Ann: SWI-Prolog 9.3.8

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Dear SWI-Prolog user,

SWI-Prolog 9.3.8 is ready for download. It comes with a lot of
changes, many of which are internal. Visible changes are notably to
the C/C++ interfaces. Hoghlights:

  • Introduced PL_free_term_ref() to simplify dealing with temporary
    term references that build up inside a loop. @peter.ludeman added
    support for this to C++ using PlTermScoped.

  • The C API now validates the validity of term_t handles. This
    should make the development of C/C++ extensions a more robust
    process as it will capture the vast majority of illegal use of
    term_t handles we see in the wild.

  • Some small performance improvements, preparing for more.

  • Better handling of crashes when running unattended: better
    crash reports and better guarantee that the process won’t
    deadlock during the crash reporting.

  • Better handling of the xterm interface that allows creating
    multiple consoles from the same process on X11 systems.

  • A start for supporting htmx

  • Better throughput of multiple ouput messages from Pengines over
    HTTP.

  • The Python interface now supports py_string_as(codes) (or chars)
    to get Python strings as a Prolog list.

  • Many portability issues and fixes for -fsanitize=undefined
    with input from @mgondan

    Enjoy — Jan

SWI-Prolog Changelog since version 9.3.7

  • FIXED: Type for PL_get_intptr_ex(). Breaks on Win32

  • CLEANUP: Make all code clean for clang-18 -fsanitize=undefined

  • ENHANCED: Added ‘c_cxx’ flag and env SWIPL_CXX for packs

  • FIXED: #1292: possible stack corruption in exception handling.
    Probably can only be triggered if SECURE_GC is enabled which wipes
    the unused parts of the stacks in trimStacks().

  • SANDBOX: Allow for term_singletons/2

  • FIXED: #1292 Possible stack corruption after exception.

  • FIXED: unification of zero-arity compounds

  • FIXED: Possible assertion error due to unify refactoring.

  • FIXED: thread_signal/2: may raise exception and succeed.

  • CLEANUP: Refactor unify() Split into a function that deals with
    everything except compounds and one that does the whole thing.
    This makes the function a lot easier to understand. This rewrite
    has no measurable performance implication and should make it a bit
    easier to optimize it further.

  • ENHANCED: Simplify H_VAR

  • ENHANCED: Low-level unification to constants Speeds up unification
    from foreign code to atoms and small integers.

  • ENHANCED: make/0: no longer try to update the indices of system
    libraries. These libraries are properly maintained by the build and
    installation process while the time stamps are often wrong after the
    installation process.

  • FIXED: Do not wait longer than 30 seconds after a crash. This deals
    with situations where error reporting and cleanup hangs due to
    a deadlock.

    Normally, after a fatal crash report and if the system is connected to
    a terminal, it waits for user input such that the user can attach a
    debugger to analyse the state. We now wait at max 30 seconds to avoid
    indefinite waiting if there is no human in the loop after all.

  • DOC: time/1: we do support per thread CPU time on MacOS.

  • FIXED: Properly export environment_frame in foreign predicate redo.
    The incorrect setting causes problems in the new consistency checks
    for term_t as well as confusing backtraces.

  • PORT: Possibly collapsing VM instructions on 64 bit Visible using
    gcc 14 on arm64 (Asahi Linux)

  • WASM: SWIPL() initialization changed in Emscripten Where
    SWIPL(Module) used to return a Promise that would complete
    returning the same Module, it now returns a new module object
    that is independent from the agument passed.

  • ADDED: PL_free_term_ref() In addition, this patch distinguishes
    term_t originating from predicate arguments (which cannot be freed
    and to which we cannot “write” (PL_put_*())) from user allocated
    term references.

  • ADDED: Validate arguments to the C API PL_() functions. This commit
    validates term_t, atom_t and functor_t parameters to the PL_    ()
    functions that terminates the process if it finds invalid data.

    These tests may be disabled using cmake -DVALIDATE_API=OFF. The
    validation has very little impact on the raw Prolog performance as
    most internal use of the C api bypass the public API function. It
    may have measurable impact on packages that use the C interface in
    a very time critical way.

  • ADDED: PL_api_error() to signal invalid use of the API

  • FIXED: =@=/2: attributed variables must be handled as normal variables.

  • FIXED: Determine file exports under conditional conditional
    compilation.

  • FIXED: Process multiple predicates from export/1 directives.
    To determine file exports, we considered only a single predicate
    for export/1.

  • FIXED: Stops repeated crash reports While recursive crashes where
    dedected, no appropriate action was taken, leading to endless error
    reports.

  • FIXED: ‘$open_xterm’/5: raise exeption if we cannot run xterm.
    Used to hang, waiting for output from the xterm process.

  • MODIFIED: Renamed open_xterm/5 as private '$open_xterm'/5.
    open_xterm/5 was not documented. This patch removes the implementation
    completely if the OS lacks the required POSIX pty support and renames
    the predicate to '$open_xterm'/5 if xterm consoles can be supported.
    In addition, this patch adds conditional compilation to console support
    in library(threadutil) if neither the Windows support nor the xterm
    support can be provided.

  • FIXED: Build dependency of documentation on utf8proc package

Package cpp

  • ENHANCED: Use read mutex for AtomMap::find()

  • ENHANCED: added move constructor to PlRecord to support make_pair()

  • FIXED: base class visibility

  • DOC: fix some obsolete function names

  • ENHANCED: convenience methods in PlRecordExternalCopy

  • ENHANCED: Experimental PlTermScoped API

  • DOC: PlTail is now PlTerm_tail + fix examples

  • PORT: OpenBSD does not have malloc header

Package http

  • ADDED: library(http/htmx). Support predicates for htmx.org

Package jpl

  • TEST: removed Garbo.java This file uses the deprecated finalize()
    method and does not seem to be used anywhere.

  • TEST: Find hamcrest needed for JPL tests on Fedora

  • FIXED: Illegal use of SWI-Prolog API Code as modifying predicate
    arguments.

Package ltx2htm

  • FIXED: Avoid overwriting predicate argument

Package pengines

  • ADDED: Add support for put_code/1 and put_char/1 to
    library(pengines_io)

  • CLEANUP: Use reply_json_dict/1 for replying

  • ADDED: Add support to collate multiple output events. This extends
    the HTTP protocol to wait for more output, sending multiple output
    events as one chunk. The chunk is ended if no more output is timely
    available, the max of (currently 100) output events is collected,
    or a non-output event is found.

Package plunit

  • FIXED: run_tests/0-2: correctly report combined CPU usage.

Package protobufs

  • CLEANUP: tests now run outside the build

  • TEST: Use cmake’s built swipl executable where possible

  • DOC: examples+tests using updated protobuf-compiler package

Package sgml

  • FIXED: Avoid referencig an invalid term_t

Package ssl

  • FIXED: Illegal use of SWI-Prolog API

Package swipl-win

  • PORT: Require C+±17 (was C+±11)

Package swipy

  • FIXED: accept string(Text) as input Added tests for extended
    py_string_as().

  • ADDED: support for py_string_as() option with codes or chars

Package xpce

  • CLEANUP: Use offsetof() where applicable This avoids runtime errors
    when using -fsanitize=address
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