[cfe-commits] [PATCH] Merge function types is C.

[Eli Friedman]

On Wed, Nov 28, 2012 at 1:25 PM, Richard Smith <richard at metafoo.co.uk> wrote:
> On Wed, Nov 28, 2012 at 12:59 PM, Eli Friedman <eli.friedman at gmail.com>
> wrote:
>>
>> On Wed, Nov 28, 2012 at 9:17 AM, Rafael Espíndola
>> <rafael.espindola at gmail.com> wrote:
>> > Thanks Richard for pointing me some missing cases. The attached patch
>> > takes a step back and merge only the return types.
>> >
>> > Richard suggested avoiding the merging when the new Decl is a k&r
>> > definition, but at this point of the code we haven't attached the body
>> > yet. It would also be nice if we could handle both definitions and
>> > declarations uniformly.
>> >
>> > I debugged why CodeGen was complaining and the problem is that by
>> > merging just the function types we end up with a ParmVarDecl whose
>> > type doesn't match the corresponding type in the FunctionProtoType and
>> > CodeGen asserts. Two options that would still let us merge the full
>> > types is making CodeGen cope with it (produce a llvm cast) or patching
>> > the type of the ParmVarDecl too. Do you think we should do it?
>>
>> Patching the type of the ParmVarDecl would be appropriate.
>
>
> Given:
>
> int f(int);
> int f(a)
>   char a;
> {
>   return sizeof(a);
> }
>
> I would expect 1 to be returned, not 4.

Yes, you're right.

I was thinking of:
int f(int (*)[10]);
int f(int (*x)[]) {
  return sizeof(*x); // 40
}

But maybe not relevant to this discussion?

-Eli