From d4e2ae119e3f6d6e5d430cf810ea4dc396ecd9b7 Mon Sep 17 00:00:00 2001
From: "jan.nijtmans" <nijtmans@users.sourceforge.net>
Date: Fri, 21 Jan 2022 14:44:58 +0000
Subject: Undo part of [26539e78a7]. Although Tcl_GetRange() does it's own
 parameter check, it's caller doesn't have to do it any more. However, put
 back these check, better not depend on the improved behavior of Tcl_GetRange
 (yet). This gives the freedom to bring back Tcl_GetRange() to how it was in
 Tcl 8.6.10, if desired

---
 generic/tclCmdMZ.c     | 20 +++++++++++---------
 generic/tclExecute.c   | 26 ++++++++++++++++++++++----
 generic/tclStringObj.c |  7 ++++---
 3 files changed, 37 insertions(+), 16 deletions(-)

diff --git a/generic/tclCmdMZ.c b/generic/tclCmdMZ.c
index bf75d44..34fd6bf 100644
--- a/generic/tclCmdMZ.c
+++ b/generic/tclCmdMZ.c
@@ -394,14 +394,10 @@ Tcl_RegexpObjCmd(
 
 		newPtr = Tcl_NewListObj(2, objs);
 	    } else {
-		if (i <= info.nsubs) {
-		    if (info.matches[i].end <= 0) {
-			TclNewObj(newPtr);
-		    } else {
-			newPtr = Tcl_GetRange(objPtr,
-				offset + info.matches[i].start,
-				offset + info.matches[i].end - 1);
-		    }
+		if ((i <= info.nsubs) && (info.matches[i].end > 0)) {
+		    newPtr = Tcl_GetRange(objPtr,
+			    offset + info.matches[i].start,
+			    offset + info.matches[i].end - 1);
 		} else {
 		    TclNewObj(newPtr);
 		}
@@ -2187,7 +2183,13 @@ StringRangeCmd(
 	return TCL_ERROR;
     }
 
-    if (last >= 0) {
+    if (first < 0) {
+	first = 0;
+    }
+    if (last >= length) {
+	last = length;
+    }
+    if (last >= first) {
 	Tcl_SetObjResult(interp, Tcl_GetRange(objv[1], first, last));
     }
     return TCL_OK;
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index a3b0401..e5a6b71 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -5609,10 +5609,16 @@ TEBCresume(
 	    goto gotError;
 	}
 
-	if (toIdx < 0) {
-	    TclNewObj(objResultPtr);
-	} else {
+	if (fromIdx < 0) {
+	    fromIdx = 0;
+	}
+	if (toIdx >= length) {
+	    toIdx = length;
+	}
+	if (toIdx >= fromIdx) {
 	    objResultPtr = Tcl_GetRange(OBJ_AT_DEPTH(2), fromIdx, toIdx);
+	} else {
+	    TclNewObj(objResultPtr);
 	}
 	TRACE_APPEND(("\"%.30s\"\n", O2S(objResultPtr)));
 	NEXT_INST_V(1, 3, 1);
@@ -5646,6 +5652,13 @@ TEBCresume(
 	}
 
 	toIdx = TclIndexDecode(toIdx, length - 1);
+	if (toIdx < 0) {
+	    goto emptyRange;
+	} else if (toIdx >= length) {
+	    toIdx = length - 1;
+	}
+
+	assert ( toIdx >= 0 && toIdx < length );
 
 	/*
 	assert ( fromIdx != TCL_INDEX_BEFORE );
@@ -5659,8 +5672,13 @@ TEBCresume(
 	if (fromIdx == TCL_INDEX_AFTER) {
 	    goto emptyRange;
 	}
+
 	fromIdx = TclIndexDecode(fromIdx, length - 1);
-	if (toIdx >= 0) {
+	if (fromIdx < 0) {
+	    fromIdx = 0;
+	}
+
+	if (fromIdx <= toIdx) {
 	    objResultPtr = Tcl_GetRange(valuePtr, fromIdx, toIdx);
 	} else {
 	emptyRange:
diff --git a/generic/tclStringObj.c b/generic/tclStringObj.c
index b4f05dd..9e0e4af 100644
--- a/generic/tclStringObj.c
+++ b/generic/tclStringObj.c
@@ -819,6 +819,7 @@ Tcl_GetRange(
 	FillUnicodeRep(objPtr);
 	stringPtr = GET_STRING(objPtr);
     }
+
     if (last < 0 || last >= stringPtr->numChars) {
 	last = stringPtr->numChars - 1;
     }
@@ -829,12 +830,12 @@ Tcl_GetRange(
 #if TCL_UTF_MAX == 4
     /* See: bug [11ae2be95dac9417] */
     if ((first > 0) && ((stringPtr->unicode[first] & 0xFC00) == 0xDC00)
-		&& ((stringPtr->unicode[first-1] & 0xFC00) == 0xD800)) {
+	    && ((stringPtr->unicode[first-1] & 0xFC00) == 0xD800)) {
 	++first;
     }
     if ((last + 1 < stringPtr->numChars)
-		&& ((stringPtr->unicode[last+1] & 0xFC00) == 0xDC00)
-		&& ((stringPtr->unicode[last] & 0xFC00) == 0xD800)) {
+	    && ((stringPtr->unicode[last+1] & 0xFC00) == 0xDC00)
+	    && ((stringPtr->unicode[last] & 0xFC00) == 0xD800)) {
 	++last;
     }
 #endif
-- 
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