llvm-project/clang/test/SemaTemplate/subst-into-subst.cpp

35 lines
1.3 KiB
C++

// RUN: %clang_cc1 -std=c++2a -verify %s
// When forming and checking satisfaction of atomic constraints, we will
// substitute still-dependent template arguments into an expression, and later
// substitute into the result. This creates some unique situations; check that
// they work.
namespace SubstIntoResolvedTypeTemplateArg {
template<int, class> struct X {};
template<class T> concept A = true;
template<class T> concept B = sizeof(T) != 0;
template<class T> concept C = B<X<1, T>>;
int f(A auto); // expected-note {{candidate}}
int f(C auto); // expected-note {{candidate}}
int k1 = f(0); // expected-error {{ambiguous}}
template<class T> concept D = A<T> && B<X<1, T>>;
int f(D auto);
int k2 = f(0); // ok
// The atomic constraint formed from B<X<(int)'\1', T>> is identical to the
// one formed from C, even though the template arguments are written as
// different expressions; the "equivalent" rules are used rather than the
// "identical" rules when matching template arguments in concept-ids.
template<class T> concept E = A<T> && B<X<(int)'\1', T>>;
int g(C auto);
int g(E auto); // expected-note {{candidate}}
int k3 = g(0);
int g(D auto); // expected-note {{candidate}}
int k4 = g(0); // expected-error {{ambiguous}}
}