[PATCH] fix -Wsign-compare error in objc-act.c (PR objc/50743)

[Mikael Pettersson <mikpe@it.uu.se>]

This fixes a bootstrap failure on trunk with objc enabled, caused by a
recent change which introduced for-loops that compare a size_t index
variable with a TREE_VEC_LENGTH limit.  TREE_VEC_LENGTH returns a signed
integer, resulting in a signed/unsigned comparison.  The C++ front-end
fails to catch this error due to PR50012, but the C front-end correctly
catches it, breaking --disable-build-poststage1-with-cxx bootstraps.

Fixed by casting TREE_VEC_LENGTH to size_t before the comparisons.

Nicola Pero said the patch looked good, but also said he couldn't formally
approve it.

Ok for trunk?

(I don't have svn write access so I'll need someone else to commit it if
it's approved.)

/Mikael

gcc/objc/

2011-10-16  Mikael Pettersson  <mikpe@it.uu.se>

	PR objc/50743
	* objc-act.c (check_duplicates): Cast TREE_VEC_LENGTH result
	to size_t to avoid signed/unsigned comparison.
	(insert_method_into_method_map): Likewise.

--- gcc-4.7-20111015/gcc/objc/objc-act.c.~1~	2011-10-14 12:19:01.000000000 +0200
+++ gcc-4.7-20111015/gcc/objc/objc-act.c	2011-10-16 11:53:56.000000000 +0200
@@ -5070,7 +5070,7 @@ check_duplicates (tree method, int metho
      alignment.  */
   if (!warn_strict_selector_match)
     {
-      for (i = 0; i < TREE_VEC_LENGTH (method); i++)
+      for (i = 0; i < (size_t) TREE_VEC_LENGTH (method); i++)
 	if (!comp_proto_with_proto (first_method, TREE_VEC_ELT (method, i), 0))
 	  goto issue_warning;
       
@@ -5103,7 +5103,7 @@ check_duplicates (tree method, int metho
 	      identifier_to_locale (gen_method_decl (first_method)));
     }
   
-  for (i = 0; i < TREE_VEC_LENGTH (method); i++)
+  for (i = 0; i < (size_t) TREE_VEC_LENGTH (method); i++)
     {
       bool type = TREE_CODE (TREE_VEC_ELT (method, i)) == INSTANCE_METHOD_DECL;
       
@@ -5825,7 +5825,7 @@ insert_method_into_method_map (bool clas
 	  /* Check all the existing prototypes.  If any matches the
 	     one we need to add, there is nothing to do because it's
 	     already there.  */
-	  for (i = 0; i < TREE_VEC_LENGTH (existing_entry); i++)
+	  for (i = 0; i < (size_t) TREE_VEC_LENGTH (existing_entry); i++)
 	    if (comp_proto_with_proto (method, TREE_VEC_ELT (existing_entry, i), 1))
 	      return;
 
@@ -5837,7 +5837,7 @@ insert_method_into_method_map (bool clas
 	  new_entry = make_tree_vec (TREE_VEC_LENGTH (existing_entry) + 1);
 	  
 	  /* Copy the methods from the existing vector.  */
-	  for (i = 0; i < TREE_VEC_LENGTH (existing_entry); i++)
+	  for (i = 0; i < (size_t) TREE_VEC_LENGTH (existing_entry); i++)
 	    TREE_VEC_ELT (new_entry, i) = TREE_VEC_ELT (existing_entry, i);
 	  
 	  /* Add the new method at the end.  */