Use more TCL_AUTO_LENGTH, when appropriate

15 files changed, 72 insertions, 65 deletions

diff --git a/doc/Encoding.3 b/doc/Encoding.3
index 3c654ba..c3161e1 100644
--- a/doc/Encoding.3
+++ b/doc/Encoding.3
@@ -83,7 +83,7 @@ specified encoding that are to be converted to UTF-8.  For the
 UTF-8 characters to be converted to the specified encoding.
 .AP "const TCHAR" *tsrc in
 An array of Windows TCHAR characters to convert to UTF-8.
-.AP int srcLen in
+.AP size_t srcLen in
 Length of \fIsrc\fR or \fItsrc\fR in bytes.  If the length is negative, the
 encoding-specific length of the string is used.
 .AP Tcl_DString *dstPtr out
diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index c22ec71..0a4e91d 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -4647,7 +4647,7 @@ Tcl_EvalEx(
     Tcl_Interp *interp,		/* Interpreter in which to evaluate the
 				 * script. Also used for error reporting. */
     const char *script,		/* First character of script to evaluate. */
-    size_t numBytes,		/* Number of bytes in script. If (size_t)-1, the
+    size_t numBytes,		/* Number of bytes in script. If -1, the
 				 * script consists of all bytes up to the
 				 * first null character. */
     int flags)			/* Collection of OR-ed bits that control the
@@ -4662,7 +4662,7 @@ TclEvalEx(
     Tcl_Interp *interp,		/* Interpreter in which to evaluate the
 				 * script. Also used for error reporting. */
     const char *script,		/* First character of script to evaluate. */
-    size_t numBytes,		/* Number of bytes in script. If (size_t)-1, the
+    size_t numBytes,		/* Number of bytes in script. If -1, the
 				 * script consists of all bytes up to the
 				 * first NUL character. */
     int flags,			/* Collection of OR-ed bits that control the
@@ -4727,7 +4727,7 @@ TclEvalEx(
 	}
     }
 
-    if (numBytes == (size_t)-1) {
+    if (numBytes == TCL_AUTO_LENGTH) {
 	numBytes = strlen(script);
     }
     Tcl_ResetResult(interp);
diff --git a/generic/tclBinary.c b/generic/tclBinary.c
index 0cc35b9..4c6ccc9 100644
--- a/generic/tclBinary.c
+++ b/generic/tclBinary.c
@@ -663,12 +663,12 @@ UpdateStringOfByteArray(
      */
 
     size = length;
-    for (i = 0; (i < length) && (size != (size_t)-1); i++) {
+    for (i = 0; (i < length) && (size != TCL_AUTO_LENGTH); i++) {
 	if ((src[i] == 0) || (src[i] > 127)) {
 	    size++;
 	}
     }
-    if (size == (size_t)-1) {
+    if (size == TCL_AUTO_LENGTH) {
 	Tcl_Panic("max size for a Tcl value exceeded");
     }
 
@@ -718,7 +718,7 @@ TclAppendBytesToByteArray(
     if (Tcl_IsShared(objPtr)) {
 	Tcl_Panic("%s called with shared object","TclAppendBytesToByteArray");
     }
-    if (len == (size_t)-1) {
+    if (len == TCL_AUTO_LENGTH) {
 	Tcl_Panic("%s must be called with definite number of bytes to append",
 		"TclAppendBytesToByteArray");
     }
diff --git a/generic/tclCompExpr.c b/generic/tclCompExpr.c
index 2950087..7afb0e0 100644
--- a/generic/tclCompExpr.c
+++ b/generic/tclCompExpr.c
@@ -1819,7 +1819,7 @@ int
 Tcl_ParseExpr(
     Tcl_Interp *interp,		/* Used for error reporting. */
     const char *start,		/* Start of source string to parse. */
-    size_t numBytes,		/* Number of bytes in string. If (size_t)-1, the
+    size_t numBytes,		/* Number of bytes in string. If -1, the
 				 * string consists of all bytes up to the
 				 * first null character. */
     Tcl_Parse *parsePtr)	/* Structure to fill with information about
@@ -1833,7 +1833,7 @@ Tcl_ParseExpr(
     Tcl_Parse *exprParsePtr = TclStackAlloc(interp, sizeof(Tcl_Parse));
 				/* Holds the Tcl_Tokens of substitutions. */
 
-    if (numBytes == (size_t)-1) {
+    if (numBytes == TCL_AUTO_LENGTH) {
 	numBytes = (start ? strlen(start) : 0);
     }
 
diff --git a/generic/tclCompile.c b/generic/tclCompile.c
index aa4adca..7e10512 100644
--- a/generic/tclCompile.c
+++ b/generic/tclCompile.c
@@ -2104,7 +2104,7 @@ TclCompileScript(
 				 * serves as context for finding and compiling
 				 * commands. May not be NULL. */
     const char *script,		/* The source script to compile. */
-    size_t numBytes,		/* Number of bytes in script. If (size_t)-1, the
+    size_t numBytes,		/* Number of bytes in script. If -1, the
 				 * script consists of all bytes up to the
 				 * first null character. */
     CompileEnv *envPtr)		/* Holds resulting instructions. */
diff --git a/generic/tclEncoding.c b/generic/tclEncoding.c
index bbc1b20..06041f1 100644
--- a/generic/tclEncoding.c
+++ b/generic/tclEncoding.c
@@ -1048,7 +1048,7 @@ Tcl_ExternalToUtfDString(
     Tcl_Encoding encoding,	/* The encoding for the source string, or NULL
 				 * for the default system encoding. */
     const char *src,		/* Source string in specified encoding. */
-    size_t srcLen,		/* Source string length in bytes, or (size_t)-1 for
+    size_t srcLen,		/* Source string length in bytes, or -1 for
 				 * encoding-specific string length. */
     Tcl_DString *dstPtr)	/* Uninitialized or free DString in which the
 				 * converted string is stored. */
@@ -1070,7 +1070,7 @@ Tcl_ExternalToUtfDString(
 
     if (src == NULL) {
 	srcLen = 0;
-    } else if (srcLen == (size_t)-1) {
+    } else if (srcLen == TCL_AUTO_LENGTH) {
 	srcLen = encodingPtr->lengthProc(src);
     }
 
@@ -1122,7 +1122,7 @@ Tcl_ExternalToUtf(
     Tcl_Encoding encoding,	/* The encoding for the source string, or NULL
 				 * for the default system encoding. */
     const char *src,		/* Source string in specified encoding. */
-    size_t srcLen,		/* Source string length in bytes, or (size_t)-1
+    size_t srcLen,		/* Source string length in bytes, or -1
 				 * for encoding-specific string length. */
     int flags,			/* Conversion control flags. */
     Tcl_EncodingState *statePtr,/* Place for conversion routine to store state
@@ -1160,7 +1160,7 @@ Tcl_ExternalToUtf(
 
     if (src == NULL) {
 	srcLen = 0;
-    } else if (srcLen == (size_t)-1) {
+    } else if (srcLen == TCL_AUTO_LENGTH) {
 	srcLen = encodingPtr->lengthProc(src);
     }
     if (statePtr == NULL) {
@@ -1239,7 +1239,7 @@ Tcl_UtfToExternalDString(
     Tcl_Encoding encoding,	/* The encoding for the converted string, or
 				 * NULL for the default system encoding. */
     const char *src,		/* Source string in UTF-8. */
-    size_t srcLen,		/* Source string length in bytes, or (size_t)-1 for
+    size_t srcLen,		/* Source string length in bytes, or -1 for
 				 * strlen(). */
     Tcl_DString *dstPtr)	/* Uninitialized or free DString in which the
 				 * converted string is stored. */
@@ -1261,7 +1261,7 @@ Tcl_UtfToExternalDString(
 
     if (src == NULL) {
 	srcLen = 0;
-    } else if (srcLen == (size_t)-1) {
+    } else if (srcLen == TCL_AUTO_LENGTH) {
 	srcLen = strlen(src);
     }
     flags = TCL_ENCODING_START | TCL_ENCODING_END;
@@ -1315,7 +1315,7 @@ Tcl_UtfToExternal(
     Tcl_Encoding encoding,	/* The encoding for the converted string, or
 				 * NULL for the default system encoding. */
     const char *src,		/* Source string in UTF-8. */
-    size_t srcLen,		/* Source string length in bytes, or (size_t)-1
+    size_t srcLen,		/* Source string length in bytes, or -1
 				 * for strlen(). */
     int flags,			/* Conversion control flags. */
     Tcl_EncodingState *statePtr,/* Place for conversion routine to store state
@@ -1350,7 +1350,7 @@ Tcl_UtfToExternal(
 
     if (src == NULL) {
 	srcLen = 0;
-    } else if (srcLen == (size_t)-1) {
+    } else if (srcLen == TCL_AUTO_LENGTH) {
 	srcLen = strlen(src);
     }
     if (statePtr == NULL) {
@@ -1940,7 +1940,7 @@ LoadEscapeEncoding(
 	Tcl_DString lineString;
 
 	Tcl_DStringInit(&lineString);
-	if (Tcl_Gets(chan, &lineString) == (size_t)-1) {
+	if (Tcl_Gets(chan, &lineString) == TCL_IO_FAILURE) {
 	    break;
 	}
 	line = Tcl_DStringValue(&lineString);
diff --git a/generic/tclEnv.c b/generic/tclEnv.c
index abf361b..e69fb29 100644
--- a/generic/tclEnv.c
+++ b/generic/tclEnv.c
@@ -217,7 +217,7 @@ TclSetEnv(
     Tcl_MutexLock(&envMutex);
     index = TclpFindVariable(name, &length);
 
-    if (index == (size_t)-1) {
+    if (index == TCL_AUTO_LENGTH) {
 #ifndef USE_PUTENV
 	/*
 	 * We need to handle the case where the environment may be changed
@@ -301,7 +301,7 @@ TclSetEnv(
      * string in the cache.
      */
 
-    if ((index != (size_t)-1) && (environ[index] == p)) {
+    if ((index != TCL_AUTO_LENGTH) && (environ[index] == p)) {
 	ReplaceString(oldValue, p);
 #ifdef HAVE_PUTENV_THAT_COPIES
     } else {
@@ -417,7 +417,7 @@ TclUnsetEnv(
      * needless work and to avoid recursion on the unset.
      */
 
-    if (index == (size_t)-1) {
+    if (index == TCL_AUTO_LENGTH) {
 	Tcl_MutexUnlock(&envMutex);
 	return;
     }
@@ -522,7 +522,7 @@ TclGetEnv(
     Tcl_MutexLock(&envMutex);
     index = TclpFindVariable(name, &length);
     result = NULL;
-    if (index != (size_t)-1) {
+    if (index != TCL_AUTO_LENGTH) {
 	Tcl_DString envStr;
 
 	result = Tcl_ExternalToUtfDString(NULL, environ[index], -1, &envStr);
diff --git a/generic/tclIO.c b/generic/tclIO.c
index ff6bf0c..30ed68d 100644
--- a/generic/tclIO.c
+++ b/generic/tclIO.c
@@ -3988,7 +3988,7 @@ size_t
 Tcl_Write(
     Tcl_Channel chan,		/* The channel to buffer output for. */
     const char *src,		/* Data to queue in output buffer. */
-    size_t srcLen)			/* Length of data in bytes, or (size_t)-1 for
+    size_t srcLen)			/* Length of data in bytes, or -1 for
 				 * strlen(). */
 {
     /*
@@ -4002,14 +4002,14 @@ Tcl_Write(
     chanPtr = statePtr->topChanPtr;
 
     if (CheckChannelErrors(statePtr, TCL_WRITABLE) != 0) {
-	return -1;
+	return TCL_IO_FAILURE;
     }
 
-    if (srcLen == (size_t)-1) {
+    if (srcLen == TCL_AUTO_LENGTH) {
 	srcLen = strlen(src);
     }
     if (WriteBytes(chanPtr, src, srcLen) == -1) {
-	return -1;
+	return TCL_IO_FAILURE;
     }
     return srcLen;
 }
@@ -4109,12 +4109,12 @@ Tcl_WriteChars(
     Tcl_Obj *objPtr;
 
     if (CheckChannelErrors(statePtr, TCL_WRITABLE) != 0) {
-	return (size_t)-1;
+	return TCL_IO_FAILURE;
     }
 
     chanPtr = statePtr->topChanPtr;
 
-    if (len == (size_t)-1) {
+    if (len == TCL_AUTO_LENGTH) {
 	len = strlen(src);
     }
     if (statePtr->encoding) {
@@ -4182,7 +4182,7 @@ Tcl_WriteObj(
     chanPtr = statePtr->topChanPtr;
 
     if (CheckChannelErrors(statePtr, TCL_WRITABLE) != 0) {
-	return (size_t)-1;
+	return TCL_IO_FAILURE;
     }
     if (statePtr->encoding == NULL) {
 	src = (char *) TclGetByteArrayFromObj(objPtr, &srcLen);
@@ -4518,7 +4518,7 @@ Tcl_GetsObj(
     Tcl_EncodingState oldState;
 
     if (CheckChannelErrors(statePtr, TCL_READABLE) != 0) {
-	return (size_t)-1;
+	return TCL_IO_FAILURE;
     }
 
     /*
@@ -4533,7 +4533,7 @@ Tcl_GetsObj(
 
 	/* TODO: Do we need this? */
 	UpdateInterest(chanPtr);
-	return (size_t)-1;
+	return TCL_IO_FAILURE;
     }
 
     /*
@@ -5586,7 +5586,7 @@ Tcl_Read(
     chanPtr = statePtr->topChanPtr;
 
     if (CheckChannelErrors(statePtr, TCL_READABLE) != 0) {
-	return (size_t)-1;
+	return TCL_IO_FAILURE;
     }
 
     return DoRead(chanPtr, dst, bytesToRead, 0);
@@ -5627,7 +5627,7 @@ Tcl_ReadRaw(
 
     assert(bytesToRead > 0);
     if (CheckChannelErrors(statePtr, TCL_READABLE | CHANNEL_RAW_MODE) != 0) {
-	return (size_t)-1;
+	return TCL_IO_FAILURE;
     }
 
     /*
@@ -5737,7 +5737,7 @@ Tcl_ReadChars(
     Tcl_Channel chan,		/* The channel to read. */
     Tcl_Obj *objPtr,		/* Input data is stored in this object. */
     size_t toRead,		/* Maximum number of characters to store, or
-				 * (size_t)-1 to read all available data (up to EOF or
+				 * -1 to read all available data (up to EOF or
 				 * when channel blocks). */
     int appendFlag)		/* If non-zero, data read from the channel
 				 * will be appended to the object. Otherwise,
@@ -5793,7 +5793,7 @@ DoReadChars(
     Channel *chanPtr,		/* The channel to read. */
     Tcl_Obj *objPtr,		/* Input data is stored in this object. */
     size_t toRead,			/* Maximum number of characters to store, or
-				 * (size_t)-1 to read all available data (up to EOF or
+				 * -1 to read all available data (up to EOF or
 				 * when channel blocks). */
     int appendFlag)		/* If non-zero, data read from the channel
 				 * will be appended to the object. Otherwise,
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 1a9feda..3b7225c 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -4170,7 +4170,7 @@ typedef const char *TclDTraceStr;
 /*
  * Invalidate the string rep first so we can use the bytes value for our
  * pointer chain, and signal an obj deletion (as opposed to shimmering) with
- * 'length == (size_t)-1'.
+ * 'length == TCL_AUTO_LENGTH'.
  * Use empty 'if ; else' to handle use in unbraced outer if/else conditions.
  */
 
@@ -4182,7 +4182,7 @@ typedef const char *TclDTraceStr;
 		    && ((objPtr)->bytes != &tclEmptyString)) { \
 		Tcl_Free((objPtr)->bytes); \
 	    } \
-	    (objPtr)->length = (size_t)-1; \
+	    (objPtr)->length = TCL_AUTO_LENGTH; \
 	    TclFreeObjStorage(objPtr); \
 	    TclIncrObjsFreed(); \
 	} else { \
diff --git a/generic/tclStubInit.c b/generic/tclStubInit.c
index d16a80e..7064ec1 100644
--- a/generic/tclStubInit.c
+++ b/generic/tclStubInit.c
@@ -115,6 +115,9 @@ Tcl_WinUtfToTChar(
     Tcl_DString *dsPtr)
 {
     Tcl_DStringInit(dsPtr);
+    if (!string) {
+	return NULL;
+    }
     return (char *)Tcl_UtfToUniCharDString(string, len, dsPtr);
 }
 
@@ -124,9 +127,13 @@ Tcl_WinTCharToUtf(
     size_t len,
     Tcl_DString *dsPtr)
 {
-    if (len != (size_t)-1) {
+    Tcl_DStringInit(dsPtr);
+    if (!string) {
+	return NULL;
+    }
+    if (len != TCL_AUTO_LENGTH) {
 	len /= 2;
-    } else if (len == -1) {
+    } else {
 	len = wcslen((wchar_t *)string);
     }
     Tcl_DStringInit(dsPtr);
diff --git a/generic/tclUtf.c b/generic/tclUtf.c
index 3bfb68f..cf32345 100644
--- a/generic/tclUtf.c
+++ b/generic/tclUtf.c
@@ -425,7 +425,7 @@ Tcl_UtfToUniCharDString(
     const char *p, *end;
     size_t oldLength;
 
-    if (length == (size_t)-1) {
+    if (length == TCL_AUTO_LENGTH) {
 	length = strlen(src);
     }
 
@@ -527,7 +527,7 @@ Tcl_NumUtfChars(
      * single-byte char case specially.
      */
 
-    if (length == (size_t)-1) {
+    if (length == TCL_AUTO_LENGTH) {
 	while (*src != '\0') {
 	    src += TclUtfToUniChar(src, &ch);
 	    i++;
@@ -806,7 +806,7 @@ Tcl_UtfAtIndex(
     int len = 1;
 #endif
 
-    if (index != (size_t)-1) {
+    if (index != TCL_AUTO_LENGTH) {
 	while (index--) {
 #if TCL_UTF_MAX <= 4
 	    src += (len = TclUtfToUniChar(src, &ch));
diff --git a/generic/tclUtil.c b/generic/tclUtil.c
index 93242e4..9a35e4e 100644
--- a/generic/tclUtil.c
+++ b/generic/tclUtil.c
@@ -390,7 +390,7 @@ TclMaxListLength(
 {
     size_t count = 0;
 
-    if ((numBytes == 0) || ((numBytes == (size_t)-1) && (*bytes == '\0'))) {
+    if ((numBytes == 0) || ((numBytes == TCL_AUTO_LENGTH) && (*bytes == '\0'))) {
 	/* Empty string case - quick exit */
 	goto done;
     }
@@ -406,7 +406,7 @@ TclMaxListLength(
      */
 
     while (numBytes) {
-	if ((numBytes == (size_t)-1) && (*bytes == '\0')) {
+	if ((numBytes == TCL_AUTO_LENGTH) && (*bytes == '\0')) {
 	    break;
 	}
 	if (TclIsSpaceProc(*bytes)) {
@@ -417,9 +417,9 @@ TclMaxListLength(
 	    count++;
 	    do {
 		bytes++;
-		numBytes -= (numBytes != (size_t)-1);
+		numBytes -= (numBytes != TCL_AUTO_LENGTH);
 	    } while (numBytes && TclIsSpaceProc(*bytes));
-	    if ((numBytes == 0) || ((numBytes == (size_t)-1) && (*bytes == '\0'))) {
+	    if ((numBytes == 0) || ((numBytes == TCL_AUTO_LENGTH) && (*bytes == '\0'))) {
 		break;
 	    }
 
@@ -428,7 +428,7 @@ TclMaxListLength(
 	     */
 	}
 	bytes++;
-	numBytes -= (numBytes != (size_t)-1);
+	numBytes -= (numBytes != TCL_AUTO_LENGTH);
     }
 
     /*
@@ -1012,7 +1012,7 @@ Tcl_ScanCountedElement(
 size_t
 TclScanElement(
     const char *src,		/* String to convert to Tcl list element. */
-    size_t length,		/* Number of bytes in src, or (size_t)-1. */
+    size_t length,		/* Number of bytes in src, or -1. */
     char *flagPtr)		/* Where to store information to guide
 				 * Tcl_ConvertElement. */
 {
@@ -1329,7 +1329,7 @@ Tcl_ConvertElement(
 size_t
 Tcl_ConvertCountedElement(
     register const char *src,	/* Source information for list element. */
-    size_t length,		/* Number of bytes in src, or (size_t)-1. */
+    size_t length,		/* Number of bytes in src, or -1. */
     char *dst,			/* Place to put list-ified element. */
     int flags)			/* Flags produced by Tcl_ScanElement. */
 {
@@ -1362,7 +1362,7 @@ Tcl_ConvertCountedElement(
 size_t
 TclConvertElement(
     register const char *src,	/* Source information for list element. */
-    size_t length,		/* Number of bytes in src, or (size_t)-1. */
+    size_t length,		/* Number of bytes in src, or -1. */
     char *dst,			/* Place to put list-ified element. */
     int flags)			/* Flags produced by Tcl_ScanElement. */
 {
@@ -1381,7 +1381,7 @@ TclConvertElement(
      * No matter what the caller demands, empty string must be braced!
      */
 
-    if ((src == NULL) || (length == 0) || (*src == '\0' && length == (size_t)-1)) {
+    if ((src == NULL) || (length == 0) || (*src == '\0' && length == TCL_AUTO_LENGTH)) {
 	src = &tclEmptyString;
 	length = 0;
 	conversion = CONVERT_BRACE;
@@ -2656,12 +2656,12 @@ Tcl_DStringAppend(
     const char *bytes,		/* String to append. If length is -1 then this
 				 * must be null-terminated. */
     size_t length)			/* Number of bytes from "bytes" to append. If
-				 * (size_t)-1, then append all of bytes, up to null
+				 * -1, then append all of bytes, up to null
 				 * at end. */
 {
     size_t newSize;
 
-    if (length == (size_t)-1) {
+    if (length == TCL_AUTO_LENGTH) {
 	length = strlen(bytes);
     }
     newSize = length + dsPtr->length;
@@ -2680,7 +2680,7 @@ Tcl_DStringAppend(
 	    memcpy(newString, dsPtr->string, dsPtr->length);
 	    dsPtr->string = newString;
 	} else {
-	    size_t offset = (size_t)-1;
+	    size_t offset = TCL_AUTO_LENGTH;
 
 	    /* See [16896d49fd] */
 	    if (bytes >= dsPtr->string
@@ -2690,7 +2690,7 @@ Tcl_DStringAppend(
 
 	    dsPtr->string = Tcl_Realloc(dsPtr->string, dsPtr->spaceAvl);
 
-	    if (offset != (size_t)-1) {
+	    if (offset != TCL_AUTO_LENGTH) {
 		bytes = dsPtr->string + offset;
 	    }
 	}
diff --git a/generic/tclZlib.c b/generic/tclZlib.c
index d05d774..f2c3cb9 100644
--- a/generic/tclZlib.c
+++ b/generic/tclZlib.c
@@ -1329,7 +1329,7 @@ Tcl_ZlibStreamGet(
     (void) TclGetByteArrayFromObj(data, &existing);
 
     if (zshPtr->mode == TCL_ZLIB_STREAM_INFLATE) {
-	if (count == (size_t)-1) {
+	if (count == TCL_AUTO_LENGTH) {
 	    /*
 	     * The only safe thing to do is restict to 65k. We might cause a
 	     * panic for out of memory if we just kept growing the buffer.
@@ -1486,7 +1486,7 @@ Tcl_ZlibStreamGet(
 	}
     } else {
 	Tcl_ListObjLength(NULL, zshPtr->outData, &listLen);
-	if (count == (size_t)-1) {
+	if (count == TCL_AUTO_LENGTH) {
 	    count = 0;
 	    for (i=0; i<listLen; i++) {
 		Tcl_ListObjIndex(NULL, zshPtr->outData, i, &itemObj);
diff --git a/win/tclWin32Dll.c b/win/tclWin32Dll.c
index 03bcc7c..25bddee 100644
--- a/win/tclWin32Dll.c
+++ b/win/tclWin32Dll.c
@@ -466,14 +466,14 @@ TclWinDriveLetterForVolMountPoint(
 TCHAR *
 Tcl_WinUtfToTChar(
     const char *string,		/* Source string in UTF-8. */
-    size_t len,			/* Source string length in bytes, or (size_t)-1
+    size_t len,			/* Source string length in bytes, or -1
 				 * for strlen(). */
     Tcl_DString *dsPtr)		/* Uninitialized or free DString in which the
 				 * converted string is stored. */
 {
     Tcl_DStringInit(dsPtr);
     if (!string) {
-	return (TCHAR *)Tcl_DStringValue(dsPtr);
+	return NULL;
     }
     return Tcl_UtfToUniCharDString(string, len, dsPtr);
 }
@@ -481,18 +481,18 @@ Tcl_WinUtfToTChar(
 char *
 Tcl_WinTCharToUtf(
     const TCHAR *string,	/* Source string in Unicode. */
-    size_t len,			/* Source string length in bytes, or (size_t)-1
+    size_t len,			/* Source string length in bytes, or -1
 				 * for platform-specific string length. */
     Tcl_DString *dsPtr)		/* Uninitialized or free DString in which the
 				 * converted string is stored. */
 {
     Tcl_DStringInit(dsPtr);
     if (!string) {
-	return Tcl_DStringValue(dsPtr);
+	return NULL;
     }
-    if (len != (size_t)-1) {
+    if (len != TCL_AUTO_LENGTH) {
 	len /= 2;
-    } else if (len < 0) {
+    } else {
 	len = wcslen(string);
     }
     return Tcl_UniCharToUtfDString(string, len, dsPtr);
diff --git a/win/tclWinPipe.c b/win/tclWinPipe.c
index 0313708..eda9fe0 100644
--- a/win/tclWinPipe.c
+++ b/win/tclWinPipe.c
@@ -851,7 +851,7 @@ TclpCloseFile(
  * Results:
  *	Returns the process id for the child process. If the pid was not known
  *	by Tcl, either because the pid was not created by Tcl or the child
- *	process has already been reaped, -1 is returned.
+ *	process has already been reaped, (size_t)-1 is returned.
  *
  * Side effects:
  *	None.