[cfe-dev] K&R style argument lists and the type system

Eli Friedman eli.friedman at gmail.com
Mon Aug 25 17:50:48 PDT 2008

On Mon, Aug 25, 2008 at 4:20 PM, steve naroff <snaroff at apple.com> wrote:
>> Any ideas for how to solve this?  We could always map definitions
>> identifier-lists to FunctionTypeNoProto, but that means a good chunk
>> of additional code to check type-merging doesn't do bad stuff to a
>> definition and allow CodeGen to synthesize the type of such a function
>> definition properly.
> This makes more sense to me, since there is no prototype for a(x,y).
> I think it's better to keep the old style function definition separate from
> the modern syntax/semantics...

Bleh, I think we have to encode the exact signature into the type
system somehow.  Consider the following testcase:

int a(x) float x; {return x;}
int b(int x) {return x;}
int c(int x) {return (x ? a : b)(1);}

This is a constraint violation per C99, which would be completely
unintuitive to diagnose without encoding the fact that "a" takes float
into the type.

gcc apparently screws up this case; it doesn't print a warning even
with -std=c99 -pedantic.  Although, the standard is a bit screwy here.


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