Fixed bug submitted by Bruce Lilly <blilly@erols.com> where character

ranges would yield unexpected behavior in a caseless scanner.
Also, flex now emits a warning if the range looks like trouble.

diff --git a/parse.y b/parse.y
index 5e6167cc29cad94238c6a768aee459a105a571ef..4cde223a9f4c8eefe8e46b1307c4ee9e3cf26097 100644 (file)
--- a/parse.y
+++ b/parse.y
@@ -109,6 +109,13 @@ int scon_stk_ptr;
 static int madeany = false;  /* whether we've made the '.' character class */
 int previous_continued_action; /* whether the previous rule's action was '|' */
 
+#define format_warn3(fmt, a1, a2) \
+       do{ \
+        char fw3_msg[MAXLINE];\
+        snprintf( fw3_msg, MAXLINE,(fmt), (a1), (a2) );\
+        warn( fw3_msg );\
+       }while(0)
+
 /* Expand a POSIX character class expression. */
 #define CCL_EXPR(func) \
        do{ \
@@ -787,13 +794,39 @@ fullccl           :  '[' ccl ']'
 
 ccl            :  ccl CHAR '-' CHAR
                        {
-                       if ( caseins )
-                               {
-                               if ( $2 >= 'A' && $2 <= 'Z' )
-                                       $2 = clower( $2 );
-                               if ( $4 >= 'A' && $4 <= 'Z' )
-                                       $4 = clower( $4 );
-                               }
+
+                       if (caseins)
+                         {
+                           /* Squish the character range to lowercase only if BOTH
+                            * ends of the range are uppercase.
+                            */
+                           if (isupper ($2) && isupper ($4))
+                             {
+                               $2 = tolower ($2);
+                               $4 = tolower ($4);
+                             }
+
+                           /* If one end of the range has case and the other
+                            * does not, or the cases are different, then we're not
+                            * sure what range the user is trying to express.
+                            * Examples: [@-z] or [S-t]
+                            */
+                           else if (has_case ($2) != has_case ($4)
+                                    || (has_case ($2) && (b_islower ($2) != b_islower ($4))))
+                             format_warn3 (
+                             _("the character range [%c-%c] is ambiguous in a case-insensitive scanner"),
+                                           $2, $4);
+
+                           /* If the range spans uppercase characters but not
+                            * lowercase (or vice-versa), then should we automatically
+                            * include lowercase characters in the range?
+                            * Example: [@-_] spans [a-z] but not [A-Z]
+                            */
+                           else if (!has_case ($2) && !has_case ($4) && !range_covers_case ($2, $4))
+                             format_warn3 (
+                             _("the character range [%c-%c] is ambiguous in a case-insensitive scanner"),
+                                           $2, $4);
+                         }
 
                        if ( $2 > $4 )
                                synerr( _("negative range in character class") );