The C analyzer seems to fail when `--disable-gil` is set
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Description
Bug report
Bug description:
When running the C analyzer's check-c-globals script locally, I noticed this failure on gc_free_threading.c:
$ python3.13 Tools/c-analyzer/check-c-globals.py Python/gc_free_threading.c
analyzing files...
.# requested file: </home/peter/develop/cpython/Python/gc_free_threading.c>
-------------------------
Non-constant global variables are generally not supported
in the CPython repo. We use a tool to analyze the C code
and report if any unsupported globals are found. The tool
may be run manually with:
./python Tools/c-analyzer/check-c-globals.py --format summary [FILE]
Occasionally the tool is unable to parse updated code.
If this happens then add the file to the "EXCLUDED" list
in Tools/c-analyzer/cpython/_parser.py and create a new
issue for fixing the tool (and CC ericsnowcurrently
on the issue).
If the tool reports an unsupported global variable and
it is actually const (and thus supported) then first try
fixing the declaration appropriately in the code. If that
doesn't work then add the variable to the "should be const"
section of Tools/c-analyzer/cpython/ignored.tsv.
If the tool otherwise reports an unsupported global variable
then first try to make it non-global, possibly adding to
PyInterpreterState (for core code) or module state (for
extension modules). In an emergency, you can add the
variable to Tools/c-analyzer/cpython/globals-to-fix.tsv
to get CI passing, but doing so should be avoided. If
this course it taken, be sure to create an issue for
eliminating the global (and CC ericsnowcurrently).
ERROR: unmatched text (/home/peter/develop/cpython/Python/gc_free_threading.c starting at line 524):
extern int (*__Static_assert_function (void)) [!!sizeof ( struct inline-1 )] ; extern int (*__Static_assert_function (void)) [!!sizeof (struct { int __error_if_negative: ( 16 < 256 && 8 < 16 && 8 > 0 ) ? 2 : -1; })] ; typedef struct { PyObject **start; PyObject **end; } gc_span_t; typedef struct { Py_ssize_t size; Py_ssize_t capacity; gc_span_t *stack; } gc_span_stack_t; typedef struct { unsigned int in; unsigned int out; _PyObjectStack stack; gc_span_stack_t spans; PyObject *buffer[256]; _Bool ...
This only comes up when ./configure --disable-gil is used beforehand (which is a little odd, considering a release build of Python is being used, not the local compiled version), so it doesn't show up in CI.
cc @ericsnowcurrently
CPython versions tested on:
CPython main branch, 3.14
Operating systems tested on:
Linux
Linked PRs
- gh-156969
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with Tools/c-analyzer/check-c-globals.py and reproduce the failure against Python/gc_free_threading.c using the command in the report. Read the parser-related guidance in Tools/c-analyzer/cpython/_parser.py and check linked PR gh-156969. Done means the analyzer processes this file without the reported unmatched-text failure.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- c, python
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 25/100