/// DeclDefinedWithinScope - Return true if the specified decl is defined at or
/// within the 'Within' scope. The current Scope is CurScope.
///
-/// NOTE: This method is extremely inefficient (linear scan), this should not be
-/// used in common cases.
+/// FIXME: This method is extremely inefficient (linear scan), this should not
+/// be used in common cases. Replace with the more modern DeclContext. We need
+/// to make sure both assignments below produce an error.
+///
+/// int main(int argc) {
+/// int xx;
+/// ^(int X) {
+/// xx = 4; // error (variable is not assignable)
+/// argc = 3; // no error.
+/// };
+/// }
///
static bool DeclDefinedWithinScope(ScopedDecl *D, Scope *Within,
Scope *CurScope) {