C++ PATCH for c++/84820, no error for invalid qualified-id

[Jason Merrill]

The problem here was that although cp_parser_declarator returned
cp_error_declarator, we then wrapped it in another declarator, hiding
the problem.

Tested x86_64-pc-linux-gnu, applying to trunk.

commit 44b23ac745e9f249ff3971fcb4021facbbf8741c
Author: Jason Merrill <ja...@redhat.com>
Date:   Thu Mar 15 00:14:04 2018 -0400

            PR c++/84820 - no error for invalid qualified-id.
    
            * parser.c (cp_parser_make_indirect_declarator): Don't wrap
            cp_error_declarator.

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 0a82f415196..119f6c078f7 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -3823,7 +3823,7 @@ cp_parser_make_indirect_declarator (enum tree_code code, tree class_type,
 				    cp_declarator *target,
 				    tree attributes)
 {
-  if (code == ERROR_MARK)
+  if (code == ERROR_MARK || target == cp_error_declarator)
     return cp_error_declarator;
 
   if (code == INDIRECT_REF)
diff --git a/gcc/testsuite/g++.dg/parse/error21.C b/gcc/testsuite/g++.dg/parse/error21.C
index 8c717d7e811..920a4909e15 100644
--- a/gcc/testsuite/g++.dg/parse/error21.C
+++ b/gcc/testsuite/g++.dg/parse/error21.C
@@ -8,6 +8,5 @@ void foo()
   // Check that we do not complain about an unused
   // compiler-generated variable.
   A& = a; // { dg-error "6:expected unqualified-id before '=' token" "6" }
-  // { dg-error "8:'a' was not declared in this scope" "8" { target *-*-* } .-1 }
 }
 
diff --git a/gcc/testsuite/g++.dg/parse/qualified5.C b/gcc/testsuite/g++.dg/parse/qualified5.C
new file mode 100644
index 00000000000..dff934e98b1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/qualified5.C
@@ -0,0 +1,13 @@
+// PR c++/84820
+
+struct A {};
+
+template<int> struct B : A
+{
+  B()
+  {
+    A(&A::foo);			// { dg-error "foo" }
+  }
+};
+
+B<0> b;