[PATCH] ls: placate gcc-4.7.0's -Wstrict-overflow

[Jim Meyering]

I built the latest gcc from git/svn (4.7.0 20110528)
and got a new -Wstrict-overflow warning:

    ls.c: In function 'main':
    ls.c:2291:9: error: assuming signed overflow does not occur when\
    simplifying conditional to constant [-Werror=strict-overflow]

This fixes it:

>From 31bbcc7abfdc476bf23da4a1911bda35910c9fe8 Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Sat, 28 May 2011 22:10:00 +0200
Subject: [PATCH] ls: placate gcc-4.7.0's -Wstrict-overflow

* src/ls.c (enum parse_state): Define.
(parse_ls_color): Use enum names in place of constants,
thus avoiding the offending -1.
---
 src/ls.c |   54 +++++++++++++++++++++++++++++++++++-------------------
 1 files changed, 35 insertions(+), 19 deletions(-)

diff --git a/src/ls.c b/src/ls.c
index 1c8d0d8..af18da0 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -2265,12 +2265,21 @@ get_funky_string (char **dest, const char **src, bool 
equals_end,
   return state != ST_ERROR;
 }

+enum parse_state
+  {
+    PS_START = 1,
+    PS_2,
+    PS_3,
+    PS_4,
+    PS_DONE,
+    PS_FAIL
+  };
+
 static void
 parse_ls_color (void)
 {
   const char *p;               /* Pointer to character being parsed */
   char *buf;                   /* color_buf buffer pointer */
-  int state;                   /* State of parser */
   int ind_no;                  /* Indicator number */
   char label[3];               /* Indicator label */
   struct color_ext_type *ext;  /* Extension we are working on */
@@ -2287,12 +2296,12 @@ parse_ls_color (void)
      advance.  */
   buf = color_buf = xstrdup (p);

-  state = 1;
-  while (state > 0)
+  enum parse_state state = PS_START;
+  while (true)
     {
       switch (state)
         {
-        case 1:                /* First label character */
+        case PS_START:         /* First label character */
           switch (*p)
             {
             case ':':
@@ -2313,32 +2322,32 @@ parse_ls_color (void)
               ext->ext.string = buf;

               state = (get_funky_string (&buf, &p, true, &ext->ext.len)
-                       ? 4 : -1);
+                       ? PS_4 : PS_FAIL);
               break;

             case '\0':
-              state = 0;       /* Done! */
-              break;
+              state = PS_DONE; /* Done! */
+              goto done;

             default:   /* Assume it is file type label */
               label[0] = *(p++);
-              state = 2;
+              state = PS_2;
               break;
             }
           break;

-        case 2:                /* Second label character */
+        case PS_2:             /* Second label character */
           if (*p)
             {
               label[1] = *(p++);
-              state = 3;
+              state = PS_3;
             }
           else
-            state = -1;        /* Error */
+            state = PS_FAIL;   /* Error */
           break;

-        case 3:                /* Equal sign after indicator label */
-          state = -1;  /* Assume failure...  */
+        case PS_3:             /* Equal sign after indicator label */
+          state = PS_FAIL;     /* Assume failure...  */
           if (*(p++) == '=')/* It *should* be...  */
             {
               for (ind_no = 0; indicator_name[ind_no] != NULL; ++ind_no)
@@ -2348,29 +2357,36 @@ parse_ls_color (void)
                       color_indicator[ind_no].string = buf;
                       state = (get_funky_string (&buf, &p, false,
                                                  &color_indicator[ind_no].len)
-                               ? 1 : -1);
+                               ? PS_START : PS_FAIL);
                       break;
                     }
                 }
-              if (state == -1)
+              if (state == PS_FAIL)
                 error (0, 0, _("unrecognized prefix: %s"), quotearg (label));
             }
           break;

-        case 4:                /* Equal sign after *.ext */
+        case PS_4:             /* Equal sign after *.ext */
           if (*(p++) == '=')
             {
               ext->seq.string = buf;
               state = (get_funky_string (&buf, &p, false, &ext->seq.len)
-                       ? 1 : -1);
+                       ? PS_START : PS_FAIL);
             }
           else
-            state = -1;
+            state = PS_FAIL;
           break;
+
+        case PS_FAIL:
+          goto done;
+
+        default:
+          abort ();
         }
     }
+ done:

-  if (state < 0)
+  if (state == PS_FAIL)
     {
       struct color_ext_type *e;
       struct color_ext_type *e2;
--
1.7.5.2.660.g9f46c