https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67301
--- Comment #2 from Jeffrey Walton <noloader at gmail dot com> ---
(In reply to Andrew Pinski from comment #1)
> Try:
> int main(int argc, char* argv[])
> {
> __asm__ __volatile__ (
>
> "\t movl %[__ARGC], %%eax \n"
> :
> : [__ARGC] "r" (argc)
> );
>
> return 0;
> }
>
> Basically the syntax for naming operands is [XYZ] but since it is optional,
> [ is used to say it is optional part of the syntax. Yes it is slightly
> confusing but that is what you get when you use [] as both part of the
> actual syntax and saying it is an optional part.
Oh, I see. Yes, that's confusing.
When I read it, I thought the double square brackets were a typo that should
have read something like the following, meaning the asmSymbolicName is optional
(which it is):
[ [asmSymbolicName] constraint (cexpression) ]
Perhaps the docs should call that out specifically to avoid confusion?
