Branch: stable (switch to development),

version to version

SWI-Prolog Changelog from version 10.0.0 to 10.0.1

[Feb 17 2026]

TEST: added tests for library(record)

[Feb 18 2026]

FIXED: reload_foreign_libraries/0. Failed with type error.

[Feb 17 2026]

TEST: Fixed Debug build test on Windows to avoid C stack overflow. Based on PR by Eric Tauber. This replacement builds on the new Prolog flag build_type and rewrites the test suite to use PlUnit.
ADDED: Prolog flag build_type, representing the CMake build type used.
FIXED: library(main): make spy options default to the user module.

[Feb 15 2026]

BUILD: added comments to scripts/configure
BUILD: added comments to CMakeLists.txt for protobufs test

[Jan 23 2026]

DOC: clarified details of heap allocation

[Feb 16 2026]

PORT: Minimize C stack on MSVC debug builds.

[Feb 15 2026]

TEST: Skip test_thread_exit if alert signal == 0
PORT: Include platform pthread headers and includes for pthread config.
FIXED: #1465 Overflow issue in trie handling. This is the result of replacing an int incorrectly with bool.

[Feb 14 2026]

FIXED: PThreads4W exit crash in MSVC Debug builds Without this, the system crashes during process exit.
ENHANCED: listing/1,2: show number of clauses in other threads.

[Feb 13 2026]

ADDED: listing/2: option thread(+ThreadId) This lists the clauses for a thread-local predicate as they can be seen for the given thread (rather than the calling thread).
MODIFIED: Modified PL_put_dict() to be a bool function. All usage in packages assumed bool and this is a more consistent interface. Invalid keys now generate a fatal ABI error and dupiicate keys a normal Prolog exception. As this function is not used much and there is no clean way to fix the current bugs without changing the API we will backport this to the stable series as is.
FIXED: dict_pairs/3 could create dicts with duplicate keys. Mistake changing types to bool. This changes the dict ordering functions to return _PL_dict_status_t, which is now also returned by PL_put_dict().
CLEANUP: Avoid unreferenced variable warning for MSVC

[Feb 12 2026]

BUILD: MSVC Sanitize build
TEST: Windows pipe test by using absolute batch file path The pipe:cat1 test was failing because the batch file path was relative. cmd /c couldn't find pltest-XXXX.bat. Fixed using absolute_file_name/2.
BUILD: Use proper CMake dependencies for building the INDEX.pl files Since we no longer merge the package library files with the main library and since CMake has evolved, we can get rid of the ugly "run always" approach to building the INDEX.pl files and create a proper custom rule with the proper dependencies.

[Feb 11 2026]

FIXED: Hashing over uninitialized memory on 32-bit systems. On 32-bit systems, clause references are created in part from unitialized memory. This leads to crashes in atom-gc for clause references.
TEST: Add alternative bitint term hash for 32 bit engines.
PORT: Remove /D_DEBUG and /DO_DEBUG from MSVC Sanitize build flags MSVC AddressSanitizer requires the release CRT (/MD), but /D_DEBUG causes the STL to reference debug-CRT symbols (_CrtDbgReport) and makes Python headers demand python3XX_d.lib.

[Feb 10 2026]

PORT: MSVC debug build CRT mismatch for plugins
PORT: MSVC debug build: variadic macros and PRETTY_FUNCTION
PORT: Set CMAKE_MSVC_RUNTIME_LIBRARY globally for MSVC builds
PORT: Fix MSVC C4334 warning in pl-buffer.c
PORT: Drop xpce on < 64 bit platforms.
BUILD: Extend build_home.pl to support multi-config generators There was specific code to support Microsoft Visual Studio. This patch supports multi-config generators on platforms that leave the modules in the package directories such as ninja -G "Ninja Multi-Config"

[Feb 9 2026]

PORT: Avoid undefined ms_snprintf() and renamed to c99_snprintf().

[Feb 8 2026]

PORT: Add /EHsc to MAKE_CXX_FLAGS for MSVC. Thanks to Eric Tauber.
CLEANUP: Avoid implict enum conversion warnings. Based on #1445 by Eric Tauber.

[Feb 6 2026]

FIXED: Make PL_query(PL_QUERY_HALTING) return true inside atexit() handlers. This addresses the cleanup in package nlp cleanup issues.

[Feb 5 2026]

PORT: Make exit() work properly in Windows with Asan and Debug enabled. Thanks to Eric Tauber.

[Feb 4 2026]

PORT: Avoid calling sleep() after Lsan detects a leak.
PORT: Updated scripts/macos-deps.h for SDL3 Updated version and build instructions for building a universal binary.
ADDED: check_installation/0: report OpenSSL version

[Feb 2 2026]

PORT: Exclude LeakSanitizer code on Windows (MSVC ASan lacks LSan support)

[Feb 3 2026]

FIXED: Bignum allocation issues. This may lead to memory corruption on LibBF as well as using GMP on arithmetic errors. Found by Eric Taucher while debugging the MSVC compiled version.

[Feb 1 2026]

FIXED: Tabling with attributed variables: memory management. Make sure avm in trie_lookup_abstract() never points below the allocated buffer. It is not clear to me whether that is strictly necessary, but MSYS-2 using clang and Asan suggests it is. I do not understand why this is not reported using Asan under Linux. Surely this prevents reading below the buffer, causing a SEGV if it is tried anyway.

[Jan 31 2026]

TEST: term_hash/2 for indirect data types (bigints, floats) term_hash/2 is platform dependent as it hashes the binary representations of indirect types (big int, rational, float). The test succeeds if the produced hash is one of a set. When using LibBF, the hash also depends on whether the limb size is 32 bits or 64 bits. The C compiler must support a twice as wide integer type, i.e., the choice depends on HAVE_INT128.
FIXED: term_hash/2: exception when exhausting memory. Also cleanup types.
CLEANUP: Avoid reading uninitialized local variable. Not entirely sure why the popSegStack() can fail. Surely it does on the XSB tests from tests/xsb/sub_tests/xsb_test_sub.pl. In debug mode we set dstate such that accessing it crashes. This seems not to be the case.
FIXED: Windows: ms_snprintf null-termination bug for edge case

[Jan 30 2026]

PORT: Ensure default 4Mb C-stack on Windows Otherwise the default is 2Mb for MinGW and 1Mb for MSVC
FIXED: When specified, also set the C-stack limit for swipl-win

[Jan 29 2026]

PORT: Compile MacOSX bundle using gcc. This provides about 40% performance improvement.

[Jan 27 2026]

PORT: Support CMake < 3.24 Using CMake < 3.24 the build was broken due to the usage of cmake -E env ... -- ... We now omit that for older cmake version. This implies that building in e.g build.gcc=14 does not work for these versions.

[Jan 24 2026]

FIXED: write_term/2: handle partial(true) for backquoted text.
FIXED: write_term/2 using option partial(true) to separate quoted objects. Found by Joachim Schimpf
DOC: write_term/2: handling of back_quotes and module options

[Jan 23 2026]

FIXED: write_term/3 and friends to get default back_quotes from flags.

[Jan 22 2026]

PORT: Better support for Homebrew dependencies (MacOS) This ensures SDL3 comes from Homebrew if both provided by Macports and Homebrew and configure maps gcc=14 to Homebrew gcc.
PORT: Make configure work for build.gcc=15 on MacOS. Compiler is called gcc-mp-15 and it does not support -g3.

[Jan 21 2026]

ENHANCED: edit/1: merging module and file. If a spec resolves to a file and module with the same name, edit the module.

[Jan 19 2026]

FIXED: Allow building only the core system (no packages at all). Stop installing libraries that depend on packages and do not warn if library(editline) is not present.
FIXED: #1436 check_installation/0: check editline, also on Windows.
FIXED: CpuCount() typing

[Jan 18 2026]

FIXED: Type issues on 32 bit platforms

[Jan 15 2026]

CLEANUP: Types Restore API affecting type changes of -Wconversion cleanup, introduce new integer aliases and enums to replace int with more appropriate types. Propagate these through the system (incomplete).

[Jan 10 2026]

CLEANUP: Make likely/unlikely silent.

[Jan 5 2026]

FIXED: #1431 format/2: handling ~d on gmp evaluation returning a small int.

[Dec 31 2025]

ENHANCED: edit/1: if multiple hits are in the same file, take most specific. Thus, if both the file and some object inside the file match, use the object. Also xpce classes are more specific that the module they are contained in.

[Dec 25 2025]

FIXED: edit/1 for normal predicates. Broken after integrating foreign predicates.

[Dec 23 2025]

FIXED: UBSAN: Calling event handler with too many arguments.

[Dec 22 2025]

UBSAN: Avoid offset to NULL pointer
UBSAN: Possible increment of NULL pointer This is benign, but officially undefined.
FIXED: Type handling for PL_thread_at_exit(). Resulted in reported undefined behaviour due to non-matching function prototype.

[Dec 18 2025]

CLEANUP: Unconditionally use fpclassify() This is available on any system providing C99 and we already demand C11.

[Dec 17 2025]

PORT: Make compile using Emscripten
ADDED: Extract the source location of foreign predicates. Added '$foreign_predicate_source'/2. Requires debug symbols and addr2line or similar.

[Dec 16 2025]

THEME: Support PceEmacs bookmark view in the dark theme,

[Dec 15 2025]

DOC: library(persistency): document generation of asserta_<pred>

[Dec 14 2025]

UBSAN: Avoid bit shift == sizeof(x) The proposed change is not pretty, but it avoids another UBSAN error if low (64 bit) is << by 64 bits. [Dec 12 2025]
UBSAN: Avoid bit shifts in MT RNG

[Dec 10 2025]

FIX: UBSAN check Avoid memcpy(NULL, _, 0)

[Dec 9 2025]

FIXED: bigint cache allocation error Can lead to buffer overflow.

[Dec 7 2025]

CLEANUP: use snprintf to avoid deprecation warnings
PORT: replace sprintf by snprintf to avoid deprecation warnings

[Dec 4 2025]

BUILD: Updated scripts/configure Simplified, added --help option and allow for both extracting features from the name and using commandline arguments.
FIXED: Undefined ep_has_console/1 message when enabling the debugger.

Package archive

[Jan 22 2026]

CLEANUP: avoid -Wconversion warnings

Package bdb

[Jan 22 2026]

CLEANUP: Avoid -Wconversion warnings You might wish to check if the assertions are needed/solve a problem.

Package clib

[Feb 8 2026]

CLEANUP: Bool types and avoid conversion warnings for Windows

[Jan 31 2026]

PORT: Ensure ssize_t is defined when using MSVC

[Jan 18 2026]

ENHANCE: use size_t to avoid -Wconversion errors I also added a few casts I considered safe. Dubious casts are highlighted. [Nov 20 2025]
DOC: minor fix in comment

[Dec 7 2025]

PORT: replace sprintf by snprintf to avoid deprecation warnings

Package cpp

[Jan 23 2026]

ENHANCED: make it easier to generate the standard form of exceptions

[Jan 22 2026]

CLEANUP: add more default qid=0

[Jan 21 2026]

CLEANUP: Plx_exception() has default qid=0

[Jan 20 2026]

CLEANUP: change PL_exception() to Plx_exception()

[Jan 12 2026]

ASAN: add comment

[Jan 9 2026]

ASAN: avoid uninitialized buffer in fread This silences an ASAN error mentioned in https://github.com/SWI-Prolog/packages-cpp/issues/105.
1. I don't really see the point, but maybe clang's ASAN does not like

to write into "reserved" but not initialized memory areas.

Alternatively, and that may be the reason for the ASAN complaint:

buf in the outer std::string(buf, size) function is not "officially" initialized. [Dec 4 2025]

DOC: fix description of PlQuery::next_solution()

Package http

[Feb 10 2026]

BUILD: Add zlib to doc generation dependencies

[Jan 25 2026]

ENHANCED: http_post_data/3 to raise an exception if the data is not recognised.

[Jan 22 2026]

CLEANUP: avoid -Wconversion warnings

[Dec 16 2025]

ADDED: Extended predicate option declaration for http_read_data/3 Added the common JSON options. Note that these options only work if the plugin library(http/http_json) is loaded.

Package jpl

[Jan 24 2026]

CLEANUP: avoid -Wconversion, improve UTF16 support On systems with wchar_t is 4 bytes (pretty much anything but Windows), convert Prolog Unicode code points > 0xffff to/from UTF-16.

Package json

[Jan 22 2026]

CLEANUP: avoid -Wconversion warning

[Jan 2 2026]

FIXED: Server side handling for methods without parameters. Now accepts omitted params field as well as ""params: {} as valid input for such a method.
FIXED: Correctly call methods that take no parameters

[Dec 29 2025]

ADDED: json_call/4: option async(:Goal) Extends async(true) to get an asynchronous reply.
FIXED: json_method/1: Avoid discontiguous messages
ADDED: Print a warning if the server receives a non-implemented notification.

[Dec 25 2025]

ADDED: json_rpc_call/4, etc: option thread_alias(+Atom)

[Dec 24 2025]

ADDED: JSON RPC server: set json_rpc_stream global variable while dispatching. This variable provides access to the underlying stream. This may be used to identify the connection.

[Dec 9 2025]

FIXED: Apply header to server van using client in full duplex mode. Also code cleanup, avoiding code duplication between client and server by adding json_rpc_common.pl
ADDED: json_call/3 option async(true) JSON RPC allows calls with a request id not to send a reply. This option adds an id, but does not wait for a reply.

Package libedit

[Jan 5 2026]

FIXED: Build on Windows for enhanced background write handling.

[Jan 3 2026]

ENHANCED: Refreshing the terminal on background writes.

Package nlp

[Feb 6 2026]

FIXED: Crash during cleanup on Windows This patch replaces the pthread specific handling of the thread specific stemmers with __thread__ and using Prolog's ``PL_thread_at_exit'' to clean stemmers for terminated threads.
This is a safe solution that also avoids the need for platform specific code.

Package plunit

[Dec 10 2025]

FIXED: Allow for concurrent loading of unit test files.

Package sgml

[Jan 22 2026]

CLEANUP: avoid -Wconversion warnings

[Dec 7 2025]

CLEANUP: Use snprintf to avoid deprecation warnings

Package ssl

[Jan 22 2026]

CLEANUP: avoid -Wconversion warnings

Package table

[Jan 22 2026]

CLEANUP: avoid -Wconversion warnings

[Dec 7 2025]

FIXED: Windows: close memory leak after error.
CLEANUP: use snprintf to avoid deprecation warnings

Package tipc

[Jan 23 2026]

CLEANUP: Modernise exception handling, use bool and update PlDoc
CLEANUP: avoid -Wconversion warnings

Package utf8proc

[Jan 22 2026]

CLEANUP: avoid -Wconversion warnings

[Dec 23 2025]

FIXED: #1 UBSAN: adding to NULL pointer.

Package xpce

[Feb 13 2026]

ENHANCED: PceEmacs to list thread-local clauses. If a PceEmacs window is embedded in the debugger, fetch the target debug thread and list the clauses as the debuggee sees them.

[Feb 10 2026]

FIXED: undefined Dprintf and _T symbols in terminal.c debug code
FIXED: MSVC C4319 warning and potential bug in clearDFlagProgramObject() Cast mask to uintptr_t before applying bitwise NOT. Without this, ~mask produces a 32-bit result on Win64 (unsigned long is 32 bits) that gets zero-extended to 64-bit uintptr_t, incorrectly clearing the upper 32 bits of dflags.

[Feb 5 2026]

CLEANUP: Remove old deprecated usage of SunOS on_exit()

[Feb 2 2026]

ADDED: implementation for 3d rounded corners box r_3d_box()
ENHANCED: 3d effect rendering. Notably makes scrollbars look better.
PORT: Support MSVC
FIXED: GUI Tracer: remove non-functioning Help menu entries. Links to the manual and notably xpce manual seem unnecessary. Also removed the About as it is all part of the integrated Prolog IDE tools.

[Jan 28 2026]

ADDED: PceEmacs: associate emacs_<mode>_mode module with mode. And define style/2 and def_style/2 for style mapping. This is used by the experimental LSP client and should be used by the other modes, notably the Prolog mode.

[Jan 26 2026]

CLEANUP: Avoid suspicious sizeof() handling warning by clangd

[Jan 22 2026]

FIXED: Use `font<-average_char_width` for width computations This used to be `font<-ex`, but this is the height of the x character. This notably fixes the default width of PceEmacs windows to hold 80 characters rather than a few less (depending on the font).
FIXED: PceEmacs Prolog mode: find-references to avoid duplicates.

[Jan 21 2026]

FIXED: class text_buffer: LSP position reporting for wide-character buffers.
FIXED: Epilog: underline could continue in scrollbar.

[Jan 19 2026]

FIXED: text->underline. Underline was relative to top instead of base.

[Jan 13 2026]

ENHANCED: When opening one of xpce's manual tools, do not show @manual. This additional window is often needed and especially on systems that do not allow for window placement, this is annoying.

[Jan 7 2026]

ENHANCED: Make most errors that result from buggy program print a backtrace

[Jan 5 2026]

ADDED: PceEmacs: (empty) markdown mode. Allows for user extension, so we can play with markdown LSP servers.

[Dec 31 2025]

ENHANCED: editor->align: minimize the change This reduces change/undo info and keeps the buffer marked clean if no change happens.
FIXED: Collecting LSP change message could corrupt edit modifications.
ADDED: Broadcast pce_emacs(saved(Buffer)) when a buffer was saved. Can be used to trigger an LSP didSave() event, automatically recompile, etc.

[Dec 29 2025]

FIXED: Avoid undefined @nil->update in bookmark handling.

[Dec 25 2025]

ENHANCED: Only display output from help/1 in GUI when invoked from the gui.

[Dec 24 2025]

ADDED: error->feedback type backtrace to force errors to dump a backtrace.

[Dec 23 2025]

FIXED: Avoid memory corruption when ->initialise fails. The partial object may have references. If so, leave its final destruction to the reference count dropping to zero.

[Dec 18 2025]

CLEANUP: Replace all calls to sprintf() with snprintf()
FIXED: Thread monitor. Broken due to changes to class image. New code is simplified by using image->fill and num rather than int|real type.
FIXED: image->fill to accept a colour. Filling with images is currently not supported.

[Dec 17 2025]

ADDED: Exploit features to edit foreign predicates directly.
FIXED: swipl-win: deadlock when trying to attach a console to the xpce (main) thread.
FIXED: Underline colour when using default underline. If a line contains two fragments with different colour and underline, the first used the colour of the second.

[Dec 16 2025]

ADDED: Update bookmarks both when saving and colouring.
FIXED: PceEmacs bookmarks: update when saving the buffer.
ADDED: PceEmacs Prolog mode: find_references (Alt-?)
FIXED: PceEmacs bookmarks displaying the full path.

[Dec 14 2025]

ENHANCED: PceEmacs bookmark list Create nodes per file and provide proper highlighting
ADDED: Class grbox: allow for baseline vertical aligment.
FIXED: Class grbox was not displaying
ADDED: parbox->initialise: allow adding content
FIXED: Class parbox redraw handling for opacity.

[Dec 13 2025]

ENHANCED: Style PceEmacs bookmarks
ADDED: Support background of style in class tbox.

[Dec 12 2025]

ENHANCED: PceEmacs bookmark handling. Allow bookmarks on a selection inside a line. Working on a non-persistent bookmark instance that we can use for dynamic sets such as search hits, references, errors, etc.
ENHANCED: @emacs->goto_source_location: use new line_pos and length
ADDED: Class source_location: line_pos and length fields.

[Dec 11 2025]

ADDED: PceEmacs: allow adding new type-based prompting.

[Dec 10 2025]

ADDED: editor<-dabbrev_candidates: mode user0 This mode allows completion that is more targeted than searching the current buffer. It is intended to support intelligent completion using M-/.
MODIFIED: Removed image<->foreground and image<->background. Also removes corresponding initialization arguments from class pixmap and image->set_pixel and image->clear_pixel.
Use image->pixel to set pixels in an image.
CLEANUP: Remove bitmap<-display. Bitmaps are no longer related to a specific display.
CLEANUP: Removed image<->depth All our images are now 32-bit RGBA
MODIFIED: Removed bitmap<->transparent No longer needed. This also removes the second argument from ->initialise.
CLEANUP: Removed image->mask Since we have an alpha channel on images this is no longer needed.
ADDED: Icons for LSP fix and tweak operations
ADDED: class label: allow image selection to be scaled using ->width
ADDED: image->resize. Now only sets the width and height.
CLEANUP: Removed a lot of outdated image code
FIXED: LSP change message for consecutive backward delete.
FIXED: class text_buffer: undo handling. Undo may be lost if two consecutive changes that can be merged are executed on a virgin buffer.

[Dec 9 2025]

FIXED: r_3d_box(): device offset for filling the box was applied twice.

[Dec 8 2025]

ADDED: PceEmacs: support hovering fragment icons.
ADDED: PceEmacs: quick action for commenting xpce get methods.
FIXED: Class editor: align line spacing between normal and bold fonts.
ENHANCED: Moved font ascent and descent to main object. This allows for adjusting the line spacing of a font, such that we can ensure consistent line spacing for normal and bold font in editors.
ENHANCED: Class font: properly compute ex Instead of using simulation, being 1/2*h.
ADDED: ``editor->hover_fragment_icon: fragment*, [area]'' Called from the margin to act on hovering the margin icons.

[Dec 7 2025]

FIXED: Underline in class tbox

[Dec 6 2025]

FIXED: PceEmacs: keep LSP servers in sync on M-x revert
ENHANCED: text_margin: indicate that a fragment icon can be clicked.
FIXED: text_margin: display fragment that appears on first line
ADDED: text_margin->icon_size to scale icons.
ADDED: Margin icons for LSP diagnostic types

[Dec 5 2025]

FIXED: Broadcast changes due to white space normalisation while saving
ENHANCED: Class editor: use real bold font instead of simulated. This results in cleaner and more efficient rendering.

[Dec 4 2025]

ADDED: style->underline is now either a boolean or a colour Colour is also supported by text->underline. Future versions may also add names for specific underline styles.
This patch also replaces the use of fixed offset and thickness for the line by using the Pango suggested values for the current font. This makes underlined text look more natural, in particular when using larger fonts.
FIXED: Re-implement style->grey Was lost in conversion to SDL.
FIXED: Avoid warning on freed object when closing a PceEmacs window This is harmless, but annoying.

Package yaml

[Jan 22 2026]

CLEANUP: avoid -Wconversion warnings