[Bug target/100643] [11/12 Regression] ICE in ix86_mangle_function_version_assembler_name, at config/i386/i386-features.c:2809 since r11-7693-g1c7bec8bfbc5457c

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100643

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
The C frontend accepts it when you make the outer function 'int foo(void)'.

When you make the testcase

int foo(void) __attribute__((target("avx")));
int foo(void) __attribute__((target("default")));
int foo(void)
{
  return 124;
}

then the C++ frontend rejects it as

t.c:3:5: error: missing 'target' attribute for multi-versioned 'int foo()'
    3 | int foo(void)
      |     ^~~
t.c:2:5: note: previous declaration of 'int foo()'
    2 | int foo(void) __attribute__((target("default")));
      |     ^~~

when you make it

int foo(void)
{
  return 124;
}
int foo(void) __attribute__((target("avx")));
int foo(void) __attribute__((target("default")));

it is accepted.