[Bug c++/104924] New: bad_variant_access When using iostream and variant as modules

[yunior.eury at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104924

            Bug ID: 104924
           Summary: bad_variant_access When using iostream and variant as
                    modules
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yunior.eury at gmail dot com
  Target Milestone: ---

When compiling the following:

```
export module Chapter2;
import <iostream>;
import <variant>;
export {
class Object
 {
   std::variant<float, int> var;
 };
}

```

I get the following error in gcc:
/usr/local/include/c++/11.2.1/variant:1285:9: internal compiler error: in
build_op_delete_call, at cp/call.c:7144
 1285 |   class bad_variant_access : public exception

If I change the order of the imports, then it compiles fine:
```
export module Chapter2;
import <variant>;
import <iostream>;
export {
class Object
 {
   std::variant<float, int> var;
 };
}```


g++ version:
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/11/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 11.2.0-7ubuntu2'
--with-bugurl=file:///usr/share/doc/gcc-11/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr
--with-gcc-major-version-only --program-suffix=-11
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib
--enable-libphobos-checking=release --with-target-system-zlib=auto
--enable-objc-gc=auto --enable-multiarch --disable-werror --enable-cet
--with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32
--enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none=/build/gcc-11-ZPT0kp/gcc-11-11.2.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-11-ZPT0kp/gcc-11-11.2.0/debian/tmp-gcn/usr
--without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
--with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.2.0 (Ubuntu 11.2.0-7ubuntu2) 

I compile the stl header files with the following commands:
```
g++ -std=c++20 -fmodules-ts -xc++-system-header iostream
g++ -std=c++20 -fmodules-ts -xc++-system-header variant
```

This looks very similar to Bug 103256.


Is this behavior expected?


Thanks in advance.
Lorenzo