GCC 4.4 is supposed to support "SFINAE for expressions" - but the following
piece of code fails hard, without SFINAE
----
typedef void Ft(int);
struct A { operator Ft*(); };
struct B { operator Ft*(); };
struct C : A, B { };
template<typename C> decltype(C()(0)) f(int);
template<typename C> void f(...);
int main() { f<C>(0); }
----
main.cpp: In function 'int main()':
main.cpp:8: error: conversion from 'C' to 'void (*)(int)' is ambiguous
main.cpp:3: note: candidates are: B::operator void (*)(int)()
main.cpp:2: note: A::operator void (*)(int)()
----
The call within the decltype specifier is ill-formed - which should be a
deduction failure but shouldn't cause the program to become ill-formed.
--
Summary: SFINAE for expressions doesn't consider ambiguous
conversion sequences
Product: gcc
Version: 4.4.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: schaub-johannes at web dot de
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41468
