Fails to build with GCC 15 due to -Wincompatible-pointer-types

[glaubitz]

With GCC 15, function declarations with no parameters can no longer be used for functions that take parameters.

As a result, pyo fails to build from source with GCC 15 with the following error:

[   13s] gcc -fno-strict-overflow -Wsign-compare -DNDEBUG -O2 -Wall -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -Werror=return-type -g -DOPENSSL_LOAD_CONF -fwrapv -fno-semantic-interposition -O2 -Wall -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -Werror=return-type -g -IVendor/ -O2 -Wall -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -Werror=return-type -g -IVendor/ -O2 -Wall -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -Werror=return-type -flto=auto -g -fPIC -DUSE_PORTAUDIO -DUSE_PORTMIDI -DUSE_OSC -DUSE_JACK -DJACK_NEW_API -Iinclude -I/usr/include -I/usr/local/include -I/usr/include/python3.12 -c src/engine/dummymodule.c -o build/temp.linux-x86_64-cpython-312/src/engine/dummymodule.o -Wno-strict-prototypes -Wno-strict-aliasing -O3 -g0 -DNDEBUG
[   13s] src/engine/dummymodule.c: In function ‘Dummy_setProcMode’:
[   13s] src/engine/dummymodule.c:48:35: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(Dummy *)’ [-Wincompatible-pointer-types]
[   13s]    48 |             self->muladd_func_ptr = Dummy_postprocessing_ii;
[   13s]       |                                   ^
[   13s] src/engine/dummymodule.c:29:13: note: ‘Dummy_postprocessing_ii’ declared here
[   13s]    29 | static void Dummy_postprocessing_ii(Dummy *self) { POST_PROCESSING_II };
[   13s]       |             ^~~~~~~~~~~~~~~~~~~~~~~
[   13s] src/engine/dummymodule.c:52:35: error: assignment to ‘void (*)(void)’ from incompatible pointer type ‘void (*)(Dummy *)’ [-Wincompatible-pointer-types]
[   13s]    52 |             self->muladd_func_ptr = Dummy_postprocessing_ai;
[   13s]       |                                   ^
[   13s] src/engine/dummymodule.c:30:13: note: ‘Dummy_postprocessing_ai’ declared here
[   13s]    30 | static void Dummy_postprocessing_ai(Dummy *self) { POST_PROCESSING_AI };
[   13s]       |             ^~~~~~~~~~~~~~~~~~~~~~~

[belangeo]

That would be too much of a refactor to do this at the moment (not even sure how I will handle that)... I can repro in godbolt, but Apple clang seems to be more compliant than gcc! Is it working on your side if you add "-Wno-incompatible-pointer-types" in the extra_compile_args?

[micwoj92]

This issue is already fixed with https://github.com/belangeo/pyo/commit/425bb1119641e04d6b978880197211b587775cce

I was running against different errors with gcc15.

src/engine/dummymodule.c: In function ‘Dummy_compute_next_data_frame’:
src/engine/dummymodule.c:109:6: error: too many arguments to function ‘self->muladd_func_ptr’; expected 0, have 1
  109 |     (*self->muladd_func_ptr)(self);
      |     ~^~~~~~~~~~~~~~~~~~~~~~~ ~~~~
In file included from src/engine/dummymodule.c:24:
include/pyomodule.h:616:12: note: declared here
  616 |     void (*muladd_func_ptr)(); \
      |            ^~~~~~~~~~~~~~~
include/dummymodule.h:29:5: note: in expansion of macro ‘pyo_audio_HEAD’
   29 |     pyo_audio_HEAD
      |     ^~~~~~~~~~~~~~

These can be "fixed" by using -std=c17 , but then it still fails with:

src/engine/vbap.c:16:41: error: ‘M_PI’ undeclared here (not in a function)
   16 | static float ang_to_rad = (float)(2.0 * M_PI / 360.0);
      |                                         ^~~~
error: command '/usr/bin/gcc' failed with exit code 1

[infectedresearch]

Is there a path to making pyo work in linux? Right now it seems like you can't build any version.

[felixniemeyer]

Confirming this issue on Manjaro Linux with GCC 15.2.1 and Python 3.13.

Error Summary: Multiple compilation errors related to function pointers with incompatible signatures, including:

• error: too many arguments to function 'self->mode_func_ptr'; expected 0, have 1
• error: too many arguments to function 'self->muladd_func_ptr'; expected 0, have 1

Affected files:

• src/engine/dummymodule.c
• src/engine/triggermodule.c
• Multiple other modules

Attempted workarounds:

• Installing with --minimal flag still fails with the same errors
• Installing from PyPI (1.0.5) and latest git both fail

The root cause appears to be in include/pyomodule.h:614-616 where function pointers are declared without parameters:

void (*mode_func_ptr)();
void (*muladd_func_ptr)();

But they're called throughout the codebase with self as an argument, which is now rejected by GCC 15.

Looking forward to PR #313 being merged!