[gcc r11-7535] c++: ICE with -Wshadow and enumerator in template [PR99120]

[Marek Polacek]

https://gcc.gnu.org/g:c2e64c33d9d903f0a52565ad98300feea0ffc580

commit r11-7535-gc2e64c33d9d903f0a52565ad98300feea0ffc580
Author: Marek Polacek <polacek@redhat.com>
Date:   Fri Mar 5 10:41:41 2021 -0500

    c++: ICE with -Wshadow and enumerator in template [PR99120]
    
    We crash here, because in a template, an enumerator doesn't have
    a type until we've called finish_enum_value_list.  But our -Wshadow
    implementation, check_local_shadow, is called when we pushdecl in
    build_enumerator, which takes place before finish_enum_value_list.
    
    gcc/cp/ChangeLog:
    
            PR c++/99120
            * name-lookup.c (check_local_shadow): Check if the type of decl
            is non-null before checking TYPE_PTR*.
    
    gcc/testsuite/ChangeLog:
    
            PR c++/99120
            * g++.dg/warn/Wshadow-17.C: New test.

Diff:
---
 gcc/cp/name-lookup.c                   |  7 ++++---
 gcc/testsuite/g++.dg/warn/Wshadow-17.C | 11 +++++++++++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index f57708700c2..092fa6b8768 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -3309,7 +3309,7 @@ check_local_shadow (tree decl)
   /* Don't warn for artificial things that are not implicit typedefs.  */
   if (DECL_ARTIFICIAL (decl) && !DECL_IMPLICIT_TYPEDEF_P (decl))
     return;
-  
+
   if (nonlambda_method_basetype ())
     if (tree member = lookup_member (current_nonlambda_class_type (),
 				     DECL_NAME (decl), /*protect=*/0,
@@ -3321,8 +3321,9 @@ check_local_shadow (tree decl)
 	   is a function or a pointer-to-function.  */
 	if (!OVL_P (member)
 	    || TREE_CODE (decl) == FUNCTION_DECL
-	    || TYPE_PTRFN_P (TREE_TYPE (decl))
-	    || TYPE_PTRMEMFUNC_P (TREE_TYPE (decl)))
+	    || (TREE_TYPE (decl)
+		&& (TYPE_PTRFN_P (TREE_TYPE (decl))
+		    || TYPE_PTRMEMFUNC_P (TREE_TYPE (decl)))))
 	  {
 	    auto_diagnostic_group d;
 	    if (warning_at (DECL_SOURCE_LOCATION (decl), OPT_Wshadow,
diff --git a/gcc/testsuite/g++.dg/warn/Wshadow-17.C b/gcc/testsuite/g++.dg/warn/Wshadow-17.C
new file mode 100644
index 00000000000..0dee397796f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wshadow-17.C
@@ -0,0 +1,11 @@
+// PR c++/99120
+// { dg-options "-Wshadow" }
+
+struct S {
+  void X();
+
+  template<typename T>
+  void fn () {
+    enum { X };
+  }
+};