Template type conversion operator not used leading to erroneous compilation error


Bugzilla Link	21772
Version	3.5
OS	Linux
Reporter	LLVM Bugzilla Contributor
CC	@DougGregor,@tavianator

Extended Description

The following code looks like valid C++ 11 but fails with error

"no matching constructor for initialization of 'Ptr'"

It compiles ok on gcc 4.9. Based on example code taken from Stroustrup's The C++ Programming Language 4th edition, pp 764-765.

template struct Ptr { Ptr(T* pp) : p{pp} { }

template <typename U>
explicit operator Ptr<U>(); // Convert Ptr<T> to Ptr<U>

private: T* p; };

template template Ptr::operator Ptr() { return Ptr{p}; }

struct Shape {}; struct Circle : Shape {};

int main() { Circle c; Ptr pc{&c}; // The following instantiation causes the // error. Ptr::operator Ptr() should be getting // implicitly called on the argument pc, before the result is used // to call Ptr's default copy constructor. Ptr ps{pc}; }

llvm / llvm-project

Template type conversion operator not used leading to erroneous compilation error #22146

Extended Description