[Bug c++/110328] New: Module related optimization is too aggressive

["m-matti-a.lehtonen at iki dot fi" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110328

            Bug ID: 110328
           Summary: Module related optimization is too aggressive
           Product: gcc
           Version: 12.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: m-matti-a.lehtonen at iki dot fi
  Target Milestone: ---

Created attachment 55375
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55375&action=edit
Example sources

When the module example (files test.cc and test2.cc) is compiles as
> g++-12 --std=c++20 -Wall -Wextra -Werror -pedantic  -fmodules-ts -O1  -DNDEBUG test2.cc test.cc
it generates the following error:
> In file included from test.cc:4,
> of module test, imported at test2.cc:5:
> In destructor ‘virtual std::bad_optional_access::~bad_optional_access()’,
>     inlined from ‘virtual std::bad_optional_access::~bad_optional_access()’ at > test2.cc:8:15:
> /usr/include/c++/12/optional:102:13: error: ‘this’ is used uninitialized [-Werror=uninitialized]
>   102 |     virtual ~bad_optional_access() = default;
>       |             ^
> In file included from test2.cc:2:
> /usr/include/c++/12/optional: In destructor ‘virtual std::bad_optional_access::~bad_optional_access()’:
> /usr/include/c++/12/optional:102:13: note: ‘this’ was declared here
>   102 |     virtual ~bad_optional_access() = default;
>       |             ^

If the if statement at test2.cc is uncommented, no error is generated.

If basically the same code (file test3.cc) is compiled without using modules,
no problem
> g++-12 --std=c++20 -Wall -Wextra -Werror -pedantic -O1  -DNDEBUG test3.cc

Exact version and system (Ubuntu 22.04.2 LTS)
> $ g++-12  --version
> g++-12 (Ubuntu 12.3.0-1ubuntu1~22.04) 12.3.0