UnresolvedMemberExpr should have an expr location of the member (not the base)

This matches the behavior of MemberExpr and makes diagnostics such as
"reference to non-static member function must be called" more legible in
the case that the base & member are split over multiple lines (prior to
this change the diagnostic would point to the base, not the member -
making it very unclear in chained multi-line builder-style calls)

llvm-svn: 183149

clang/include/clang/AST/ExprCXX.h

@@ -3387,6 +3387,10 @@ public:
   // expression refers to.
   SourceLocation getMemberLoc() const { return getNameLoc(); }
 
+  // \brief Return the preferred location (the member name) for the arrow when
+  // diagnosing a problem with this expression.
+  SourceLocation getExprLoc() const LLVM_READONLY { return getMemberLoc(); }
+
   SourceLocation getLocStart() const LLVM_READONLY {
     if (!isImplicitAccess())
       return Base->getLocStart();

clang/test/SemaCXX/overloaded-operator.cpp

@@ -396,7 +396,8 @@ namespace rdar9136502 {
   };
 
   void f(X x, Y y) {
-    y << x.i; // expected-error{{reference to non-static member function must be called}}
+    y << x
+      .i; // expected-error{{reference to non-static member function must be called}}
   }
 }