Merge 8.7

25 files changed, 135 insertions, 122 deletions

diff --git a/.travis.yml b/.travis.yml
index a3b4b7d..ab80836 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -120,9 +120,9 @@ jobs:
         - BUILD_DIR=unix
         - CFGOPT="--enable-symbols=mem"
 # Testing on Mac, various styles
-    - name: "macOS/Clang/Xcode 11.7/Shared"
+    - name: "macOS/Clang/Xcode 12/Shared"
       os: osx
-      osx_image: xcode11.7
+      osx_image: xcode12
       env:
         - BUILD_DIR=macosx
       install: []
@@ -130,14 +130,14 @@ jobs:
         - make all
         # The styles=develop avoids some weird problems on OSX
         - make test styles=develop
-    - name: "macOS/Clang/Xcode 11.7/Shared/Unix-like"
+    - name: "macOS/Clang/Xcode 12/Shared/Unix-like"
       os: osx
-      osx_image: xcode11.7
+      osx_image: xcode112
       env:
         - BUILD_DIR=unix
-    - name: "macOS/Clang/Xcode 11.7/Shared/libtommath"
+    - name: "macOS/Clang/Xcode 12/Shared/libtommath"
       os: osx
-      osx_image: xcode11.7
+      osx_image: xcode12
       env:
         - BUILD_DIR=macosx
       install: []
@@ -146,18 +146,26 @@ jobs:
         homebrew:
           packages:
             - libtommath
-    - name: "macOS/Clang++/Xcode 11.7/Shared"
+    - name: "macOS/Clang++/Xcode 12/Shared"
       os: osx
-      osx_image: xcode11.7
+      osx_image: xcode12
       env:
         - BUILD_DIR=unix
         - CFGOPT="CC=clang++ --enable-framework CFLAGS=-Dregister=dont+use+register CPPFLAGS=-D__private_extern__=extern"
       script:
         - make all tcltest
+# Newer MacOS versions
+    - name: "macOS/Clang/Xcode 12/Universal Apps/Shared"
+      os: osx
+      osx_image: xcode12u
+      env:
+        - BUILD_DIR=macosx
+      install: []
+      script: *mactest
 # Older MacOS versions
     - name: "macOS/Clang/Xcode 11/Shared"
       os: osx
-      osx_image: xcode11
+      osx_image: xcode11.7
       env:
         - BUILD_DIR=macosx
       install: []
@@ -171,7 +179,7 @@ jobs:
       script: *mactest
     - name: "macOS/Clang/Xcode 9/Shared"
       os: osx
-      osx_image: xcode9.2
+      osx_image: xcode9.4
       env:
         - BUILD_DIR=macosx
       install: []
diff --git a/generic/tclCompCmdsGR.c b/generic/tclCompCmdsGR.c
index 221ac3a..780f7b8 100644
--- a/generic/tclCompCmdsGR.c
+++ b/generic/tclCompCmdsGR.c
@@ -874,7 +874,7 @@ TclCompileLappendCmd(
      */
 
     if (numWords > 2) {
-	Tcl_Token *valueTokenPtr = TokenAfter(varTokenPtr);
+	valueTokenPtr = TokenAfter(varTokenPtr);
 
 	CompileWord(envPtr, valueTokenPtr, interp, 2);
     }
diff --git a/generic/tclCompExpr.c b/generic/tclCompExpr.c
index 476ff14..a630ad4 100644
--- a/generic/tclCompExpr.c
+++ b/generic/tclCompExpr.c
@@ -2463,8 +2463,8 @@ CompileExprTree(
 	    if (optimize) {
 		int length;
 		const char *bytes = TclGetStringFromObj(literal, &length);
-		int index = TclRegisterLiteral(envPtr, bytes, length, 0);
-		Tcl_Obj *objPtr = TclFetchLiteral(envPtr, index);
+		int idx = TclRegisterLiteral(envPtr, bytes, length, 0);
+		Tcl_Obj *objPtr = TclFetchLiteral(envPtr, idx);
 
 		if ((objPtr->typePtr == NULL) && (literal->typePtr != NULL)) {
 		    /*
@@ -2484,7 +2484,7 @@ CompileExprTree(
 		    objPtr->internalRep = literal->internalRep;
 		    literal->typePtr = NULL;
 		}
-		TclEmitPush(index, envPtr);
+		TclEmitPush(idx, envPtr);
 	    } else {
 		/*
 		 * When optimize==0, we know the expression is a one-off and
@@ -2510,7 +2510,7 @@ CompileExprTree(
 
 		if (ExecConstantExprTree(interp, nodes, next, litObjvPtr)
 			== TCL_OK) {
-		    int index;
+		    int idx;
 		    Tcl_Obj *objPtr = Tcl_GetObjResult(interp);
 
 		    /*
@@ -2524,8 +2524,8 @@ CompileExprTree(
 			const char *bytes
 				= Tcl_GetStringFromObj(objPtr, &numBytes);
 
-			index = TclRegisterLiteral(envPtr, bytes, numBytes, 0);
-			tableValue = TclFetchLiteral(envPtr, index);
+			idx = TclRegisterLiteral(envPtr, bytes, numBytes, 0);
+			tableValue = TclFetchLiteral(envPtr, idx);
 			if ((tableValue->typePtr == NULL) &&
 				(objPtr->typePtr != NULL)) {
 			    /*
@@ -2537,9 +2537,9 @@ CompileExprTree(
 			    objPtr->typePtr = NULL;
 			}
 		    } else {
-			index = TclAddLiteralObj(envPtr, objPtr, NULL);
+			idx = TclAddLiteralObj(envPtr, objPtr, NULL);
 		    }
-		    TclEmitPush(index, envPtr);
+		    TclEmitPush(idx, envPtr);
 		} else {
 		    TclCompileSyntaxError(interp, envPtr);
 		}
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index 13f328c..867cdd7 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -6427,8 +6427,8 @@ TEBCresume(
 	if (TclHasIntRep(valuePtr,  &tclBooleanType)) {
 	    objResultPtr = TCONST(1);
 	} else {
-	    int result = (TclSetBooleanFromAny(NULL, valuePtr) == TCL_OK);
-	    objResultPtr = TCONST(result);
+	    int res = (TclSetBooleanFromAny(NULL, valuePtr) == TCL_OK);
+	    objResultPtr = TCONST(res);
 	}
 	TRACE_WITH_OBJ(("\"%.30s\" => ", O2S(valuePtr)), objResultPtr);
 	NEXT_INST_F(1, 0, 1);
@@ -6622,7 +6622,7 @@ TEBCresume(
     }
     {
 	ForeachInfo *infoPtr;
-	Tcl_Obj *listPtr, **elements, *tmpPtr;
+	Tcl_Obj *listPtr, **elements;
 	ForeachVarList *varListPtr;
 	int numLists, listLen, numVars;
 	int listTmpDepth;
diff --git a/generic/tclIOUtil.c b/generic/tclIOUtil.c
index 2879bcb..fcce215 100644
--- a/generic/tclIOUtil.c
+++ b/generic/tclIOUtil.c
@@ -3173,7 +3173,7 @@ Tcl_LoadFile(
     }
 
     if (fsPtr->loadFileProc != NULL) {
-	int retVal = ((Tcl_FSLoadFileProc2 *)(void *)(fsPtr->loadFileProc))
+	retVal = ((Tcl_FSLoadFileProc2 *)(void *)(fsPtr->loadFileProc))
 		(interp, pathPtr, handlePtr, &unloadProcPtr, flags);
 
 	if (retVal == TCL_OK) {
diff --git a/generic/tclInterp.c b/generic/tclInterp.c
index 6417668..434d9f4 100644
--- a/generic/tclInterp.c
+++ b/generic/tclInterp.c
@@ -621,30 +621,41 @@ NRInterpCmd(
     static const char *const options[] = {
 	"alias",	"aliases",	"bgerror",	"cancel",
 	"children",	"create",	"debug",	"delete",
+	"eval",		"exists",	"expose",	"hide",
+	"hidden",	"issafe",	"invokehidden",
+	"limit",	"marktrusted",	"recursionlimit",
+	"share",	"slaves",	"target",	"transfer",
+	NULL
+    };
+    static const char *const optionsNoSlaves[] = {
+	"alias",	"aliases",	"bgerror",	"cancel",
+	"children",	"create",	"debug",	"delete",
 	"eval",		"exists",	"expose",
 	"hide",		"hidden",	"issafe",
 	"invokehidden",	"limit",	"marktrusted",	"recursionlimit",
-	"slaves",	"share",	"target",	"transfer",
-	NULL
+	"share",	"target",	"transfer",	NULL
     };
     enum option {
 	OPT_ALIAS,	OPT_ALIASES,	OPT_BGERROR,	OPT_CANCEL,
 	OPT_CHILDREN,	OPT_CREATE,	OPT_DEBUG,	OPT_DELETE,
-	OPT_EVAL,	OPT_EXISTS,	OPT_EXPOSE,
-	OPT_HIDE,	OPT_HIDDEN,	OPT_ISSAFE,
-	OPT_INVOKEHID,	OPT_LIMIT,	OPT_MARKTRUSTED,OPT_RECLIMIT,
-	OPT_SLAVES,	OPT_SHARE,	OPT_TARGET,	OPT_TRANSFER
+	OPT_EVAL,	OPT_EXISTS,	OPT_EXPOSE,	OPT_HIDE,
+	OPT_HIDDEN,	OPT_ISSAFE,	OPT_INVOKEHID,
+	OPT_LIMIT,	OPT_MARKTRUSTED,OPT_RECLIMIT,
+	OPT_SHARE,	OPT_SLAVES,	OPT_TARGET,	OPT_TRANSFER
     };
 
     if (objc < 2) {
 	Tcl_WrongNumArgs(interp, 1, objv, "cmd ?arg ...?");
 	return TCL_ERROR;
     }
-    if (Tcl_GetIndexFromObj(interp, objv[1], options, "option", 0,
-	    &index) != TCL_OK) {
+    if (Tcl_GetIndexFromObj(NULL, objv[1], options,
+	    "option", 0, &index) != TCL_OK) {
+	/* Don't report the "slaves" option as possibility */
+	Tcl_GetIndexFromObj(interp, objv[1], optionsNoSlaves,
+		"option", 0, &index);
 	return TCL_ERROR;
     }
-    switch ((enum option) index) {
+    switch ((enum option)index) {
     case OPT_ALIAS: {
 	Tcl_Interp *parentInterp;
 
diff --git a/generic/tclPkg.c b/generic/tclPkg.c
index b55ad3e..cda74b1 100644
--- a/generic/tclPkg.c
+++ b/generic/tclPkg.c
@@ -1368,9 +1368,9 @@ TclNRPackageObjCmd(
 		    newObjvPtr, NULL);
 	    return TCL_OK;
 	} else {
-	    int i, newobjc = objc-3;
 	    Tcl_Obj *const *newobjv = objv + 3;
 
+	    newobjc = objc - 3;
 	    if (CheckAllRequirements(interp, objc-3, objv+3) != TCL_OK) {
 		return TCL_ERROR;
 	    }
diff --git a/generic/tclResult.c b/generic/tclResult.c
index 4b9df6c..1fb2ad0 100644
--- a/generic/tclResult.c
+++ b/generic/tclResult.c
@@ -841,19 +841,19 @@ SetupAppendBuffer(
 
     totalSpace = newSpace + iPtr->appendUsed;
     if (totalSpace >= iPtr->appendAvl) {
-	char *newSpace;
+	char *newSpacePtr;
 
 	if (totalSpace < 100) {
 	    totalSpace = 200;
 	} else {
 	    totalSpace *= 2;
 	}
-	newSpace = (char *)ckalloc(totalSpace);
-	strcpy(newSpace, iPtr->result);
+	newSpacePtr = (char *)ckalloc(totalSpace);
+	strcpy(newSpacePtr, iPtr->result);
 	if (iPtr->appendResult != NULL) {
 	    ckfree(iPtr->appendResult);
 	}
-	iPtr->appendResult = newSpace;
+	iPtr->appendResult = newSpacePtr;
 	iPtr->appendAvl = totalSpace;
     } else if (iPtr->result != iPtr->appendResult) {
 	strcpy(iPtr->appendResult, iPtr->result);
diff --git a/generic/tclScan.c b/generic/tclScan.c
index dfd6b88..1eefafe 100644
--- a/generic/tclScan.c
+++ b/generic/tclScan.c
@@ -937,16 +937,16 @@ Tcl_ScanObjCmd(
 	    } else if (flags & SCAN_BIG) {
 		if (flags & SCAN_UNSIGNED) {
 		    mp_int big;
-		    int code = Tcl_GetBignumFromObj(interp, objPtr, &big);
+		    int res = Tcl_GetBignumFromObj(interp, objPtr, &big);
 
-		    if (code == TCL_OK) {
+		    if (res == TCL_OK) {
 			if (mp_isneg(&big)) {
-			    code = TCL_ERROR;
+			    res = TCL_ERROR;
 			}
 			mp_clear(&big);
 		    }
 
-		    if (code == TCL_ERROR) {
+		    if (res == TCL_ERROR) {
 			if (objs != NULL) {
 			    ckfree(objs);
 			}
diff --git a/generic/tclStringObj.c b/generic/tclStringObj.c
index 7486631..66647f0 100644
--- a/generic/tclStringObj.c
+++ b/generic/tclStringObj.c
@@ -2443,10 +2443,10 @@ Tcl_AppendFormatToObj(
 		goto errorMsg;
 	    }
 	    if (ch == 'A') {
-		char *p = TclGetString(segment) + 1;
-		*p = 'x';
-		p = strchr(p, 'P');
-		if (p) *p = 'p';
+		char *q = TclGetString(segment) + 1;
+		*q = 'x';
+		q = strchr(q, 'P');
+		if (q) *q = 'p';
 	    }
 	    break;
 	}
@@ -3561,7 +3561,7 @@ TclStringFirst(
     int lh, ln = Tcl_GetCharLength(needle);
     Tcl_Obj *result;
     int value = -1;
-    Tcl_UniChar *check, *end, *uh, *un;
+    Tcl_UniChar *checkStr, *endStr, *uh, *un;
 
     if (start < 0) {
 	start = 0;
@@ -3627,12 +3627,12 @@ TclStringFirst(
 	/* Don't start the loop if there cannot be a valid answer */
 	goto firstEnd;
     }
-    end = uh + lh;
+    endStr = uh + lh;
 
-    for (check = uh + start; check + ln <= end; check++) {
-	if ((*check == *un) && (0 ==
-		memcmp(check + 1, un + 1, (ln-1) * sizeof(Tcl_UniChar)))) {
-	    value =  (check - uh);
+    for (checkStr = uh + start; checkStr + ln <= endStr; checkStr++) {
+	if ((*checkStr == *un) && (0 ==
+		memcmp(checkStr + 1, un + 1, (ln-1) * sizeof(Tcl_UniChar)))) {
+	    value =  (checkStr - uh);
 	    goto firstEnd;
 	}
     }
@@ -3668,7 +3668,7 @@ TclStringLast(
     int lh, ln = Tcl_GetCharLength(needle);
     Tcl_Obj *result;
     int value = -1;
-    Tcl_UniChar *check, *uh, *un;
+    Tcl_UniChar *checkStr, *uh, *un;
 
     if (ln == 0) {
 	/*
@@ -3714,14 +3714,14 @@ TclStringLast(
 	/* Don't start the loop if there cannot be a valid answer */
 	goto lastEnd;
     }
-    check = uh + last + 1 - ln;
-    while (check >= uh) {
-	if ((*check == un[0])
-		&& (0 == memcmp(check+1, un+1, (ln-1)*sizeof(Tcl_UniChar)))) {
-	    value = (check - uh);
+    checkStr = uh + last + 1 - ln;
+    while (checkStr >= uh) {
+	if ((*checkStr == un[0])
+		&& (0 == memcmp(checkStr+1, un+1, (ln-1)*sizeof(Tcl_UniChar)))) {
+	    value = (checkStr - uh);
 	    goto lastEnd;
 	}
-	check--;
+	checkStr--;
     }
   lastEnd:
     TclNewIntObj(result, value);
diff --git a/generic/tclTest.c b/generic/tclTest.c
index 5ebbfdd..1523666 100644
--- a/generic/tclTest.c
+++ b/generic/tclTest.c
@@ -7488,8 +7488,6 @@ TestconcatobjCmd(
 		"\n\t* (e) concatObj does not have refCount 0", NULL);
     }
     if (concatPtr == tmpPtr) {
-	int len;
-
 	result = TCL_ERROR;
 	Tcl_AppendResult(interp, "\n\t* (e) concatObj is not a new obj ",
 		NULL);
@@ -7520,8 +7518,6 @@ TestconcatobjCmd(
 		"\n\t* (f) concatObj does not have refCount 0", NULL);
     }
     if (concatPtr == tmpPtr) {
-	int len;
-
 	result = TCL_ERROR;
 	Tcl_AppendResult(interp, "\n\t* (f) concatObj is not a new obj ",
 		NULL);
@@ -7553,8 +7549,6 @@ TestconcatobjCmd(
 		"\n\t* (g) concatObj does not have refCount 0", NULL);
     }
     if (concatPtr == tmpPtr) {
-	int len;
-
 	result = TCL_ERROR;
 	Tcl_AppendResult(interp, "\n\t* (g) concatObj is not a new obj ",
 		NULL);
diff --git a/generic/tclTrace.c b/generic/tclTrace.c
index 1b59852..cf9da4f 100644
--- a/generic/tclTrace.c
+++ b/generic/tclTrace.c
@@ -1177,7 +1177,7 @@ Tcl_UntraceCommand(
     CommandTrace *tracePtr;
     CommandTrace *prevPtr;
     Command *cmdPtr;
-    Interp *iPtr = (Interp *) interp;
+    Interp *iPtr = (Interp *)interp;
     ActiveCommandTrace *activePtr;
     int hasExecTraces = 0;
 
@@ -1252,7 +1252,6 @@ Tcl_UntraceCommand(
 	 */
 
 	if (cmdPtr->compileProc != NULL) {
-	    Interp *iPtr = (Interp *) interp;
 	    iPtr->compileEpoch++;
 	}
     }
diff --git a/generic/tclUtil.c b/generic/tclUtil.c
index f6d815b..170a85e 100644
--- a/generic/tclUtil.c
+++ b/generic/tclUtil.c
@@ -3757,7 +3757,7 @@ GetEndOffsetFromObj(
 	if (*bytes != 'e') {
 	    int numType;
 	    const char *opPtr;
-	    int length, t1 = 0, t2 = 0;
+	    int t1 = 0, t2 = 0;
 
 	    /* Value doesn't start with "e" */
 
@@ -3774,7 +3774,7 @@ GetEndOffsetFromObj(
 	     * Quick scan to see if multi-value list is even possible.
 	     * This relies on TclGetString() returning a NUL-terminated string.
 	     */
-	    if ((TclMaxListLength(TclGetString(objPtr), -1, NULL) > 1)
+	    if ((TclMaxListLength(bytes, -1, NULL) > 1)
 
 		    /* If it's possible, do the full list parse. */
 	            && (TCL_OK == Tcl_ListObjLength(NULL, objPtr, &length))
diff --git a/generic/tclVar.c b/generic/tclVar.c
index 3d46790..a48cf96 100644
--- a/generic/tclVar.c
+++ b/generic/tclVar.c
@@ -119,17 +119,17 @@ VarHashNextVar(
  * access is denied.
  */
 
-static const char *noSuchVar =		"no such variable";
-static const char *isArray =		"variable is array";
-static const char *needArray =		"variable isn't array";
-static const char *noSuchElement =	"no such element in array";
-static const char *danglingElement =
+static const char NOSUCHVAR[] =		"no such variable";
+static const char ISARRAY[] =		"variable is array";
+static const char NEEDARRAY[] =		"variable isn't array";
+static const char NOSUCHELEMENT[] =	"no such element in array";
+static const char DANGLINGELEMENT[] =
 	"upvar refers to element in deleted array";
-static const char *danglingVar =
+static const char DANGLINGVAR[] =
 	"upvar refers to variable in deleted namespace";
-static const char *badNamespace =	"parent namespace doesn't exist";
-static const char *missingName =	"missing variable name";
-static const char *isArrayElement =
+static const char BADNAMESPACE[] =	"parent namespace doesn't exist";
+static const char MISSINGNAME[] =	"missing variable name";
+static const char ISARRAYELEMENT[] =
 	"name refers to an element in an array";
 
 /*
@@ -649,7 +649,7 @@ TclObjLookupVarEx(
 
 		if (flags & TCL_LEAVE_ERR_MSG) {
 		    TclObjVarErrMsg(interp, part1Ptr, part2Ptr, msg,
-			    noSuchVar, -1);
+			    NOSUCHVAR, -1);
 		    Tcl_SetErrorCode(interp, "TCL", "VALUE", "VARNAME", NULL);
 		}
 		return NULL;
@@ -674,7 +674,7 @@ TclObjLookupVarEx(
 		if (part2Ptr != NULL) {
 		    if (flags & TCL_LEAVE_ERR_MSG) {
 			TclObjVarErrMsg(interp, part1Ptr, part2Ptr, msg,
-				needArray, -1);
+				NEEDARRAY, -1);
 			Tcl_SetErrorCode(interp, "TCL", "VALUE", "VARNAME",
 				NULL);
 		    }
@@ -939,7 +939,7 @@ TclLookupSimpleVar(
 	    Tcl_Obj *tailPtr;
 
 	    if (!create) {	/* Var wasn't found and not to create it. */
-		*errMsgPtr = noSuchVar;
+		*errMsgPtr = NOSUCHVAR;
 		return NULL;
 	    }
 
@@ -950,10 +950,10 @@ TclLookupSimpleVar(
 	    TclGetNamespaceForQualName(interp, varName, cxtNsPtr, flags,
 		    &varNsPtr, &dummy1Ptr, &dummy2Ptr, &tail);
 	    if (varNsPtr == NULL) {
-		*errMsgPtr = badNamespace;
+		*errMsgPtr = BADNAMESPACE;
 		return NULL;
 	    } else if (tail == NULL) {
-		*errMsgPtr = missingName;
+		*errMsgPtr = MISSINGNAME;
 		return NULL;
 	    }
 	    if (tail != varName) {
@@ -1010,7 +1010,7 @@ TclLookupSimpleVar(
 		varPtr = VarHashFindVar(tablePtr, varNamePtr);
 	    }
 	    if (varPtr == NULL) {
-		*errMsgPtr = noSuchVar;
+		*errMsgPtr = NOSUCHVAR;
 	    }
 	}
     }
@@ -1088,7 +1088,7 @@ TclLookupArrayElement(
 	if (!createArray) {
 	    if (flags & TCL_LEAVE_ERR_MSG) {
 		TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg,
-			noSuchVar, index);
+			NOSUCHVAR, index);
 		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
 			arrayNamePtr?TclGetString(arrayNamePtr):NULL, NULL);
 	    }
@@ -1103,7 +1103,7 @@ TclLookupArrayElement(
 	if (TclIsVarDeadHash(arrayPtr)) {
 	    if (flags & TCL_LEAVE_ERR_MSG) {
 		TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg,
-			danglingVar, index);
+			DANGLINGVAR, index);
 		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
 			arrayNamePtr?TclGetString(arrayNamePtr):NULL, NULL);
 	    }
@@ -1113,7 +1113,7 @@ TclLookupArrayElement(
 	TclInitArrayVar(arrayPtr);
     } else if (!TclIsVarArray(arrayPtr)) {
 	if (flags & TCL_LEAVE_ERR_MSG) {
-	    TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg, needArray,
+	    TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg, NEEDARRAY,
 		    index);
 	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
 		    arrayNamePtr?TclGetString(arrayNamePtr):NULL, NULL);
@@ -1135,7 +1135,7 @@ TclLookupArrayElement(
 	if (varPtr == NULL) {
 	    if (flags & TCL_LEAVE_ERR_MSG) {
 		TclObjVarErrMsg(interp, arrayNamePtr, elNamePtr, msg,
-			noSuchElement, index);
+			NOSUCHELEMENT, index);
 		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ELEMENT",
 			TclGetString(elNamePtr), NULL);
 	    }
@@ -1485,11 +1485,11 @@ TclPtrGetVarIdx(
     if (flags & TCL_LEAVE_ERR_MSG) {
 	if (TclIsVarUndefined(varPtr) && arrayPtr
 		&& !TclIsVarUndefined(arrayPtr)) {
-	    msg = noSuchElement;
+	    msg = NOSUCHELEMENT;
 	} else if (TclIsVarArray(varPtr)) {
-	    msg = isArray;
+	    msg = ISARRAY;
 	} else {
-	    msg = noSuchVar;
+	    msg = NOSUCHVAR;
 	}
 	TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "read", msg, index);
     }
@@ -2024,11 +2024,11 @@ TclPtrSetVarIdx(
 	if (flags & TCL_LEAVE_ERR_MSG) {
 	    if (TclIsVarArrayElement(varPtr)) {
 		TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "set",
-			danglingElement, index);
+			DANGLINGELEMENT, index);
 		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "ELEMENT", NULL);
 	    } else {
 		TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "set",
-			danglingVar, index);
+			DANGLINGVAR, index);
 		Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME", NULL);
 	    }
 	}
@@ -2041,7 +2041,7 @@ TclPtrSetVarIdx(
 
     if (TclIsVarArray(varPtr)) {
 	if (flags & TCL_LEAVE_ERR_MSG) {
-	    TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "set", isArray,index);
+	    TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "set", ISARRAY,index);
 	    Tcl_SetErrorCode(interp, "TCL", "WRITE", "ARRAY", NULL);
 	}
 	goto earlyError;
@@ -2609,7 +2609,7 @@ TclPtrUnsetVarIdx(
     if (result != TCL_OK) {
 	if (flags & TCL_LEAVE_ERR_MSG) {
 	    TclObjVarErrMsg(interp, part1Ptr, part2Ptr, "unset",
-		    ((arrayPtr == NULL) ? noSuchVar : noSuchElement), index);
+		    ((arrayPtr == NULL) ? NOSUCHVAR : NOSUCHELEMENT), index);
 	    Tcl_SetErrorCode(interp, "TCL", "UNSET", "VARNAME", NULL);
 	}
     }
@@ -4104,7 +4104,7 @@ ArraySetCmd(
     }
     if (arrayPtr) {
 	CleanupVar(varPtr, arrayPtr);
-	TclObjVarErrMsg(interp, arrayNameObj, NULL, "set", needArray, -1);
+	TclObjVarErrMsg(interp, arrayNameObj, NULL, "set", NEEDARRAY, -1);
 	Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
 		TclGetString(arrayNameObj), NULL);
 	return TCL_ERROR;
@@ -4223,7 +4223,7 @@ ArraySetCmd(
 	     */
 
 	    TclObjVarErrMsg(interp, arrayNameObj, NULL, "array set",
-		    needArray, -1);
+		    NEEDARRAY, -1);
 	    Tcl_SetErrorCode(interp, "TCL", "WRITE", "ARRAY", NULL);
 	    return TCL_ERROR;
 	}
@@ -5124,7 +5124,7 @@ Tcl_VariableObjCmd(
 	     */
 
 	    TclObjVarErrMsg(interp, varNamePtr, NULL, "define",
-		    isArrayElement, -1);
+		    ISARRAYELEMENT, -1);
 	    Tcl_SetErrorCode(interp, "TCL", "UPVAR", "LOCAL_ELEMENT", NULL);
 	    return TCL_ERROR;
 	}
@@ -6702,7 +6702,7 @@ ArrayDefaultCmd(
 
 	    CleanupVar(varPtr, arrayPtr);
 	    TclObjVarErrMsg(interp, arrayNameObj, NULL, "array default set",
-		    needArray, -1);
+		    NEEDARRAY, -1);
 	    Tcl_SetErrorCode(interp, "TCL", "LOOKUP", "VARNAME",
 		    TclGetString(arrayNameObj), NULL);
 	    return TCL_ERROR;
@@ -6713,7 +6713,7 @@ ArrayDefaultCmd(
 	     */
 
 	    TclObjVarErrMsg(interp, arrayNameObj, NULL, "array default set",
-		    needArray, -1);
+		    NEEDARRAY, -1);
 	    Tcl_SetErrorCode(interp, "TCL", "WRITE", "ARRAY", NULL);
 	    return TCL_ERROR;
 	}
diff --git a/generic/tclZlib.c b/generic/tclZlib.c
index 34bf78d..5254b84 100644
--- a/generic/tclZlib.c
+++ b/generic/tclZlib.c
@@ -3945,7 +3945,7 @@ TclZlibInit(
     cfg[0].key = "zlibVersion";
     cfg[0].value = zlibVersion();
     cfg[1].key = NULL;
-    Tcl_RegisterConfig(interp, "zlib", cfg, "iso8859-1");
+    Tcl_RegisterConfig(interp, "zlib", cfg, "utf-8");
 
     /*
      * Allow command type introspection to do something sensible with streams.
diff --git a/library/http/http.tcl b/library/http/http.tcl
index eec05b8..df8fe2d 100644
--- a/library/http/http.tcl
+++ b/library/http/http.tcl
@@ -746,6 +746,7 @@ proc http::geturl {url args} {
 	-strict		boolean
 	-timeout	integer
 	-validate	boolean
+	-headers	dict
     }
     set state(charset)	$defaultCharset
     set options {
@@ -759,9 +760,8 @@ proc http::geturl {url args} {
     foreach {flag value} $args {
 	if {[regexp -- $pat $flag]} {
 	    # Validate numbers
-	    if {
-		[info exists type($flag)] &&
-		![string is $type($flag) -strict $value]
+	    if {($flag eq "-headers") ? [catch {dict size $value}] :
+		([info exists type($flag)] && ![string is $type($flag) -strict $value])
 	    } {
 		unset $token
 		return -code error \
diff --git a/macosx/Tcl-Common.xcconfig b/macosx/Tcl-Common.xcconfig
index 0670479..39301db 100644
--- a/macosx/Tcl-Common.xcconfig
+++ b/macosx/Tcl-Common.xcconfig
@@ -19,7 +19,7 @@ GCC_NO_COMMON_BLOCKS = YES
 GCC_DYNAMIC_NO_PIC = YES
 GCC_VERSION = 4.2
 GCC = gcc-$(GCC_VERSION)
-WARNING_CFLAGS = -Wall -Wwrite-strings -Wextra -Wdeclaration-after-statement -Wno-unused-parameter -Wno-missing-field-initializers -Wno-unused-value -Winit-self -Wpointer-arith -Wcast-align -Wdisabled-optimization -Winline $(WARNING_CFLAGS)
+WARNING_CFLAGS = -Wall -Wextra -Wshadow -Wwrite-strings -Wpointer-arith -Wc++-compat -Wdeclaration-after-statement -Winit-self -Wcast-align -Wdisabled-optimization -Winline $(WARNING_CFLAGS)
 BINDIR = $(PREFIX)/bin
 CFLAGS = $(CFLAGS)
 CPPFLAGS = -mmacosx-version-min=$(MACOSX_DEPLOYMENT_TARGET) $(CPPFLAGS)
diff --git a/tests/http.test b/tests/http.test
index 7454ab8..a525691 100644
--- a/tests/http.test
+++ b/tests/http.test
@@ -444,6 +444,9 @@ test http-3.33 {http::geturl application/xml is text} -body {
 } -cleanup {
     catch { http::cleanup $token }
 } -result {test 4660 /test}
+test http-3.34 {http::geturl -headers not a dict} -returnCodes error -body {
+    http::geturl http://test/t -headers NoDict
+} -result {Bad value for -headers (NoDict), must be dict}
 
 test http-4.1 {http::Event} -body {
     set token [http::geturl $url -keepalive 0]
diff --git a/tests/interp.test b/tests/interp.test
index 4453d90..f428207 100644
--- a/tests/interp.test
+++ b/tests/interp.test
@@ -32,7 +32,7 @@ test interp-1.1 {options for interp command} -returnCodes error -body {
 } -result {wrong # args: should be "interp cmd ?arg ...?"}
 test interp-1.2 {options for interp command} -returnCodes error -body {
     interp frobox
-} -result {bad option "frobox": must be alias, aliases, bgerror, cancel, children, create, debug, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, slaves, share, target, or transfer}
+} -result {bad option "frobox": must be alias, aliases, bgerror, cancel, children, create, debug, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, share, target, or transfer}
 test interp-1.3 {options for interp command} {
     interp delete
 } ""
@@ -50,13 +50,13 @@ test interp-1.6 {options for interp command} -returnCodes error -body {
 } -result {wrong # args: should be "interp children ?path?"}
 test interp-1.7 {options for interp command} -returnCodes error -body {
     interp hello
-} -result {bad option "hello": must be alias, aliases, bgerror, cancel, children, create, debug, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, slaves, share, target, or transfer}
+} -result {bad option "hello": must be alias, aliases, bgerror, cancel, children, create, debug, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, share, target, or transfer}
 test interp-1.8 {options for interp command} -returnCodes error -body {
     interp -froboz
-} -result {bad option "-froboz": must be alias, aliases, bgerror, cancel, children, create, debug, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, slaves, share, target, or transfer}
+} -result {bad option "-froboz": must be alias, aliases, bgerror, cancel, children, create, debug, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, share, target, or transfer}
 test interp-1.9 {options for interp command} -returnCodes error -body {
     interp -froboz -safe
-} -result {bad option "-froboz": must be alias, aliases, bgerror, cancel, children, create, debug, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, slaves, share, target, or transfer}
+} -result {bad option "-froboz": must be alias, aliases, bgerror, cancel, children, create, debug, delete, eval, exists, expose, hide, hidden, issafe, invokehidden, limit, marktrusted, recursionlimit, share, target, or transfer}
 test interp-1.10 {options for interp command} -returnCodes error -body {
     interp target
 } -result {wrong # args: should be "interp target path alias"}
diff --git a/unix/configure b/unix/configure
index d48d687..6cb5f24 100755
--- a/unix/configure
+++ b/unix/configure
@@ -5036,7 +5036,7 @@ fi
     if test "$GCC" = yes; then :
 
 	CFLAGS_OPTIMIZE=-O2
-	CFLAGS_WARNING="-Wall -Wextra -Wwrite-strings -Wpointer-arith"
+	CFLAGS_WARNING="-Wall -Wextra -Wshadow -Wwrite-strings -Wpointer-arith"
 	case "${CC}" in
 	    *++|*++-*)
 		;;
diff --git a/unix/tcl.m4 b/unix/tcl.m4
index a4824ff..3050bf2 100644
--- a/unix/tcl.m4
+++ b/unix/tcl.m4
@@ -966,7 +966,7 @@ AC_DEFUN([SC_CONFIG_CFLAGS], [
     CFLAGS_DEBUG=-g
     AS_IF([test "$GCC" = yes], [
 	CFLAGS_OPTIMIZE=-O2
-	CFLAGS_WARNING="-Wall -Wextra -Wwrite-strings -Wpointer-arith"
+	CFLAGS_WARNING="-Wall -Wextra -Wshadow -Wwrite-strings -Wpointer-arith"
 	case "${CC}" in
 	    *++|*++-*)
 		;;
diff --git a/win/configure b/win/configure
index b08eb15..828b1d3 100755
--- a/win/configure
+++ b/win/configure
@@ -4215,7 +4215,7 @@ $as_echo "using shared flags" >&6; }
 
 	CFLAGS_DEBUG=-g
 	CFLAGS_OPTIMIZE="-O2 -fomit-frame-pointer"
-	CFLAGS_WARNING="-Wall -Wextra -Wwrite-strings -Wpointer-arith"
+	CFLAGS_WARNING="-Wall -Wextra -Wshadow -Wwrite-strings -Wpointer-arith"
 	LDFLAGS_DEBUG=
 	LDFLAGS_OPTIMIZE=
 
diff --git a/win/tcl.m4 b/win/tcl.m4
index 0fd2271..83cfa6b 100644
--- a/win/tcl.m4
+++ b/win/tcl.m4
@@ -673,7 +673,7 @@ AC_DEFUN([SC_CONFIG_CFLAGS], [
 
 	CFLAGS_DEBUG=-g
 	CFLAGS_OPTIMIZE="-O2 -fomit-frame-pointer"
-	CFLAGS_WARNING="-Wall -Wextra -Wwrite-strings -Wpointer-arith"
+	CFLAGS_WARNING="-Wall -Wextra -Wshadow -Wwrite-strings -Wpointer-arith"
 	LDFLAGS_DEBUG=
 	LDFLAGS_OPTIMIZE=
 
diff --git a/win/tclWinFile.c b/win/tclWinFile.c
index d2777d7..89f485a 100644
--- a/win/tclWinFile.c
+++ b/win/tclWinFile.c
@@ -1094,7 +1094,6 @@ TclpMatchInDirectory(
 	do {
 	    const char *utfname;
 	    int checkDrive = 0, isDrive;
-	    DWORD attr;
 
 	    native = data.cFileName;
 	    attr = data.dwFileAttributes;
@@ -1445,7 +1444,6 @@ TclpGetUserHome(
     int rc = 0;
     const char *domain;
     WCHAR *wName, *wHomeDir, *wDomain;
-    WCHAR buf[MAX_PATH];
 
     Tcl_DStringInit(bufferPtr);
 
@@ -1511,6 +1509,7 @@ TclpGetUserHome(
 		size = lstrlenW(wHomeDir);
 		Tcl_WCharToUtfDString(wHomeDir, size, bufferPtr);
 	    } else {
+		WCHAR buf[MAX_PATH];
 		/*
 		 * User exists but has no home dir. Return
 		 * "{GetProfilesDirectory}/<user>".
@@ -2818,7 +2817,6 @@ TclpObjNormalizePath(
 	     */
 
 	    int len;
-	    char *path;
 	    Tcl_Obj *tmpPathPtr;
 
 	    tmpPathPtr = Tcl_NewStringObj(Tcl_DStringValue(&ds),
diff --git a/win/tclWinSerial.c b/win/tclWinSerial.c
index 328fbad..f0035b9 100644
--- a/win/tclWinSerial.c
+++ b/win/tclWinSerial.c
@@ -1826,7 +1826,7 @@ SerialSetOptionProc(
      */
 
     if ((len > 4) && (strncmp(optionName, "-ttycontrol", len) == 0)) {
-	int i, result = TCL_OK;
+	int i, res = TCL_OK;
 
 	if (Tcl_SplitList(interp, value, &argc, &argv) == TCL_ERROR) {
 	    return TCL_ERROR;
@@ -1844,7 +1844,7 @@ SerialSetOptionProc(
 
 	for (i = 0; i < argc - 1; i += 2) {
 	    if (Tcl_GetBoolean(interp, argv[i+1], &flag) == TCL_ERROR) {
-		result = TCL_ERROR;
+		res = TCL_ERROR;
 		break;
 	    }
 	    if (strncasecmp(argv[i], "DTR", strlen(argv[i])) == 0) {
@@ -1856,7 +1856,7 @@ SerialSetOptionProc(
 			Tcl_SetErrorCode(interp, "TCL", "OPERATION",
 				"FCONFIGURE", "TTY_SIGNAL", NULL);
 		    }
-		    result = TCL_ERROR;
+		    res = TCL_ERROR;
 		    break;
 		}
 	    } else if (strncasecmp(argv[i], "RTS", strlen(argv[i])) == 0) {
@@ -1868,7 +1868,7 @@ SerialSetOptionProc(
 			Tcl_SetErrorCode(interp, "TCL", "OPERATION",
 				"FCONFIGURE", "TTY_SIGNAL", NULL);
 		    }
-		    result = TCL_ERROR;
+		    res = TCL_ERROR;
 		    break;
 		}
 	    } else if (strncasecmp(argv[i], "BREAK", strlen(argv[i])) == 0) {
@@ -1880,7 +1880,7 @@ SerialSetOptionProc(
 			Tcl_SetErrorCode(interp, "TCL", "OPERATION",
 				"FCONFIGURE", "TTY_SIGNAL", NULL);
 		    }
-		    result = TCL_ERROR;
+		    res = TCL_ERROR;
 		    break;
 		}
 	    } else {
@@ -1891,13 +1891,13 @@ SerialSetOptionProc(
 		    Tcl_SetErrorCode(interp, "TCL", "VALUE", "TTY_SIGNAL",
 			    NULL);
 		}
-		result = TCL_ERROR;
+		res = TCL_ERROR;
 		break;
 	    }
 	}
 
 	ckfree(argv);
-	return result;
+	return res;
     }
 
     /*