[Bug c++/127431] New: struct field default = address of label can cause assembly with reference to undefined local label

[alanas.00 at mail dot ru via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127431

            Bug ID: 127431
           Summary: struct field default = address of label can cause
                    assembly with reference to undefined local label
           Product: gcc
           Version: 16.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: alanas.00 at mail dot ru
  Target Milestone: ---

1. save this code as a.c++:

```
inline auto f() {
label:
        struct address_of_label_container {
                void *a = &&label;
        };
        return address_of_label_container{};
}

decltype(f()) global_variable;
```

2. run g++ -S a.c++


generated a.s:

```
        .file   "a.c++"
        .text
        .globl  global_variable
        .data
        .align 8
        .type   global_variable, @object
        .size   global_variable, 8
global_variable:
        .quad   .L1
        .ident  "GCC: (SUSE Linux) 16.2.0"
        .section        .note.GNU-stack,"",@progbits
```

.L1 is not defined anywhere but is used to initialize global_variable

clang++ has similar bug:
https://github.com/llvm/llvm-project/issues/219659#issuecomment-5468553973