[cfe-dev] Function Instantiation: Where? Or is it?

[Larisse Voufo]

On Mon, Jan 31, 2011 at 5:50 PM, Douglas Gregor <dgregor at apple.com> wrote:

>
> On Jan 31, 2011, at 1:43 PM, Larisse Voufo wrote:
>
> Thanks. That was a lot helpful. However, I do have another question.
> Consider the following two case scenari:
>
> Case 1:
> ------------
> The previous one, with
> (1) f() defined as a concept member, and
> (2) func() a restricted template
>
>
> Case 2:
> ------------
> (1) f() is a global function, and
> (2) func() is a simple template, as in
>
> void f() { }
>
> template<typename T>
> void func(T a) {
>     f(0);
> }
>
> int main(int argc, char **argv)
> {
>     int i=0;
>     func<int>(i);
> }
>
>
> Observation:
> ----------------------
> In both cases, f() never seems to be "marked for instantiation", at least
> not through Sema::
> MarkDeclarationReferenced. However, f() does seem to eventually get
> instantiated in the "Case 2" somehow, whereas it never does in "Case 1". Any
> idea?
>
> 1) When does f() get instantiated in "Case 2"?
>
>
> Case 2 is ill-formed, but the general rule is that
> MarkDeclarationReferenced will get called when we use that function in a
> potentially evaluated context, either in non-template code or during
> template instantiation.
>
> Sorry about this. I meant for the definition of f() to take an integer in
as argument...


> 2) is this connected to lookup somehow?
>      I have made some very minor changes in Sema::CppLookupName(), and I'm
> not sure how this could affect instantiation...
>
>
> It's more likely that you haven't added any logic to permit the
> instantiation of functions defined within concept maps.
>

Any rule of thumb on how to add such logic? Say, for example how is this
currently setup for  "(corrected) Case 2"?



>
> - Doug
>
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