Re: new #pragma pack failure

[Zack Weinberg <zack at wolery dot cumb dot org>]

On Sat, Sep 09, 2000 at 02:21:40PM -0500, Robert Lipe wrote:
> I'm not certain that this was introduced with Zack's patch
...
> but there's been a recent regression with HANDLE_SYSV_PRAGMA code.   This
> following code isn't malformed; this construct returns the packing to the
> default.   But GCC now complains about it.
> 
> $ cat /tmp/p.c
> #pragma pack()
> (robertl) rjlhome:/play/negcs/gcc/stage1
> $ ./xgcc -c -B./ /tmp/p.c
> /tmp/p.c:1: warning: malformed '#pragma pack' - ignored

It wasn't introduced by that patch, but it is my fault. :)  The
big integrated preprocessor patch that went in a couple of days ago
contains, among other things, a total rewrite of the #pragma parser.
And I got this case wrong.

This patch fixes the problem for me; I'm bootstrapping now.  Since
you're up on these things, could you write up some tests for #pragma
pack?

zw

	* c-pragma.c (handle_pragma_pack): Correct parsing logic so it
	won't give a spurious error for '#pragma pack()'.  Simplify
	control flow for readability.  'reset' action is not necessary.

===================================================================
Index: c-pragma.c
--- c-pragma.c	2000/09/08 22:17:24	1.36
+++ c-pragma.c	2000/09/09 20:47:34
@@ -188,59 +188,57 @@ handle_pragma_pack (dummy)
   tree x, id = 0;
   int align;
   enum cpp_ttype token;
-  enum { set, reset, push, pop } action;
+  enum { set, push, pop } action;
 
   if (c_lex (&x) != CPP_OPEN_PAREN)
     BAD ("missing '(' after '#pragma pack' - ignored");
 
   token = c_lex (&x);
   if (token == CPP_CLOSE_PAREN)
-    action = reset;
+    {
+      action = set;
+      align = 0;
+    }
   else if (token == CPP_NUMBER)
     {
       align = TREE_INT_CST_LOW (x);
       action = set;
+      if (c_lex (&x) != CPP_CLOSE_PAREN)
+	BAD ("malformed '#pragma pack' - ignored");
     }
   else if (token == CPP_NAME)
     {
-      if (!strcmp (IDENTIFIER_POINTER (x), "push"))
+      const char *op = IDENTIFIER_POINTER (x);
+      if (!strcmp (op, "push"))
 	action = push;
-      else if (!strcmp (IDENTIFIER_POINTER (x), "pop"))
+      else if (!strcmp (op, "pop"))
 	action = pop;
       else
-	BAD2 ("unknown action '%s' for '#pragma pack' - ignored",
-	      IDENTIFIER_POINTER (x));
-    }
-  else
-    BAD ("malformed '#pragma pack' - ignored");
+	BAD2 ("unknown action '%s' for '#pragma pack' - ignored", op);
 
-  token = c_lex (&x);
-  if ((action == set || action == reset) && token != CPP_CLOSE_PAREN)
-    BAD ("malformed '#pragma pack' - ignored");
-  if ((action == push || action == pop) && token != CPP_COMMA)
-    BAD2 ("malformed '#pragma pack(%s[, id], <n>)' - ignored",
-	  action == push ? "push" : "pop");
+      if (c_lex (&x) != CPP_COMMA)
+	BAD2 ("malformed '#pragma pack(%s[, id], <n>)' - ignored", op);
 
-  if (action == push || action == pop)
-    {
       token = c_lex (&x);
       if (token == CPP_NAME)
 	{
 	  id = x;
 	  if (c_lex (&x) != CPP_COMMA)
-	    BAD2 ("malformed '#pragma pack(%s[, id], <n>)' - ignored",
-		  action == push ? "push" : "pop");
+	    BAD2 ("malformed '#pragma pack(%s[, id], <n>)' - ignored", op);
 	  token = c_lex (&x);
 	}
+
       if (token == CPP_NUMBER)
 	align = TREE_INT_CST_LOW (x);
       else
-	BAD2 ("malformed '#pragma pack(%s[, id], <n>)' - ignored",
-	      action == push ? "push" : "pop");
+	BAD2 ("malformed '#pragma pack(%s[, id], <n>)' - ignored", op);
 
       if (c_lex (&x) != CPP_CLOSE_PAREN)
 	BAD ("malformed '#pragma pack' - ignored");
     }
+  else
+    BAD ("malformed '#pragma pack' - ignored");
+
   if (c_lex (&x) != CPP_EOF)
     warning ("junk at end of '#pragma pack'");
 
@@ -261,7 +259,6 @@ handle_pragma_pack (dummy)
   switch (action)
     {
     case set:   SET_GLOBAL_ALIGNMENT (align);  break;
-    case reset: SET_GLOBAL_ALIGNMENT (0);      break;
     case push:  push_alignment (align, id);    break;
     case pop:   pop_alignment (id);            break;
     }