https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108279
--- Comment #17 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- It's not part of the ABI for the Arm 32-bit Architecture (AAPCS32). https://github.com/ARM-software/abi-aa/blob/main/aapcs32/aapcs32.rst You can file an issue there if you want, though I don't know how interested the maintainers will be in that optional language feature.
