Index: doc/GetInt.3
==================================================================
--- doc/GetInt.3
+++ doc/GetInt.3
@@ -87,14 +87,14 @@
 .QW \fB,\fR
 as a decimal point is not supported nor should any other sort of
 inter-digit separator be present.
 .PP
 \fBTcl_GetBoolean\fR expects \fIsrc\fR to specify a boolean
-value.  If \fIsrc\fR is any of \fB0\fR, \fBfalse\fR,
+value.  If \fIsrc\fR is any of \fB0\fR, \fB-\fR, \fBfalse\fR,
 \fBno\fR, or \fBoff\fR, then \fBTcl_GetBoolean\fR stores a zero
 value at \fI*boolPtr\fR.
-If \fIsrc\fR is any of \fB1\fR, \fBtrue\fR, \fByes\fR, or \fBon\fR,
+If \fIsrc\fR is any of \fB1\fR, \fB+\fR, \fBtrue\fR, \fByes\fR, or \fBon\fR,
 then 1 is stored at \fI*boolPtr\fR.
 Any of these values may be abbreviated, and upper-case spellings
 are also acceptable.
 
 .SH KEYWORDS

Index: generic/tclGet.c
==================================================================
--- generic/tclGet.c
+++ generic/tclGet.c
@@ -123,11 +123,11 @@
 
 int
 Tcl_GetBoolean(
     Tcl_Interp *interp,		/* Interpreter used for error reporting. */
     const char *src,		/* String containing one of the boolean values
-				 * 1, 0, true, false, yes, no, on, off. */
+				 * 1, 0, +, -, true, false, yes, no, on, off. */
     int *boolPtr)		/* Place to store converted result, which will
 				 * be 0 or 1. */
 {
     Tcl_Obj obj;
     int code;

Index: generic/tclLink.c
==================================================================
--- generic/tclLink.c
+++ generic/tclLink.c
@@ -65,11 +65,11 @@
  */
 
 static char *		LinkTraceProc(ClientData clientData,Tcl_Interp *interp,
 			    const char *name1, const char *name2, int flags);
 static Tcl_Obj *	ObjValue(Link *linkPtr);
-static int		GetInvalidIntFromObj(Tcl_Obj *objPtr,
+static int		GetInvalidIntOrBooleanFromObj(Tcl_Obj *objPtr,
 				int *intPtr);
 static int		GetInvalidDoubleFromObj(Tcl_Obj *objPtr,
 				double *doublePtr);
 
 /*
@@ -382,28 +382,28 @@
 
     switch (linkPtr->type) {
     case TCL_LINK_INT:
 	if (Tcl_GetIntFromObj(NULL, valueObj, &linkPtr->lastValue.i)
 		!= TCL_OK) {
-	    if (GetInvalidIntFromObj(valueObj, &linkPtr->lastValue.i)
+	    if (GetInvalidIntOrBooleanFromObj(valueObj, &linkPtr->lastValue.i)
 		    != TCL_OK) {
 		Tcl_ObjSetVar2(interp, linkPtr->varName, NULL, ObjValue(linkPtr),
 		    TCL_GLOBAL_ONLY);
-		return (char *) "variable must have integer value";
+		return (char *) "variable must have integer or boolean value";
 	    }
 	}
 	LinkedVar(int) = linkPtr->lastValue.i;
 	break;
 
     case TCL_LINK_WIDE_INT:
 	if (Tcl_GetWideIntFromObj(NULL, valueObj, &linkPtr->lastValue.w)
 		!= TCL_OK) {
-	    if (GetInvalidIntFromObj(valueObj, &valueInt)
+	    if (GetInvalidIntOrBooleanFromObj(valueObj, &valueInt)
 		    != TCL_OK) {
 		Tcl_ObjSetVar2(interp, linkPtr->varName, NULL, ObjValue(linkPtr),
 		    TCL_GLOBAL_ONLY);
-		return (char *) "variable must have integer value";
+		return (char *) "variable must have integer or boolean value";
 	    }
 	    linkPtr->lastValue.w = (Tcl_WideInt) valueInt;
 	}
 	LinkedVar(Tcl_WideInt) = linkPtr->lastValue.w;
 	break;
@@ -439,71 +439,71 @@
 	break;
 
     case TCL_LINK_CHAR:
 	if (Tcl_GetIntFromObj(NULL, valueObj, &valueInt) != TCL_OK
 		|| valueInt < SCHAR_MIN || valueInt > SCHAR_MAX) {
-	    if (GetInvalidIntFromObj(valueObj, &valueInt)
+	    if (GetInvalidIntOrBooleanFromObj(valueObj, &valueInt)
 		    != TCL_OK) {
 		Tcl_ObjSetVar2(interp, linkPtr->varName, NULL, ObjValue(linkPtr),
 			TCL_GLOBAL_ONLY);
-		return (char *) "variable must have char value";
+		return (char *) "variable must have char or boolean value";
 	    }
 	}
 	linkPtr->lastValue.c = (char)valueInt;
 	LinkedVar(char) = linkPtr->lastValue.c;
 	break;
 
     case TCL_LINK_UCHAR:
 	if (Tcl_GetIntFromObj(NULL, valueObj, &valueInt) != TCL_OK
 		|| valueInt < 0 || valueInt > UCHAR_MAX) {
-	    if (GetInvalidIntFromObj(valueObj, &valueInt)
+	    if (GetInvalidIntOrBooleanFromObj(valueObj, &valueInt)
 		    != TCL_OK) {
 		Tcl_ObjSetVar2(interp, linkPtr->varName, NULL, ObjValue(linkPtr),
 			TCL_GLOBAL_ONLY);
-		return (char *) "variable must have unsigned char value";
+		return (char *) "variable must have unsigned char or boolean value";
 	    }
 	}
 	linkPtr->lastValue.uc = (unsigned char) valueInt;
 	LinkedVar(unsigned char) = linkPtr->lastValue.uc;
 	break;
 
     case TCL_LINK_SHORT:
 	if (Tcl_GetIntFromObj(NULL, valueObj, &valueInt) != TCL_OK
 		|| valueInt < SHRT_MIN || valueInt > SHRT_MAX) {
-	    if (GetInvalidIntFromObj(valueObj, &valueInt)
+	    if (GetInvalidIntOrBooleanFromObj(valueObj, &valueInt)
 		    != TCL_OK) {
 		Tcl_ObjSetVar2(interp, linkPtr->varName, NULL, ObjValue(linkPtr),
 			TCL_GLOBAL_ONLY);
-		return (char *) "variable must have short value";
+		return (char *) "variable must have short or boolean value";
 	    }
 	}
 	linkPtr->lastValue.s = (short)valueInt;
 	LinkedVar(short) = linkPtr->lastValue.s;
 	break;
 
     case TCL_LINK_USHORT:
 	if (Tcl_GetIntFromObj(NULL, valueObj, &valueInt) != TCL_OK
 		|| valueInt < 0 || valueInt > USHRT_MAX) {
-	    if (GetInvalidIntFromObj(valueObj, &valueInt)
+	    if (GetInvalidIntOrBooleanFromObj(valueObj, &valueInt)
 		    != TCL_OK) {
 		Tcl_ObjSetVar2(interp, linkPtr->varName, NULL, ObjValue(linkPtr),
 			TCL_GLOBAL_ONLY);
-		return (char *) "variable must have unsigned short value";
+		return (char *) "variable must have unsigned short or boolean value";
 	    }
 	}
 	linkPtr->lastValue.us = (unsigned short)valueInt;
 	LinkedVar(unsigned short) = linkPtr->lastValue.us;
 	break;
 
     case TCL_LINK_UINT:
 	if (Tcl_GetWideIntFromObj(NULL, valueObj, &valueWide) != TCL_OK
 		|| valueWide < 0 || valueWide > UINT_MAX) {
-	    if (GetInvalidIntFromObj(valueObj, &valueInt)
+	    if (GetInvalidIntOrBooleanFromObj(valueObj, &valueInt)
 		    != TCL_OK) {
 		Tcl_ObjSetVar2(interp, linkPtr->varName, NULL, ObjValue(linkPtr),
 			TCL_GLOBAL_ONLY);
-		return (char *) "variable must have unsigned int value";
+		return (char *) "variable must have unsigned int or boolean value";
 	    }
 	    linkPtr->lastValue.ui = (unsigned int)valueInt;
 	} else {
 	    linkPtr->lastValue.ui = (unsigned int)valueWide;
 	}
@@ -511,15 +511,15 @@
 	break;
 
     case TCL_LINK_LONG:
 	if (Tcl_GetWideIntFromObj(NULL, valueObj, &valueWide) != TCL_OK
 		|| valueWide < LONG_MIN || valueWide > LONG_MAX) {
-	    if (GetInvalidIntFromObj(valueObj, &valueInt)
+	    if (GetInvalidIntOrBooleanFromObj(valueObj, &valueInt)
 		    != TCL_OK) {
 		Tcl_ObjSetVar2(interp, linkPtr->varName, NULL, ObjValue(linkPtr),
 			TCL_GLOBAL_ONLY);
-		return (char *) "variable must have long value";
+		return (char *) "variable must have long or boolean value";
 	    }
 	    linkPtr->lastValue.l = (long)valueInt;
 	} else {
 	    linkPtr->lastValue.l = (long)valueWide;
 	}
@@ -527,15 +527,15 @@
 	break;
 
     case TCL_LINK_ULONG:
 	if (Tcl_GetWideIntFromObj(NULL, valueObj, &valueWide) != TCL_OK
 		|| valueWide < 0 || (Tcl_WideUInt) valueWide > ULONG_MAX) {
-	    if (GetInvalidIntFromObj(valueObj, &valueInt)
+	    if (GetInvalidIntOrBooleanFromObj(valueObj, &valueInt)
 		    != TCL_OK) {
 		Tcl_ObjSetVar2(interp, linkPtr->varName, NULL, ObjValue(linkPtr),
 			TCL_GLOBAL_ONLY);
-		return (char *) "variable must have unsigned long value";
+		return (char *) "variable must have unsigned long or boolean value";
 	    }
 	    linkPtr->lastValue.ul = (unsigned long)valueInt;
 	} else {
 	    linkPtr->lastValue.ul = (unsigned long)valueWide;
 	}
@@ -545,15 +545,15 @@
     case TCL_LINK_WIDE_UINT:
 	/*
 	 * FIXME: represent as a bignum.
 	 */
 	if (Tcl_GetWideIntFromObj(NULL, valueObj, &valueWide) != TCL_OK) {
-	    if (GetInvalidIntFromObj(valueObj, &valueInt)
+	    if (GetInvalidIntOrBooleanFromObj(valueObj, &valueInt)
 		    != TCL_OK) {
 		Tcl_ObjSetVar2(interp, linkPtr->varName, NULL, ObjValue(linkPtr),
 			TCL_GLOBAL_ONLY);
-		return (char *) "variable must have unsigned wide int value";
+		return (char *) "variable must have unsigned wide int or boolean value";
 	    }
 	    linkPtr->lastValue.uw = (Tcl_WideUInt)valueInt;
 	} else {
 	    linkPtr->lastValue.uw = (Tcl_WideUInt)valueWide;
 	}
@@ -686,21 +686,20 @@
     SetInvalidRealFromAny		/* setFromAnyProc */
 };
 
 static int
 SetInvalidRealFromAny(Tcl_Interp *interp, Tcl_Obj *objPtr) {
-    int length;
     const char *str;
     const char *endPtr;
 
-    str = TclGetStringFromObj(objPtr, &length);
-    if ((length == 1) && (str[0] == '.')){
+    str = TclGetString(objPtr);
+    if ((objPtr->length == 1) && (str[0] == '.')){
 	objPtr->typePtr = &invalidRealType;
 	objPtr->internalRep.doubleValue = 0.0;
 	return TCL_OK;
     }
-    if (TclParseNumber(NULL, objPtr, NULL, str, length, &endPtr,
+    if (TclParseNumber(NULL, objPtr, NULL, str, objPtr->length, &endPtr,
 	    TCL_PARSE_DECIMAL_ONLY) == TCL_OK) {
 	/* If number is followed by [eE][+-]?, then it is an invalid
 	 * double, but it could be the start of a valid double. */
 	if (*endPtr == 'e' || *endPtr == 'E') {
 	    ++endPtr;
@@ -718,31 +717,27 @@
     return TCL_ERROR;
 }
 
 
 /*
- * This function checks for integer representations, which are valid
- * when linking with C variables, but which are invalid in other
- * contexts in Tcl. Handled are "", "+", "-", "0x", "0b" and "0o"
- * (upperand lowercase). See bug [39f6304c2e].
+ * This function checks for integer or boolean representations,
+ * which are valid when linking with C variables, but which are
+ * invalid in other contexts in Tcl. Handled are "", "0x", "0b"
+ * and "0o" (upperand lowercase). See bug [39f6304c2e].
  */
 int
-GetInvalidIntFromObj(Tcl_Obj *objPtr,
+GetInvalidIntOrBooleanFromObj(Tcl_Obj *objPtr,
 				int *intPtr)
 {
-    int length;
-    const char *str = TclGetStringFromObj(objPtr, &length);
-
-    if ((length == 1) && strchr("+-", str[0])) {
-	*intPtr = (str[0] == '+');
-	return TCL_OK;
-    } else if ((length == 0) ||
-	    ((length == 2) && (str[0] == '0') && strchr("xXbBoO", str[1]))) {
+    const char *str = TclGetString(objPtr);
+
+    if ((objPtr->length == 0) ||
+	    ((objPtr->length == 2) && (str[0] == '0') && strchr("xXbBoO", str[1]))) {
 	*intPtr = 0;
 	return TCL_OK;
     }
-    return TCL_ERROR;
+    return Tcl_GetBooleanFromObj(NULL, objPtr, intPtr);
 }
 
 /*
  * This function checks for double representations, which are valid
  * when linking with C variables, but which are invalid in other
@@ -751,26 +746,31 @@
  */
 int
 GetInvalidDoubleFromObj(Tcl_Obj *objPtr,
 				double *doublePtr)
 {
-    int intValue, result;
+    const char *str;
 
     if ((objPtr->typePtr == &invalidRealType) ||
 	    (SetInvalidRealFromAny(NULL, objPtr) == TCL_OK)) {
 	*doublePtr = objPtr->internalRep.doubleValue;
 	return TCL_OK;
     }
-    result = GetInvalidIntFromObj(objPtr, &intValue);
-    if (result == TCL_OK) {
-	*doublePtr = (double) intValue;
+    str = TclGetString(objPtr);
+    if ((objPtr->length == 1) && strchr("+-", str[0])) {
+       *doublePtr = (double)(str[0] == '+');
+       return TCL_OK;
+    } else if ((objPtr->length == 0) ||
+           ((objPtr->length == 2) && (str[0] == '0') && strchr("xXbBoO", str[1]))) {
+       *doublePtr = 0.0;
+       return TCL_OK;
     }
-    return result;
+    return TCL_ERROR;
 }
 
 /*
  * Local Variables:
  * mode: c
  * c-basic-offset: 4
  * fill-column: 78
  * End:
  */

Index: generic/tclObj.c
==================================================================
--- generic/tclObj.c
+++ generic/tclObj.c
@@ -2002,13 +2002,14 @@
 
 static int
 ParseBoolean(
     register Tcl_Obj *objPtr)	/* The object to parse/convert. */
 {
-    int i, length, newBool;
+    int newBool;
     char lowerCase[6];
-    const char *str = TclGetStringFromObj(objPtr, &length);
+    const char *str = TclGetString(objPtr);
+    size_t i, length = objPtr->length;
 
     if ((length == 0) || (length > 5)) {
 	/*
          * Longest valid boolean string rep. is "false".
          */
@@ -2026,10 +2027,22 @@
     case '1':
 	if (length == 1) {
 	    newBool = 1;
 	    goto numericBoolean;
 	}
+	return TCL_ERROR;
+    case '-':
+	if (length == 1) {
+	    newBool = 0;
+	    goto goodBoolean;
+	}
+	return TCL_ERROR;
+    case '+':
+	if (length == 1) {
+	    newBool = 1;
+	    goto goodBoolean;
+	}
 	return TCL_ERROR;
     }
 
     /*
      * Force to lower case for case-insensitive detection. Filter out known
@@ -2080,18 +2093,15 @@
 	    newBool = 0;
 	    goto goodBoolean;
 	}
 	return TCL_ERROR;
     case 'o':
-	if (length < 2) {
-	    return TCL_ERROR;
-	}
-	if (strncmp(lowerCase, "on", (size_t) length) == 0) {
-	    newBool = 1;
+	if (strncmp(lowerCase, "off", (size_t) length) == 0) {
+	    newBool = 0;
 	    goto goodBoolean;
-	} else if (strncmp(lowerCase, "off", (size_t) length) == 0) {
-	    newBool = 0;
+	} else if (strncmp(lowerCase, "on", (size_t) length) == 0) {
+	    newBool = 1;
 	    goto goodBoolean;
 	}
 	return TCL_ERROR;
     default:
 	return TCL_ERROR;

Index: tests/link.test
==================================================================
--- tests/link.test
+++ tests/link.test
@@ -65,11 +65,11 @@
     testlink delete
 } -constraints {testlink} -body {
     testlink set 43 1.23 4 - 56785678 64 250 30000 60000 0xbeefbabe 12321 32123 3.25 1231231234
     testlink create 1 1 1 1 1 1 1 1 1 1 1 1 1 1
     list [catch {set int 09a} msg] $msg $int
-} -result {1 {can't set "int": variable must have integer value} 43}
+} -result {1 {can't set "int": variable must have integer or boolean value} 43}
 test link-2.3 {writing bad values into variables} -setup {
     testlink delete
 } -constraints {testlink} -body {
     testlink set 43 1.23 4 - 56785678 64 250 30000 60000 0xbeefbabe 12321 32123 3.25 1231231234
     testlink create 1 1 1 1 1 1 1 1 1 1 1 1 1 1
@@ -86,11 +86,11 @@
     testlink delete
 } -constraints {testlink} -body {
     testlink set 43 1.23 4 - 56785678 64 250 30000 60000 0xbeefbabe 12321 32123 3.25 1231231234
     testlink create 1 1 1 1 1 1 1 1 1 1 1 1 1 1
     list [catch {set wide gorp} msg] $msg $bool
-} -result {1 {can't set "wide": variable must have integer value} 1}
+} -result {1 {can't set "wide": variable must have integer or boolean value} 1}
 test link-2.6 {writing C variables from Tcl} -constraints {testlink} -setup {
     testlink delete
 } -body {
     testlink set 43 1.21 4 - 56785678 64 250 30000 60000 0xbaadbeef 12321 32123 3.25 1231231234
     testlink create 1 1 1 1 1 1 1 1 1 1 1 1 1 1
@@ -307,11 +307,11 @@
 	set y abc
     }
     testlink create 1 1 1 1 1 1 1 1 1 1 1 1 1 1
     testlink set -4 {} {} {} {} {} {} {} {} {} {} {} {} {}
     list [catch x msg] $msg $int
-} -result {1 {can't set "y": variable must have integer value} -4}
+} -result {1 {can't set "y": variable must have integer or boolean value} -4}
 test link-7.5 {access to linked variables via upvar} -setup {
     testlink delete
 } -constraints {testlink} -body {
     proc x {} {
 	upvar real y
@@ -340,11 +340,11 @@
 	set y abc
     }
     testlink create 1 1 1 1 1 1 1 1 1 1 1 1 1 1
     testlink set -4 16.3 1 {} 778899 {} {} {} {} {} {} {} {} {}
     list [catch x msg] $msg $wide
-} -result {1 {can't set "y": variable must have integer value} 778899}
+} -result {1 {can't set "y": variable must have integer or boolean value} 778899}
 
 test link-8.1 {Tcl_UpdateLinkedVar procedure} {testlink} {
     proc x args {
 	global x int real bool string wide
 	lappend x $args $int $real $bool $string $wide