https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66289
Bug ID: 66289
Summary: [5/6 Regression] "error: ambiguous template
instantiation" with partial specialization defined in
terms of alias template
Product: gcc
Version: 5.0
Status: UNCONFIRMED
Keywords: rejects-valid
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
Target Milestone: ---
5.1 and later incorrectly reject this, but it should compile because
foo<shared_ptr<A<T>>> is more specialized than foo<shared_ptr<T>>:
template<typename T> struct A {};
template<typename T> struct shared_ptr { };
template<typename T> using APtr = shared_ptr<A<T>>;
template<typename T> struct foo;
template<typename T> struct foo<shared_ptr<T>> { };
template<typename T> struct foo<APtr<T>> { };
foo<shared_ptr<A<int>>> aa;
amb.cc:10:25: error: ambiguous template instantiation for ‘struct
foo<shared_ptr<A<int> > >’
foo<shared_ptr<A<int>>> aa;
^
amb.cc:7:29: note: candidates are: template<class T> struct foo<shared_ptr<T> >
[with T = A<int>]
template<typename T> struct foo<shared_ptr<T>> { };
^
amb.cc:8:29: note: template<class T> struct foo<APtr<T> > [with
T = int]
template<typename T> struct foo<APtr<T>> { };
^
amb.cc:10:25: error: aggregate ‘foo<shared_ptr<A<int> > > aa’ has incomplete
type and cannot be defined
foo<shared_ptr<A<int>>> aa;
^
