[cfe-dev] Explicit instantiation with body?

[Larisse Voufo]

On Wed, Jun 19, 2013 at 10:43 AM, John McCall <rjmccall at apple.com> wrote:

> On Jun 19, 2013, at 9:15 AM, Larisse Voufo <lvoufo at google.com> wrote:
> > Just out of curiosity, I have noticed that Clang currently allows the
> following program:
> >
> > template<typename T> T f() { return 13; }
> > template int f() { return 1; }
> >
> > It essentially parses the body of the explicit instantiation only to
> ignore it.
> > Was this a conscious decision?
>

I just spoke to Richard Smith about this, and it appears that the current
behavior is a bit different from the way I just described it above.
The declaration for the template instantiation is parsed, but the
'template' keyword is ignored, which leads to two different behaviors for
the calls f() and f<int>().
While f() returns 1, f<int>() returns 13. f() picks up the declaration "int
f() { return 1; }" while f<int>() picks up the template declaration and
implicitly instantiates it.


>
> No;  please file a bug.  You cannot define a function in an explicit
> instantiation.
>

I can quickly fix this or submit a patch. Should I still file a bug?


>
> > GCC 4.6.3 rejects the program with "expected ‘;’ before ‘{’ token".
>
> Well, hopefully we can do better than that.
>

What do you have in mind?


> John.
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