* generic/tclCmdMZ.c (Tcl_SwitchObjCmd): [Bug 3106532]: Corrected

	resulting indexes from -indexvar option to be usable with [string
	range]; this was always the intention (and is consistent with [regexp
	-indices] too).
	***POTENTIAL INCOMPATIBILITY***
	Uses of [switch -regexp -indexvar] that previously compensated for the
	wrong offsets (by subtracting 1 from the end indices) now do not need
	to do so as the value is correct.

3 files changed, 31 insertions, 8 deletions

diff --git a/ChangeLog b/ChangeLog
index 2ac4bb6..e8cecb8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,14 @@
 2012-05-17  Donal K. Fellows  <dkf@users.sf.net>
 
+	* generic/tclCmdMZ.c (Tcl_SwitchObjCmd): [Bug 3106532]: Corrected
+	resulting indexes from -indexvar option to be usable with [string
+	range]; this was always the intention (and is consistent with [regexp
+	-indices] too).
+	***POTENTIAL INCOMPATIBILITY***
+	Uses of [switch -regexp -indexvar] that previously compensated for the
+	wrong offsets (by subtracting 1 from the end indices) now do not need
+	to do so as the value is correct.
+
 	* library/safe.tcl (safe::InterpInit): Ensure that the module path is
 	constructed in the correct order.
 	(safe::AliasGlob): [Bug 2964715]: More extensive handling of what
diff --git a/generic/tclCmdMZ.c b/generic/tclCmdMZ.c
index c5bb72d..7e94d9f 100644
--- a/generic/tclCmdMZ.c
+++ b/generic/tclCmdMZ.c
@@ -3758,8 +3758,12 @@ TclNRSwitchObjCmd(
 	    if (indexVarObj != NULL) {
 		Tcl_Obj *rangeObjAry[2];
 
-		rangeObjAry[0] = Tcl_NewLongObj(info.matches[j].start);
-		rangeObjAry[1] = Tcl_NewLongObj(info.matches[j].end);
+		if (info.matches[j].end > 0) {
+		    rangeObjAry[0] = Tcl_NewLongObj(info.matches[j].start);
+		    rangeObjAry[1] = Tcl_NewLongObj(info.matches[j].end-1);
+		} else {
+		    rangeObjAry[0] = rangeObjAry[1] = Tcl_NewIntObj(-1);
+		}
 
 		/*
 		 * Never fails; the object is always clean at this point.
diff --git a/tests/switch.test b/tests/switch.test
index 255be00..a03948b 100644
--- a/tests/switch.test
+++ b/tests/switch.test
@@ -536,7 +536,7 @@ test switch-11.6 {-matchvar unwritable} {
 
 test switch-12.1 {regexp matching with -indexvar} {
     switch -regexp -indexvar x -- abc {.(.). {set x}}
-} {{0 3} {1 2}}
+} {{0 2} {1 1}}
 test switch-12.2 {regexp matching with -indexvar} {
     set x GOOD
     switch -regexp -indexvar x -- abc {.(.).. {list $x z}}
@@ -544,7 +544,7 @@ test switch-12.2 {regexp matching with -indexvar} {
 } GOOD
 test switch-12.3 {regexp matching with -indexvar} {
     switch -regexp -indexvar x -- "a b c" {.(.). {set x}}
-} {{0 3} {1 2}}
+} {{0 2} {1 1}}
 test switch-12.4 {regexp matching with -indexvar} {
     set x BAD
     switch -regexp -indexvar x -- "a b c" {
@@ -560,22 +560,32 @@ test switch-12.6 {-indexvar unwritable} {
     set x {}
     list [catch {switch -regexp -indexvar x(x) -- abc . {set x}} msg] $x $msg
 } {1 {} {can't set "x(x)": variable isn't array}}
+test switch-12.7 {[Bug 3106532] -indexvar should be directly usable with [string range]} {
+    set str abcdef
+    switch -regexp -indexvar x -- $str ^... {string range $str {*}[lindex $x 0]}
+} abc
+test switch-12.8 {-indexvar and matched empty strings} {
+    switch -regexp -indexvar x -- abcdef ^...(x?) {return $x}
+} {{0 2} {3 2}}
+test switch-12.9 {-indexvar and unmatched strings} {
+    switch -regexp -indexvar x -- abcdef ^...(x)? {return $x}
+} {{0 2} {-1 -1}}
 
 test switch-13.1 {-indexvar -matchvar combinations} {
     switch -regexp -indexvar x -matchvar y abc {
 	. {list $x $y}
     }
-} {{{0 1}} a}
+} {{{0 0}} a}
 test switch-13.2 {-indexvar -matchvar combinations} {
     switch -regexp -indexvar x -matchvar y abc {
 	.$ {list $x $y}
     }
-} {{{2 3}} c}
+} {{{2 2}} c}
 test switch-13.3 {-indexvar -matchvar combinations} {
     switch -regexp -indexvar x -matchvar y abc {
 	(.)(.)(.) {list $x $y}
     }
-} {{{0 3} {0 1} {1 2} {2 3}} {abc a b c}}
+} {{{0 2} {0 0} {1 1} {2 2}} {abc a b c}}
 test switch-13.4 {-indexvar -matchvar combinations} {
     set x -
     set y -
@@ -597,7 +607,7 @@ test switch-13.6 {-indexvar -matchvar combinations} {
     list [catch {
 	switch -regexp -indexvar x -matchvar y(y) abc {. {list $x $y}}
     } msg] $x $y $msg
-} {1 {{0 1}} - {can't set "y(y)": variable isn't array}}
+} {1 {{0 0}} - {can't set "y(y)": variable isn't array}}
 
 test switch-14.1 {-regexp -- compilation [Bug 1854399]} {
     switch -regexp -- 0 {