[Bug c++/110925] New: Unnecessary dynamic initialization in trivial cases

[janschultke at googlemail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110925

            Bug ID: 110925
           Summary: Unnecessary dynamic initialization in trivial cases
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: janschultke at googlemail dot com
  Target Milestone: ---

## Code to Reproduce

int z = 0;
int x = z;

## Expected Output (delivered by clang trunk -O3)

x:
        .zero   4
z:
        .zero   4

## Actual Output (x86_64 GCC 14 -O3) (https://godbolt.org/z/95d9hj3he)

_GLOBAL__sub_I_z:
        mov     eax, DWORD PTR z[rip]
        mov     DWORD PTR x[rip], eax
        ret
x:
        .zero   4
z:
        .zero   4


## Explanation

The implementation is allowed to turn this into static initialization. See
https://eel.is/c++draft/basic.start.static#3. However, GCC emits unnecessary
dynamic initialization code.