[SYCL] Fix address space assertion with templates (#2798)

In certain complex template instantiations, address space mismatches
cause the compiler to assert instead of issuing errors gracefully.
This fixes one such case identified in PR #2763.

Signed-off-by: Premanand M Rao <[email protected]>

Author: premanandrao

clang/include/clang/AST/Type.h

@@ -384,8 +384,8 @@ class Qualifiers {
          | (((uint32_t) space) << AddressSpaceShift);
   }
   void removeAddressSpace() { setAddressSpace(LangAS::Default); }
-  void addAddressSpace(LangAS space) {
-    assert(space != LangAS::Default);
+  void addAddressSpace(LangAS space, bool AllowDefaultAddrSpace = false) {
+    assert(space != LangAS::Default || AllowDefaultAddrSpace);
     setAddressSpace(space);
   }
 

clang/lib/Sema/SemaInit.cpp

@@ -4905,7 +4905,8 @@ static void TryReferenceInitializationCore(Sema &S,
     // Add addr space conversion if required.
     if (T1Quals.getAddressSpace() != T2Quals.getAddressSpace()) {
       auto T4Quals = cv1T4.getQualifiers();
-      T4Quals.addAddressSpace(T1Quals.getAddressSpace());
+      T4Quals.addAddressSpace(T1Quals.getAddressSpace(),
+                              S.getLangOpts().SYCLIsDevice);
       QualType cv1T4WithAS = S.Context.getQualifiedType(T2, T4Quals);
       Sequence.AddQualificationConversionStep(cv1T4WithAS, ValueKind);
       cv1T4 = cv1T4WithAS;

clang/test/SemaSYCL/sycl-templ-addr-space.cpp

@@ -0,0 +1,52 @@
+// RUN: %clang_cc1 -fsycl -fsycl-is-device -triple spir64 -verify %s
+
+// Test that the compiler no longer asserts while processing this test case.
+
+template <int N>
+struct integral_constant {
+  static constexpr int val = N;
+};
+template <typename T>
+T &&convert(int);
+template <typename T>
+auto declval(convert<T>(0));
+template <typename Op1, typename Op2>
+class sub_group {
+  template <typename T, decltype(declval<T>)>
+  // expected-note@+1 {{possible target for call}}
+  static integral_constant<true> binary_op();
+  // expected-error@+1 {{reference to overloaded function could not be resolved; did you mean to call it?}}
+  decltype(binary_op<Op1, Op2>) i;
+};
+// expected-note-re@+2 {{in instantiation {{.*}} requested here}}
+template <typename n>
+struct group : sub_group<n, int> {
+};
+template <typename T>
+struct wrapper {
+  typedef T val;
+};
+class element_type {
+};
+struct Container {
+  using __element_type = __attribute__((opencl_global)) element_type;
+};
+template <bool, class Base, class> using BaseImpl = Base;
+// expected-note-re@+1 2{{candidate constructor {{.*}} not viable: {{.*}}}}
+template <int> class id_type {
+  template <class...> struct Base;
+  // expected-note-re@+1 {{in instantiation {{.*}} requested here}}
+  template <class Der> struct Base<Der> : BaseImpl<Der::val, Base<>, Der> {};
+  // expected-note-re@+1 {{in instantiation {{.*}} requested here}}
+  template <typename T> using Base2 = wrapper<typename Base<group<T>>::val>;
+  // expected-note-re@+3 {{in instantiation {{.*}} requested here}}
+  // expected-note-re@+2 {{in instantiation {{.*}} required here}}
+  // expected-note-re@+1 {{candidate template ignored: {{.*}}}}
+  template <typename T, typename = Base2<T>> id_type(T &);
+};
+id_type<1> get() {
+  Container::__element_type *ElemPtr;
+  // expected-error@+2 {{no viable conversion from returned value of type 'Container::__element_type' (aka '__global element_type') to function return type 'id_type<1>'}}
+  // expected-note-re@+1 {{while substituting {{.*}}}}
+  return ElemPtr[0];
+}