited runtime support for shared memory parallelism and effect handlers.

This multicore support is the culmination of more than 8 years of effort, and required a full rewrite of the OCaml runtime environment. Consequently, OCaml 5.0.0 is expected to be a more experimental version of OCaml than the usual OCaml releases.

In this release, the native compiler only supports the x86-64 and arm64 architectures. In terms of operating systems, Linux, the BSDs, macOS and mingw64 on Windows are supported.

We are planning to restore the support for most previously supported architectures and operating systems, and address remaining known issues over the course of the next year.

Don't let those words of caution hinder your experimentation with OCaml 5: OCaml 5 as a language is fully compatible with OCaml 4 down to the performance characteristics of your programs. In other words, any code that works with OCaml 4 should work the same with OCaml 5.

The currently known exceptions to this rule are:

  • the removal of many long-deprecated functions and modules
  • changes to the internal runtime API
  • the performance of ephemerons is currently (and temporarily) strongly degraded.

Please report any unexpected behaviours on the OCaml issue tracker and post any questions or comments you might have on our discussion forums.

During the maturing period for OCaml 5, the OCaml 4.14 branch will be maintained by backporting bug fixes from the OCaml 5 branch at regular intervals. The next release on the OCaml 4.14 branch, OCaml 4.14.1, should soon follow this release.

The full list of changes can be found in the changelog below.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands:

opam update
opam switch create 5.0.0

It might be also interesting to check the new support for parallelism by installing the domainslib library with

opam install domainslib

The source code for the release candidate is also directly available on:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.0.0+options <option_list>

where <option_list> is a comma-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.0.0+flambda+nffa ocaml-variants.5.0.0+options ocaml-option-flambda ocaml-option-no-flat-float-array

The command line above is slightly more complicated for opam versions before 2.1:

opam update
opam switch create <switch_name> --packages=ocaml-variants.5.0.0+options,<option_list>

In both cases, all available options can be listed with opam search ocaml-option.

See full changelog

OCaml 5.0.0 (16 December 2022)

  • #10831: Multicore OCaml (Enguerrand Decorne, Stephen Dolan, Tom Kelly, Sadiq Jaffer, Anil Madhavapeddy, Sudha Parimala, KC Sivaramakrishnan, Leo White, the Tarides multicore team, review by Florian Angeletti, Damien Doligez, Xavier Leroy, Guillaume Munch-Maccagnoni, Olivier Nicole, Nicolás Ojeda Bär, Gabriel Scherer, the OCaml core development team, and many other valued reviewers.)

Runtime system:

  • #11400: Runtime events counters fixes Fixes mismatch between OCaml and C APIs, removes events from 4.x that are not present in the 5.0 GC and adds some missing probes. (Sadiq Jaffer, review by Gabriel Scherer, Florian Angeletti)

  • #11368: Runtime events buffer size OCAMLRUNPARAMS fix The runtime events buffer size can now be set via the 'e' OCAMLRUNPARAM. This is previously mistakenly enabled/disabled tracing instead. (Sadiq Jaffer, review by KC Sivaramakrishnan, David Allsopp, Damien Doligez)

  • #11308: Add environment variable to preserve runtime_events after exit If the environment variable OCAML_RUNTIME_EVENTS_PRESERVE exists then the runtime will not remove the runtime events ring buffers at exit. This makes tracing very short running programs more reliable. (Sadiq Jaffer, review by KC Sivaramakrishnan)

  • #10964: Ring-buffer based runtime tracing (runtime_events) Runtime_events is a very low overhead runtime tracing system designed for continuous monitoring of OCaml applications. (Sadiq Jaffer, review by Anil Madhavapeddy, Enguerrand Decorne, Richard Warburton, Gabriel Scherer, Sabine Schmaltz, Florian Angeletti, Patrick Ferris, Tom Kelly)

  • (breaking change) #10723: do not use -flat-namespace linking for macOS. (Carlo Cabrera, review by Damien Doligez)

  • (breaking change) #10863, #10933: Remove support for old, unprefixed C runtime function names such as alloc. The new names prefixed with caml_ must be used instead, such as caml_alloc. Consequently, it is no longer needed to define CAML_NAME_SPACE to avoid bringing unprefixed names into scope: this is now the default behavior. (Nicolás Ojeda Bär, review by Xavier Leroy)

  • #10902: Do not register empty code fragments in natdynlink. (David Allsopp, review by Xavier Leroy and Damien Doligez)

  • #10965: caml_fatal_error_hook, GC timing hooks, and caml_scan_roots_hook are now atomic variables. Restore GC timing hooks in multicore. (Guillaume Munch-Maccagnoni, review by Enguerrand Decorne, Xavier Leroy, Gabriel Scherer, and KC Sivaramakrishnan)

  • #11209: Add a public and thread-safe timing hook running at domain termination, after this domain has stopped running any OCaml code: caml_domain_terminated_hook. This can be useful for implementing domain-local state in C. (Guillaume Munch-Maccagnoni, review by Xavier Leroy and Gabriel Scherer)

  • #10875, #11731: Add option to allocate fiber stacks and sigaltstacks with mmap(MAP_STACK) instead of malloc. This is exposed via a configure --enable-mmap-map-stack option, and is enabled by default on OpenBSD where it is mandatory. (Anil Madhavapeddy, review by Gabriel Scherer, Tom Kelly, Michael Hendricks and KC Sivaramakrishnan).

  • #10950: Do not use mmap to allocate Caml_state. In order to reduce virtual memory usage, we dynamically allocate the domain_state structure. (Enguerrand Decorne, KC Sivaramakrishnan and Tom Kelly, review by Anil Madhavapeddy and Gabriel Scherer)

  • #11010: Use strerror_r for reentrant error string conversion. (Anil Madhavapeddy and Xavier Leroy, review by same and Edwin Török)

  • #11002, #11066, #11086: Do not use Begin_roots/End_roots macros in the runtime system. Also fix a missing root registration in the implementation of Unix.write on Windows. (Nicolás Ojeda Bär, Daniel Bünzli and Antonin Décimo, review by Xavier Leroy and David Allsopp)

  • #11022: Track GC work for all managed bigarray allocations (Stephen Dolan, report by Andrew Hunter, review by Damien Doligez)

  • #10802: Use 4.12 value macros and helpers in C code (Antonin Décimo, review by Gabriel Scherer)

  • #11105: Fix handling of fiber stack cache with multiple domains (Jon Ludlam, KC Sivaramakrishnan and Tom Kelly)

  • #11054: Respect user provided maximum stack space Make sure the stack we initially request is sized accordingly to the user provided settings. tmc/stack_space is also updated by this PR in order to account for this change. (Enguerrand Decorne, report by Jon Ludlam, review by Tom Kelly, KC Sivaramakrishnan and Gabriel Scherer)

  • #11238: Increase the default limit for the stack size to 128 Mi words, i.e. 1 Gib for 64-bit platforms and 512 Mib for 32-bit platforms. (Xavier Leroy, review by Sébastien Hinderer)

  • (breaking change) #11295: An ISO C 2011 compliant compiler, including full support for atomic types, is now required to build the OCaml runtime system. (Xavier Leroy, review by David Allsopp and Sébastien Hinderer)
  • #10915, #11039, #11057, #11095, #11190: Implement quality treatment for asynchronous actions in multicore. Reimplement the old behaviour of caml_process_pending* for multicore. (Guillaume Munch-Maccagnoni, review by Sadiq Jaffer and Gabriel Scherer)

  • #11303: Ensure that GC is not invoked from bounds check failures (Stephen Dolan, review by Sadiq Jaffer and Xavier Leroy)

  • #11304: Fix data race on Windows file descriptors (Olivier Nicole and Xavier Leroy, review by Xavier Leroy, David Allsopp, and Sadiq Jaffer)

  • (breaking change) #11337: pass 'flags' metadata to root scanners, to optimize stack scanning in the bytecode interpreter. Changes the interface of user-provided root-scanning hooks. (Gabriel Scherer, review by Xavier Leroy, Guillaume Munch-Maccagnoni, Sadiq Jaffer and Tom Kelly)
  • #11144: Restore frame-pointers support for amd64 (Fabrice Buoro, review by Frederic Bour and KC Sivaramakrishnan)
  • (breaking change) #11255: in the C interface, &Field(v, i) now has type volatile value * instead of value * in OCaml 4. This makes the memory model for mixed OCaml/C code better defined, but can cause warnings or type errors in user C code. (KC Sivaramakrishnan, review by Xavier Leroy, Gabriel Scherer and Guillaume Munch-Maccagnoni, additional discussions with Stephen Dolan and Luc Maranget)
  • #5299, #4787, #11138, #11272, #11506: To help debugging, Caml_state now dynamically checks that the domain lock is held, and fails otherwise (with a fatal error at most entry points of the C API, or systematically in debug mode). A new variable Caml_state_opt is introduced, and is NULL when the domain lock is not held. This allows to test from C code if the current thread holds the lock of its domain. (Guillaume Munch-Maccagnoni, review by Florian Angeletti, Damien Doligez, Sadiq Jaffer, Xavier Leroy, and Gabriel Scherer)

  • #11223: The serialization format of custom blocks changed in 4.08, but the deserializer would still support the pre-4.08 format. OCaml 5.x removed support for this old format; provide a clear error message in this case. (Hugo Heuzard, review by Gabriel Scherer)

  • #11504, #11522: Use static allocation in caml_make_float_vect in no-flat-float-array mode, it's more efficient and avoids a a race condition (Xavier Leroy, report by Guillaume Munch-Maccagnoni, review by David Allsopp)

  • #11652: Fix benign off-by-one error in Windows implementation of caml_mem_map. (David Allsopp, review by Gabriel Scherer)

  • #11669, #11704: Fix construction of Effect.Unhandled exceptions in the bytecode interpreter. (David Allsopp and Xavier Leroy, report by Samuel Hym, review by Xavier Leroy and Gabriel Scherer)

Code generation and optimizations:

  • #10972: ARM64 multicore support: OCaml & C stack separation; dynamic stack size checks; fiber and effects support. (Tom Kelly and Xavier Leroy, review by KC Sivaramakrishnan, Xavier Leroy Guillaume Munch-Maccagnoni, Eduardo Rafael, Stephen Dolan and Gabriel Scherer)
  • (breaking change) #10845 Emit frametable size on amd64 BSD (OpenBSD, FreeBSD, NetBSD) systems (emitted for Linux in #8805) (Hannes Mehnert, review by Nicolás Ojeda Bär)

Standard library:

  • #10742: Use LXM as the pseudo-random number generator for module Random. Add Random.State.split and Random.split to "split" a PRNG off another PRNG. (Xavier Leroy, review by Gabriel Scherer and Hugo Heuzard)
  • (breaking change) #10867, #11345: Remove deprecated values: Array.create, Array.make_float, Array.create_matrix, Bytes.uppercase, Bytes.lowercase, Bytes.capitalize, Bytes.uncapitalize, Char.lowercase, Char.uppercase, Filename.temp_dir_name, Int32.format, Int64.format, Nativeint.format, Format.bprintf, Format.kprintf, Format.set_all_formatter_output_functions, Format.get_all_formatter_output_functions, Format.pp_set_all_formatter_output_functions, Format.pp_get_all_formatter_output_functions, Format.pp_open_tag, Format.pp_close_tag, Format.open_tag, Format.close_tag, Format.formatter_tag_functions, Format.pp_set_formatter_tag_functions, Format.pp_get_formatter_tag_functions, Format.set_formatter_tag_functions, Format.get_formatter_tag_functions, Gc (mutability of the fields of type Gc.control), Lazy.lazy_from_fun, Lazy.lazy_from_val, Lazy.lazy_is_val, Obj.set_tag, Obj.truncate, Obj.final_tag, Obj.extension_constructor, Obj.extension_name, Obj.extension_id, Scanf.stdib, Scanf.fscanf, Scanf.kfscanf, Stdlib.( & ), Stdlib.( or ), String.set, String.copy, String.fill, String.unsafe_set, String.unsafe_fill, String.uppercase, String.lowercase, String.capitalize, String.uncapitalize, Thread.kill, Thread.wait_write, Thread.wait_read, the whole ThreadUnix module, the infix operator (.[]<-). (Nicolás Ojeda Bär, review by Damien Doligez)

  • (breaking change) #10896: Remove Stream, Genlex and Pervasives. Also remove legacy standalone bigarray library (the Bigarray module is now part of the standard library). (Nicolás Ojeda Bär, review by Kate Deplaix and Anil Madhavapeddy)

  • #10921: Use getentropy, when available, to seed the generator during Random.self_init (Michael Hendricks, review by Gabriel Scherer, Xavier Leroy, and Anil Madhavapeddy)
  • (breaking change) #10924: Add deprecated attribute to Printexc.catch, Printf.kprintf and Unix.SO_ERROR. (Nicolás Ojeda Bär, review by Damien Doligez)
  • #10986: Add Scanf.sscanf_opt, Scanf.bscanf_opt and Scanf.scanf_opt. (Nicolás Ojeda Bär, review by Florian Angeletti and Gabriel Scherer)
  • (breaking change) #11157: Rename "hash" in the "Hashtbl.SeededHashedType" signature to "seeded_hash". This allows defining both seeded and unseeded hash functions in the same module. (Nicolás Ojeda Bär, review by Gabriel Scherer and Xavier Leroy)
  • #8878: Add String.hash and String.seeded_hash. (Tom Kelly, review by Alain Frisch and Nicolás Ojeda Bär)

Other libraries:

  • (breaking change) #9071, #9100, #10935: Reimplement Thread.exit() as raising the exception Thread.Exit, and mark Thread.exit as deprecated. The new implementation changes the behavior compared with the OCaml 4 implementation. For example, the new implementation causes Fun.finally finalizers to be run and catch-all exception handlers to prevent termination. (Jacques-Henri Jourdan and Xavier Leroy, review by Damien Doligez, Guillaume Munch-Maccagnoni, Gabriel Scherer, and Enguerrand Decorne)
  • #11034: Dynlink library, add a global lock to make dynlinking thread-safe. (Florian Angeletti, review by Gabriel Scherer)

  • #11087: deprecate Thread.wait_timed_read, Thread.wait_timed_write, Thread.select, Thread.wait_pid. The same functionality is available in the Unix module. (Nicolás Ojeda Bär, review by Anil Madhavapeddy)

  • #11309, #11424, #11427, #11545: Add Domain.recommended_domain_count. (Christiano Haesbaert, Konstantin Belousov, review by David Allsopp, KC Sivaramakrishnan, Gabriel Scherer, Nicolas Ojeda Bar)

  • #11461, #11466: Fix gethostbyaddr for IPv6 arguments and make it domain-safe (Olivier Nicole, Nicolás Ojeda Bär, David Allsopp and Xavier Leroy, review by the same)

  • #11479: Make Unix.symlink domain-safe on Windows (Olivier Nicole, review by Xavier Leroy and David Allsopp)

Tools:

  • (breaking change) #11004: Litmus tests for checking the implementation of the memory model. (Luc Maranget, review by Gabriel Scherer and Xavier Leroy)
  • #11024: Handle alerts in ocamldoc. The alert [@@alert deprecated] is handled specifically and it's no longer needed to duplicate the deprecated annotation (the alert for the compiler and the tag for the documentation). Every other alerts also appear in the documentation. (Jules Aguillon, review by Florian Angeletti)

  • #11065: Port the bytecode debugger to 5.0, adding support for effect handlers. (Damien Doligez and @fabbing, review by @fabbing and Xavier Leroy)

  • #11079: Add the -nobanners option to dumpobj. (Sébastien Hinderer, review by Gabriel Scherer and Vincent Laviron)

  • #11100: Fix ocamltest to make sure failed tests are not counted as "unexpected error". (Damien Doligez, review by Sébastien Hinderer)

  • #11245: Merge the common code of ocamlcp and ocamloptp into a single module. (David Allsopp, review by Sébastien Hinderer)

  • #11382: OCamlmktop use a new initialization module "OCamlmktop_init" to preserve backward-compatibility with user-module provided modules that install toplevel printers. (Florian Angeletti, review by Gabriel Scherer and David Allsopp)

Manual and documentation:

  • #11058: runtime/HACKING.adoc tips on debugging the runtime (Gabriel Scherer, review by Enguerrand Decorne and Nicolás Ojeda Bär)

  • #11093: Add an effect handlers tutorial (KC Sivaramakrishnan, review by François Pottier, Gabriel Scherer, François Bobot and Wiktor Kuchta)

  • #11192: Better documentation for condition variables. (François Pottier, review by Luc Maranget, Xavier Leroy, and Wiktor Kuchta)

  • #11093: Add tutorials on parallelism features and the relaxed memory model (KC Sivaramakrishnan, review by Damien Doligez, Anil Madhavapeddy, Gabriel Scherer, Thomas Leonard, Tom Ridge, Xavier Leroy, Luc Maranget, Fabrice Buoro, Olivier Nicole, Guillaume Munch-Maccagnoni, Jacques-Henri Jourdan)

  • #11640: Add Flambda commonly-used options to the ocamlopt manpage (Amandine Nangah, review by David Allsopp, Florian Angeletti, Sébastien Hinderer, and Vincent Laviron)

  • #11676: Fix missing since annotation in the Sys and Format modules (Github user Bukolab99, review by Florian Angeletti)

  • #11813: Make new multicore chapters easier to discover, and emphasize impact on C bindings. (Edwin Török, review by KC Sivaramakrishnan, and Florian Angeletti)

Compiler user-interface and warnings:

  • #9140, #11131: New command-line flag -nocwd to not include implicit the current directory to the load path. (Thomas Roglin, review by Gabriel Scherer and Nicolás Ojeda Bär)

  • #11089: Add 'since ' information to compiler warnings. (André Maroneze, review by Florian Angeletti and Gabriel Scherer)

  • #10909: Disable warning 59 (assignment to immutable blocks) unless flambda invariant checks are enabled. (Vincent Laviron, review by Gabriel Scherer)

  • #10981, #11276: Implement a -cmi-file option for ocamlc and ocamlopt. (Sébastien Hinderer, review by Damien Doligez, Daniel Bünzli and Florian Angeletti)

  • (breaking change) #11049: Stop padding 1-digit compiler minor version numbers. (So for instance OCaml 5.0 rather than 5.00) (Sébastien Hinderer, review by David Allsopp, Florian Angeletti and Xavier Leroy)
  • #11184, #11670: Stop calling ranlib on created / installed libraries (Sébastien Hinderer and Xavier Leroy, review by the same)

  • #11253: Deprecate ocaml script and ocamlnat script where script has no extension and is an implicit basename. (David Allsopp, review by Florian Angeletti and Sébastien Hinderer)

Internal/compiler-libs changes:

  • #10878, #10909: restore flambda after the Multicore merge. (Vincent Laviron, review by Gabriel Scherer and Xavier Leroy)

  • #10864, #10888: restore afl-fuzz mode for sequential programs. (Jan Midtgaard, review by Xavier Leroy and Gabriel Scherer)

  • #11008, #11047: rework GC statistics in the Multicore runtime (Gabriel Scherer, review by Enguerrand Decorne)

  • #11058: basic debugging documentation in runtime/HACKING.adoc (Gabriel Scherer, review by Enguerrand Decorne and Nicolás Ojeda Bär)

  • #11199: Stop installing topdirs.cmi twice. The toplevel now reads topdirs.cmi from +compiler-libs, as the debugger does. (David Allsopp, review by Sébastien Hinderer)

  • #11007, #11399: META files for the stdlib, compiler-libs and other libraries (unix, dynlink, str, runtime_events, threads, ocamldoc) are now installed along with the compiler. (David Allsopp, Florian Angeletti, Nicolás Ojeda Bär and Sébastien Hinderer, review by Daniel Bünzli, Kate Deplaix, Anil Madhavapeddy and Gabriel Scherer)

Build system:

  • (breaking change) #10893: Remove configuration options --disable-force-safe-string and DEFAULT_STRING=unsafe as well as --enable-force-safe-string and DEFAULT_STRING=safe which are now the default unconditionally. (Kate Deplaix, review by Gabriel Scherer and David Allsopp)
  • #11092: Build native-code compilers on OpenBSD/aarch64. (Christopher Zimmermann, review by Anil Madhavapeddy)

  • #11126: Build system: make it possible to choose which ocamldep (and flags) to use when computing dependencies for the compiler. Add a -no-slash option to ocamldep to let users override -slash. (Sébastien Hinderer, review by David Allsopp)

  • #11147: Factorize the stdlib-related compilation flags. Make it possible to control them consistently through the STDLIBFLAGS build variable. Make sure ocamldoc and ocamllex get compiled and linked with debugging information (-g). (Sébastien Hinderer, review by Gabriel Scherer)

  • #11149: Make the bootstrap process reproducible on systems with non-big-endian floating point. If the boot/ artefacts are up-to-date, this means that running make bootstrap on any platform should not change the images in boot/ and paves the way for automated testing that the bootstrap is repeatable. (David Allsopp, review by Damien Doligez and Sébastien Hinderer)

  • #11160: otherlibs: merge win32unix into unix. (Sébastien Hinderer, review by David Allsopp, Nicolás Ojeda Bär, Xavier Leroy, Vincent Laviron and Antonin Décimo)

  • (breaking change) #11198, #11298: Install the Dynlink, Str and Unix libraries to individual subdirectories of LIBDIR. The compiler, debugger and toplevel automatically add -I +lib if required, but display an alert. (David Allsopp, review by Florian Angeletti, Nicolás Ojeda Bär, Valentin Gatien-Baron and Sébastien Hinderer)
  • #11200: Install ocamlprof's Profiling runtime module to a +profiling, removing it from the default namespace. (David Allsopp, review by Sébastien Hinderer)

  • #11294: Switch minimum required autoconf to 2.71. (David Allsopp, review by Xavier Leroy)

  • #11370, #11373: Don't pass CFLAGS to flexlink during configure. (David Allsopp, report by William Hu, review by Xavier Leroy and Sébastien Hinderer)

  • #11487: Thwart FMA test optimization during configure (William Hu, review by David Allsopp and Sébastien Hinderer)

  • #11097: Build native-code compilers on NetBSD/aarch64 (Kate Deplaix, review by Anil Madhavapeddy)

Bug fixes:

  • #10768, #11340: Fix typechecking regression when combining first class modules and GADTs. (Jacques Garrigue, report by François Thiré, review by Matthew Ryan)

  • #10790: don't drop variance and injectivity annotations when pretty printing with constraints (for example, with type +!'a t = ...). (Florian Angeletti, report by Luke Maurer, review by Matthew Ryan and Gabriel Scherer)

  • #11167: Fix memory leak from signal stack. (Antoni Żewierżejew, review by Gabriel Scherer and Enguerrand Decorne)

  • #11112: harden -use-runtime against spaces or quotes in the provided path (Gabriel Scherer, report by Brahima Dibassi, review by David Allsopp)

  • #11068, #11070: Fix typo in function name given in Unix_error exception for Unix.readlink on Windows. (David Allsopp, report by Xia Li-yao)

  • #10807: Don't duplicate standard handles in the child process spawned by win32unix Unix.create_process if the handles were already inheritable. Fix broken signalling of EOF on standard handles if they were already inheritable. (Antonin Décimo, review by Xavier Leroy and Nicolás Ojeda Bär)

  • #10868: Fix off-by-1 bug when initializing frame hashtables (Jonah Beckford, review by Tom Kelly, Nicolás Ojeda Bär and KC Sivaramakrishnan)

  • #11077: Make dumpobj compatible with absence of naked pointer support (Olivier Nicole and Jan Midtgaard, review by Gabriel Scherer)

  • #11111: fix fork() usage in ocamltest C code. When calling fork() from C code with the Multicore runtime active, one needs to call caml_atfork_hook() on the forked child before it can use the OCaml runtime. (Gabriel Scherer, review by Xavier Leroy, report by Brahima Dibassi)

  • #10809: Use the WSA_FLAG_NO_HANDLE_INHERIT on Windows when creating sockets with WSASocket if the cloexec (non-inheritable) parameter is true. Fixes a race condition where a child process could inherit the socket and deadlock the parent. (Antonin Décimo, review by Xavier Leroy)

  • #11194, #11609: Fix inconsistent type variable names in "unbound type var" messages (Ulysse Gérard and Florian Angeletti, review Florian Angeletti and Gabriel Scherer)

  • #11204: Fix regression introduced in 4.14.0 that would trigger Warning 17 when calling virtual methods introduced by constraining the self type from within the class definition. (Nicolás Ojeda Bär, review by Leo White)

  • #11263, #11267: caml/misc.h: check whether _MSC_VER is defined before using it to ensure that the headers can always be used in code which turns on -Wundef (or equivalent). (David Allsopp and Nicolás Ojeda Bär, review by Nicolás Ojeda Bär and Sébastien Hinderer)

  • #11289, #11405: fix some leaks on systhread termination (Fabrice Buoro, Enguerrand Decorne, Gabriel Scherer, review by Xavier Leroy and Florian Angeletti, report by Romain Beauxis)

  • #11314, #11416: fix non-informative error message for module inclusion (Florian Angeletti, report by Thierry Martinez, review by Gabriel Scherer)

  • #11358, #11379: Refactor the initialization of bytecode threading, This avoids a "dangling pointer" warning of GCC 12.1. (Xavier Leroy, report by Armaël Guéneau, review by Gabriel Scherer)

  • #11387, module type with constraints no longer crash the compiler in presence of both shadowing warnings and the -bin-annot compiler flag. (Florian Angeletti, report by Christophe Raffalli, review by Gabriel Scherer)

  • #11392, #11392: assertion failure with -rectypes and external definitions (Gabriel Scherer, review by Florian Angeletti, report by Dmitrii Kosarev)

  • #11417: Fix regression allowing virtual methods in non-virtual classes. (Leo White, review by Florian Angeletti)

  • #11468: Fix regression from #10186 (OCaml 4.13) detecting IPv6 on Windows for mingw-w64 i686 port. (David Allsopp, review by Xavier Leroy and Sébastien Hinderer)

  • #11482, #11542: Fix random crash in large closure allocation (Damien Doligez, report by Thierry Martinez and Vincent Laviron, review by Xavier Leroy)

  • #11508, #11509: make Bytes.escaped domain-safe (Christiano Haesbaert and Gabriel Scherer, review by Xavier Leroy, report by Jan Midtgaard and Tom Kelly)

  • #11516, #11524: Fix the deprecated_mutable attribute. (Chris Casinghino, review by Nicolás Ojeda Bär and Florian Angeletti)

  • #11576: Fix bug in Bigarray.Genarray.init in the the case of zero-dimensional arrays. (Nicolás Ojeda Bär, Jeremy Yallop, report by Masayuki Takeda, review by Jeremy Yallop and Florian Angeletti)

  • #11587: Prevent integer comparison from being used on pointers (Vincent Laviron, review by Gabriel Scherer)

  • #11622: Prevent stack overflow when printing a constructor or record mismatch error involving recursive types. (Florian Angeletti, review by Gabriel Scherer)

  • #11662, #11673: fix a memory leak when using Dynlink, the bug was only present in development version of OCaml 5. (Stephen Dolan, report by Andre Maroneze, review by Gabriel Scherer)

  • #11732: Ensure that types from packed modules are always generalised (Stephen Dolan and Leo White, review by Jacques Garrigue)

  • #11737: Fix segfault condition in Unix.stat under Windows in the presence of multiple threads. (Marc Lasson, Nicolás Ojeda Bär, review by Gabriel Scherer and David Allsopp)

  • #11776: Extend environment with functor parameters in strengthen_lazy. (Chris Casinghino and Luke Maurer, review by Gabriel Scherer)

  • #11533, #11534: follow synonyms again in #show_module_type (this had stopped working in 4.14.0) (Gabriel Scherer, review by Jacques Garrigue, report by Yaron Minsky)

The release of OCaml version 4.14.1 is imminent.

This companion release to the OCaml 5.0.0 release will backport many safe bug fixes from the currently experimental 5.0 branch to the stable 4.14 branch. A full list of bug fixes is available below.

In order to ensure that the future release works as expected, we are testing a release candidate during the upcoming weeks.

If you find any bugs, please report them here on GitHub.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1:

opam update
opam switch create 4.14.1~rc1

For previous version of opam, the switch creation command line is slightly more verbose:

opam update
opam switch create 4.14.1~rc1 --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

It might be also interesting to check the new support for parallelism by installing the domainslib library with

opam install domainslib

The source code for the release candidate is available on

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.4.14.1~rc1+options <option_list>

where <option_list> is a comma-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 4.14.1~rc1+flambda+nffa ocaml-variants.4.14.1~rc1+options ocaml-option-flambda ocaml-option-no-flat-float-array

The command line above is slightly more complicated for opam versions before 2.1:

opam update
opam switch create <switch_name> --packages=ocaml-variants.4.14.1~rc1+options,<option_list> --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

In both cases, all available options can be listed with opam search ocaml-option.

See full changelog

Changes Since OCaml 4.14.0

Compiler User-Interface and Warnings:

  • #11184, #11670: Stop calling ranlib on created / installed libraries (Sébastien Hinderer and Xavier Leroy, review by the same)

Build System:

  • #11370, #11373: Don't pass CFLAGS to flexlink during configure. (David Allsopp, report by William Hu, review by Xavier Leroy and Sébastien Hinderer)

  • #11487: Thwart FMA test optimisation during configure (William Hu, review by David Allsopp and Sébastien Hinderer)

Bug Fixes:

  • #10768, #11340: Fix typechecking regression when combining first class modules and GADTs. (Jacques Garrigue, report by François Thiré, review by Matthew Ryan)

  • #11204: Fix regression introduced in 4.14.0 that would trigger Warning 17 when calling virtual methods introduced by constraining the self type from within the class definition. (Nicolás Ojeda Bär, review by Leo White)

  • #11263, #11267: caml/{memory,misc}.h: check whether _MSC_VER is defined before using it to ensure that the headers can always be used in code which turns on -Wundef (or equivalent). (David Allsopp and Nicolás Ojeda Bär, review by Nicolás Ojeda Bär and Sébastien Hinderer)

  • #11314, #11416: fix non-informative error message for module inclusion (Florian Angeletti, report by Thierry Martinez, review by Gabriel Scherer)

  • #11358, #11379: Refactor the initialisation of bytecode threading, This avoids a "dangling pointer" warning of GCC 12.1. (Xavier Leroy, report by Armaël Guéneau, review by Gabriel Scherer)

  • #11387, module type with constraints no longer crash the compiler in presence of both shadowing warnings and the -bin-annot compiler flag. (Florian Angeletti, report by Christophe Raffalli, review by Gabriel Scherer)

  • #11392, #11392: assertion failure with -rectypes and external definitions (Gabriel Scherer, review by Florian Angeletti, report by Dmitrii Kosarev)

  • #11417: Fix regression allowing virtual methods in non-virtual classes. (Leo White, review by Florian Angeletti)

  • #11468: Fix regression from #10186 (OCaml 4.13) detecting IPv6 on Windows for mingw-w64 i686 port. (David Allsopp, review by Xavier Leroy and Sébastien Hinderer)

  • #11489, #11496: More prudent deallocation of alternate signal stack (Xavier Leroy, report by @rajdakin, review by Florian Angeletti)

  • #11516, #11524: Fix the deprecated_mutable attribute. (Chris Casinghino, review by Nicolás Ojeda Bär and Florian Angeletti)

  • #11194, #11609: Fix inconsistent type variable names in "unbound type var" messages (Ulysse Gérard and Florian Angeletti, review Florian Angeletti and Gabriel Scherer)

  • #11622: Prevent stack overflow when printing a constructor or record mismatch error involving recursive types. (Florian Angeletti, review by Gabriel Scherer)

  • #11732: Ensure that types from packed modules are always generalised (Stephen Dolan and Leo White, review by Jacques Garrigue)

  • #11737: Fix segfault condition in Unix.stat under Windows in the presence of multiple threads. (Marc Lasson, Nicolás Ojeda Bär, review by Gabriel Scherer and David Allsopp)

  • #11776: Extend environment with functor parameters in strengthen_lazy. (Chris Casinghino and Luke Maurer, review by Gabriel Scherer)

  • #11533, #11534: follow synonyms again in #show_module_type (this had stopped working in 4.14.0) (Gabriel Scherer, review by Jacques Garrigue, report by Yaron Minsky)

  • #11768, #11788: Fix crash at start-up of bytecode programs in no-naked-pointers mode caused by wrong initialisation of caml_global_data (Xavier Leroy, report by Etienne Millon, review by Gabriel Scherer)

The release of OCaml version 5.0.0 is imminent. As a final step before the release, we are publishing a release candidate that you can test while waiting for the release in the upcoming weeks.

If you find any bugs, please report them on OCaml's issue tracker.

Compared to the second beta release, this release contains one toplevel bug fix and a minor type system fix.

If you are interested by the bug fixes beyond the new Multicore runtime, the full change log for OCaml 5.0.0 is available on GitHub

A short summary of the changes since the second beta release is also available below.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1:

opam update
opam switch create 5.0.0~rc1

For previous version of opam, the switch creation command line is slightly more verbose:

opam update
opam switch create 5.0.0~rc1 --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

It might be also interesting to check the new support for parallelism by installing the domainslib library with

opam install domainslib

The source code for the release candidate is also directly available on:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.0.0~rc1+options <option_list>

where <option_list> is a comma-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.0.0~rc1+flambda+nffa ocaml-variants.5.0.0~rc1+options ocaml-option-flambda ocaml-option-no-flat-float-array

The command line above is slightly more complicated for opam versions before 2.1:

opam update
opam switch create <switch_name> --packages=ocaml-variants.5.0.0~rc1+options,<option_list> --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

In both cases, all available options can be listed with opam search ocaml-option.

See full changelog

Changes Since the Second Beta Release

Bug Fixes

  • #11776: Extend environment with functor parameters in strengthen_lazy. (Chris Casinghino and Luke Maurer, review by Gabriel Scherer)

  • #11533, #11534: follow synonyms again in #show_module_type (this had stopped working in 4.14.0) (Gabriel Scherer, review by Jacques Garrigue, report by Yaron Minsky)

The release of OCaml 5.0.0 is drawing close.

In order to test the most recent bug fixes and to help you update your software and libraries ahead of the release, we have released a second beta version of OCaml 5.0.0, (see below for the installation instructions).

If you find any bugs, please report them on OCaml's issue tracker.

Compared to the first beta release, this second beta contains many small internal standard library fixes, one configuration fix and many small bug fixes.

We also have few updates of the documentation, which introduce two new alerts: one for the unstable modules Domain and Effect, and another for functions doing unsynchronized_access to mutable state in the standard library. Those two alerts are disabled by default, but are available for interested users.

The first release candidate for OCaml 5.0.0 is expected to follow closely this second beta release.

If you are interested in the ongoing list of bug fixes, the updated change log for OCaml 5.0.0 is available on GitHub.

You can also follow the state of the opam ecosystem on http://check.ocamllabs.io/.

A short summary of the changes since the first beta release is also available below.


Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1:

opam update
opam switch create 5.0.0~beta2

For previous versions of opam, the switch creation command line is slightly more verbose:

opam update
opam switch create 5.0.0~beta2 --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

It might also be interesting to check the new support for parallelism by installing the domainslib library with

opam install domainslib

The source code for the beta release is also available at these addresses:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.0.0~beta2+options <option_list>

where option_list is a comma-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.0.0~beta2+flambda+nffa ocaml-variants.5.0.0~beta2+options ocaml-option-flambda ocaml-option-no-flat-float-array

The command line above is slightly more complicated for opam versions before 2.1:

opam update
opam switch create <switch_name> --packages=ocaml-variants.5.0.0~beta2+options,<option_list> --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

In both cases, all available options can be listed with opam search ocaml-option.

See full changelog

Changes since the first beta

Configuration changes

  • #11097: Build native-code compilers on NetBSD/aarch64 (Kate Deplaix, review by Anil Madhavapeddy)

Bug fixes

  • #10875, +#11731: Add option to allocate fiber stacks and sigaltstacks with mmap(MAP_STACK) instead of malloc. This is exposed via a configure –enable-mmap-map-stack option, and is enabled by default on OpenBSD where it is mandatory. (Anil Madhavapeddy, review by Gabriel Scherer, Tom Kelly, Michael Hendricks and KC Sivaramakrishnan).
  • #11652: Fix benign off-by-one error in Windows implementation of caml_mem_map. (David Allsopp, review by Gabriel Scherer)
  • #11669, #11704: Fix construction of Effect.Unhandled exceptions in the bytecode interpreter. (David Allsopp and Xavier Leroy, report by Samuel Hym, review by Xavier Leroy and Gabriel Scherer)
  • #11184, +#11670: Stop calling ranlib on created / installed libraries (Sébastien Hinderer and Xavier Leroy, review by the same)
  • #11194, #11609: Fix inconsistent type variable names in “unbound type var” messages (Ulysse Gérard and Florian Angeletti, review Florian Angeletti and Gabriel Scherer)
  • #11622: Prevent stack overflow when printing a constructor or record mismatch error involving recursive types. (Florian Angeletti, review by Gabriel Scherer)
  • #11662, #11673: fix a memory leak when using Dynlink, the bug was only present in development version of OCaml 5. (Stephen Dolan, report by Andre Maroneze, review by Gabriel Scherer)
  • #11732: Ensure that types from packed modules are always generalised (Stephen Dolan and Leo White, review by Jacques Garrigue)
  • #11737: Fix segfault condition in Unix.stat under Windows in the presence of multiple threads. (Marc Lasson, Nicolás Ojeda Bär, review by Gabriel Scherer and David Allsopp)

Documentation

  • #11193, #11227: documentation on concurrency safety for mutable data types and states in the standard library. A unsynchronized_access alert have been added for functions that require user synchronizations on concurrent access. The new alert is diabled by default. (Florian Angeletti, review by François Pottier and KC Sivaramakrishnan )
  • #11526, add a unstable alert to the Domain and Effect modules. The new alert is disabled by default. (Florian Angeletti, review by Nicolás Ojeda Bär, Daniel Bünzli, and Kate Deplaix)
  • #11640: Add Flambda commonly-used options to the ocamlopt manpage (Amandine Nangah, review by David Allsopp, Florian Angeletti, Sébastien Hinderer, and Vincent Laviron)

The release of OCaml 5.0.0 is drawing near. The standard library has been stabilized and many opam packages already work with this release. After two alpha releases, we have released the first beta version to help you update your software and libraries ahead of the release (see below for the installation instructions).

If you find any bugs, please report them on GitHub issues.

Compared to the last alpha release, this beta contains many small, internal runtime fixes (in particular in the systhreads library).

At the user level, the interface of the Domain and Effect module has been tweaked to be (hopefully) more forward-compatible:

  • Exceptions related to effects are now defined in the Effecŧ module.
  • The value Domain.recommended_domain_count is no longer a constant and the function Domain.at_each_spawn has been removed.

With those changes, the standard library should be stable now.

If you are interested in the ongoing list of bug fixes, the updated change log for OCaml 5.0.0 is available on GitHub.

You can also follow the state of the opam ecosystem on this opam-repository issues, and at check.ocamllabs.io

A short summary of the changes since the last alpha release is also available below.

Installation Instructions

The base compiler can be installed as an opam switch with the following commands on opam 2.1:

opam update
opam switch create 5.0.0~beta1

For previous versions of opam, the switch creation command line is slightly more verbose:

opam update
opam switch create 5.0.0~beta1 --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

It might also be interesting to check the new support for parallelism by installing the domainslib library with

opam install domainslib

The source code for the beta release is also available at these addresses:

Fine-Tuned Compiler Configuration

If you want to tweak the configuration of the compiler, you can switch to the option variant with:

opam update
opam switch create <switch_name> ocaml-variants.5.0.0~beta1+options <option_list>

where option_list is a comma-separated list of ocaml-option-* packages. For instance, for a flambda and no-flat-float-array switch:

opam switch create 5.0.0~beta1+flambda+nffa ocaml-variants.5.0.0~beta1+options ocaml-option-flambda ocaml-option-no-flat-float-array

The command line above is slightly more complicated for opam versions before 2.1:

opam update
opam switch create <switch_name> --packages=ocaml-variants.5.0.0~beta1+options,<option_list> --repositories=default,beta=git+https://github.com/ocaml/ocaml-beta-repository.git

In both cases, all available options can be listed with opam search ocaml-option.

Optional opam Alpha Repository

During the beta release, if your dependencies are not yet compatible with OCaml 5.0.0, you might want to check the alpha opam repository: https://github.com/kit-ty-kate/opam-alpha-repository.

Which can be installed with

opam repo add alpha git+https://github.com/kit-ty-kate/opam-alpha-repository.git

You can check that the alpha repository has been correctly installed with

$ opam repo
<><> Repository configuration for switch 5.0.0~beta1 <><><><><><><><><><><><><>
 1 alpha   git+https://github.com/kit-ty-kate/opam-alpha-repository.git
 2 default https://opam.ocaml.org

This alpha repository contains various fixes that are in the process of being upstreamed, but it should be less and less required with the progress of the beta release.

See full changelog

Changes Since Last Alpha Release

Stdlib Changes

  • #11309, #11424, #11427, +#11545: Add Domain.recommended_domain_count. (Christiano Haesbaert, Konstantin Belousov, review by David Allsopp, KC Sivaramakrishnan, Gabriel Scherer, Nicolas Ojeda Bar)
  • #11423: Move the effect exceptions to the Effect module (KC Sivaramakrishnan, Xavier Leroy, Florian Angeletti, review by Florian Angeletti, Xavier Leroy, and KC Sivaramakrishnan)

  • #11593: Remove Domain.at_each_spawn (Florian Angeletti, review by Guillaume Munch-Maccagnoni and KC Sivaramakrishnan)

Bug Fixes

  • #11303: Ensure that GC is not invoked from bounds check failures (Stephen Dolan, review by Sadiq Jaffer and Xavier Leroy)

  • #5299, #4787, #11138, #11272, #11506: To help debugging, Caml_state now dynamically checks that the domain lock is held and fails otherwise (with a fatal error at most entry points of the C API, or systematically in debug mode). A new variable Caml_state_opt is introduced and is NULL when the domain lock is not held. This allows to test from C code if the current thread holds its domain lock. (Guillaume Munch-Maccagnoni, review by Florian Angeletti, Damien Doligez, Sadiq Jaffer, Xavier Leroy, and Gabriel Scherer)

  • #11223: The serialisation format of custom blocks changed in 4.08, but the deserialiser would still support the pre-4.08 format. OCaml 5.x removed support for this old format and provided a clear error message in this case. (Hugo Heuzard, review by Gabriel Scherer)

  • #11504, #11522: Use static allocation for caml_make_float_vect in no-flat-float-array mode, it's more efficient and avoids a race condition (Xavier Leroy, report by Guillaume Munch-Maccagnoni, review by David Allsopp)

  • #11461, #11466: Fix gethostbyaddr for IPv6 arguments and make it domain-safe (Olivier Nicole, Nicolás Ojeda Bär, David Allsopp and Xavier Leroy, review by the same)

  • #11479: Make Unix.symlink domain-safe on Windows (Olivier Nicole, review by Xavier Leroy and David Allsopp)

  • #11294: Switch minimum required autoconf to 2.71. (David Allsopp, review by Xavier Leroy)

  • #11370, #11373: Don't pass CFLAGS to flexlink during configure. (David Allsopp, report by William Hu, review by Xavier Leroy and Sébastien Hinderer)

  • #11487: Thwart FMA test optimization during configure (William Hu, review by David Allsopp and Sébastien Hinderer)

  • #11468: Fix regression from #10186 (OCaml 4.13) detecting IPv6 on Windows for mingw-w64 i686 port. (David Allsopp, review by Xavier Leroy and Sébastien Hinderer)

  • #11482, #11542: Fix random crash in large closure allocation (Damien Doligez, report by Thierry Martinez and Vincent Laviron, review by Xavier Leroy)

  • #11508, #11509: make Bytes.escaped domain-safe (Christiano Haesbaert and Gabriel Scherer, review by Xavier Leroy, report by Jan Midtgaard and Tom Kelly)

  • #11516, #11524: Fix the deprecated_mutable attribute. (Chris Casinghino, review by Nicolás Ojeda Bär and Florian Angeletti)

  • #11576: Fix bug in Bigarray.Genarray.init in the the case of zero-dimensional arrays. (Nicolás Ojeda Bär, Jeremy Yallop, report by Masayuki Takeda, review by Jeremy Yallop and Florian Angeletti)

  • #11587: Prevent integer comparison from being used on pointers (Vincent Laviron, review by Gabriel Scherer)

Documentation Changes

  • #11093: Add tutorials on parallelism features and the relaxed memory model (KC Sivaramakrishnan, review by Damien Doligez, Anil Madhavapeddy, Gabriel Scherer, Thomas Leonard, Tom Ridge, Xavier Leroy, Luc Maranget, Fabrice Buoro, Olivier Nicole, Guillaume Munch-Maccagnoni, Jacques-Henri Jourdan)
If you want to contribute to a new release announcement, check out the Contributing Guide on GitHub.