Argument dependent lookup with class argument is recursing into base

classes that haven't been instantiated. This is generating an assertion
in DeclTemplate.h. Fix for Bug25668.

clang/lib/Sema/SemaLookup.cpp

@@ -2576,6 +2576,8 @@ namespace {
 
     bool addClassTransitive(CXXRecordDecl *RD) {
       Classes.insert(RD);
+      if (InstantiationLoc.isInvalid())
+        InstantiationLoc = RD->getLocation();
       return ClassesTransitive.insert(RD);
     }
 

clang/lib/Sema/SemaOpenMP.cpp

@@ -17549,6 +17549,7 @@ static void checkMappableExpressionList(
     auto &DeclNames = SemaRef.getASTContext().DeclarationNames;
     MapperId.setName(DeclNames.getIdentifier(
         &SemaRef.getASTContext().Idents.get("default")));
+    MapperId.setLoc(StartLoc);
   }
 
   // Iterators to find the current unresolved mapper expression.

clang/test/OpenMP/template-specialization.cpp

@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -verify -fopenmp -fsyntax-only %s
+
+// expected-no-diagnostics
+
+template <typename T>
+struct z {
+  static void aj() {
+    T f;
+#pragma omp target map(f)
+    ;
+  }
+};
+
+template <typename> class ar {};
+template <int> struct as {};
+template class z<ar<as<4>>>;