Fix [Bug 1646039]

3 files changed, 28 insertions, 26 deletions

diff --git a/ChangeLog b/ChangeLog
index a56bd78..17d4313 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2006-04-05  Donal K. Fellows  <donal.k.fellows@man.ac.uk>
+
+	* generic/tclIndexObj.c (Tcl_GetIndexFromObjStruct): Allow empty
+	strings to be matched by the Tcl_GetIndexFromObj machinery, but only
+	ever exactly. [Bug 1464039]
+
 2006-04-04  Don Porter  <dgp@users.sourceforge.net>
 
 	* generic/tclPkg.c:	Revised Bug 1162286 fix from 2005-11-08
diff --git a/generic/tclIndexObj.c b/generic/tclIndexObj.c
index bdfca15..7bc046d 100644
--- a/generic/tclIndexObj.c
+++ b/generic/tclIndexObj.c
@@ -10,7 +10,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclIndexObj.c,v 1.16.2.2 2006/02/16 20:21:54 dgp Exp $
+ * RCS: @(#) $Id: tclIndexObj.c,v 1.16.2.3 2006/04/05 13:20:09 dkf Exp $
  */
 
 #include "tclInt.h"
@@ -171,7 +171,7 @@ Tcl_GetIndexFromObjStruct(interp, objPtr, tablePtr, offset, msg, flags,
     int flags;			/* 0 or TCL_EXACT */
     int *indexPtr;		/* Place to store resulting integer index. */
 {
-    int index, length, i, numAbbrev;
+    int index, i, numAbbrev;
     char *key, *p1;
     CONST char *p2;
     CONST char * CONST *entryPtr;
@@ -195,19 +195,11 @@ Tcl_GetIndexFromObjStruct(interp, objPtr, tablePtr, offset, msg, flags,
      * abbreviations unless TCL_EXACT is set in flags.
      */
 
-    key = Tcl_GetStringFromObj(objPtr, &length);
+    key = TclGetString(objPtr);
     index = -1;
     numAbbrev = 0;
 
     /*
-     * The key should not be empty, otherwise it's not a match.
-     */
-    
-    if (key[0] == '\0') {
-	goto error;
-    }
-    
-    /*
      * Scan the table looking for one of:
      *  - An exact match (always preferred)
      *  - A single abbreviation (allowed depending on flags)
@@ -235,9 +227,13 @@ Tcl_GetIndexFromObjStruct(interp, objPtr, tablePtr, offset, msg, flags,
 	}
     }
     /*
-     * Check if we were instructed to disallow abbreviations.
+     * Check if we were instructed to disallow abbreviations. Note that we do
+     * not allow the empty string as an abbreviation of anything; it is only
+     * processed by this function as a non-error case if the table of strings
+     * has an entry in it that is itself an empty string. This only matters in
+     * the case where the table has a singleton entry.
      */
-    if ((flags & TCL_EXACT) || (numAbbrev != 1)) {
+    if ((flags & TCL_EXACT) || (key[0] == '\0') || (numAbbrev != 1)) {
 	goto error;
     }
 
diff --git a/tests/indexObj.test b/tests/indexObj.test
index dee0dfa..168b225 100644
--- a/tests/indexObj.test
+++ b/tests/indexObj.test
@@ -8,7 +8,7 @@
 # See the file "license.terms" for information on usage and redistribution
 # of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 #
-# RCS: @(#) $Id: indexObj.test,v 1.7.18.1 2006/02/16 20:21:54 dgp Exp $
+# RCS: @(#) $Id: indexObj.test,v 1.7.18.2 2006/04/05 13:20:14 dkf Exp $
 
 if {[lsearch [namespace children] ::tcltest] == -1} {
     package require tcltest
@@ -43,6 +43,12 @@ test indexObj-1.6 {forced exact match} {
 test indexObj-1.7 {forced exact match} {
     testindexobj 1 0 x abc def xalb xyz alm x
 } {5}
+test indexObj-1.8 {exact match of empty values} {
+    testindexobj 1 1 {} a aa aaa {} b bb bbb
+} 3
+test indexObj-1.9 {exact match of empty values} {
+    testindexobj 1 0 {} a aa aaa {} b bb bbb
+} 3
 
 test indexObj-2.1 {no match} {
     list [catch {testindexobj 1 1 dddd abc def xalb xyz alm x} msg] $msg
@@ -62,6 +68,12 @@ test indexObj-2.5 {omit error message} {
 test indexObj-2.6 {TCL_EXACT => no "ambiguous" error message} {
     list [catch {testindexobj 1 0 d dumb daughter a c} msg] $msg
 } {1 {bad token "d": must be dumb, daughter, a, or c}}
+test indexObj-2.7 {exact match of empty values} {
+    list [catch {testindexobj 1 1 {} a b c} msg] $msg
+} {1 {ambiguous token "": must be a, b, or c}}
+test indexObj-2.8 {exact match of empty values: singleton case} {
+    list [catch {testindexobj 1 1 {} a} msg] $msg
+} {1 {bad token "": must be a}}
 
 test indexObj-3.1 {cache result to skip next lookup} {
     testindexobj check 42
@@ -114,15 +126,3 @@ test indexObj-6.4 {Tcl_GetIndexFromObjStruct} {
 # cleanup
 ::tcltest::cleanupTests
 return
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