From a9ee0e23a74887fa13df5404af6ff606a89bcc91 Mon Sep 17 00:00:00 2001
From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Tue, 29 Nov 2016 12:41:21 +0000
Subject: [PATCH] [AST] Use static_assert to verify types instead of undefined
 classes.

No functionliaty change intended.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@288133 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/clang/AST/CanonicalType.h |  8 ++++----
 include/clang/AST/Type.h          | 18 ++++++++----------
 2 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/include/clang/AST/CanonicalType.h b/include/clang/AST/CanonicalType.h
index 77510afeec..25f6172be9 100644
--- a/include/clang/AST/CanonicalType.h
+++ b/include/clang/AST/CanonicalType.h
@@ -630,8 +630,8 @@ CanQual<T> CanQual<T>::CreateUnsafe(QualType Other) {
 template<typename T>
 template<typename U>
 CanProxy<U> CanQual<T>::getAs() const {
-  ArrayType_cannot_be_used_with_getAs<U> at;
-  (void)at;
+  static_assert(!TypeIsArrayType<T>::value,
+                "ArrayType cannot be used with getAs!");
 
   if (Stored.isNull())
     return CanProxy<U>();
@@ -645,8 +645,8 @@ CanProxy<U> CanQual<T>::getAs() const {
 template<typename T>
 template<typename U>
 CanProxy<U> CanQual<T>::castAs() const {
-  ArrayType_cannot_be_used_with_getAs<U> at;
-  (void)at;
+  static_assert(!TypeIsArrayType<U>::value,
+                "ArrayType cannot be used with castAs!");
 
   assert(!Stored.isNull() && isa<U>(Stored.getTypePtr()));
   return CanQual<U>::CreateUnsafe(Stored);
diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index 0a0a32511f..b4651da490 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -5916,17 +5916,15 @@ inline const PartialDiagnostic &operator<<(const PartialDiagnostic &PD,
 
 // Helper class template that is used by Type::getAs to ensure that one does
 // not try to look through a qualified type to get to an array type.
-template <typename T, bool isArrayType = (std::is_same<T, ArrayType>::value ||
-                                          std::is_base_of<ArrayType, T>::value)>
-struct ArrayType_cannot_be_used_with_getAs {};
-
-template<typename T>
-struct ArrayType_cannot_be_used_with_getAs<T, true>;
+template <typename T>
+using TypeIsArrayType =
+    std::integral_constant<bool, std::is_same<T, ArrayType>::value ||
+                                     std::is_base_of<ArrayType, T>::value>;
 
 // Member-template getAs<specific type>'.
 template <typename T> const T *Type::getAs() const {
-  ArrayType_cannot_be_used_with_getAs<T> at;
-  (void)at;
+  static_assert(!TypeIsArrayType<T>::value,
+                "ArrayType cannot be used with getAs!");
 
   // If this is directly a T type, return it.
   if (const T *Ty = dyn_cast<T>(this))
@@ -5956,8 +5954,8 @@ inline const ArrayType *Type::getAsArrayTypeUnsafe() const {
 }
 
 template <typename T> const T *Type::castAs() const {
-  ArrayType_cannot_be_used_with_getAs<T> at;
-  (void) at;
+  static_assert(!TypeIsArrayType<T>::value,
+                "ArrayType cannot be used with castAs!");
 
   if (const T *ty = dyn_cast<T>(this)) return ty;
   assert(isa<T>(CanonicalType));
-- 
2.50.1