[Bug c++/40315] template instantiation fails when using const typename

["redi at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>]

------- Comment #3 from redi at gcc dot gnu dot org  2009-08-26 14:51 -------
(In reply to comment #2)
> IIUC, the top-level const qualifier on "const typename Foo<D>::double3" in the
> primary template applies to the type, which is not known during phase 1

i.e. it's equivalent to "typename Foo<D>::double3 const" which is equivalent to
simply "typename Foo<D>::double3) because top-level cv-qualifiers are removed
from function parameters.

but when double3 is known to be an array type, which is replaced by a pointer
in a parameter list, then the declaration's meaning changes.

Consider:

typedef double  double3[3];
void f(const double3);
typedef void (*ptr)(const double*);
ptr p = f;

This demonstrates that the declaration of 'f' is equivalent to:

void f(const double*);

not

void f(double* const);

According to [dcl.fct] array parameters are replaced with pointers before
top-level cv-qualifiers are deleted.

I think GCC is correct, the template specializations are invalid.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40315