[Sema] Better static assert diagnostics for expressions involving temporaries/casts/....

Summary:
Handles expressions such as:
 - `std::is_const<T>()`
 - `std::is_const<T>()()`;
 - `std::is_same(decltype(U()), V>::value`;

Reviewers: aaron.ballman, Quuxplusone

Subscribers: cfe-commits, llvm-commits

Differential Revision: https://reviews.llvm.org/D55552

llvm-svn: 349729

1 files changed, 41 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/static-assert-cxx17.cpp b/clang/test/SemaCXX/static-assert-cxx17.cpp
index 67b3541bea1..7fff59e7f80 100644
--- a/clang/test/SemaCXX/static-assert-cxx17.cpp
+++ b/clang/test/SemaCXX/static-assert-cxx17.cpp
@@ -54,3 +54,44 @@ void foo5() {
 }
 template void foo5<int, float>();
 // expected-note@-1{{in instantiation of function template specialization 'foo5<int, float>' requested here}}
+
+struct ExampleTypes {
+  explicit ExampleTypes(int);
+  using T = int;
+  using U = float;
+};
+
+template <class T>
+struct X {
+  int i = 0;
+  int j = 0;
+  constexpr operator bool() const { return false; }
+};
+
+template <class T>
+void foo6() {
+  static_assert(X<typename T::T>());
+  // expected-error@-1{{static_assert failed due to requirement 'X<int>()'}}
+  static_assert(X<typename T::T>{});
+  // expected-error@-1{{static_assert failed due to requirement 'X<int>{}'}}
+  static_assert(X<typename T::T>{1, 2});
+  // expected-error@-1{{static_assert failed due to requirement 'X<int>{1, 2}'}}
+  static_assert(X<typename T::T>({1, 2}));
+  // expected-error@-1{{static_assert failed due to requirement 'X<int>({1, 2})'}}
+  static_assert(typename T::T{0});
+  // expected-error@-1{{static_assert failed due to requirement 'int{0}'}}
+  static_assert(typename T::T(0));
+  // expected-error@-1{{static_assert failed due to requirement 'int(0)'}}
+  static_assert(sizeof(X<typename T::T>) == 0);
+  // expected-error@-1{{static_assert failed due to requirement 'sizeof(X<int>) == 0'}}
+  static_assert((const X<typename T::T> *)nullptr);
+  // expected-error@-1{{static_assert failed due to requirement '(const X<int> *)nullptr'}}
+  static_assert(static_cast<const X<typename T::T> *>(nullptr));
+  // expected-error@-1{{static_assert failed due to requirement 'static_cast<const X<int> *>(nullptr)'}}
+  static_assert((const X<typename T::T>[]){} == nullptr);
+  // expected-error@-1{{static_assert failed due to requirement '(X<int> const[0]){} == nullptr'}}
+  static_assert(sizeof(X<decltype(X<typename T::T>().X<typename T::T>::~X())>) == 0);
+  // expected-error@-1{{static_assert failed due to requirement 'sizeof(X<void>) == 0'}}
+}
+template void foo6<ExampleTypes>();
+// expected-note@-1{{in instantiation of function template specialization 'foo6<ExampleTypes>' requested here}}