https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118136
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #3)
> >+__attribute__((naked)) void custom_start() {
> calls
>
> This is not defined code as naked is only to be used with one inline-asm
> without any calls.
Plus NOT all targets implement the naked attribute.
From
https://gcc.gnu.org/onlinedocs/gcc-14.2.0/gcc/x86-Function-Attributes.html#index-naked-function-attribute_002c-x86
"While using extended asm or a mixture of basic asm and C code may appear to
work, they cannot be depended upon to work reliably and are not supported."
So at least the naked attribute causes the testcase to be invalid/undefined.
