https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66968
Bug ID: 66968
Summary: Incorrect template argument shown in diagnostic
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
Target Milestone: ---
Compiling this invalid code produces an error as expected:
template<typename T> struct thing { };
template<typename T, typename XXX>
bool operator==(const thing<T>&, const thing<XXX>&);
struct nested { typedef int name; };
template<typename A, typename B>
void func(typename A::name const&, const B) { }
template<typename A, typename B>
void func(typename A::name const&, const thing<B>) { }
int main()
{
thing<int> ti;
func<nested>(1, ti);
}
However the error has an error:
y.cc: In function ‘int main()’:
y.cc:17:21: error: call of overloaded ‘func(int, thing<int>&)’ is ambiguous
func<nested>(1, ti);
^
y.cc:9:6: note: candidate: void func(const typename A::name&, B) [with A =
nested; B = thing<int>; typename A::name = int]
void func(typename A::name const&, const B) { }
^
y.cc:12:6: note: candidate: void func(const typename A::name&, thing<XXX>)
[with A = nested; B = int; typename A::name = int]
void func(typename A::name const&, const thing<B>) { }
^
Note that the second candidate shows thing<XXX>, where does that XXX come
from?!
The "[with ...]" output correctly shows the template parameter B but B doesn't
appear in the candidate. For some reason XXX is shown instead, which is only
ever mentioned in the operator== declaration above, which is never used!
