GNU attributes for malloc and C++-modules

Clang Frontend Using Clang
1

I’ve never used it in my code before __attribute__ ((__malloc__)).
There are several cases, for example:
reallocarray has __malloc__ (__builtin_free, 1) and is second function reallocarray differs only by attributes.
This is only information to optimization? but fopen has __attribute__ ((__malloc__ (fclose, 1))

Problem that clang++ called

clang++ -std=c++20 -fmodules-ts --precompile -x c+±module hello.cpp.i

give errors:

In file included from /home/andrzej/wazne/gitmy/my_c/modules/bazel/normalnie/hello.cpp:2:
In file included from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41:
In file included from /usr/include/c++/11/cmath:47:
In file included from /usr/include/c++/11/bits/std_abs.h:38:
/usr/include/stdlib.h:566:21: error: '__malloc__' attribute takes no arguments
    __attribute__ ((__malloc__ (__builtin_free, 1)));
                    ^
/usr/include/stdlib.h:570:38: error: '__malloc__' attribute takes no arguments
     noexcept (true) __attribute__ ((__malloc__ (reallocarray, 1)));
                                     ^
/usr/include/stdlib.h:799:22: error: '__malloc__' attribute takes no arguments
     __attribute__ ((__malloc__ (__builtin_free, 1))) ;

Where hello.cpp.i is preprocessed followwing file

export module hello;
#include <bits/stdc++.h>

I am trying make modules with fragments of standard library to use it instead #include;
modules not allowed arguments attribute malloc,
changing
__attribute__ ((__malloc__ (args))
to
__attribute__ ((__malloc__ ())
give only optimization case or problem freeing?

2

The issue has nothing to do with modules specifically. The errors are because Clang’s implementation of the malloc attribute accepts no arguments – we don’t support the variant that accepts a deallocator argument like GCC does.

As I understand the attribute in GCC, the deallocator information is only used for diagnostics and not for optimization decisions.