Index: generic/tclDecls.h
==================================================================
--- generic/tclDecls.h
+++ generic/tclDecls.h
@@ -4035,70 +4035,83 @@
 #undef Tcl_GetBooleanFromObj
 #undef Tcl_GetBoolean
 #undef TclGetByteArrayFromObj
 #undef Tcl_GetByteArrayFromObj
 #if defined(USE_TCL_STUBS)
-#   if TCL_MAJOR_VERSION < 9 || !defined(TCL_NO_DEPRECATED)
-#	define Tcl_GetBytesFromObj(interp, objPtr, sizePtr) \
-		(sizeof(*(sizePtr)) <= sizeof(int) ? \
-			tclStubsPtr->tclGetBytesFromObj(interp, objPtr, (int *)(void *)(sizePtr)) : \
-			tclStubsPtr->tcl_GetBytesFromObj(interp, objPtr, (Tcl_Size *)(void *)(sizePtr)))
-#	define Tcl_GetStringFromObj(objPtr, sizePtr) \
-		(sizeof(*(sizePtr)) <= sizeof(int) ? \
-			tclStubsPtr->tclGetStringFromObj(objPtr, (int *)(void *)(sizePtr)) : \
-			tclStubsPtr->tcl_GetStringFromObj(objPtr, (Tcl_Size *)(void *)(sizePtr)))
-#	define Tcl_GetUnicodeFromObj(objPtr, sizePtr) \
-		(sizeof(*(sizePtr)) <= sizeof(int) ? \
-			tclStubsPtr->tclGetUnicodeFromObj(objPtr, (int *)(void *)(sizePtr)) : \
-			tclStubsPtr->tcl_GetUnicodeFromObj(objPtr, (Tcl_Size *)(void *)(sizePtr)))
-#   endif
-#define Tcl_GetIndexFromObjStruct(interp, objPtr, tablePtr, offset, msg, flags, indexPtr) \
+#   if defined(TCL_8_API) || TCL_MAJOR_VERSION == 8
+#       define Tcl_GetBytesFromObj(interp, objPtr, sizePtr)    \
+	(sizeof(*(sizePtr)) <= sizeof(int) ? \
+		tclStubsPtr->tclGetBytesFromObj(interp, objPtr, (int *)(void *)(sizePtr)) : \
+		tclStubsPtr->tcl_GetBytesFromObj(interp, objPtr, (Tcl_Size *)(void *)(sizePtr)))
+#       define Tcl_GetStringFromObj(objPtr, sizePtr) \
+	(sizeof(*(sizePtr)) <= sizeof(int) ? \
+		tclStubsPtr->tclGetStringFromObj(objPtr, (int *)(void *)(sizePtr)) : \
+		tclStubsPtr->tcl_GetStringFromObj(objPtr, (Tcl_Size *)(void *)(sizePtr)))
+#       if TCL_MAJOR_VERSION > 8
+#           define Tcl_GetByteArrayFromObj(objPtr, sizePtr) \
+        	(sizeof(*(sizePtr)) <= sizeof(int) ? \
+		tclStubsPtr->tclGetBytesFromObj(NULL, objPtr, (int *)(void *)(sizePtr)) : \
+		tclStubsPtr->tcl_GetBytesFromObj(NULL, objPtr, (Tcl_Size *)(void *)(sizePtr)))
+#       else
+#           define Tcl_GetByteArrayFromObj(objPtr, sizePtr) \
+	        (sizeof(*(sizePtr)) <= sizeof(int) ? \
+		tclStubsPtr->tclGetByteArrayFromObj(objPtr, (int *)(void *)(sizePtr)) : \
+		tclStubsPtr->tcl_GetByteArrayFromObj(objPtr, (Tcl_Size *)(void *)(sizePtr)))
+#       endif
+#       define Tcl_GetUnicodeFromObj(objPtr, sizePtr) \
+	     (sizeof(*(sizePtr)) <= sizeof(int) ? \
+		tclStubsPtr->tclGetUnicodeFromObj(objPtr, (int *)(void *)(sizePtr)) : \
+		tclStubsPtr->tcl_GetUnicodeFromObj(objPtr, (Tcl_Size *)(void *)(sizePtr)))
+#   else /* TCL_8_API */
+#       if TCL_MAJOR_VERSION > 8
+#           define Tcl_GetByteArrayFromObj(objPtr, sizePtr) \
+            tclStubsPtr->tcl_GetBytesFromObj(NULL, objPtr, (Tcl_Size *)(void *)(sizePtr))
+#       else
+#           define Tcl_GetByteArrayFromObj(objPtr, sizePtr) \
+	    tclStubsPtr->tcl_GetByteArrayFromObj(objPtr, (Tcl_Size *)(void *)(sizePtr))
+#       endif /* TCL_MAJOR_VERSION > 8 */
+#   endif /* TCL_8_API */
+#   define Tcl_GetIndexFromObjStruct(interp, objPtr, tablePtr, offset, msg, flags, indexPtr) \
 	(tclStubsPtr->tcl_GetIndexFromObjStruct((interp), (objPtr), (tablePtr), (offset), (msg), \
 		(flags)|(int)(sizeof(*(indexPtr))<<1), (indexPtr)))
-#define Tcl_GetBooleanFromObj(interp, objPtr, boolPtr) \
+#   define Tcl_GetBooleanFromObj(interp, objPtr, boolPtr) \
 	((sizeof(*(boolPtr)) == sizeof(int) && (TCL_MAJOR_VERSION == 8)) ? tclStubsPtr->tcl_GetBooleanFromObj(interp, objPtr, (int *)(boolPtr)) : \
 	Tcl_GetBoolFromObj(interp, objPtr, (TCL_NULL_OK-2)&(int)sizeof((*(boolPtr))), (char *)(boolPtr)))
-#define Tcl_GetBoolean(interp, src, boolPtr) \
+#   define Tcl_GetBoolean(interp, src, boolPtr) \
 	((sizeof(*(boolPtr)) == sizeof(int) && (TCL_MAJOR_VERSION == 8)) ? tclStubsPtr->tcl_GetBoolean(interp, src, (int *)(boolPtr)) : \
 	Tcl_GetBool(interp, src, (TCL_NULL_OK-2)&(int)sizeof((*(boolPtr))), (char *)(boolPtr)))
-#if TCL_MAJOR_VERSION > 8
-#define Tcl_GetByteArrayFromObj(objPtr, sizePtr) \
-	(sizeof(*(sizePtr)) <= sizeof(int) ? \
-		tclStubsPtr->tclGetBytesFromObj(NULL, objPtr, (int *)(void *)(sizePtr)) : \
-		tclStubsPtr->tcl_GetBytesFromObj(NULL, objPtr, (Tcl_Size *)(void *)(sizePtr)))
-#else
-#define Tcl_GetByteArrayFromObj(objPtr, sizePtr) \
-	(sizeof(*(sizePtr)) <= sizeof(int) ? \
-		tclStubsPtr->tclGetByteArrayFromObj(objPtr, (int *)(void *)(sizePtr)) : \
-		tclStubsPtr->tcl_GetByteArrayFromObj(objPtr, (Tcl_Size *)(void *)(sizePtr)))
-#endif
-#else
-#define Tcl_GetBytesFromObj(interp, objPtr, sizePtr) \
+#else
+#   if defined(TCL_8_API) || TCL_MAJOR_VERSION == 8
+#       define Tcl_GetBytesFromObj(interp, objPtr, sizePtr) \
 	(sizeof(*(sizePtr)) <= sizeof(int) ? \
 		TclGetBytesFromObj(interp, objPtr, (int *)(void *)(sizePtr)) : \
 		(Tcl_GetBytesFromObj)(interp, objPtr, (Tcl_Size *)(void *)(sizePtr)))
-#define Tcl_GetIndexFromObjStruct(interp, objPtr, tablePtr, offset, msg, flags, indexPtr) \
-	((Tcl_GetIndexFromObjStruct)((interp), (objPtr), (tablePtr), (offset), (msg), \
-		(flags)|(int)(sizeof(*(indexPtr))<<1), (indexPtr)))
-#define Tcl_GetBooleanFromObj(interp, objPtr, boolPtr) \
-	((sizeof(*(boolPtr)) == sizeof(int) && (TCL_MAJOR_VERSION == 8)) ? Tcl_GetBooleanFromObj(interp, objPtr, (int *)(boolPtr)) : \
-	Tcl_GetBoolFromObj(interp, objPtr, (TCL_NULL_OK-2)&(int)sizeof((*(boolPtr))), (char *)(boolPtr)))
-#define Tcl_GetBoolean(interp, src, boolPtr) \
-	((sizeof(*(boolPtr)) == sizeof(int) && (TCL_MAJOR_VERSION == 8)) ? Tcl_GetBoolean(interp, src, (int *)(boolPtr)) : \
-	Tcl_GetBool(interp, src, (TCL_NULL_OK-2)&(int)sizeof((*(boolPtr))), (char *)(boolPtr)))
-#define Tcl_GetStringFromObj(objPtr, sizePtr) \
+#       define Tcl_GetStringFromObj(objPtr, sizePtr) \
 	(sizeof(*(sizePtr)) <= sizeof(int) ? \
 		TclGetStringFromObj(objPtr, (int *)(void *)(sizePtr)) : \
 		(Tcl_GetStringFromObj)(objPtr, (Tcl_Size *)(void *)(sizePtr)))
-#define Tcl_GetByteArrayFromObj(objPtr, sizePtr) \
+#       define Tcl_GetByteArrayFromObj(objPtr, sizePtr) \
 	(sizeof(*(sizePtr)) <= sizeof(int) ? \
 		TclGetBytesFromObj(NULL, objPtr, (int *)(void *)(sizePtr)) : \
 		(Tcl_GetBytesFromObj)(NULL, objPtr, (Tcl_Size *)(void *)(sizePtr)))
-#define Tcl_GetUnicodeFromObj(objPtr, sizePtr) \
-	(sizeof(*(sizePtr)) <= sizeof(int) ? \
+#       define Tcl_GetUnicodeFromObj(objPtr, sizePtr) \
+        (sizeof(*(sizePtr)) <= sizeof(int) ?                                \
 		TclGetUnicodeFromObj(objPtr, (int *)(void *)(sizePtr)) : \
 		(Tcl_GetUnicodeFromObj)(objPtr, (Tcl_Size *)(void *)(sizePtr)))
+#   else /* TCL_8_API */
+#       define Tcl_GetByteArrayFromObj(objPtr, sizePtr) \
+                Tcl_GetBytesFromObj(NULL, objPtr, (Tcl_Size *)(void *)(sizePtr))
+#   endif /* TCL_8_API */
+#   define Tcl_GetIndexFromObjStruct(interp, objPtr, tablePtr, offset, msg, flags, indexPtr) \
+	((Tcl_GetIndexFromObjStruct)((interp), (objPtr), (tablePtr), (offset), (msg), \
+		(flags)|(int)(sizeof(*(indexPtr))<<1), (indexPtr)))
+#   define Tcl_GetBooleanFromObj(interp, objPtr, boolPtr) \
+	((sizeof(*(boolPtr)) == sizeof(int) && (TCL_MAJOR_VERSION == 8)) ? Tcl_GetBooleanFromObj(interp, objPtr, (int *)(boolPtr)) : \
+	Tcl_GetBoolFromObj(interp, objPtr, (TCL_NULL_OK-2)&(int)sizeof((*(boolPtr))), (char *)(boolPtr)))
+#   define Tcl_GetBoolean(interp, src, boolPtr) \
+	((sizeof(*(boolPtr)) == sizeof(int) && (TCL_MAJOR_VERSION == 8)) ? Tcl_GetBoolean(interp, src, (int *)(boolPtr)) : \
+	Tcl_GetBool(interp, src, (TCL_NULL_OK-2)&(int)sizeof((*(boolPtr))), (char *)(boolPtr)))
 #endif
 
 #ifdef TCL_MEM_DEBUG
 #   undef Tcl_Alloc
 #   define Tcl_Alloc(x) \
@@ -4166,10 +4179,11 @@
 		? (Tcl_Size (*)(const char *, wchar_t *))tclStubsPtr->tcl_UtfToUniChar \
 		: (Tcl_Size (*)(const char *, wchar_t *))Tcl_UtfToChar16)
 #   define Tcl_WCharLen (sizeof(wchar_t) != sizeof(short) \
 		? (Tcl_Size (*)(wchar_t *))tclStubsPtr->tcl_UniCharLen \
 		: (Tcl_Size (*)(wchar_t *))Tcl_Char16Len)
+#if defined(TCL_8_API) || TCL_MAJOR_VERSION == 8
 #   undef Tcl_ListObjGetElements
 #   define Tcl_ListObjGetElements(interp, listPtr, objcPtr, objvPtr) (sizeof(*(objcPtr)) == sizeof(int) \
 		? tclStubsPtr->tclListObjGetElements((interp), (listPtr), (int *)(void *)(objcPtr), (objvPtr)) \
 		: tclStubsPtr->tcl_ListObjGetElements((interp), (listPtr), (Tcl_Size *)(void *)(objcPtr), (objvPtr)))
 #   undef Tcl_ListObjLength
@@ -4194,10 +4208,11 @@
 		: tclStubsPtr->tcl_FSSplitPath((pathPtr), (Tcl_Size *)(void *)(lenPtr)))
 #   undef Tcl_ParseArgsObjv
 #   define Tcl_ParseArgsObjv(interp, argTable, objcPtr, objv, remObjv) (sizeof(*(objcPtr)) == sizeof(int) \
 		? tclStubsPtr->tclParseArgsObjv((interp), (argTable), (int *)(void *)(objcPtr), (objv), (remObjv)) \
 		: tclStubsPtr->tcl_ParseArgsObjv((interp), (argTable), (Tcl_Size *)(void *)(objcPtr), (objv), (remObjv)))
+#endif /* TCL_8_API */
 #else
 #   define Tcl_WCharToUtfDString (sizeof(wchar_t) != sizeof(short) \
 		? (char *(*)(const wchar_t *, Tcl_Size, Tcl_DString *))Tcl_UniCharToUtfDString \
 		: (char *(*)(const wchar_t *, Tcl_Size, Tcl_DString *))Tcl_Char16ToUtfDString)
 #   define Tcl_UtfToWCharDString (sizeof(wchar_t) != sizeof(short) \
@@ -4207,11 +4222,12 @@
 		? (Tcl_Size (*)(const char *, wchar_t *))Tcl_UtfToUniChar \
 		: (Tcl_Size (*)(const char *, wchar_t *))Tcl_UtfToChar16)
 #   define Tcl_WCharLen (sizeof(wchar_t) != sizeof(short) \
 		? (Tcl_Size (*)(wchar_t *))Tcl_UniCharLen \
 		: (Tcl_Size (*)(wchar_t *))Tcl_Char16Len)
-#if !defined(BUILD_tcl) && !defined(TCL_NO_DEPRECATED)
+#if !defined(BUILD_tcl)
+#if defined(TCL_8_API) || TCL_MAJOR_VERSION == 8
 #   define Tcl_ListObjGetElements(interp, listPtr, objcPtr, objvPtr) (sizeof(*(objcPtr)) == sizeof(int) \
 		? TclListObjGetElements((interp), (listPtr), (int *)(void *)(objcPtr), (objvPtr)) \
 		: (Tcl_ListObjGetElements)((interp), (listPtr), (Tcl_Size *)(void *)(objcPtr), (objvPtr)))
 #   define Tcl_ListObjLength(interp, listPtr, lengthPtr) (sizeof(*(lengthPtr)) == sizeof(int) \
 		? TclListObjLength((interp), (listPtr), (int *)(void *)(lengthPtr)) \
@@ -4229,10 +4245,11 @@
 		? TclFSSplitPath((pathPtr), (int *)(void *)(lenPtr)) \
 		: (Tcl_FSSplitPath)((pathPtr), (Tcl_Size *)(void *)(lenPtr)))
 #   define Tcl_ParseArgsObjv(interp, argTable, objcPtr, objv, remObjv) (sizeof(*(objcPtr)) == sizeof(int) \
 		? TclParseArgsObjv((interp), (argTable), (int *)(void *)(objcPtr), (objv), (remObjv)) \
 		: (Tcl_ParseArgsObjv)((interp), (argTable), (Tcl_Size *)(void *)(objcPtr), (objv), (remObjv)))
+#endif /* TCL_8_API */
 #endif /* !defined(BUILD_tcl) */
 #endif
 
 /*
  * Deprecated Tcl procedures:

Index: unix/configure
==================================================================
--- unix/configure
+++ unix/configure
@@ -808,10 +808,11 @@
 enable_corefoundation
 enable_load
 enable_symbols
 enable_langinfo
 enable_dll_unloading
+enable_tcl8api
 with_tzdata
 enable_dtrace
 enable_framework
 enable_zipfs
 '
@@ -1458,10 +1459,11 @@
                           on)
   --enable-symbols        build with debugging symbols (default: off)
   --enable-langinfo       use nl_langinfo if possible to determine encoding at
                           startup, otherwise use old heuristic (default: on)
   --enable-dll-unloading  enable the 'unload' command (default: on)
+  --enable-tcl8api        enable the Tcl 8 compatibility API (default: off)
   --enable-dtrace         build with DTrace support (default: off)
   --enable-framework      package shared libraries in MacOSX frameworks
                           (default: off)
   --enable-zipfs          build with Zipfs support (default: on)
 
@@ -10650,10 +10652,28 @@
 
 if test $tcl_ok = yes; then
 
 printf "%s\n" "#define TCL_UNLOAD_DLLS 1" >>confdefs.h
 
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $tcl_ok" >&5
+printf "%s\n" "$tcl_ok" >&6; }
+
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether to use Tcl 8 compatibility API" >&5
+printf %s "checking whether to use Tcl 8 compatibility API... " >&6; }
+# Check whether --enable-tcl8api was given.
+if test ${enable_tcl8api+y}
+then :
+  enableval=$enable_tcl8api; tcl_ok=$enableval
+else $as_nop
+  tcl_ok=no
+fi
+
+if test $tcl_ok = yes; then
+
+printf "%s\n" "#define TCL_8_API 1" >>confdefs.h
+
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $tcl_ok" >&5
 printf "%s\n" "$tcl_ok" >&6; }
 
 #------------------------------------------------------------------------

Index: unix/configure.ac
==================================================================
--- unix/configure.ac
+++ unix/configure.ac
@@ -663,10 +663,20 @@
     [tcl_ok=$enableval], [tcl_ok=yes])
 if test $tcl_ok = yes; then
     AC_DEFINE(TCL_UNLOAD_DLLS, 1, [Do we allow unloading of shared libraries?])
 fi
 AC_MSG_RESULT([$tcl_ok])
+
+AC_MSG_CHECKING([whether to use Tcl 8 compatibility API])
+AC_ARG_ENABLE(tcl8api,
+    AS_HELP_STRING([--enable-tcl8api],
+	[enable the Tcl 8 compatibility API (default: off)]),
+    [tcl_ok=$enableval], [tcl_ok=no])
+if test $tcl_ok = yes; then
+    AC_DEFINE(TCL_8_API, 1, [Tcl 8 compatibility API enabled?])
+fi
+AC_MSG_RESULT([$tcl_ok])
 
 #------------------------------------------------------------------------
 #	Check whether the timezone data is supplied by the OS or has
 #	to be installed by Tcl. The default is autodetection, but can
 #	be overridden on the configure command line either way.

Index: win/rules.vc
==================================================================
--- win/rules.vc
+++ win/rules.vc
@@ -815,15 +815,18 @@
 # CONFIG_CHECK - 1 -> check current build configuration against Tcl
 #           configuration (ignored for Tcl itself)
 # _USE_64BIT_TIME_T - forces a build using 64-bit time_t for 32-bit build
 #           (CRT library should support this, not needed for Tcl 9.x)
 # TCL_UTF_MAX=3 - forces a build using UTF-16 internally (not recommended).
+# TCL_8_API - 0 -> Tcl 8 compatible API is disabled
+#             1 -> Tcl 8 API enabled (default)
 # Further, LINKERFLAGS are modified based on above.
 
 # Default values for all the above
 STATIC_BUILD	= 0
 TCL_THREADS	= 1
+TCL_8_API       = 0
 DEBUG		= 0
 SYMBOLS		= 0
 PROFILE		= 0
 PGO		= 0
 MSVCRT		= 1
@@ -875,13 +878,22 @@
 !message *** Compile explicitly for non-threaded tcl
 TCL_THREADS = 0
 USE_THREAD_ALLOC= 0
 !endif
 
+!if [nmakehlp -f $(OPTS) "tcl8api"]
+!message *** Disable Tcl 8 API compatibility macros
+TCL_8_API = 1
+!endif
+
+# NOTE: THIS MUST COME AFTER THE notcl8api CHECK ABOVE because the "-f" option
+# does *substring* checks, not exact checks so "tcl8" will match "notcl8api" as well.
+!if $(TCL_8_API)
 !if [nmakehlp -f $(OPTS) "tcl8"]
 !message *** Build for Tcl8
 TCL_BUILD_FOR = 8
+!endif
 !endif
 
 !if $(TCL_MAJOR_VERSION) == 8
 !if [nmakehlp -f $(OPTS) "time64bit"]
 !message *** Force 64-bit time_t
@@ -1367,11 +1379,11 @@
 # options that we will pass to the compiler and linker. The main
 # makefile should use these in combination with whatever other flags
 # and switches are specific to it.
 # The following macros are defined, names are for historical compatibility:
 # OPTDEFINES - /Dxxx C macro flags based on user-specified OPTS
-# COMPILERFLAGS - /Dxxx C macro flags independent of any configuration options
+# COMPILERFLAGS - /Dxxx C macro flags independent of any configuration opttions
 # crt - Compiler switch that selects the appropriate C runtime
 # cdebug - Compiler switches related to debug AND optimizations
 # cwarn - Compiler switches that set warning levels
 # cflags - complete compiler switches (subsumes cdebug and cwarn)
 # ldebug - Linker switches controlling debug information and optimization
@@ -1449,16 +1461,20 @@
 !endif
 
 # _ATL_XP_TARGETING - Newer SDK's need this to build for XP
 COMPILERFLAGS  = /D_ATL_XP_TARGETING
 !endif
+
 !if "$(TCL_UTF_MAX)" == "3"
 OPTDEFINES	= $(OPTDEFINES) /DTCL_UTF_MAX=3
 !endif
 !if "$(TCL_BUILD_FOR)" == "8"
 OPTDEFINES	= $(OPTDEFINES) /DTCL_MAJOR_VERSION=8
 !endif
+!if $(TCL_8_API)
+OPTDEFINES	= $(OPTDEFINES) /DTCL_8_API=1
+!endif
 
 # Like the TEA system only set this non empty for non-Tk extensions
 # Note: some extensions use PACKAGE_NAME and others use PACKAGE_TCLNAME
 # so we pass both
 !if !$(DOING_TCL) && !$(DOING_TK)