Re: Template type deduction failure when using reference types
Marcus wrote:
Hello all,
Can anyone help me with a particularly obscure error? The following
code fails to compile on g++
template<typename retT, typename argT>
void func(retT (*funcPtr)(argT), argT argument)
{}
void func1(int a) {}
void func2(int& a) {}
int main()
{
int val = 1;
int& valref = val;
func(&func1, valref);//Succeeds
func(&func2, valref);//Fails
}
The compiler appears to lose the ampersand from argT when it creates
the function. I'm completely stuck on this one so any help would be
greatly appreciated.
"argT" is deduced to different types in the second function call. It's "int"
for the right function parameter, but it is "int&" for the left function
parameter. Thus you have a contradiction, and type deduction fails.
You are going to need to make the left parameter a non-deduced context so
that it won't participate
template<typename T> struct identity { typedef T type; };
template<typename retT, typename argT>
void func(retT (*funcPtr)(argT), typename identity<argT>::type argument)
{}
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