[C++20][Modules] error: '_freea' has different definitions in different modules

[Ivan171]

Environment

Windows 10
Clang 18.0.0git (https://github.com/llvm/llvm-project f9da4c6)
MSVC 17.8.3

Reproducer

// mod2.cpp

module;

#include <algorithm>

export module mod2;

// mod1.cpp

module;

#include <string_view>

export module mod1;

import mod2;

$ clang++.exe -std=c++20 -fno-delayed-template-parsing -fno-ms-compatibility -x c++-module mod2.cpp --precompile
$ clang++.exe -std=c++20 -fno-delayed-template-parsing -fno-ms-compatibility -x c++-module mod1.cpp -fprebuilt-module-path=.
In module 'mod2' imported from mod1.cpp:7:
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\ucrt\malloc.h:150:29: error: '_freea' has different definitions in
      different modules; definition in module 'mod2.<global>' first difference is function body
  150 |     __inline void __CRTDECL _freea(_Pre_maybenull_ _Post_invalid_ void* _Memory)
      |     ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  151 |     {
      |     ~
  152 |         unsigned int _Marker;
      |         ~~~~~~~~~~~~~~~~~~~~~
  153 |         if (_Memory)
      |         ~~~~~~~~~~~~
  154 |         {
      |         ~
  155 |             _Memory = (char*)_Memory - _ALLOCA_S_MARKER_SIZE;
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  156 |             _Marker = *(unsigned int*)_Memory;
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  157 |             if (_Marker == _ALLOCA_S_HEAP_MARKER)
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  158 |             {
      |             ~
  159 |                 free(_Memory);
      |                 ~~~~~~~~~~~~~~
  160 |             }
      |             ~
  161 |             #ifdef _ASSERTE
      |             ~~~~~~~~~~~~~~~
  162 |             else if (_Marker != _ALLOCA_S_STACK_MARKER)
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  163 |             {
      |             ~
  164 |                 _ASSERTE(("Corrupted pointer passed to _freea" && 0));
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  165 |             }
      |             ~
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\ucrt\malloc.h:150:29: note: but in '' found a different body
  150 |     __inline void __CRTDECL _freea(_Pre_maybenull_ _Post_invalid_ void* _Memory)
      |     ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  151 |     {
      |     ~
  152 |         unsigned int _Marker;
      |         ~~~~~~~~~~~~~~~~~~~~~
  153 |         if (_Memory)
      |         ~~~~~~~~~~~~
  154 |         {
      |         ~
  155 |             _Memory = (char*)_Memory - _ALLOCA_S_MARKER_SIZE;
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  156 |             _Marker = *(unsigned int*)_Memory;
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  157 |             if (_Marker == _ALLOCA_S_HEAP_MARKER)
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  158 |             {
      |             ~
  159 |                 free(_Memory);
      |                 ~~~~~~~~~~~~~~
  160 |             }
      |             ~
  161 |             #ifdef _ASSERTE
      |             ~~~~~~~~~~~~~~~
  162 |             else if (_Marker != _ALLOCA_S_STACK_MARKER)
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  163 |             {
      |             ~
  164 |                 _ASSERTE(("Corrupted pointer passed to _freea" && 0));
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  165 |             }
      |             ~
1 error generated.

[Ivan171]

Preprocessed files

[llvmbot]

@llvm/issue-subscribers-clang-modules

Author: Ivan171 (Ivan171)

### Environment Windows 10 Clang 18.0.0git (https://github.com/llvm/llvm-project f9da4c6) MSVC 17.8.3

Reproducer

// mod2.cpp

module;

#include <algorithm>

export module mod2;

// mod1.cpp

module;

#include <string_view>

export module mod1;

import mod2;

$ clang++.exe -std=c++20 -fno-delayed-template-parsing -fno-ms-compatibility -x c++-module mod2.cpp --precompile
$ clang++.exe -std=c++20 -fno-delayed-template-parsing -fno-ms-compatibility -x c++-module mod1.cpp -fprebuilt-module-path=.
In module 'mod2' imported from mod1.cpp:7:
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\ucrt\malloc.h:150:29: error: '_freea' has different definitions in
      different modules; definition in module 'mod2.<global>' first difference is function body
  150 |     __inline void __CRTDECL _freea(_Pre_maybenull_ _Post_invalid_ void* _Memory)
      |     ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  151 |     {
      |     ~
  152 |         unsigned int _Marker;
      |         ~~~~~~~~~~~~~~~~~~~~~
  153 |         if (_Memory)
      |         ~~~~~~~~~~~~
  154 |         {
      |         ~
  155 |             _Memory = (char*)_Memory - _ALLOCA_S_MARKER_SIZE;
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  156 |             _Marker = *(unsigned int*)_Memory;
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  157 |             if (_Marker == _ALLOCA_S_HEAP_MARKER)
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  158 |             {
      |             ~
  159 |                 free(_Memory);
      |                 ~~~~~~~~~~~~~~
  160 |             }
      |             ~
  161 |             #ifdef _ASSERTE
      |             ~~~~~~~~~~~~~~~
  162 |             else if (_Marker != _ALLOCA_S_STACK_MARKER)
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  163 |             {
      |             ~
  164 |                 _ASSERTE(("Corrupted pointer passed to _freea" && 0));
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  165 |             }
      |             ~
C:\Program Files (x86)\Windows Kits\10\include\10.0.22621.0\ucrt\malloc.h:150:29: note: but in '' found a different body
  150 |     __inline void __CRTDECL _freea(_Pre_maybenull_ _Post_invalid_ void* _Memory)
      |     ~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  151 |     {
      |     ~
  152 |         unsigned int _Marker;
      |         ~~~~~~~~~~~~~~~~~~~~~
  153 |         if (_Memory)
      |         ~~~~~~~~~~~~
  154 |         {
      |         ~
  155 |             _Memory = (char*)_Memory - _ALLOCA_S_MARKER_SIZE;
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  156 |             _Marker = *(unsigned int*)_Memory;
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  157 |             if (_Marker == _ALLOCA_S_HEAP_MARKER)
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  158 |             {
      |             ~
  159 |                 free(_Memory);
      |                 ~~~~~~~~~~~~~~
  160 |             }
      |             ~
  161 |             #ifdef _ASSERTE
      |             ~~~~~~~~~~~~~~~
  162 |             else if (_Marker != _ALLOCA_S_STACK_MARKER)
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  163 |             {
      |             ~
  164 |                 _ASSERTE(("Corrupted pointer passed to _freea" && 0));
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  165 |             }
      |             ~
1 error generated.

[ChuanqiXu9]

Maybe the reproducer can be fixed if we make #79240

[ChuanqiXu9]

@Ivan171 I've landed #79240. Could you try to test again and your original workload?

[Ivan171]

@Ivan171 I've landed #79240. Could you try to test again and your original workload?

That fixed it.

I'm converting my project to modules, one file at time. I have maybe 10% or 15% converted, and today was the first time I got it to build without any errors. I'll keep converting it and if any error shows up, I'll try to reduce it and report it.

Thanks!

[ChuanqiXu9]

@Ivan171 I've landed #79240. Could you try to test again and your original workload?

That fixed it.

I'm converting my project to modules, one file at time. I have maybe 10% or 15% converted, and today was the first time I got it to build without any errors. I'll keep converting it and if any error shows up, I'll try to reduce it and report it.

Thanks!

Thanks for reporting it too.

BTW, if you're making a toy and want to get a feeling about modules, it is suggested to use std modules from https://libcxx.llvm.org/Modules.html. Or if you still want to use libstdc++, it is suggested to mock a std module for that by yourself.