https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77335
Bug ID: 77335
Summary: templates and ambiguous call to overloaded function
Product: gcc
Version: 6.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: pyer4 at free dot fr
Target Milestone: ---
In some cases, function overloading seems to create ambiguity. When the
function contains multiple template arguments. Encountered on MSVC2015, and
tested at : http://melpon.org/wandbox/permlink/mtfWJXEtQ8lEP8ub
template<class> struct A { };
template<template<class> class, class> struct B { };
template<class, class> struct C { };
template<template<class> class TT, class T, class U> void f(TT<T>, B<TT, T>, U)
{ }
template<template<class> class TT, class T, class V> void f(TT<T>, B<TT, T>,
C<TT<T>, V>) { }
int main()
{
A<int> a;
B<A, int> b;
C<A<int>, long> c;
f(a, b, c);//ambiguity error
}
--------------------------------------------------
Another example :
template <class T>
class BX {
public :
BX() {}
~BX() {}
};
template <class T1, class T2>
class G {
public :
G() {}
~G() {}
};
template <template <class T> class T1, class T>
class DT {};
class B {
public :
template <template <class T> class T1, class T, class M>
static void func(const M& m, const DT<T1, T>* dt, T1<T>& val) {}
template <template <class T> class T1, class T, class M>
static void func(const G<T1<T>, M>& g, const DT<T1, T>* dt, T1<T>& val) {}
//here is a small variation of func as a test
template <template <class T> class T1, class T, class M>
static void func2(const M& m, const DT<T1, T>* dt) {}
template <template <class T> class T1, class T, class M>
static void func2(const G<T1<T>, M>& g, const DT<T1, T>* dt) {}
};
int main() {
BX< int > bx;
G<BX< int >, int> g;
DT<BX, int>* dt;
B::func(g, dt, bx);//Error C2668 'B::func': ambiguous call to overloaded
function
B::func2(g, dt);//no error
}
Problem also submitted at :
http://stackoverflow.com/questions/39060180/c-templates-and-ambiguous-call-to-overloaded-function
