[C++ Patch] PR 84636 ("internal compiler error: Segmentation fault (identifier_p()/grokdeclarator())")

[Paolo Carlini]

Hi,

while working on some additional location fixes to grokbitfield - 
preparing testcases - I stumbled into this ICE on invalid, where in 
grokdeclarator we try to use identifier_p on a null unqualified_id. In 
practice, clang and edg behave in different ways and since I couldn't 
decide which one I liked best I prepared two different patches which, 
respectively, implement similar behaviors: the former avoids the 
grokdeclarator ICE and delegates to the checks in grokbitfield for the 
diagnostics; the latter issues a specific error about the missing 
identifier after a function type (note, in any case we want to do that 
when staticp == 2 too, otherwise we crash later for a static version of 
the declaration). Tested both onx86_64-linux, as usual.

Thanks, Paolo.

////////////////

Index: cp/decl.c
===================================================================
--- cp/decl.c   (revision 266268)
+++ cp/decl.c   (working copy)
@@ -12165,7 +12165,8 @@ grokdeclarator (const cp_declarator *declarator,
     }
 
   if (ctype && TREE_CODE (type) == FUNCTION_TYPE && staticp < 2
-      && !(identifier_p (unqualified_id)
+      && !(unqualified_id
+          && identifier_p (unqualified_id)
           && IDENTIFIER_NEWDEL_OP_P (unqualified_id)))
     {
       cp_cv_quals real_quals = memfn_quals;
@@ -12245,8 +12246,9 @@ grokdeclarator (const cp_declarator *declarator,
            error ("invalid use of %<::%>");
            return error_mark_node;
          }
-       else if (TREE_CODE (type) == FUNCTION_TYPE
-                || TREE_CODE (type) == METHOD_TYPE)
+       else if ((TREE_CODE (type) == FUNCTION_TYPE
+                 || TREE_CODE (type) == METHOD_TYPE)
+                && !bitfield)
          {
            int publicp = 0;
            tree function_context;
Index: testsuite/g++.dg/parse/bitfield3.C
===================================================================
--- testsuite/g++.dg/parse/bitfield3.C  (revision 266263)
+++ testsuite/g++.dg/parse/bitfield3.C  (working copy)
@@ -5,5 +5,5 @@ typedef void (func_type)();
 
 struct A
 {
-  friend func_type f : 2; /* { dg-error "with non-integral type" } */
+  friend func_type f : 2; /* { dg-error "20:.f. is neither function nor member 
function" } */
 };
Index: testsuite/g++.dg/parse/bitfield6.C
===================================================================
--- testsuite/g++.dg/parse/bitfield6.C  (nonexistent)
+++ testsuite/g++.dg/parse/bitfield6.C  (working copy)
@@ -0,0 +1,6 @@
+// PR c++/84636
+
+typedef void a();
+struct A {
+a: 1;  // { dg-error "bit-field .\\<anonymous\\>. with non-integral type" }
+};
Index: cp/decl.c
===================================================================
--- cp/decl.c   (revision 266268)
+++ cp/decl.c   (working copy)
@@ -12164,15 +12164,24 @@ grokdeclarator (const cp_declarator *declarator,
        type = build_pointer_type (type);
     }
 
-  if (ctype && TREE_CODE (type) == FUNCTION_TYPE && staticp < 2
-      && !(identifier_p (unqualified_id)
-          && IDENTIFIER_NEWDEL_OP_P (unqualified_id)))
+  if (ctype && TREE_CODE (type) == FUNCTION_TYPE)
     {
-      cp_cv_quals real_quals = memfn_quals;
-      if (cxx_dialect < cxx14 && constexpr_p
-         && sfk != sfk_constructor && sfk != sfk_destructor)
-       real_quals |= TYPE_QUAL_CONST;
-      type = build_memfn_type (type, ctype, real_quals, rqual);
+      if (!unqualified_id)
+       {
+         error_at (declspecs->locations[ds_type_spec],
+                   "declarator requires an identifier");
+         type = error_mark_node;
+       }
+      else if (staticp < 2
+              && !(identifier_p (unqualified_id)
+                   && IDENTIFIER_NEWDEL_OP_P (unqualified_id)))
+       {
+         cp_cv_quals real_quals = memfn_quals;
+         if (cxx_dialect < cxx14 && constexpr_p
+             && sfk != sfk_constructor && sfk != sfk_destructor)
+           real_quals |= TYPE_QUAL_CONST;
+         type = build_memfn_type (type, ctype, real_quals, rqual);
+       }
     }
 
   {
Index: testsuite/g++.dg/parse/bitfield6.C
===================================================================
--- testsuite/g++.dg/parse/bitfield6.C  (nonexistent)
+++ testsuite/g++.dg/parse/bitfield6.C  (working copy)
@@ -0,0 +1,6 @@
+// PR c++/84636
+
+typedef void a();
+struct A {
+  a: 1;  // { dg-error "3:declarator requires an identifier" }
+};