Decltype needs to have a dependent type if the expr passed to it is type dependent. Fixes PR4444.

llvm-svn: 74175

clang/lib/AST/ASTContext.cpp

@@ -1666,6 +1666,9 @@ QualType ASTContext::getTypeOfType(QualType tofType) {
 /// getDecltypeForExpr - Given an expr, will return the decltype for that
 /// expression, according to the rules in C++0x [dcl.type.simple]p4
 static QualType getDecltypeForExpr(const Expr *e, ASTContext &Context) {
+  if (e->isTypeDependent())
+    return Context.DependentTy;
+  
   // If e is an id expression or a class member access, decltype(e) is defined
   // as the type of the entity named by e.
   if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(e)) {

clang/test/SemaCXX/decltype-pr4444.cpp

@@ -0,0 +1,6 @@
+// RUN: clang-cc -fsyntax-only -verify %s -std=c++0x
+
+template<typename T, T t>
+struct TestStruct {
+   typedef decltype(t+2) sum_type;
+};