[Bug c++/56377] New: [4.8 Regression] <missing> template args in substitution-failure diagnostics

["pl.smith.mail at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56377

             Bug #: 56377
           Summary: [4.8 Regression] <missing> template args in
                    substitution-failure diagnostics
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: pl.smith.mail@gmail.com


When a candidate function for which substituion failed is listed in a
diagnostic, if the failure stems from a template parameter that have an
explicit argument, the explicit arguments are listed as <missing>.

For example:

template <typename T>
typename T::type f();

int main () {
  f<int>();
}

Produces (4.8, no flags):

test.cpp: In function ×âËint main()×ââ:
test.cpp:5:10: error: no matching function for call to 'f()'
   f<int>();
          ^
test.cpp:5:10: note: candidate is:
test.cpp:2:18: note: template<class T> typename T::type f()
 typename T::type f();
                  ^
test.cpp:2:18: note:   template argument deduction/substitution failed:
  *************
test.cpp: In substitution of 'template<class T> typename T::type f() [with T =
<missing>]':
  *************
test.cpp:5:10:   required from here
test.cpp:2:18: error: 'int' is not a class, struct, or union type

In 4.7 it is "[with T = int]".