On Fri, Oct 2, 2015 at 4:01 PM, mats petersson <m...@planetcatfish.com> wrote: > Since "varargs" often involve some kind of special passing mechanisms [I've > seen implementations that build data block and pass a pointer to that, > rather than passing on the stack, for example], or additional code in the > recipient function, I would say that `f2()` does not mean `f2(...)`.
I kind of wondered if that was the case. If that's reality, perhaps we may want to consider naming it FunctionDecl::hasVarArgs() or something that specifies the difference is in whether we need to care about packaging up the argument list so it can be used with va_start() and friends? ~Aaron > > -- > Mats > > On 2 October 2015 at 20:16, Aaron Ballman via cfe-commits > <cfe-commits@lists.llvm.org> wrote: >> >> Given the following two function declarations: >> >> void f1(...); >> void f2(); >> >> It makes sense to me that isVariadic() returns true for f1 in both C >> and C++. It makes sense to me that isVariadic() returns false for f2 >> in C++. I am confused as to why it returns false instead of true for >> C, however. >> >> In C11, 6.7.6.3p9 states: If the list terminates with an ellipsis (, >> ...), no information about the number or types of the parameters after >> the comma is supplied. >> >> p14 states, in part: "The empty list in a function declarator that is >> not part of a definition of that function specifies that no >> information about the number or types of the parameters is supplied." >> >> It seems to me that for function *declarations* (not definitions), >> isVariadic() should return true for f2 in C. Is there a reason it >> doesn't currently behave that way, or is this a bug? >> >> I ask because I was writing an AST matcher for isVariadic() for an >> in-progress checker, but the checker was failing to catch that f2 was >> a variadic function. I am not certain whether >> FunctionDecl::isVariadic() should be changed, whether the AST matcher >> isVariadic() should be smarter about C code, or whether the checker >> itself needs to be smarter about this particular behavior in C code. >> My gut reaction is that FunctionDecl::isVariadic() has a bug, but from >> looking at code elsewhere, everything seems to assume isVariadic() >> implies the ellipsis, which makes me think I just need to make my >> checker smarter. >> >> Thanks! >> >> ~Aaron >> _______________________________________________ >> cfe-commits mailing list >> cfe-commits@lists.llvm.org >> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits > > _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
