Hi Martin,
By calling builtin_decl_explicit rather than builtin_decl_implicit
the updated patch in the attachment avoids test failures due to
missing warnings on targets with support for long double but whose
libc doesn't support C99 functions like fabsl (such as apparently
aarch64-linux).
[...]
gcc/testsuite/ChangeLog:
PR testsuite/88098
* gcc.dg/Wbuiltin-declaration-mismatch-4.c: Adjust.
* gcc.dg/Wbuiltin-declaration-mismatch-5.c: New test.
is the Wbuiltin-declaration-mismatch-5.c testcase still supposed to be
part of the patch? It's in the ChangeLog, but missing from the revised
patch.