[gcc r12-932] c++: ICE with using and enum [PR100659]

[Jason Merrill <jason@gcc.gnu.org>]

https://gcc.gnu.org/g:fe9a6614a16b5ea7f12141c50b6b7de984390ed8

commit r12-932-gfe9a6614a16b5ea7f12141c50b6b7de984390ed8
Author: Jason Merrill <jason@redhat.com>
Date:   Wed May 19 16:40:24 2021 -0400

    c++: ICE with using and enum [PR100659]
    
    Here the code for 'using enum' is confused by the combination of a
    using-decl and an enum that are not from 'using enum'; this CONST_DECL is
    from the normal unscoped enum scoping.
    
            PR c++/100659
    
    gcc/cp/ChangeLog:
    
            * cp-tree.h (CONST_DECL_USING_P): Check for null TREE_TYPE.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/parse/access13.C: New test.

Diff:
---
 gcc/cp/cp-tree.h                      | 1 +
 gcc/testsuite/g++.dg/parse/access13.C | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 860ed795299..aa202715873 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -3553,6 +3553,7 @@ struct GTY(()) lang_decl {
    created by handle_using_decl.  */
 #define CONST_DECL_USING_P(NODE)			\
   (TREE_CODE (NODE) == CONST_DECL			\
+   && TREE_TYPE (NODE)					\
    && TREE_CODE (TREE_TYPE (NODE)) == ENUMERAL_TYPE	\
    && DECL_CONTEXT (NODE) != TREE_TYPE (NODE))
 
diff --git a/gcc/testsuite/g++.dg/parse/access13.C b/gcc/testsuite/g++.dg/parse/access13.C
new file mode 100644
index 00000000000..41463c5dde5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/access13.C
@@ -0,0 +1,7 @@
+// PR c++/100659
+
+template <typename> struct A
+{
+  A::E::V;		       // { dg-warning "access decl" }
+  enum { V };		       // { dg-error "conflicts with a previous decl" }
+};