Allow sizeof(UnrelatedClass::field) in C++11 class template methods

This feature works outside of templates by forming a DeclRefExpr to a
FieldDecl instead of a MemberExpr, which requires a base object in
addition to the FieldDecl.

Previously, while building up the template AST before instantiation, we
formed a CXXDependentScopeMemberExpr, which always instantiates to a
MemberExpr. Now, in unevaluated contexts we form a
DependentScopeDeclRefExpr, which is a more flexible node that can
instantiate to either a MemberExpr or a DeclRefExpr depending on lookup
results.

Fixes PR26893.

llvm-svn: 263279

1 files changed, 26 insertions, 1 deletions

diff --git a/clang/test/SemaTemplate/instantiate-sizeof.cpp b/clang/test/SemaTemplate/instantiate-sizeof.cpp
index bf66fdc17c6..04793f785e6 100644
--- a/clang/test/SemaTemplate/instantiate-sizeof.cpp
+++ b/clang/test/SemaTemplate/instantiate-sizeof.cpp
@@ -1,5 +1,4 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
-// expected-no-diagnostics
 
 // Make sure we handle contexts correctly with sizeof
 template<typename T> void f(T n) {
@@ -9,3 +8,29 @@ template<typename T> void f(T n) {
 int main() {
   f<int>(1);
 }
+
+// Make sure we handle references to non-static data members in unevaluated
+// contexts in class template methods correctly. Previously we assumed these
+// would be valid MemberRefExprs, but they have no 'this' so we need to form a
+// DeclRefExpr to the FieldDecl instead.
+// PR26893
+template <class T>
+struct M {
+  M() {}; // expected-note {{in instantiation of default member initializer 'M<S>::m' requested here}}
+  int m = *T::x; // expected-error {{invalid use of non-static data member 'x'}}
+  void f() {
+    // These are valid.
+    static_assert(sizeof(T::x) == 8, "ptr");
+    static_assert(sizeof(*T::x) == 4, "int");
+  }
+};
+struct S { int *x; };
+template struct M<S>; // expected-note {{in instantiation of member function 'M<S>::M' requested here}}
+
+// Similar test case for PR26893.
+template <typename T=void>
+struct bar {
+  struct foo { int array[10]; };
+  int baz() { return sizeof(foo::array); }
+};
+template struct bar<>;