[Bug c++/44283] bad error recovery for explicit template instantiation in wrong namespace

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44283

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-04-12 12:35:07 UTC ---
(In reply to comment #0)
> namespace NS
> {
>     typedef int X;
> 
>     template<typename T> void f(X f, T t) { }
> }
> 
> template void f(X, int);     // (1)
> 
> template void f(int, char);  // (2)


Clang does very well for this:

t.cc:8:15: error: explicit instantiation of 'f' does not refer to a function
template, member function, member
      class, or static data member
template void f(X, int);     // (1)
              ^
t.cc:10:15: error: explicit instantiation of 'f' does not refer to a function
template, member function,
      member class, or static data member
template void f(int, char);  // (2)
              ^
2 errors generated.



> If the invalid instantiation is for a class template the diagnostic is fine:
> 
> namespace NS
> {
>     template<typename T> struct S;
> }
> 
> template struct S<X>;
> 
> bug2.cc:6:17: error: 'S' is not a template
> bug2.cc:6:19: error: 'X' was not declared in this scope
> bug2.cc:6:17: error: explicit instantiation of non-template type 'S'


Clang is similar:

t.cc:6:19: error: use of undeclared identifier 'X'
template struct S<X>;
                  ^
t.cc:6:17: error: explicit instantiation of non-template struct 'S'
template struct S<X>;
                ^
2 errors generated.



> namespace NS
> {
>     template<int N> void g() { }
> }
> 
> template void g<0>();
> 
> bug3.cc:6:15: error: variable or field 'g' declared void
> bug3.cc:6:16: error: expected ';' before '<' token


Clang is not much better here:

t.cc:6:16: error: expected ';' after top level declarator
template void g<0>();
               ^
1 error generated.



EDG's diagnostics are still the best for these examples.