[cfe-dev] [PATCH] Function redeclaration and PR2360

[Eli Friedman]

On Tue, May 27, 2008 at 11:19 AM, Argiris Kirtzidis <akyrtzi at gmail.com> wrote:
> Eli Friedman wrote:
>>
>> This means that references to a function before a
>> redeclaration refer to the old declaration, and references to a
>> function after a redeclaration refer to the new declaration.
>
> How about these cases:
>
> int a(int); // #1
> int a();    // #2
> int b(void) {a();} // should refer to #2 or is more accurate to refer to #1
> ?

a refers to #2; but note that per the rules about redeclaration, the
type of #2 is actually int(int).  (See C99 6.2.7 p3 and p4.)  clang
doesn't implement this bit correctly yet, though.

> And:
>
> int a(int x = 5); // #1
> int a(int x);  // #2
> int b(void) {a();} // Shouldn't it refer to #1 ?

a again refers to #2; the only way that really makes sense here is to
have #2 point to the default argument from #1.  Take the following
example:

int a(int x, int y = 3);
int a(int x = 5, int y);

Neither version of a has all the arguments; we have to propagate them
forward somehow.  This is currently done in
Sema::MergeCXXFunctionDecl.

Note that there is currently a small bug here currently: declarations
can't determine whether they own a default argument, so we end up
leaking them.

-Eli