https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114011
Bug ID: 114011
Summary: Feature request: __goto__
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: pskocik at gmail dot com
Target Milestone: ---
Gcc has __volatile__.
I can only assume the rationale for it is so that inline asm macros can
do __asm __volatile__ and not have to worry about user-redefines of the
volatile keyword (which while not quite approved by the standard, is sometimes
practically useful).
While the __asm syntax also allows the goto keyword, there's currently no
__goto__ counterpart to __volatile__, which could similarly protect against
goto redefines.
Adding it is trivial and consistent with the already existing
volatile/__volatile__ pair. Would you consider it?
(
Why am I redefining goto? I'm basically doing it within the confines of a macro
framework to force a static context check on gotos to prevent gotos out of
scopes where doing it would be an error.
Something like:
enum { DISALLOW_GOTO_HERE = 0 }; //normally, goto is allowed
#define goto while(_Generic((int(*)[!DISALLOW_GOTO_HERE])0, int(*)[1]:1)) goto
//statically checked goto
int main(void){
goto next; next:; //OK, not disallowed in this context
#if 0 //would fail to compile
enum {DISALLOW_GOTO_HERE=1}; //disallowed in this context
goto next2; next2:;
#endif
}
While this redefine does not syntactically disturb C, it does disturb `__asm
goto()`, which I, unfortunately, have one very frequently used instance of, and
since there's no way to suppress an object macro redefine, I'd like to be able
to change it to `__asm __goto__` and have it peacefully coexist with the goto
redefine.
)
