OCaml Changelog

(Changes that can break existing programs are marked with a "*")

Restored and New Backends:

• #12276, #12601: Native-code compilation for POWER (64 bits, little-endian) (Xavier Leroy, review by KC Sivaramakrishnan, Anil Madhavapeddy, and Stephen Dolan)

• #12667: Extend the latter to POWER 64 bits, big-endian, ELFv2 ABI (A. Wilcox, review by Xavier Leroy)

Runtime System:

• #12193: Reintroduce GC compaction for shared pools. Adds a parallel compactor for the shared pools (which contain major heap blocks sized less than 128 words). Explicit only for now, on calls to Gc.compact. (Sadiq Jaffer, Nick Barnes, review by Anil Madhavapeddy, Damien Doligez, David Allsopp, Miod Vallat, Artem Pianykh, Stephen Dolan, Mark Shinwell, and KC Sivaramakrishnan)

• #12114: Add ThreadSanitizer support (Fabrice Buoro and Olivier Nicole, based on an initial work by Anmol Sahoo, review by Damien Doligez, Sébastien Hinderer, Jacques-Henri Jourdan, Luc Maranget, Guillaume Munch-Maccagnoni, Gabriel Scherer)

• #12850: Update Gc.quick_stat data at the end of major cycles and compaction. This PR adds an additional caml_collect_gc_stats_sample_stw to the major heap cycling STW. This means that Gc.quick_stat now actually reflects the state of the heap after a major cycle or compaction. (Sadiq Jaffer, review by Miod Vallat and Gabriel Scherer)

• #12859: Ensure Gc.compact does a full major before the compactor runs (Sadiq Jaffer, review by Leo White, Mark Shinwell, Gabriel Scherer, Josh Berdine, David Allsopp, and KC Sivaramakrishnan)

• #10111: Increase the detail of location information for debugging events to allow the end-line number and character offset to be reported. (David Allsopp, review by Nick Barnes, Enguerrand Decorne and Stephen Dolan)

• #10403, #12202: Introduce caml_ext_table_add_noexc that does not raise Out_of_memory exceptions, and use it inside the blocking sections of caml_read_directory. Also, check for overflows in EXT table sizes. (Xavier Leroy, report by Arseniy Alekseyev, review by Gabriel Scherer)

• #11332, #12702: Make sure Bool_val(v) has type bool in C++ (Xavier Leroy, report by ygrek, review by Gabriel Scherer)

• #12772, #12787: Avoid using _Bool in public headers for the sake of C++ compatibility (Guillaume Munch-Maccagnoni, report by KC Sivaramakrishnan, review by Xavier Leroy and KC Sivaramakrishnan)

• #12223: Constify constructors and flags tables in C code. Now these tables will go in the read-only segment where they belong. (Antonin Décimo, review by Gabriel Scherer and Xavier Leroy)

• #12234: Make instrumented time calculation more thread-safe on macOS. (Anil Madhavapeddy, review by Daniel Bünzli and Xavier Leroy)

• #12235, #12468: Introduce and use the CAMLnoret macro as a lighter alternative to CAMLnoreturn_start / CAMLnoreturn_end. Implement it so as to conform with C11, C23, C++11, C++17. (Xavier Leroy and Dhruv Maroo, with help from Antonin Décimo, review by Gabriel Scherer and David Allsopp)

• #12275: caml/stack.h: More abstract macros to describe OCaml stacks and how to traverse them, supporting more stack layouts. (Xavier Leroy, review by KC Sivaramakrishnan and Fabrice Buoro)

• #12268: Deliver Out_of_memory exception if domain creation fails due to memory resource exhaustion. Previously, it was always a Failure. (Anil Madhavapeddy, review by David Allsopp)

• #12300, #12314: Discard out_channel buffered data on permanent I/O error (Xavier Leroy, report by Török Edwin, review by Anil Madhavapeddy and Nicolás Ojeda Bär)

• #11386: Simplifications and fixes to Multicore systhreads implementation. (Guillaume Munch-Maccagnoni, review by Anil Madhavapeddy and KC Sivaramakrishnan)

• #12875, #12879, #12882: Execute preemptive systhread switching as a delayed pending action. This ensures that one can reason within the FFI that no mutation happens on the same domain when allocating on the OCaml heap from C, consistently with OCaml 4. This also fixes further bugs with the Multicore systhreads implementation. (Guillaume Munch-Maccagnoni, bug reports and suggestion by Mark Shinwell, review by Nick Barnes and Stephen Dolan)

• #12408: Domain.spawn no longer leaks its functional argument for the whole duration of the children's domain lifetime. (Guillaume Munch-Maccagnoni, review by Gabriel Scherer)

• #12409: Fix unsafety and deadlocks should an asynchronous exception arise at specific locations during domain creation and shutdown. (Guillaume Munch-Maccagnoni, review by Gabriel Scherer)

• #11911, #12381: Restore statmemprof functionality in part, with some API changes in Gc.Memprof. (Nick Barnes, review by Jacques-Henri Jourdan and Guillaume Munch-Maccagnoni).

• #12430: Simplify dynamic bytecode loading in Meta.reify_bytecode (Stephen Dolan, review by Sébastien Hinderer, Vincent Laviron and Xavier Leroy)

• #12489: Fix an error-handling bug in caml_alloc_sprintf (Stephen Dolan, report by Chris Casinghino, review by Jeremy Yallop and Xavier Leroy)

• #11307: Finish adapting the implementation of asynchronous actions for Multicore: soundness, liveness, and performance issues. Do not crash if a signal handler is called from an unregistered C thread and other possible soundness issues. Prevent issues where joins on other domains could make the toplevel unresponsive to Ctrl-C. Avoid needless repeated polling in C code when callbacks cannot run immediately. (Guillaume Munch-Maccagnoni, review by Enguerrand Decorne, Xavier Leroy, and KC Sivaramakrishnan)

• #12634: Simplify TSan backtrace bookkeeping upon raise (Olivier Nicole and Fabrice Buoro, review by Gabriel Scherer)

• (Breaking Change) #12686: Some primitives had the wrong types to be callable from the bytecode interpreter. Either fix their types, mark them as CAMLexport instead of CAMLprim, or remove them entirely if no longer used. (Xavier Leroy, review by David Allsopp)

• #12700, continuing #11763 and trying to address #12660: Use the correct types for primitives when generating the table of primitives used by ocamlrun. (Xavier Leroy, motivation, review and improvements by Antonin Décimo)

• #12345, #12710: Fix issues with finaliser orphaning at domain termination (KC Sivaramakrishnan, report by Gabriel Scherer, review by Gabriel Scherer, Sadiq Jaffer and Fabrice Buoro)

• #12599: Refactor Dynlink startup to avoid parsing bytecode sections twice (Stephen Dolan, review by David Allsopp, Hugo Heuzard, Damien Doligez and Xavier Leroy)

• #12678, #12898: Free channel buffers on close rather than on finalisation (Damien Doligez, review by Jan Midtgaard and Gabriel Scherer, report by Jan Midtgaard)

• #12681: Fix TSan false positives due to volatile write handling (Olivier Nicole, Fabrice Buoro, and Anmol Sahoo, review by Luc Maranget, Gabriel Scherer, Hernan Ponce de Leon, and Xavier Leroy)

• #12743: Use pthread_sigmask instead of sigprocmask. Updates usage of sigprocmask to pthread_sigmask in otherlibs/unix. (Max Slater, review by Miod Vallat and Xavier Leroy)

• #12769: Unify MSVC and MinGW-w64 code paths, by always using WinAPI directly. (David Allsopp, Antonin Décimo, and Samuel Hym, review by Nicolas Ojeda Bar)

• #11911, #12382, #12383: Restore statmemprof functionality in part (backtrace buffers, per-thread and per-domain data structures, GC/allocation interface). (Nick Barnes, review by Gabriel Scherer, Fabrice Buoro, Sadiq Jaffer, Guillaume Munch-Maccagnoni, and Jacques-Henri Jourdan).

• #12735: Store both ends of the stack chain in continuations (Leo White, review by Miod Vallat and KC Sivaramakrishnan)

• #12746: Simplify and clean up TSan annotations (Olivier Nicole, review by Miod Vallat and Fabrice Buoro)

• #12809: Add ThreadSanitizer support to FreeBSD/AMD64 (Miod Vallat, review by Gabriel Scherer)

• #12810: Port ThreadSanitizer support to Linux and macOS on arm64 (Miod Vallat, review by Tim McGilchrist)

• #12811: Define and use the CAMLthread_local macro for TLS variables. (Antonin Décimo and Samuel Hym, review by Miod Vallat and Xavier Leroy)

• #12814: More detailed failure messages from input_value and Marshal.from_* (Xavier Leroy, review by Stephen Dolan and Anil Madhavapeddy)

• #12815: Correctly format multiline locations in exception backtraces in the compiler driver's style. (David Allsopp, review by Gabriel Scherer)

• #12773, #12830, #12834: Rewrite caml_c_thread_(un)register to fix various bugs. (Guillaume Munch-Maccagnoni, reported by Miod Vallat, suggested by Hari Hara Naveen S, reviewed by Fabrice Buoro, Gabriel Scherer, and Miod Vallat)

• #12876: Port ThreadSanitizer support to Linux on POWER (Miod Vallat, review by Tim McGilchrist)

• #12886: Reinitialise I/O mutexes after fork (Max Slater, review by Guillaume Munch-Maccagnoni and Xavier Leroy)

• #12907: Port ThreadSanitizer support to Linux on RiscV (Miod Vallat, review by Nicolás Ojeda Bär and Fabrice Buoro)

• #12915: Port ThreadSanitizer support to Linux on s390x (Miod Vallat, review by Tim McGilchrist)

• #12934: Fix data races between marking and sweeping functions (Olivier Nicole, suggested by Stephen Dolan, review by Gabriel Scherer, Miod Vallat, and Damien Doligez)

Language Features:

• #12295, #12568: Give while true a polymorphic type, similarly to assert false (Jeremy Yallop, review by Nicolás Ojeda Bär and Gabriel Scherer, suggestion by Rodolphe Lepigre and John Whitington)

• #12044: Add local module open syntax for types.

    module A = struct
      type t = int
      type r = unit
      type s = string
    end
  
    type example = A.(t * r * s)
  

  (Alistair O'Brien, review by Gabriel Scherer, Nicolás Ojeda Bär, and Florian Angeletti)

• #11252, RFC 27: Support raw identifier syntax \#foo (Stephen Dolan, review by David Allsopp, Gabriel Scherer, and Olivier Nicole)

• #12315: Use type annotations from arguments in let rec (Stephen Dolan, review by Gabriel Scherer)

• #12375: Allow use of [@untagged] for all immediate types like char, bool, and variant with only constant constructors. (Christophe Raffalli, review by Gabriel Scherer)

• (Breaking Change) #12502: The compiler now normalises the newline sequence \r\n to a single \n character during lexing to guarantee that the semantics of newlines in string literals are not modified by Windows tools transforming \n into \r\n in source files. Warning 29 [eol-in-string] is not emitted anymore, as the normalisation gives more robust semantics to newlines in string literals. (Gabriel Scherer and Damien Doligez, review by Daniel Bünzli, David Allsopp, Andreas Rossberg, Xavier Leroy, report by Andreas Rossberg)

Standard Library:

• #11563: Add the Dynarray module to the stdlib. Dynamic arrays are arrays whose length can be changed by adding or removing elements at the end, similar to 'vectors' in C++ or Rust. (Gabriel Scherer, Simon Cruanes, and Florian Angeletti, review by Daniel Bünzli, Guillaume Munch-Maccagnoni, Clément Allain, Damien Doligez, Wiktor Kuchta, and Pieter Goetschalckx)

• #12716: Add Format.pp_print_nothing function. (Léo Andrès, review by Gabriel Scherer and Nicolás Ojeda Bär)

• (Breaking Change) #6732, #12423: Make Buffer.add_substitute surjective and fix its documentation. (Damien Doligez, review by Antonin Décimo)

• (Breaking Change) #10775, #12499: Half-precision, floating-point elements in Bigarray. (Anton Yabchinskiy, review by Xavier Leroy and Nicolás Ojeda Bär)

• #11517, #12477: Expose pp_infinity in interface of the format module and check that margin is less than pp_infinity when setting or checking geometry. (Janith Petangoda, reported by Simmo Saan, reviewed by Florian Angeletti, Simmo Saan, Josh Berdine, and Gabriel Scherer)

• #12217: Add Array.shuffle. (Daniel Bünzli, review by Nicolás Ojeda Bär, David Allsopp, and Alain Frisch)

• #12212: Add cache-aligned constructor for atomics. The patch ensures that all allocations (of the right size) in the shared heap are aligned. (Bartosz Modelski with Gabriel Scherer, Guillaume Munch-Maccagnoni, Xavier Leroy, review by Alain Frisch, Anil Madhavapeddy, Gabriel Scherer, Guillaume Munch-Maccagnoni, KC Sivaramakrishnan, Stefan Muenzel, Xavier Leroy)

• #12307: Add BLAKE2b hashing and an MD5 submodule to the Digest module. (Xavier Leroy, review by Olivier Nicole, Gabriel Scherer, Wiktor Kuchta, Daniel Bünzli, David Allsopp)

• #12365: Add In_channel.input_bigarray, In_channel.really_input_bigarray, Out_channel.output_bigarray, Unix.read_bigarray, Unix.write_bigarray, Unix.single_write_bigarray. (Nicolás Ojeda Bär, review by Jeremy Yallop, Xavier Leroy, Gabriel Scherer, David Allsopp)

• #12455: Add Array.init_matrix, Float.Array.make_matrix, Float.Array.init_matrix. (Glen Mével, review by Xavier Leroy, Gabriel Scherer, Jeremy Yallop, Nicolas Ojeda Bar)

• (Breaking Change) #12455: Array.make_matrix dimx dimy f now raises Invalid_argument when dimx = 0 && dimy < 0. This was already specified but not enforced. (Glen Mével, report by Jeremy Yallop, review by Nicolas Ojeda Bar)

• #12459: Add Random.int_in_range, Random.int32_in_range, Random.int64_in_range, Random.nativeint_in_range, and their counterpart in Random.State. (Glen Mével and Xavier Leroy, review by Gabriel Scherer, Xavier Leroy, Florian Angeletti)

• #12459: Random: Restore compatibility between 32-bit integers (JavaScript) and 63-bit integers (64-bit OCaml). For Random.full_int this was guaranteed in 4.14 but wrongly removed in 5.0. (Xavier Leroy, review by Glen Mével)

• #12511: Minor performance improvements and cleanups in the implementation of modules Int32, Int64, and Nativeint (Xavier Leroy, review by Gabriel Scherer and Daniel Bünzli)

• #12558: Adapt GC alarms for Multicore and fix their documentation. (Guillaume Munch-Maccagnoni, review by KC Sivaramakrishnan and Gabriel Scherer)

• #12625: Remove the Closure module from Obj (Vincent Laviron, review by Xavier Leroy)

• #12758, #12998: Remove the Marshal.Compression flag to the Marshal.to_* functions. The compilers are still able to use ZSTD compression for compilation artefacts. This is a forward port and clean-up of the emergency fix that was introduced in OCaml 5.1.1 by #12734. (Xavier Leroy, review by Damien Doligez)

• #12784: Fix computation of minor-heap allocation in Gc.counters() and Gc.allocated_bytes(). (Nick Barnes, review by Gabriel Scherer)

• #12770: Add Fun.compose. (Justin Frank, review by Nicolás Ojeda Bär, Daniel Bünzli, and Jeremy Yallop)

• #12845: Add {In,Out}_channel.is_binary_mode as the dual of set_binary_mode. This function was previously only available in the internal C API. (David Allsopp, review by Nicolás Ojeda Bär and Xavier Leroy)

Type System:

• #12313, #11799: Do not rebuild as-pattern types when a ground type annotation is given. This allows to work around problems with GADTs in as-patterns. (Jacques Garrigue, report by Leo White, review by Gabriel Scherer)

Code Generation and Optimisations:

• #11239: On x86-64 and RISC-V, reduce alignment of OCaml stacks from 16 to 8. This reduces stack usage. It's only C stacks that require 16-alignment. (Xavier Leroy, review by Gabriel Scherer and Stephen Dolan)

• #12311: On POWER, 32-bit FP numbers stored in memory (e.g., in Bigarrays) were not correctly rounded sometimes. (Xavier Leroy, review by Anil Madhavapeddy and Tim McGilchrist)

• #12551, #12608, #12782, #12596: Overhaul of recursive value compilation. Non-function recursive bindings are now forbidden from Lambda onwards, and they're compiled using a new Value_rec_compiler module. (Vincent Laviron and Lunia Ayanides, review by Gabriel Scherer, Stefan Muenzel and Nathanaëlle Courant)

• #1809, #12181: Rewrite compare x y op 0 to x op y when values are integers (Xavier Clerc, Stefan Muenzel, review by Gabriel Scherer and Vincent Laviron)

• #12825: Disable common subexpression elimination for atomic loads... again. (Gabriel Scherer, review by KC Sivaramakrishnan, Xavier Leroy and Vincent Laviron, report by Vesa Karvonen)

Other Libraries:

• #12213: Dynlink library, improve legibility of error messages (Samuel Hym, review by Gabriel Scherer and Nicolás Ojeda Bär)

• (Breaking Change) #12686: Runtime_events library, C API: define caml_runtime_events_{start,pause,resume} as returning void instead of value. (Xavier Leroy, review by David Allsopp)

Compiler User-Interface and Warnings:

• #11989, #12246, RFC 31: New flag, -H, to allow for transitive dependencies without including them in the initial environment. (Chris Casinghino, François Bobot, and Gabriel Scherer, review by Leo White and Stefan Muenzel, RFC by François Bobot)

• (Breaking Change) #10613, #12405: Simplify the values used for the system variable (system: in ocamlopt -config or the Config.system constant). In particular, s390x and ppc64 now report "linux" instead of "elf"; all variants of 32-bit ARM on Linux now report "linux"; OpenBSD now reports "openbsd" instead of "bsd" for 32-bit ARM; FreeBSD, NetBSD, and OpenBSD now report the same value for both x86_64 and x86_32; x86_32 systems matching BSD but not FreeBSD, NetBSD*, or OpenBSD* are no longer identified (as on x86_64); x86_32 Linux now reports "linux" instead of "linux_elf". (David Allsopp, request by Kate Deplaix, review by Sébastien Hinderer and Xavier Leroy)

• #12247: Configure: --disable-ocamldebug can now be used instead of --disable-debugger (which remains available for compatibility) (Gabriel Scherer, review by Damien Doligez and Sébastien Hinderer)

• #12199: Improve the error message for non-overriding inherit! (Florian Angeletti, review by Jules Aguillon)

• #12210: Uniform style for inline code in compiler messages (Florian Angeletti, review by Gabriel Scherer)

• (Breaking Change) #12278, #:12325: Remove the OCAML_FLEXLINK environment variable from the compiler drivers. This environment variable was previously used as part of the FlexDLL bootstrap procedure and existed solely for that purpose. Its removal greatly simplifies both the build system and testsuite machinery. (David Allsopp, review by Sébastien Hinderer)

• #12347: Error messages: always report missing polyvariant tags (Florian Angeletti, report by Tianbo Hao, review by Gabriel Scherer)

• #12224: Specialised error message when trying to apply non-functor module (e.g., module M = Int(Int)) (Florian Angeletti, review by Gabriel Scherer)

• #12451: Warning 53 (misplaced attributes) now works for all attributes. (Chris Casinghino, review by Florian Angeletti)

• #12622: Give hints about existential types appearing in error messages (Leo White, review by Gabriel Scherer and Florian Angeletti)

• #12671: When a class type parameter or class parameter does not match, identify which parameter in the error message, instead of saying "A type parameter" or "A parameter." (Stefan Muenzel, review by Gabriel Scherer)

• #12679: Add more detail to the error message and manual in case of invalid module type substitutions. (Stefan Muenzel, review by Gabriel Scherer and Florian Angeletti)

• #12750: Display the command executed to extract primitives in ocamlc -verbose (David Allsopp, review by Nicolás Ojeda Bär)

• #12777: Add details about the actual and expected method types to the method mismatch error messages (Javier Chávarri, review by Gabriel Scherer and Florian Angeletti)

• (Breaking Change) #12942: Fix line ordering in some module inclusion error messages (Nick Roberts, review by Florian Angeletti, report by Carl Eastlund)

Manual and Documentation:

• #12338: Clarification of the documentation of process related function in the Unix module regarding the first element of arguments and shell's PID (Christophe Raffalli, review by Florian Angeletti)

• #12473: Document in runtime/memory.c our current understanding of accesses to the OCaml heap from the C runtime code -- the problem of hybrid programs mixing two memory models (Gabriel Scherer and Guillaume Munch-Maccagnoni, review by Olivier Nicole and Xavier Leroy)

• #12456: Document the incompatibility between effects, on one hand, and caml_callback and asynchronous callbacks (signal handlers, finalisers, memprof callbacks...), on the other (Guillaume Munch-Maccagnoni, review by KC Sivaramakrishnan)

• #12694: Document in runtime/tsan.c the TSan instrumentation choices and the consequences with regard to the memory model (Olivier Nicole, review by Miod Vallat, Gabriel Scherer, Guillaume Munch-Maccagnoni and Fabrice Buoro)

• #12802: Add manual chapter about ThreadSanitizer support (Olivier Nicole, review by Miod Vallat, Sebastien Hinderer, Fabrice Buoro, Gabriel Scherer and KC Sivaramakrishnan)

• #12819: Clarify which runtime interactions are allowed in custom ops (Basile Clément, review by Guillaume Munch-Maccagnoni and Xavier Leroy)

• #12840: Manual: update runtime tracing chapter for custom events (e.g., #12335) (Lucas Pluvinage, Sadiq Jaffer and Olivier Nicole, review by Gabriel Scherer, David Allsopp, Tim McGilchrist, and Thomas Leonard)

• #13066: Update OCAMLRUNPARAM documentation for the stack size parameter l (Florian Angeletti, review by Nicolás Ojeda Bär, Tim McGilchrist, and Miod Vallat)

• #13078: Update Format tutorial on structural boxes to mention alignment questions (Edwin Török, review by Florian Angeletti)

• #13092: Document the existence of the [@@poll error] built-in attribute (Florian Angeletti, review by Gabriel Scherer)

Tools:

• #12340: testsuite: collect known issues with current -short-paths implementation for existential types (Florian Angeletti, Samuel Hym, review by Florian Angeletti and Thomas Refis)

• #12147: ocamllex: allow carriage returns at the end-of-line directives (SeungCheol Jung, review by Nicolás Ojeda Bär)

• #12260: Fix invalid_argument on some external or module aliases in ocamlnat (Fabian Hemmer, review by Vincent Laviron)

• #12185: New script language for ocamltest (Damien Doligez with Florian Angeletti, Sébastien Hinderer, Gabriel Scherer, review by Sébastien Hinderer and Gabriel Scherer)

• #12371: ocamltest: fix recursive expansion of variables (Antonin Décimo, Damien Doligez, review by Sébastien Hinderer, Damien Doligez, Gabriel Scherer, and Xavier Leroy)

• (Breaking Change) #12497, #12613: Make ocamlc/ocamlopt fail with an error when no input files are specified to build an executable (Antonin Décimo, review by Sébastien Hinderer)

• #12576: ocamldep : various refactors (Antonin Décimo, review by Florian Angeletti, Gabriel Scherer, and Léo Andrès)

• #12615: ocamldoc: get rid of the odoc_literate and odoc_todo generators (Sébaistien Hinderer, review by Gabriel Scherer and Florian Angeletti)

• #12624: Use $XDG_CONFIG_DIRS in addition to $XDG_CONFIG_HOME when searching for init.ml, and use this to extend init.ml support to the toplevel when running on Windows. (David Allsopp, report by Jonah Beckford, review by Nicolás Ojeda Bär and Antonin Décimo)

• #12688: Setting the env variable NO_COLOR with an empty value no longer has effects. Previously, setting NO_COLOR with any value, including the empty value, would disable colours (unless OCAML_COLOR is also set). After this change, the user must set NO_COLOR with an non-empty value to disable colours. This reflects a specification clarification/change from the upstream website at https://no-color.org. (Favonia, review by Gabriel Scherer)

• #12744: ocamltest: run tests in recursive subdirs more eagerly (Nick Roberts, review by Nicolás Ojeda Bär)

• #12901, 12908: ocamllex: add overflow checks to prevent generating incorrect lexers; use unsigned numbers in the table encoding when possible (Vincent Laviron, report by Edwin Török, review by Xavier Leroy)

Internal/compiler-libs Changes:

• #12508 : Add compiler-side support for project-wide occurrences in Merlin by generating index tables of all identifier occurrences. This extra data in .cmt files is only added when the new flag -bin-annot-occurrences is passed. (Ulysse Gérard, Nathanaëlle Courant, suggestions by Gabriel Scherer and Thomas Refis, review by Florian Angeletti, Gabriel Scherer, and Thomas Refis)

• #12236, #12386, #12391, #12496, #12673: Use syntax as sole determiner of arity. This changes function arity to be based solely on the source program's parsetree. Previously, the heuristic for arity had more subtle heuristics that involved type information about patterns. Function arity is important because it determines when a pattern match's effects run and is an input into the fast path for function application.

  This change affects tooling; it changes the function constructs in parsetree and typedtree.

  See https://github.com/ocaml/RFCs/pull/32 for the original RFC.

  (Nick Roberts; review by Richard Eisenberg, Leo White, and Gabriel Scherer; RFC by Stephen Dolan)

• #12639: Parsing: attach a location to the RHS of Ptyp_alias and improve the 'alias type mismatch' error message. (Jules Aguillon, review by Florian Angeletti)

• #12447: Remove 32-bit targets from X86_proc.system (Masanori Ogino, review by David Allsopp)

• #12216, #12248: Prevent reordering of atomic loads during instruction scheduling. This is for reference, as instruction scheduling is currently unused in OCaml 5. (Xavier Leroy, report by Luc Maranget and KC Sivaramakrishnan, review by Nicolás Ojeda Bär)

• #12025: Split Typecore.unify_pat_types into two in order to avoid unnecessary references to the environment in type_pat (Jacques Garrigue and Takafumi Saikawa, review by Gabriel Scherer)

• #12031: Use dedicated types to represent names of compilation units and predefined exceptions in CMO files. (Sébastien Hinderer, review by Florian Angeletti, Thomas Refis, Gabriel Scherer, Vincent Laviron, Pierre Chambart, Luke Maurer, Hugo Heuzard, Xavier Leroy, and Damien Doligez)

• #12109: Pack parameters to unification in unification_environment (Takafumi Saikawa and Jacques Garrigue, review by Richard Eisenberg)

• #12331, #12361: Pack the unification data for pattern checking in Typecore (Takafumi Saikawa and Jacques Garrigue, review by Gabriel Scherer, Thomas Refis, and Florian Angeletti)

• #12229: Remove global mutable state for typechecking patterns in Typecore in favor of local mutable state. (Nick Roberts, review by Takafumi Saikawa)

• #12542: Minor bugfix to #12236: restore dropped call to instance (Nick Roberts, review by Jacques Garrigue)

• #12242: Move the computation of stack frame parameters to a separate Stackframe module, and save the parameters in the results of the Linearize pass. (Xavier Leroy, review by KC Sivaramakrishnan and Mark Shinwell)

• #12442: Document jump summaries in the pattern-matching compiler (Gabriel Scherer and Thomas Refis, review by Florian Angeletti and Vincent Laviron)

• #12446, #12792: Remove the hooks machinery around channel locking in runtime/io.c (Gabriel Scherer, review by Xavier Leroy)

• #12389, #12544, #12984, #12987: Centralise the handling of metadata for compilation units and artifacts in preparation to improve Unicode support for OCaml source files. (Florian Angeletti, review by Vincent Laviron and Gabriel Scherer)

• #12532, #12553: Improve readability of the pattern-matching debug output (Gabriel Scherer, review by Thomas Refis)

• #12537: Use C11/C++11 standard static assertion (Antonin Décimo, review by Sebastien Hinderer, Xavier Leroy, and KC Sivaramakrishnan)

• #12169: Runtime: document and enforce naming conventions around STW sections (Gabriel Scherer, review by Enguerrand Decorne, Miod Vallat, B. Szilvasy and Nick Barnes, report by KC Sivaramakrishnan)

• #12669 : Clean up some global state handling in schedgen (Stefan Muenzel, review by Miod Vallat and Gabriel Scherer)

• #12640: Make the module separator used in symbol names configurable (Miod Vallat, review by Hugo Heuzard and Xavier Leroy)

• #12691 : Clean up Ctype.expand_abbrev_gen and rename Env.add_local_type to add_local_constraint (Takafumi Saikawa and Jacques Garrigue, review by Florian Angeletti)

• #12786 : Clean up the algorithm of Ctype.limited_generalize (Takafumi Saikawa and Jacques Garrigue, review by Gabriel Scherer)

• #10691: Ast_mapper, Ast_iterator: add functions directive_argument, toplevel_directive, and toplevel_phrase (Guillaume Petiot, review by Gabriel Scherer and Kate Deplaix)

• #12764: Move all installable headers in caml/ subdirectories. (Antonin Décimo, review by Gabriel Scherer and David Allsopp)

• #12914: Slightly change the s390x assembly dialect in order to build with Clang's integrated assembler (Miod Vallat, review by Gabriel Scherer)

• #13001: Do not read_back entire shapes to get aliases' UIDs when building the usages index (Ulysse Gérard, review by Gabriel Scherer and Nathanaëlle Courant)

Build System:

• #12198, #12321, #12586, #12616, #12706, #13048: Continue the merge of the sub-Makefiles into the root Makefile started with #11243, #11248, #11268, #11420 and #11675. (Sébastien Hinderer, review by David Allsopp and Florian Angeletti)

• #12569, #12570: Remove otherlibraries as a prerequisite for runtop; use runtop-with-otherlibs to use a library from otherlibs/ (Gabriel Scherer, review by Sébastien Hinderer, suggestion by David Allsopp)

• #12652: Make magic numbers easier to bump and duplicate (Sébastien Hinderer, review by Antonin Décimo, David Allsopp and Florian Angeletti)

• (Breaking Change) #12751: --with-target-bindir configure option implemented. This option refers to the location of the runtime binaries on the target system for a cross-compiler and is embedded in executables produced by ocamlc. It does not affect the bytecode executables installed as part of the build. The old mechanism make TARGET_BINDIR=.. no longer works. (David Allsopp, review by Damien Doligez, Xavier Leroy, and Olivier Nicole)

• #12768, #13030: Detect MinGW-w64 coupling with GCC or LLVM, detect clang-cl, and fix C compiler feature detection on macOS. (Antonin Décimo, review by Miod Vallat and Sébastien Hinderer)

Bug Fixes:

• #10652, #12720: Fix evaluation order in presence of optional arguments (Jacques Garrigue, report by Leo White, review by Vincent Laviron)

• #12595, #12597: Fix a race in caml_clear_gc_stats_sample (Gabriel Scherer, review by B. Szilvasy, report by B. Szilvasy)

• #12580: Fix location of alias pattern variables (Chris Casinghino, review Gabriel Scherer, report by Milo Davis)

• #12583: Add a closing event for when EV_MAJOR_EPHE_MARK is complete (Sudha Parimala, review by Gabriel Scherer)

• #12566: caml_output_value_to_malloc wrongly uses caml_stat_alloc instead of malloc since 4.06, breaking (in pooled mode) user code that uses free on the result. Symmetrically, caml_input_value_from_malloc should use free. (Gabriel Scherer, review by Xavier Leroy and Enguerrand Decorne, report by Ido Yariv)

• #12490: Unix: protect the popen_processes hashtable with a mutex (Gabriel Scherer, report by Olivier Nicole, review by Xavier Leroy)

• #11931: Fix tricky typing bug with type substitutions (Stephen Dolan, review by Leo White and Jacques Garrigue)

• #12037, #12171: Fix get_extern_state potential NULL dereference (Alexander Skvortsov, report by Török Edwin, design by Gabriel Scherer, Xavier Leroy)

• #12635: Fix get_intern_state potential NULL dereference (Antonin Décimo, review by KC Sivaramakrishnan)

• #12032, #12059: Bug fixes related to compilation of recursive definitions (Vincent Laviron, report by Victoire Noizet, review by Gabriel Scherer)

• (Breaking Change) #12145: Loopy constraints cause ocamlc to loop. Fixed by completely removing the call to update_type in Typedecl.transl_type_decl, as the expansion is already checked by check_regularity. As a result, recursion is more polymorphic, which may cause some (essentially wrong) type declarations to have unbound type variables and some constraints unrelated to the concrete type to be ignored (see tests/typing-misc/constraints.ml). (Jacques Garrigue, report by Richard Eisenberg, review by Leo White)

• #12207, #12222: Make closure computation linear in the number of recursive functions instead of quadratic (Vincent Laviron, report by François Pottier, review by Nathanaëlle Courant and Gabriel Scherer)

• #11040, #12591: Fix a data race in major_gc.c (Gabriel Scherer, review by Guillaume Munch-Maccagnoni and KC Sivaramakrishnan, report by Sadiq Jaffer)

• #12238, #12403, #12698: Read input files in one go to avoid source reprinting issues (Gabriel Scherer, report by Mike Spivey and Vincent Laviron, review by Nicolás Ojeda Bär, Xavier Leroy and Jeremy Yallop)

• #12334, #12368: Bad error message with mutually recursive abbreviations (Jacques Garrigue, report by Richard Eisenberg, review by Gabriel Scherer and Richard Eisenberg)

• #12401: seek_in and seek_out sometimes returned normally when given negative offsets, instead of failing. Now both functions should consistently raise Sys_error in this case. (Nicolás Ojeda Bär, review by Gabriel Scherer)

• #12267: Fix stack alignment computation (Miod Vallat, report by Jan Midtgaard, review by Gabriel Scherer)

• #12395, #12404: Fix thread-unsafety in the fallback implementation of Unix.create_process (the one used when posix_spawnp is unavailable) (Xavier Leroy, report by Chris Vine, review by Nicolás Ojeda Bär)

• #12949: Open shadowing mistriggers (Gabriel Scherer, review by Florian Angeletti, report by Andreas Rossberg)

• #12526: Honor ocaml.inline always attribute on functions with optional arguments and default values in the Closure backend (Alain Frisch, review by Vincent Laviron)

• #12677, #12889: Make Domain.DLS thread-safe (Gabriel Scherer, review by Olivier Nicole and Damien Doligez, report by Vesa Karvonen)

• #12561: Fix crash when combining TSan and frame-pointers (Fabrice Buoro and Olivier Nicole, report by Jan Midtgaard, review by Miod Vallat and Gabriel Scherer)

• #12482: Rework bounds checking code in the POWER backend (Miod Vallat and Xavier Leroy, report by Jan Midtgaard, review by KC Sivaramakrishnan)

• #12528, #12703: Avoid pointer arithmetic overflow in Tag_val macro (very likely harmless, but can trigger alarms) (Xavier Leroy, report by Sam Goldman, review by Guillaume Munch-Maccagnoni)

• #12593: TSan should handle Effect.Unhandled correctly (Fabrice Buoro and Olivier Nicole, report by Jan Midtgaard and Miod Vallat, review by Gabriel Scherer)

• #12684: Fix locations filename in AST produced by the -pp option (Gabriel Scherer, review by Florian Angeletti)

• #12714: Check whether macros are defined before using them to ensure that the headers can always be used in code which turns on -Wundef (or equivalent). (Antonin Décimo, review by Miod Vallat, Gabriel Scherer, Xavier Leroy, and David Allsopp)

• #12726: Fix segmentation fault under Windows when executing a bytecode file if the runtime (ocamlrun.exe) cannot be found. (Vadim Zborovskii, Nicolás Ojeda Bär, report by Vadim Zborovskii, review by David Allsopp)

• #12727, #12730: Fix bug with value let-rec and labelled applications (Vincent Laviron, review by Gabriel Scherer)

• (Breaking Change) #12751: Always keep within the 128 character limit for shebang lines. Previous fix in #8622 handled building the compiler with a long prefix. This patch extends this to the bytecode executables emitted by that compiler. (David Allsopp, review by Damien Doligez, Xavier Leroy, and Olivier Nicole)

• #12755: Fix data race on global pools arrays of pool_freelist (Fabrice Buoro and Olivier Nicole, review by Gabriel Scherer)

• #12796, #12801: Fix memory corruption in caml_unix_alloc_sockaddr (Thomas Leonard, review by Nicolás Ojeda Bär)

• #12737: Fix data races in minor_gc.c and caml_natdynlink_open (Olivier Nicole, review by Stefan Muenzel, Miod Vallat, Guillaume Munch-Maccagnoni, Gabriel Scherer, and Xavier Leroy)

• #12831: Fix call to caml_call_realloc_stack for s390x in PIC mode (Vincent Laviron, report by Jerry James, review by Miod Vallat)

• (Breaking Change) #12837: Show non-generalisable type parameters in type definitions Changes type of type parameters in outcometree.mli. (Jacques Garrigue, review by Richard Eisenberg)

• #12897: Fix locking bugs in Runtime_events (Gabriel Scherer and Thomas Leonard, review by Olivier Nicole, Vincent Laviron, and Damien Doligez, report by Thomas Leonard)

• #12851: Fix race between runtime events teardown and event emission (Olivier Nicole, review by Miod Vallat and Gabriel Scherer)

• #12860: Fix an assertion that wasn't taking into account the possibility of an ephemeron pointing at static data (Mark Shinwell, review by Gabriel Scherer and KC Sivaramakrishnan)

• #12861: Fix a possible crash in the threads library (Mark Shinwell, review by Gabriel Scherer and KC Sivaramakrishnan)

• #11040, #12894: Silence false data race observed between caml_shared_try_alloc and oldify. Introduces macros to call TSan annotations which help annotate a "happens before" relationship. (Hari Hara Naveen S and Olivier Nicole, review by Gabriel Scherer and Miod Vallat)

• #12958: Fix tail-modulo-cons compilation of try-with, &&, and || expressions. (Gabriel Scherer and Nicolás Ojeda Bär, report by Sylvain Boilard, review by Gabriel Scherer)

• #12919: Fix register corruption in caml_callback2_asm on s390x. (Miod Vallat, review by Gabriel Scherer)

• #12924, #12930: Rework package constraint checking to improve interaction with immediacy (Chris Casinghino and Florian Angeletti, review by Florian Angeletti and Richard Eisenberg)

• #12969: Fix a data race in caml_darken_cont (Fabrice Buoro and Olivier Nicole, review by Gabriel Scherer and Miod Vallat)

• #12971, #12974: Fix an uncaught Ctype.Escape exception on some invalid programs forming recursive types. (Gabriel Scherer, review by Florian Angeletti, report by Neven Villani)

• #13019: Remove linking instructions for the Unix library from threads.cma. (This was done for threads.cmxa in OCaml 3.11.) Eliminates warnings from new LLD when using threads.cma of duplicated libraries. (David Allsopp, review by Nicolás Ojeda Bär)

• #13058: Add TSan instrumentation to caml_call_gc(), since it may raise exceptions. (Fabrice Buoro, Olivier Nicole, Gabriel Scherer, and Miod Vallat)

• #13079: Save and restore frame pointer across Iextcall on ARM64 (Tim McGilchrist, review by KC Sivaramakrishnan and Miod Vallat)

• #13094: Fix undefined behavior of left-shifting a negative number (Antonin Décimo, review by Miod Vallat and Nicolás Ojeda Bär)

• #13130: Minor fixes to Pprintast for raw identifiers and local module open syntax for types (Chet Murthy, review by Gabriel Scherer)

• Add support for OCaml 5.2

• Insert errors from caught located exceptions in place of the code that should have been generated by context-free rules. (#472, @NathanReb)

Added

• OCaml 5.2.0 compatibility (@Octachron, #1094, #1112)

Fixed

• Fix issues #1066 and #1095 with extended opens (@jonludlam, #1082, #1100)

Changed

• Compatible with OCaml 5.2.0 (#2510, @gpetiot, @Julow)

Fixed

• If no directory targets are defined, then do not evaluate enabled_if (#10442, @rgrinberg)

• Fix a bug where Coq projects were being rebuilt from scratch each time the dependency graph changed. (#10446, fixes #10149, @alizter)

Changed

• Revert #446: "Allow execution of included OCaml code blocks" (#451, @gpetiot). Included OCaml code blocks preserve their pre-2.4.0 behavior.

Added

• Add link flags to to ocamlmklib for ctypes stubs (#8784, @frejsoya)

• Remove some unnecessary limitations in the expansions of percent forms in install stanza. For example, the %{env:..} form can be used to select files to be installed. (#10160, @rgrinberg)

• Allow artifact expansion percent forms (%{cma:..}, %{cmo:..}, etc.) in more contexts. Previously, they would be randomly forbidden in some fields. (#10169, @rgrinberg)

• Allow %{inline_tests} in more contexts (#10191, @rgrinberg)

• Remove limitations on percent forms in the (enabled_if ..) field of libraries (#10250, @rgrinberg)

• Support dialects in dune describe pp (#10283, @emillon)

• Allow defining executables or melange emit stanzas with the same name in the same folder under different contexts. (#10220, @rgrinberg, @jchavarri)

Fixed

• coq: Delay Coq rule setup checks so OCaml-only packages can build in hybrid Coq/OCaml projects when coqc is not present. Thanks to @vzaliva for the test case and report (#9845, fixes #9818, @rgrinberg, @ejgallego)

• Fix conditional source selection with select on bigarray in OCaml 5 (#10011, @moyodiallo)

• melange: fix inconsistency in virtual library implementation. Concrete modules within a virtual library can now refer to its virtual modules too (#10051, fixes #7104, @anmonteiro)

• melange: fix a bug that would cause stale import paths to be emitted when moving source files within (include_subdirs ..) (#10286, fixes #9190, @anmonteiro)

• Dune file formatting: output utf8 if input is correctly encoded (#10113, fixes #9728, @moyodiallo)

• Fix expanding dependencies and locks specified in the cram stanza. Previously, they would be installed in the context of the cram test, rather than the cram stanza itself (#10165, @rgrinberg)

• Fix bug with dune exec --watch where the working directory would always be set to the project root rather than the directory where the command was run (#10262, @gridbugs)

• Regression fix: sign executables that are promoted into the source tree (#10263, fixes #9272, @emillon)

• Fix crash when decoding dune-package for libraries with (include_subdirs qualified) (#10269, fixes #10264, @emillon)

Changed

• Remove the --react-to-insignificant-changes option. (#10083, @rgrinberg)

Added

• Handle the error-blocks syntax (#439, @jonludlam, @gpetiot)
• Allow execution of included OCaml code blocks. Add skip to include blocks to revert to the old behavior (#446, @panglesd, @gpetiot) Warning: this is a breaking change that is reverted in the next release.
• Make MDX compatible with OCaml 5.2 (#448, @gpetiot)

Fixed

• Reduce false-positives while detecting warnings (#440, @Julow)

Fixed

• When a directory is changed to a file, correctly remove it in subsequent dune build runs. (#9327, fix #6575, @emillon)

• Fix a problem with the doc-new target where transitive dependencies were missed during compile. This leads to missing expansions in the output docs. (#9955, @jonludlam)

• coq: fix performance regression in coqdep unescaping (#10115, fixes #10088, @ejgallego, thanks to Dan Christensen for the report)

• coq: memoize coqdep parsing, this will reduce build times for Coq users, in particular for those with many .v files (#10116, @ejgallego, see also #10088)

• on Windows, use an unicode-aware version of CreateProcess to avoid crashes when paths contains non-ascii characters. (#10212, fixes #10180, @emillon)

• fix compilation on non-glibc systems due to signal.h not being pulled in spawn stubs. (#10256, @emillon)

• Add support for OCaml 5.2 (#470, fixes #466, @leostera, @ManasJayanth, @huwaireb)

• merlin binary
  • Add a "heap_mbytes" field to Merlin server responses to report heap usage (#1717)
  • Add cache stats to telemetry (#1711)
  • Add new SyntaxDocument command to find information about the node under the cursor (#1706)
  • Fix FLG -pp ppx.exe -as-pp/-dump-ast use of invalid shell redirection when direct process launch on Windows. (#1723, fixes #1722)
  • Add a query_num field to the ocamlmerlin responses to detect server crashes (#1716)
  • Jump to cases within a match statement (#1726)
  • Jump to module-type (#1728, partially fixes #1656)
  • Exposes stable functions for configuration handling and pattern variable destruction. (#1730)
• editor modes
  • vim: load merlin under the ocamlinterface and ocamllex filetypes (#1340)
  • Fix merlinpp not using binary file open (#1725, fixes #1724)

Added

• Introduce a (dynamic_include ..) stanza. This is like (include foo) but allows foo to be the target of a rule. Currently, there are some limitations on the stanzas that can be generated. For example, public executables, libraries are currently forbidden. (#9913, @rgrinberg)

• Introduce $ dune promotion list to print the list of available promotions. (#9705, @moyodiallo)

• If Sherlodoc is installed, add a search bar in generated HTML docs (#9772, @EmileTrotignon)

• Add only_sources field to copy_files stanza (#9827, fixes #9709, @jchavarri)

• The (foreign_library) stanza now supports the (enabled_if) field. (#9914, @nojb)

Fixed

• Fix $ dune install -p incorrectly recognizing packages that are supposed to be filtered (#9879, fixes #4814, @rgrinberg)

• subst: correctly handle opam files in opam/ subdirectory (#9895, fixes #9862, @emillon)

• Odoc private rules are not set up if a library is not available due to enabled_if (#9897, @rgrinberg and @jchavarri)

Changed

• When dune language 3.14 is enabled, resolve the binary in (run %{bin:..} ..) from where the binary is built. (#9708, @rgrinberg)

• boot: remove single-command bootstrap. This was an alternative bootstrap strategy that was used in certain conditions. Removal makes the bootstrap a bit slower on Linux when only a single core is available, but bootstrap is now reproducible in all cases. (#9735, fixes #9507, @emillon)

• Add an optional embed_errors argument to Context_free.map_top_down that controls how to deal with exceptions thrown by context-free rules. (#468, @NathanReb)

• Fix Longident.parse so it properly handles unparenthesized dotted operators such as +. or *.. (#111, @rgrinberg, @NathanReb)

• raising an exception does no longer cancel the whole context free phase(#453, @burnleydev1)

• Sort embedded errors that are appended to the AST by location so the compiler reports the one closer to the beginning of the file first. (#463, @NathanReb)

• Update Attribute.get to ignore loc_ghost. (#460, @ceastlund)

• Add API to manipulate attributes that are used as flags (#408, @dianaoigo)

• Update changelog to use ISO 8061 date format: YYYY-MM-DD. (#445, @ceastlund)

• Replace Caml with Stdlib. (#427, @ceastlund)

• When a transformation raises, the last valid AST is used as input to the upcoming transformations. All such errors are collected and appended as extension nodes to the final AST (#447, @burnleydev1)

• Fix a small mistake in the man pages: Embededding errors is done by default with -as-pp, not with -dump-ast (#464, @pitag-ha)

• Set appropriate binary mode when writing to stdout especially for Windows compatibility. (#466, @jonahbeckford)

• Fix performance regression for incremental builds (#9769, fixes #9738, @rgrinberg)

• Fix dune ocaml top-module to correctly handle absolute paths. (#8249, fixes #7370, @Alizter)

• subst: ignore broken symlinks when looking at source files (#9810, fixes #9593, @emillon)

• subst: do not fail on 32-bit systems when large files are encountered. Just log a warning in this case. (#9811, fixes #9538, @emillon)

• boot: sort directory entries in readdir. This makes the dune binary reproducible in terms of filesystem order. (#9861, fixes #9794, @emillon)

Fixed

• Revert to outputing a file (without content) when rendering a hidden compilation unit. This fixes cases where the dune rules would fail. (@panglesd, #1069)

Added

• Add command dune cache clear to completely delete all traces of the Dune cache. (#8975, @nojb)

• Allow to disable Coq 0.8 deprecation warning (#9439, @ejgallego)

• Allow OCAMLFIND_TOOLCHAIN to be set per context in the workspace file through the env stanza. (#9449, @rgrinberg)

• Menhir: generate .conflicts file by default. Add new field to the (menhir) stanza to control the generation of this file: (explain <blang expression>). Introduce (menhir (flags ...) (explain ...)) field in the (env) stanza, delete (menhir_flags) field. All changes are guarded under a new version of the Menhir extension, 3.0. (#9512, @nojb)

• Directory targets can now be cached. (#9535, @rleshchinskiy)

• It is now possible to use special forms such as (:include) and variables %{read-lines:} in (modules) and similar fields. Note that the dependencies introduced in this way (i.e., the files being read) must live in a different directory than the stanza making use of them. (#9578, @nojb)

• Remove warning 30 from default set for projects where dune lang is at least 3.13 (#9568, @gasche)

• Add coqdoc_flags field to coq field of env stanza, allowing the setting of workspace-wide defaults for coqdoc_flags. (#9280, fixes #9139, @Alizter)

• ctypes: fix an error where (ctypes) with no (function_description) would cause an error trying refer to a nonexistent _stubs.a dependency (#9302, fix #9300, @emillon)

Changed

• Check that package names in (depends) and related fields in dune-project are well-formed. (#9472, fixes #9270, @ElectreAAS)

Fixed

• Do not ignore (formatting ..) settings in context or workspace files (#8447, @rgrinberg)

• Fixed a bug where Dune was incorrectly parsing the output of coqdep when it was escaped, as is the case on Windows. (#9231, fixes #9218, @Alizter)

• Copying mode for sandboxes will now follow symbolic links (#9282, @rgrinberg)

• Forbid the empty (binaries ..) field in the env stanza in the workspace file unless language version is at least 3.2. (#9309, @rgrinberg)

• [Coq] Fix bug in computation of flags when composed with boot theories. (#9347, fixes #7909, @ejgallego)

• Fixed a bug where the (select) field of the (libraries) field of the (test) stanza wasn't working properly. (#9387, fixes #9365, @Alizter)

• Fix handling of the PATH argument to dune init proj NAME PATH. An intermediate directory called NAME is no longer created if PATH is supplied, so dune init proj my_project . will now initialize a project in the current working directory. (#9447, fixes #9209, @shonfeder)

• Experimental doc rules: Correctly handle the case when a package depends upon its own sublibraries (#9461, fixes #9456, @jonludlam)

• Resolve various public binaries to their build location, rather than to where they're copied in the _build/install directory (#9496, fixes #7908, @rgrinberg).

• Correctly ignore warning flags in vendored projects (#9515, @rgrinberg)

• Use watch exclusions in watch mode on MacOS (#9643, fixes #9517, @PoorlyDefinedBehaviour)

• Fix Merlin configuration for (include_subdirs qualified) modules (#9659, fixes #8297, @rgrinberg)

• Fix handling of enabled_if in binary install stanzas. Previously, we'd ignore the result of enabled_if when evaluating %{bin:..} (#9707, @rgrinberg)

Fixed

• Fix version check in runtest_alias for cram stanza (#9454, @emillon)

• Fix stack overflow when a (run) action can not be parsed. (#9530, fixes #9529, @gridbugs)

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)

Fixes

• Fix missing super & subscripts in markdown documentation. (#1170)
• Do not invoke dune at all if --fallback-read-dot-merlin flag is on. (#1173)
• Fix semantic highlighting of infix operators that contain '.'. (#1186)
• Disable highlighting unit as an enum member to fix comment highlighting bug. (#1185)
• Improve type-on-hover and type-annotate efficiency by only formatting the type of the first enclosing. (#1191, #1196)
• Fix the encoding of URI's to match how vscode does it (#1197)
• Fix parsing of completion prefixes (#1181)

Features

• Compatibility with Odoc 2.3.0, with support for the introduced syntax: tables, and "codeblock output" (#1184)
• Display text of references in doc strings (#1166)
• Add mark/remove unused actions for open, types, for loop indexes, modules, match cases, rec, and constructors (#1141)
• Offer auto-completion for the keyword in (#1217)

Added

• Add support for external search engines (@panglesd, @EmileTrotignon, #972) This includes the generation of an index and the display of the results in the UI (HTML only).
• Display 'private' keyword for private type extensions (@gpetiot, #1019)
• Allow to omit parent type in constructor reference (@panglesd, @EmileTrotignon, #933)

Fixed

• Warn and exit when table(s) is not closed (@lubegasimon, #1050)
• Hint when list(s) is not closed (@lubegasimon, #1050)
• Fix crash on functors returning an alias (@Julow, #1046)
• Fix rendering of polymorphic variants (@wikku, @panglesd, #971)
• Add references to extension declarations (@gpetiot, @panglesd, #949)

Changed

• Style: Adjusted line height in the TOC to improve readability (@sorawee, #1045)
• Style: Remove font fallback to Helvetica, Arial (@Julow, #1028)
• Style: Preformatted elements fallback to UA monospace (@toastal, #967)
• Style: Sidebar is now stuck to the left of the content instead of the left of the viewport (@EmileTrotignon, #999)

• merlin binary
  • Fix a follow-up issue to the preference of non-ghost nodes introduced in #1660 (#1690, fixes #1689)
  • Add -cache-lifespan flag, that sets cache invalidation period. (#1698, #1705)
  • Fix Merlin locate not fallbacking on the correct file in case of ambiguity (@goldfirere, #1699)
  • Fix Merlin reporting errors provoked by the recovery itself (#1709, fixes #1704)
• editor modes
  • vim: load merlin when Vim is compiled with +python3/dyn (e.g. MacVim)
  • emacs: highlight only first error line by default (#1693, fixes #1663)

Added

• Introduce $ dune ocaml doc to open and browse documentation. (#7262, fixes #6831, @EmileTrotignon)

• dune cache trim now accepts binary byte units: KiB, MiB, etc. (#8618, @Alizter)

• Introduce the runtest_alias field to the cram stanza. This allows removing default runtest alias from tests. (@rgrinberg, #8887)

• Display cache location in Dune log (#8974, @nojb)

• Dune can now be built and installed on Haiku (#8795, fix #8551, @Alizter)

• Mark installed directories in dune-package files. This fixes (package) dependencies against packages that contain such directories. (#8953, fixes #8915, @emillon)

• Introduce new experimental odoc rules (#8803, @jonjudlam)

Changed

• dune-build-info: when version="" is found in a META file, we now return None as a version string (#9177, @emillon)

• No longer force colors for OCaml 4.03 and 4.04 (#8778, @rgrinberg)

• Dependencies in the copying sandbox are now writeable (#8920, @rgrinberg)

• Rules that only use internal dune actions (write-file, echo, etc.) can now be sandboxed. (#9041, fixes #8854, @rgrinberg)

• Add test_ prefix to default test name in dune init project (#9257, fixes #9131, @9sako6)

Fixed

• Do not ignore libraries named bigarray when they are defined in conjunction with OCaml 5.0 (#8902, fixes #8901, @rgrinberg)

• Correctly ignore bigarray on recent versions of OCaml (#9076, @rgrinberg)

• Absent packages shouldn't prevent all rules from being loaded (#8948, fixes #8630, @rgrinberg)

• Correctly determine the stanza of menhir modules when (include_subdirs qualified) is enabled (@rgrinberg, #8949, fixes #7610)

• Re-run actions whenever (expand_aliases_in_sandbox) changes (#8990, @rgrinberg)

• Do not re-run rules when their location changes (#9052, @rgrinberg)

• [coq rules] Be more tolerant when coqc --print-version / --config don't work properly, and fallback to a reasonable default. This fixes problems when building Coq projects with (stdlib no) and likely other cases. (#8966, fix #8958, @Alizter, reported by Lasse Blaauwbroek)

• Dune will now run at a lower framerate of 15 fps rather than 60 when INSIDE_EMACS. (#8812, @Alizter)

• Add a new --no-confirmation argument for use in automated pipeline [#158 @AltGr - fix #132]
• Improve the error message when a file expected to be an opam file is given as argument [#150 @kit-ty-kate - partially fix #149]
• Adopt the OCaml Code of Conduct [#151 @rikusilvola]
• Changes the makefile to make sure the standard "make && make install" works [#157 @kit-ty-kate]

• Fix 5.1 support (@tmcgilchrist, odoc#1018)

Fixed

• Fix dune rpc commands on Windows (#8806, fixes #8799, @nojb)

• Fix inline_tests when the partition list is empty (#8849, fixes #8848, @hhugo)

• Fix support for OCaml 5.1: migrated code preserves generative functor warnings, without creating more. Locations are better preserved. (#432, @pitag-ha, @panglesd)

• Driver: Add -unused-code-warnings command-line flag. (#444, @ceastlund)

• Add ?warning flag to Deriving.Generator.make. (#440, @jacksonzou123 via @ceastlund)

• Restore the path_arg functionality in the V3 API. (#431, @ELLIOTTCABLE)

• Expose migration/copying/etc. functions for all AST types needed by Pprintast. (#454, @antalsz)

• Preserve quoted attributes on antiquotes in metaquot. (#441, @ncik-roberts)

• Attribute namespaces: Fix semantics of reserving multi-component namespaces. (#443, @ncik-roberts)

Added

• enabled_if now supports arch_sixtyfour variable (#8023, fixes #7997, @Alizter)

• Experimental: Added a $ dune monitor command that can connect to a running dune build in watch mode and display the errors and progress. (#8152, @Alizter)

• The progress RPC procedure now has an extra field for the In_progress constructor for the number of failed jobs. (#8212, @Alizter)

• Add a --preview flag to dune fmt which causes it to print out the changes it would make without applying them (#8289, @gridbugs)

• Introduce (source_trees ..) to the install stanza to allow installing entire source trees. (#8349, @rgrinberg)

• Add --stop-on-first-error option to dune build which will terminate the build when the first error is encountered. (#8400, @pmwhite and @Alizter)

• Dune now displays the number of errors when waiting for changes in watch mode. (#8408, fixes #6889, @Alizter)

• Add with_prefix keyword for changing the prefix of the destination of installed files matched by globs. (#8416, @gridbugs)

• Added experimental --display tui option for Dune that opens an interactive Terminal User Interface (TUI) when Dune is running. Press '?' to open up a help screen when running for more information. (#8429, @Alizter and @rgrinberg)

• Add a warnings field to dune-project files as a unified mechanism to enable or disable dune warnings (@rgrinberg, 8448)

• dune exec: support syntax like %{bin:program}. This can appear anywhere in the command line, so things like dune exec time %{bin:program} now work. (#6035, #8474, fixes #2691, @emillon, @Leonidas-from-XIV)

• Add a new alias @doc-json to build odoc documentation in JSON format. This output can be consumed by external tools. (#8178, @emillon)

Changed and Fixed

• Use posix_spawn instead of fork on MacOS. This gives us a performance boost and allows us to re-enable thread. (#8090, @rgrinberg)

• Modules that were declared in (modules_without_implementation), (private_modules) or (virtual_modules) but not declared in (modules) will raise an error. (#7674, @Alizter)

• No longer emit linkopts(javascript) in META files (#8168, @hhugo)

• RPC message styles are now serialised meaning that RPC diagnostics keep their ANSI styling. (#8516, fixes #6921, @Alizter)

• Truncate output from actions that produce too much output (@tov, #8351)

• Allow libraries to shadow OCaml built-in libraries. Previously, built-in libraries would always take precedence. (@rgrinberg, #8558)

• dune utop no longer links utop in "custom" mode, which should make this command considerably faster. (#8631, fixes #6894, @nojb)

• Ensure that package names in dune-project are valid opam package names. (#8331, @emillon)

• init: check that module names are valid (#8644, fixes #8252, @emillon)

• dune init: parse --public as a public name (#8603, fixes #7108, @emillon)

• Stop signing source files with substitutions. Sign only binaries instead (#8361, fixes #8360, @anmonteiro)

• Make copy sandbox support directory targets. (#8705, fixes #7724, @emillon)

Deprecated and Removed

• Deprecate install destination paths beginning with ".." to prevent packages escaping their designated installation directories. (#8350, @gridbugs)

• Remove warning against .dune files generated by pre Dune 2.0 (#8611, @rgrinberg)

• Remove versions 0.1 and 0.2 of the experimental ctypes extension. (#8293, @emillon)

Additions

• Source code rendering (@Julow, @panglesd, @jonludlam #909, #996, #993, #982)
• Handle tables markup (@panglesd, @gpetiot, #893)
• Initial support for assets (@trefis, #975)
• odoc-parser remerged (@jonludlam, #973) This includes table support (@gpetiot, @panglesd, ocaml-doc/odoc-parser#11 ocaml-doc/odoc-parser#14) and delimited code blocks with optional output (@jonludlam, ocaml-doc/odoc-parser#17)
• Add a tooltip to references with text (@Julow, #945)
• Add emoji to alerts in CSS (@yawaramin, #928)
• Add common language in shipped highlightjs (@Julow, #953)

Bugfixes

• Fix --hidden not always taken into account (@panglesd, #940)
• Syntax highlight labels in function arguments (@panglesd, #990)
• Ensure generated html ends with a newline (@3Rafal, #954)
• Warn against tags in pages (@Julow, #948)
• Remove unhelpful 'Unresolved_apply' errors (@gpetiot, #946)
• Allow links and references in headings (@EmileTrotignon, @panglesd, #942)
• Fix rendering of method types (@zoggy, #935)
• Fix section labelling with submodules (@EmileTrotignon, @panglesd, #931)
• LaTeX backend fixes (@Octachron, #921 #920)
• html: Remove extra space in class declarations (@Julow, #936)
• Fix rendering of unresolved references (@Julow, #957)

Added

• Add os_type label to enable/disable based on Sys.os_type (#433, @polytypic)

• Make MDX compatible with OCaml 5.1 (#435, @polytypic and @kit-ty-kate)

Changed

• Vendored the odoc-parser library, removing the need to have it as a dependency. (#430, @jonludlam)

• merlin binary
  • Fix issue with let operators and tuples (ocaml/merlin#1684, fixes ocaml/merlin#1683, fixes ocaml/ocaml-lsp#1182)
  • Fix an issue causing Merlin locate queries to hang (ocaml/merlin#1686, fixes ocaml/ocaml-lsp#1192)

• Merlin binary
  • Improve error messages for missing configuration reader (ocaml/merlin#1669)
  • Fix regression causing crash when using PPXs under Windows (ocaml/merlin#1673)
  • Fix confusion between aliased modules and module types (ocaml/merlin#1676, fixes ocaml/merlin#1667)
  • Ignore hidden branches when listing occurrences (ocaml/merlin#1677, fixes ocaml/merlin#1671)
• Editor modes
  • Emacs: fix/improve keybindings (ocaml/merlin#1668, fixes ocaml/merlin#1386): Unbind C-c C-r (to avoid shadowing tuareg-eval-region) and bind C-c C-v instead to merlin-error-check; rebind C-c C-d to merlin-document and bind C-c M-d and C-c | instead to merlin-destruct; bind C-u C-c C-t to merlin-type-expr.
  • Emacs: remove use of obsolete defadvice macro (ocaml/merlin#1675)

Changed

• Compatible with OCaml 5.1.0 (#2412, @Julow) The syntax of let-bindings changed sligthly in this version.
• Improved ocp-indent compatibility (#2428, @Julow)
• * Removed extra break in constructor declaration with comment (#2429, @Julow)
• * De-indent the object keyword in class types (#2425, @Julow)
• * Consistent formatting of arrows in class types (#2422, @Julow)

Fixed

• Fix dropped attributes on a begin-end in a match case (#2421, @Julow)
• Fix dropped attributes on begin-end in an if-then-else branch (#2436, @gpetiot)
• Fix non-stabilizing comments before a functor type argument (#2420, @Julow)
• Fix crash caused by module types with nested with module (#2419, @Julow)
• Fix ';;' formatting between doc-comments and toplevel directives (#2432, @gpetiot)

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. (T. 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)

• merlin binary
  • Constrain socket path buffer size to avoid build warnings (#1631)
  • Handle concurrent server start (#1622)
  • Omit module prefixes for constructors and record fields in the construct command (#1618). Prefixes are still produced when warning 42 (disambiguated name) is active.
  • Correctly invalidate PPX cache when pipeline ran partially (#1650, fixes #1647)
  • Prevent short-path from looping in some cases related to recursive type definitions (#1645)
  • Support parsing negative numbers in sexps (#1655)
  • Fix construct not working with inline records (#1658)
  • Improve behavior of type-enclosing on let/and operators (#1653)
  • Fix occurrences of extension constructors (#1662)
  • Improve node selection when ghosts are present (#1664, fixes #1660)
• editor modes
  • emacs: call merlin-client-logger with "interrupted" if the merlin binary itself is interrupted, not just the parsing of the result (#1626).
  • emacs: merlin-construct, with a prefix argument, now includes local values in the completion options. Alternatively, this behavior can be enabled permanently by customizing merlin-construct-with-local-values (#1644)
  • emacs: add support for opam-switch-mode (#1654, fixes #1591). See https://github.com/ProofGeneral/opam-switch-mode

Additions

• OCaml 5.1.0 compatibility (@Octachron, #956)

Fixes

• Fix flushing when using sendfile fallback (#8288, fixes #8284, @alan-j-hu)

Added

• Add dune show rules as alias of the dune rules command. (#8000, @Alizter)

• Add dune show installed-libraries as an alias of the dune installed-libraries command. (#8135, @Alizter)

• Add dune build --dump-gc-stats FILE argument to dump garbage collection stats to a named file. (#8072, @Alizter)

• Add dune describe package-entries to print all package entries (#7480, @moyodiallo)

Fixed

• Fix %{deps} to expand properly in (cat ...) when containing 2 or more items. (#8196, @Alizter)

• Fix the severity of error messages sent over RPC which was missing. (#8193, @Alizter)

• Fix bug with ppx and Reason syntax due to missing dependency in sandboxed action (#7932, fixes #7930, @Alizter)

Changed

• Improve dune describe external-lib-deps by adding the internal dependencies for more information. (#7478, @moyodiallo)

• Re-enable background file digests on Windows. The files are now open in a way that prevents race condition around deletion. (#8262, fixes #8268, @emillon)

Fixes

• Disable background digests on Windows. This prevents an issue where unremovable files would make Dune crash when the shared cache is enabled. (#8243, fixes #8228, @emillon)

• Fix permission errors when sendfile is not available (#8234, fixes #8210, @emillon)

Items marked with an asterisk (*) are changes that are likely to format existing code differently from the previous release when using the default profile.

New features

• Handle short syntax for generative functor types (#2348, @gpetiot)
• Improved error reporting for unstable or dropped comments (#2292, @gpetiot)

Removed

• Remove --numeric feature (#2333, #2357, @gpetiot)

Bug fixes

• Fix crash caused by let f (type a) :> a M.u = .. (#2399, @Julow)
• Fix crash caused by module T = (val (x : (module S))) (#2370, @Julow)
• Fix invalid formatting of then begin end (#2369, @Julow)
• Protect match after fun _ : _ -> (#2352, @Julow)
• Fix invalid formatting of (::) (#2347, @Julow)
• Fix indentation of module-expr extensions (#2323, @gpetiot)
• * Remove double parentheses around tuples in a match (#2308, @Julow)
• * Remove extra parentheses around module packs (#2305, @Julow, @gpetiot)
• Fix indentation of trailing double-semicolons (#2295, @gpetiot)
• Fix formatting of comments in "disable" chunks (#2279, @gpetiot)
• Fix non-stabilizing comments attached to private/virtual/mutable keywords (#2272, #2307, @gpetiot, @Julow)

Changes

• Improve formatting of doc-comments (#2338, #2349, #2376, #2377, #2379, #2378, @Julow) Remove unnecessary escaping and preserve empty lines.
• * Indent as-patterns that have parentheses (#2359, @Julow)
• Don't print warnings related to odoc code-blocks when '--quiet' is set (#2336, #2373, @gpetiot, @Julow)
• * Improve formatting of module arguments (#2322, @Julow)
• * Don't indent attributes after a let/val/external (#2317, @Julow)
• Consistent indentation of @@ let+ x = ... (#2315, #2396, @Julow) It was formatted differently than @@ let x = ....
• * Improve formatting of class expressions and signatures (#2301, #2328, #2387, @gpetiot, @Julow)
• * Consistent indentation of fun (type a) -> following fun x -> (#2294, @Julow)
• * Restore short-form formatting of record field aliases (#2282, #2388, @gpetiot, @Julow)
• * Restore short-form for first-class modules: ((module M) : (module S)) is formatted as (module M : S)) (#2280, #2300, @gpetiot, @Julow)
• * Improve indentation of ~label:(fun ... (#2271, #2291, #2293, #2298, #2398, @Julow) The fun keyword is docked where possible and the arguments are indented to avoid confusion with the body.
• JaneStreet profile: treat comments as doc-comments (#2261, #2344, #2354, #2365, #2392, @gpetiot, @Julow)
• Tweaks the JaneStreet profile to be more consistent with ocp-indent (#2214, #2281, #2284, #2289, #2299, #2302, #2309, #2310, #2311, #2313, #2316, #2362, #2363, @gpetiot, @Julow)

• Fix unavailable expunge on Windows (#447, @jonahbeckford)

Fixes

• Disable background operations and threaded console on macOS and other Unixes where we rely on fork. (#8100, #8121, fixes #8083, @rgrinberg, @emillon)

• Initialize async I/O thread lazily. (#8122, @emillon)

• Fix behavior of utop -stdin (#434, fixes #433, @tuohy)

• Handle bounds with Zed.next_error (#442, @tmattio)

• Load files from XDG directories (the legacy paths still work). (#431, @Skyb0rg007)

• Remove deprecated values prompt_continue, prompt_comment, smart_accept, new_prompt_hooks, at_new_prompt (#427, @emillon)

• Require OCaml 4.11.0 or newer. (#444, @emillon)

Added

• Include the time it takes to read/write state files when --trace-file is enabled (#7960, @rgrinberg)

• Include source tree scans in the traces produced by --trace-file (#7937, @rgrinberg)

• Add --all option to dune rpc status to show all Dune RPC servers running. (#8011, fix #7902, @Alizter)

• Add additional metadata to the traces provided by --trace-file whenever --trace-extended is passed (#7778, @rleshchinskiy)

• $ dune describe is now a command group, so arguments to subcommands must be passed after subcommand itself. (#7919, @Alizter)

• Add dune show command group which is an alias of dune describe. (#7946, @Alizter)

• Add dune show env command and make dune printenv an alias of it. (#7985, @Alizter)

• Add commands dune show targets and dune show aliases that display all the available targets and aliases in a given directory respectively. (#7770, grants #265, @Alizter)

• Extensions used in (dialect) can contain periods (e.g., cppo.ml). (#7782, fixes #7777, @nojb)

• The interface and implementation fields of a (dialect) are now optional (#7757, @gpetiot)

• Add (build_if) to the (test) stanza. When it evaluates to false, the executable is not built. (#7899, fixes #6938, @emillon)

• Allow (include_subdirs qualified) to be used when libraries define a (modules ...) field (#7797, fixes #7597, @anmonteiro)

• Allow multiple globs in library's (stdlib (internal_modules ..)) (@anmonteiro, #7878)

Changed

• Do not rerun OCaml syntax files on every iteration of the watch mode. This is too memory consuming. (#7894, fix #6900, @rgrinberg)

• Attach melange rules to the default alias (#7926, @haochenx)

• Compute digests and manage sandboxes in background threads (#7947, @rgrinberg)

Fixed

• Validate file extension for $ dune ocaml top-module. (#8005, fixes #8004, @3Rafal)

• Cinaps: The promotion rules for cinaps would only offer one file at a time no matter how many promotions were available. Now we offer all the promotions at once (#7901, @rgrinberg)

• Add necessary parentheses in generated opam constraints (#7682, fixes #3431, @Lucccyo)

Removed

• Remove some compatibility code for old version of dune that generated .merlin files. Now dune will never remove .merlin files automatically (#7562)

• In opam constraints, reject (and) and (or) with no arguments at parse time (#7730, @emillon)

• Fix deadlock on Windows (dune#8044, @nojb)
• When using sendfile to copy files on Linux, fall back to the portable version if it fails at runtime for some reason (NFS, etc). (dune#8049, fixes dune#8041, @emillon)

Added

• Adopt the OCaml Code of Conduct (#473, @rikusilvola)
• Added support for projects that have their OPAM files in the opam/ subdirectory. (#466, @Leonidas-from-XIV)

Changed

• Running dune-release check now attempts to discover and parse the change log, and a new flag --skip-change-log disables this behaviour. (#458, @gridbugs)
• List the main package and amount of subpackages when creating the PR to avoid very long package lists in PRs (#465, @emillon)

Fixed

• Avoid collision between branch and tag name. Tag detection got confused when branch was named the same as tag. Now it searches only for tag refs, instead of all refs. (#452, @3Rafal)
• Fix project name detection from dune-project. The parser could get confused when opam file generation is used. Now it only considers the first (name X) in the file. (#445, @emillon)

Removed

• Remove support for delegates. Previous users of this feature should now use dune-release delegate-info and wrap dune-release calls in a script. See #188 for details. (#428, @NathanReb)
• Removed support for the OPAM 1.2.2 client. This means dune-release expects the opam binary to be version 2.0 at least. (#406, #411, @Leonidas-from-XIV)

Fixes

• Fix file permissions used when specifying output files of pp and ppx. (ocaml-lsp#1153)

Features

• Add "Remove type annotation" code action. (#1039)
• Support settings through didChangeConfiguration notification (#1103)
• Add "Extract local" and "Extract function" code actions. (#870)
• Depend directly on merlin-lib 4.9 (#1070)

Fixes

• Support building with OCaml 5.0 and 5.1 (#1150)

• Disable code lens by default. The support can be re-enabled by explicitly setting it in the configuration. (#1134)

• Fix initilization of ocamlformat-rpc in some edge cases when ocamlformat is initialized concurrently (#1132)

• Kill unnecessary $ dune ocaml-merlin with SIGTERM rather than SIGKILL (#1124)

• Refactor comment parsing to use odoc-parser and cmarkit instead of octavius and omd (#1088)

  This allows users who migrated to omd 2.X to install ocaml-lsp-server in the same opam switch.

  We also slightly improved markdown generation support and fixed a couple in the generation of inline heading and module types.

• Allow opening documents that were already open. This is a workaround for neovim's lsp client (#1067)

• Disable type annotation for functions (#1054)

• Respect codeActionLiteralSupport capability (#1046)

• Fix a document syncing issue when utf-16 is the position encoding (#1004)

• Disable "Type-annotate" action for code that is already annotated. (#1037, fixes #1036)

• Fix semantic highlighting of long identifiers when using preprocessors (#1049, fixes #1034)

• Fix the type of DocumentSelector in cram document registration (#1068)

• Accept the --clientProcessId command line argument. (#1074)

• Accept --port as a synonym for --socket. (#1075)

• Fix connecting to dune rpc on Windows. (#1080)

• Adopt the OCaml Code of Conduct on the repo (ocaml-ppx/ppxlib#426, @pitag-ha)
• Clean up misleading attribute hints when declared for proper context. (ocaml-ppx/ppxlib#425, @ceastlund)
• Ast_pattern now has ebool, pbool helper, and a new map.(ocaml-ppx/ppxlib#402, @Burnleydev1)
• Multiple errors are now reported in metaquot. (ocaml-ppx/ppxlib#397, @Burnleydev1)
• Add Attribute.declare_with_attr_loc (ocaml-ppx/ppxlib#396, @dvulakh)
• Add "ns" and "res" as reserved namespaces(ocaml-ppx/ppxlib#388, @davesnx)
• Make Quoter's let binding non-recursive (ocaml-ppx/ppxlib#401, @sim642)
• Fix failure of 'lift_map_with_context' in traverse by compile-time evaluation of 'fst' and 'snd' (ocaml-ppx/ppxlib#390, @smuenzel)
• Driver: Bias the mapping from Parsetree magic numbers to Parsetree versions towards the current version, as it is usually the common case and it helps when magic numbers are ambiguous (such as on development versions) (ocaml-ppx/ppxlib#409, @shym)
• Remove unnecessary test dependencies towards base and stdio (ocaml-ppx/ppxlib#421, @kit-ty-kate)
• Update description to reflect that ppxlib contains more than a library (Update the opam description ocaml-ppx/ppxlib#422, @pitag-ha)
• Add support for OCaml 5.1, excluding OCaml 5.1.0~alpha1 (ocaml-ppx/ppxlib#428, @shym, @Octachron , @pitag-ha, @panglesd)
• Driver: Fix -locations-check option for coercions with ground (ocaml-ppx/ppxlib#428, @Octachron)