Fix crash with -fdump-ada-spec

[Eric Botcazou <ebotcazou at adacore dot com>]

This fixes a crash of the C compiler when -fdump-ada-spec is passed for:

extern void (*signal (int __sig, void (*__handler)(int)))(int);

It appears that the C parser is somewhat confused by this declaration and 
builds a FUNCTION_DECL whose type has got 2 arguments (TYPE_ARG_TYPES list) 
but which itself has got only 1 argument (DECL_ARGUMENTS list) corresponding 
to the anonymous (int) at the end.  The C++ parser doesn't have the issue.

Joseph, is that a known issue of the C parser?

The attached patch changes -fdump-ada-spec to using TYPE_ARG_TYPES for it.


2019-08-21  Eric Botcazou  <ebotcazou@adacore.com>

c-family/
	* c-ada-spec.c (dump_ada_function_declaration): Be prepared for broken
	function declarations where arguments are missing.  Rename variables.


2019-08-21  Eric Botcazou  <ebotcazou@adacore.com>

	* c-c++-common/dump-ada-spec-15.c: New test.

-- 
Eric Botcazou

Index: c-family/c-ada-spec.c
===================================================================
--- c-family/c-ada-spec.c	(revision 274744)
+++ c-family/c-ada-spec.c	(working copy)
@@ -1589,14 +1589,13 @@ dump_ada_function_declaration (pretty_printer *buf
 			       bool is_method, bool is_constructor,
 			       bool is_destructor, int spc)
 {
-  tree arg;
-  const tree node = TREE_TYPE (func);
+  tree type = TREE_TYPE (func);
+  tree arg = TYPE_ARG_TYPES (type);
+  tree t;
   char buf[17];
-  int num = 0, num_args = 0, have_args = true, have_ellipsis = false;
+  int num, num_args = 0, have_args = true, have_ellipsis = false;
 
   /* Compute number of arguments.  */
-  arg = TYPE_ARG_TYPES (node);
-
   if (arg)
     {
       while (TREE_CHAIN (arg) && arg != error_mark_node)
@@ -1627,25 +1626,29 @@ dump_ada_function_declaration (pretty_printer *buf
       pp_left_paren (buffer);
     }
 
+  /* For a function, see if we have the corresponding arguments.  */
   if (TREE_CODE (func) == FUNCTION_DECL)
-    arg = DECL_ARGUMENTS (func);
+    {
+      arg = DECL_ARGUMENTS (func);
+      for (t = arg, num = 0; t; t = DECL_CHAIN (t))
+	num++;
+      if (num < num_args)
+	arg = NULL_TREE;
+    }
   else
     arg = NULL_TREE;
 
-  if (arg == NULL_TREE)
+  /* Otherwise, only print the types.  */
+  if (!arg)
     {
       have_args = false;
-      arg = TYPE_ARG_TYPES (node);
-
-      if (arg && TREE_CODE (TREE_VALUE (arg)) == VOID_TYPE)
-	arg = NULL_TREE;
+      arg = TYPE_ARG_TYPES (type);
     }
 
   if (is_constructor)
     arg = TREE_CHAIN (arg);
 
-  /* Print the argument names (if available) & types.  */
-
+  /* Print the argument names (if available) and types.  */
   for (num = 1; num <= num_args; num++)
     {
       if (have_args)
@@ -1663,13 +1666,13 @@ dump_ada_function_declaration (pretty_printer *buf
 	      pp_string (buffer, buf);
 	    }
 
-	  dump_ada_node (buffer, TREE_TYPE (arg), node, spc, false, true);
+	  dump_ada_node (buffer, TREE_TYPE (arg), type, spc, false, true);
 	}
       else
 	{
 	  sprintf (buf, "arg%d : ", num);
 	  pp_string (buffer, buf);
-	  dump_ada_node (buffer, TREE_VALUE (arg), node, spc, false, true);
+	  dump_ada_node (buffer, TREE_VALUE (arg), type, spc, false, true);
 	}
 
       /* If the type is a pointer to a tagged type, we need to differentiate
@@ -1707,11 +1710,11 @@ dump_ada_function_declaration (pretty_printer *buf
   if (num_args > 0)
     pp_right_paren (buffer);
 
-  if (is_constructor || !VOID_TYPE_P (TREE_TYPE (node)))
+  if (is_constructor || !VOID_TYPE_P (TREE_TYPE (type)))
     {
       pp_string (buffer, " return ");
-      tree type = is_constructor ? DECL_CONTEXT (func) : TREE_TYPE (node);
-      dump_ada_node (buffer, type, type, spc, false, true);
+      tree rtype = is_constructor ? DECL_CONTEXT (func) : TREE_TYPE (type);
+      dump_ada_node (buffer, rtype, rtype, spc, false, true);
     }
 }
 

/* { dg-do compile } */
/* { dg-options "-fdump-ada-spec" } */

extern void (*signal (int __sig, void (*__handler)(int)))(int);

/* { dg-final { cleanup-ada-spec } } */