TIP #491 implementation: Threading Support: phasing out non-threaded builds

11 files changed, 340 insertions, 477 deletions

diff --git a/unix/configure b/unix/configure
index 36bc4b9..4e3e06f 100755
--- a/unix/configure
+++ b/unix/configure
@@ -699,7 +699,6 @@ ZLIB_INCLUDE
 ZLIB_SRCS
 ZLIB_OBJS
 TCLSH_PROG
-TCL_THREADS
 EGREP
 GREP
 CPP
@@ -755,7 +754,6 @@ enable_option_checking
 enable_man_symlinks
 enable_man_compression
 enable_man_suffix
-enable_threads
 with_encoding
 enable_shared
 enable_64bit
@@ -1395,7 +1393,6 @@ Optional Features:
                           use STRING as a suffix to manpage file names
                           (default: no, tcl if enabled without
                           specifying STRING)
-  --enable-threads        build with threads (default: on)
   --enable-shared         build and link with shared libraries (default: on)
   --enable-64bit          enable 64bit support (default: off)
   --enable-64bit-vis      enable 64bit Sparc VIS support (default: off)
@@ -3911,95 +3908,135 @@ $as_echo "$tcl_cv_cc_pipe" >&6; }
 fi
 
 #------------------------------------------------------------------------
-# Threads support
+# Embedded configuration information, encoding to use for the values, TIP #59
 #------------------------------------------------------------------------
 
 
-    # Check whether --enable-threads was given.
-if test "${enable_threads+set}" = set; then :
-  enableval=$enable_threads; tcl_ok=$enableval
-else
-  tcl_ok=yes
+
+# Check whether --with-encoding was given.
+if test "${with_encoding+set}" = set; then :
+  withval=$with_encoding; with_tcencoding=${withval}
 fi
 
 
-    if test "${TCL_THREADS}" = 1; then
-	tcl_threaded_core=1;
-    fi
+    if test x"${with_tcencoding}" != x ; then
 
-    if test "$tcl_ok" = "yes" -o "${TCL_THREADS}" = 1; then
-	TCL_THREADS=1
-	# USE_THREAD_ALLOC tells us to try the special thread-based
-	# allocator that significantly reduces lock contention
+cat >>confdefs.h <<_ACEOF
+#define TCL_CFGVAL_ENCODING "${with_tcencoding}"
+_ACEOF
 
-$as_echo "#define USE_THREAD_ALLOC 1" >>confdefs.h
+    else
 
+$as_echo "#define TCL_CFGVAL_ENCODING \"iso8859-1\"" >>confdefs.h
 
-$as_echo "#define _REENTRANT 1" >>confdefs.h
+    fi
 
-	if test "`uname -s`" = "SunOS" ; then
 
-$as_echo "#define _POSIX_PTHREAD_SEMANTICS 1" >>confdefs.h
+#--------------------------------------------------------------------
+# Look for libraries that we will need when compiling the Tcl shell
+#--------------------------------------------------------------------
 
-	fi
 
-$as_echo "#define _THREAD_SAFE 1" >>confdefs.h
+    #--------------------------------------------------------------------
+    # On a few very rare systems, all of the libm.a stuff is
+    # already in libc.a.  Set compiler flags accordingly.
+    #--------------------------------------------------------------------
 
-	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for pthread_mutex_init in -lpthread" >&5
-$as_echo_n "checking for pthread_mutex_init in -lpthread... " >&6; }
-if ${ac_cv_lib_pthread_pthread_mutex_init+:} false; then :
+    ac_fn_c_check_func "$LINENO" "sin" "ac_cv_func_sin"
+if test "x$ac_cv_func_sin" = xyes; then :
+  MATH_LIBS=""
+else
+  MATH_LIBS="-lm"
+fi
+
+
+    #--------------------------------------------------------------------
+    # Interactive UNIX requires -linet instead of -lsocket, plus it
+    # needs net/errno.h to define the socket-related error codes.
+    #--------------------------------------------------------------------
+
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for main in -linet" >&5
+$as_echo_n "checking for main in -linet... " >&6; }
+if ${ac_cv_lib_inet_main+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lpthread  $LIBS"
+LIBS="-linet  $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
-/* Override any GCC internal prototype to avoid an error.
-   Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.  */
-#ifdef __cplusplus
-extern "C"
-#endif
-char pthread_mutex_init ();
+
 int
 main ()
 {
-return pthread_mutex_init ();
+return main ();
   ;
   return 0;
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_pthread_pthread_mutex_init=yes
+  ac_cv_lib_inet_main=yes
 else
-  ac_cv_lib_pthread_pthread_mutex_init=no
+  ac_cv_lib_inet_main=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_pthread_pthread_mutex_init" >&5
-$as_echo "$ac_cv_lib_pthread_pthread_mutex_init" >&6; }
-if test "x$ac_cv_lib_pthread_pthread_mutex_init" = xyes; then :
-  tcl_ok=yes
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_inet_main" >&5
+$as_echo "$ac_cv_lib_inet_main" >&6; }
+if test "x$ac_cv_lib_inet_main" = xyes; then :
+  LIBS="$LIBS -linet"
+fi
+
+    ac_fn_c_check_header_mongrel "$LINENO" "net/errno.h" "ac_cv_header_net_errno_h" "$ac_includes_default"
+if test "x$ac_cv_header_net_errno_h" = xyes; then :
+
+
+$as_echo "#define HAVE_NET_ERRNO_H 1" >>confdefs.h
+
+fi
+
+
+
+    #--------------------------------------------------------------------
+    #	Check for the existence of the -lsocket and -lnsl libraries.
+    #	The order here is important, so that they end up in the right
+    #	order in the command line generated by make.  Here are some
+    #	special considerations:
+    #	1. Use "connect" and "accept" to check for -lsocket, and
+    #	   "gethostbyname" to check for -lnsl.
+    #	2. Use each function name only once:  can't redo a check because
+    #	   autoconf caches the results of the last check and won't redo it.
+    #	3. Use -lnsl and -lsocket only if they supply procedures that
+    #	   aren't already present in the normal libraries.  This is because
+    #	   IRIX 5.2 has libraries, but they aren't needed and they're
+    #	   bogus:  they goof up name resolution if used.
+    #	4. On some SVR4 systems, can't use -lsocket without -lnsl too.
+    #	   To get around this problem, check for both libraries together
+    #	   if -lsocket doesn't work by itself.
+    #--------------------------------------------------------------------
+
+    tcl_checkBoth=0
+    ac_fn_c_check_func "$LINENO" "connect" "ac_cv_func_connect"
+if test "x$ac_cv_func_connect" = xyes; then :
+  tcl_checkSocket=0
 else
-  tcl_ok=no
+  tcl_checkSocket=1
 fi
 
-	if test "$tcl_ok" = "no"; then
-	    # Check a little harder for __pthread_mutex_init in the same
-	    # library, as some systems hide it there until pthread.h is
-	    # defined.  We could alternatively do an AC_TRY_COMPILE with
-	    # pthread.h, but that will work with libpthread really doesn't
-	    # exist, like AIX 4.2.  [Bug: 4359]
-	    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for __pthread_mutex_init in -lpthread" >&5
-$as_echo_n "checking for __pthread_mutex_init in -lpthread... " >&6; }
-if ${ac_cv_lib_pthread___pthread_mutex_init+:} false; then :
+    if test "$tcl_checkSocket" = 1; then
+	ac_fn_c_check_func "$LINENO" "setsockopt" "ac_cv_func_setsockopt"
+if test "x$ac_cv_func_setsockopt" = xyes; then :
+
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for setsockopt in -lsocket" >&5
+$as_echo_n "checking for setsockopt in -lsocket... " >&6; }
+if ${ac_cv_lib_socket_setsockopt+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lpthread  $LIBS"
+LIBS="-lsocket  $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -4009,45 +4046,57 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 #ifdef __cplusplus
 extern "C"
 #endif
-char __pthread_mutex_init ();
+char setsockopt ();
 int
 main ()
 {
-return __pthread_mutex_init ();
+return setsockopt ();
   ;
   return 0;
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_pthread___pthread_mutex_init=yes
+  ac_cv_lib_socket_setsockopt=yes
 else
-  ac_cv_lib_pthread___pthread_mutex_init=no
+  ac_cv_lib_socket_setsockopt=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_pthread___pthread_mutex_init" >&5
-$as_echo "$ac_cv_lib_pthread___pthread_mutex_init" >&6; }
-if test "x$ac_cv_lib_pthread___pthread_mutex_init" = xyes; then :
-  tcl_ok=yes
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_socket_setsockopt" >&5
+$as_echo "$ac_cv_lib_socket_setsockopt" >&6; }
+if test "x$ac_cv_lib_socket_setsockopt" = xyes; then :
+  LIBS="$LIBS -lsocket"
 else
-  tcl_ok=no
+  tcl_checkBoth=1
 fi
 
-	fi
+fi
 
-	if test "$tcl_ok" = "yes"; then
-	    # The space is needed
-	    THREADS_LIBS=" -lpthread"
-	else
-	    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for pthread_mutex_init in -lpthreads" >&5
-$as_echo_n "checking for pthread_mutex_init in -lpthreads... " >&6; }
-if ${ac_cv_lib_pthreads_pthread_mutex_init+:} false; then :
+    fi
+    if test "$tcl_checkBoth" = 1; then
+	tk_oldLibs=$LIBS
+	LIBS="$LIBS -lsocket -lnsl"
+	ac_fn_c_check_func "$LINENO" "accept" "ac_cv_func_accept"
+if test "x$ac_cv_func_accept" = xyes; then :
+  tcl_checkNsl=0
+else
+  LIBS=$tk_oldLibs
+fi
+
+    fi
+    ac_fn_c_check_func "$LINENO" "gethostbyname" "ac_cv_func_gethostbyname"
+if test "x$ac_cv_func_gethostbyname" = xyes; then :
+
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for gethostbyname in -lnsl" >&5
+$as_echo_n "checking for gethostbyname in -lnsl... " >&6; }
+if ${ac_cv_lib_nsl_gethostbyname+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lpthreads  $LIBS"
+LIBS="-lnsl  $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -4057,43 +4106,46 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 #ifdef __cplusplus
 extern "C"
 #endif
-char pthread_mutex_init ();
+char gethostbyname ();
 int
 main ()
 {
-return pthread_mutex_init ();
+return gethostbyname ();
   ;
   return 0;
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_pthreads_pthread_mutex_init=yes
+  ac_cv_lib_nsl_gethostbyname=yes
 else
-  ac_cv_lib_pthreads_pthread_mutex_init=no
+  ac_cv_lib_nsl_gethostbyname=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_pthreads_pthread_mutex_init" >&5
-$as_echo "$ac_cv_lib_pthreads_pthread_mutex_init" >&6; }
-if test "x$ac_cv_lib_pthreads_pthread_mutex_init" = xyes; then :
-  tcl_ok=yes
-else
-  tcl_ok=no
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_nsl_gethostbyname" >&5
+$as_echo "$ac_cv_lib_nsl_gethostbyname" >&6; }
+if test "x$ac_cv_lib_nsl_gethostbyname" = xyes; then :
+  LIBS="$LIBS -lnsl"
 fi
 
-	    if test "$tcl_ok" = "yes"; then
-		# The space is needed
-		THREADS_LIBS=" -lpthreads"
-	    else
-		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for pthread_mutex_init in -lc" >&5
-$as_echo_n "checking for pthread_mutex_init in -lc... " >&6; }
-if ${ac_cv_lib_c_pthread_mutex_init+:} false; then :
+fi
+
+
+
+$as_echo "#define _REENTRANT 1" >>confdefs.h
+
+
+$as_echo "#define _THREAD_SAFE 1" >>confdefs.h
+
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for pthread_mutex_init in -lpthread" >&5
+$as_echo_n "checking for pthread_mutex_init in -lpthread... " >&6; }
+if ${ac_cv_lib_pthread_pthread_mutex_init+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lc  $LIBS"
+LIBS="-lpthread  $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -4113,30 +4165,35 @@ return pthread_mutex_init ();
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_c_pthread_mutex_init=yes
+  ac_cv_lib_pthread_pthread_mutex_init=yes
 else
-  ac_cv_lib_c_pthread_mutex_init=no
+  ac_cv_lib_pthread_pthread_mutex_init=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_c_pthread_mutex_init" >&5
-$as_echo "$ac_cv_lib_c_pthread_mutex_init" >&6; }
-if test "x$ac_cv_lib_c_pthread_mutex_init" = xyes; then :
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_pthread_pthread_mutex_init" >&5
+$as_echo "$ac_cv_lib_pthread_pthread_mutex_init" >&6; }
+if test "x$ac_cv_lib_pthread_pthread_mutex_init" = xyes; then :
   tcl_ok=yes
 else
   tcl_ok=no
 fi
 
-		if test "$tcl_ok" = "no"; then
-		    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for pthread_mutex_init in -lc_r" >&5
-$as_echo_n "checking for pthread_mutex_init in -lc_r... " >&6; }
-if ${ac_cv_lib_c_r_pthread_mutex_init+:} false; then :
+    if test "$tcl_ok" = "no"; then
+	# Check a little harder for __pthread_mutex_init in the same
+	# library, as some systems hide it there until pthread.h is
+	# defined.  We could alternatively do an AC_TRY_COMPILE with
+	# pthread.h, but that will work with libpthread really doesn't
+	# exist, like AIX 4.2.  [Bug: 4359]
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __pthread_mutex_init in -lpthread" >&5
+$as_echo_n "checking for __pthread_mutex_init in -lpthread... " >&6; }
+if ${ac_cv_lib_pthread___pthread_mutex_init+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lc_r  $LIBS"
+LIBS="-lpthread  $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -4146,217 +4203,91 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 #ifdef __cplusplus
 extern "C"
 #endif
-char pthread_mutex_init ();
+char __pthread_mutex_init ();
 int
 main ()
 {
-return pthread_mutex_init ();
+return __pthread_mutex_init ();
   ;
   return 0;
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_c_r_pthread_mutex_init=yes
+  ac_cv_lib_pthread___pthread_mutex_init=yes
 else
-  ac_cv_lib_c_r_pthread_mutex_init=no
+  ac_cv_lib_pthread___pthread_mutex_init=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_c_r_pthread_mutex_init" >&5
-$as_echo "$ac_cv_lib_c_r_pthread_mutex_init" >&6; }
-if test "x$ac_cv_lib_c_r_pthread_mutex_init" = xyes; then :
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_pthread___pthread_mutex_init" >&5
+$as_echo "$ac_cv_lib_pthread___pthread_mutex_init" >&6; }
+if test "x$ac_cv_lib_pthread___pthread_mutex_init" = xyes; then :
   tcl_ok=yes
 else
   tcl_ok=no
 fi
 
-		    if test "$tcl_ok" = "yes"; then
-			# The space is needed
-			THREADS_LIBS=" -pthread"
-		    else
-			TCL_THREADS=0
-			{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: Don't know how to find pthread lib on your system - you must disable thread support or edit the LIBS in the Makefile..." >&5
-$as_echo "$as_me: WARNING: Don't know how to find pthread lib on your system - you must disable thread support or edit the LIBS in the Makefile..." >&2;}
-		    fi
-		fi
-	    fi
-	fi
-
-	# Does the pthread-implementation provide
-	# 'pthread_attr_setstacksize' ?
-
-	ac_saved_libs=$LIBS
-	LIBS="$LIBS $THREADS_LIBS"
-	for ac_func in pthread_attr_setstacksize pthread_atfork
-do :
-  as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
-ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
-if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
-  cat >>confdefs.h <<_ACEOF
-#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
-_ACEOF
-
-fi
-done
-
-	LIBS=$ac_saved_libs
-    else
-	TCL_THREADS=0
     fi
-    # Do checking message here to not mess up interleaved configure output
-    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for building with threads" >&5
-$as_echo_n "checking for building with threads... " >&6; }
-    if test "${TCL_THREADS}" = 1; then
-
-$as_echo "#define TCL_THREADS 1" >>confdefs.h
-
-	if test "${tcl_threaded_core}" = 1; then
-	    { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes (threaded core)" >&5
-$as_echo "yes (threaded core)" >&6; }
-	else
-	    { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-$as_echo "yes" >&6; }
-	fi
-    else
-	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-    fi
-
-
-
-
-#------------------------------------------------------------------------
-# Embedded configuration information, encoding to use for the values, TIP #59
-#------------------------------------------------------------------------
-
-
-
-# Check whether --with-encoding was given.
-if test "${with_encoding+set}" = set; then :
-  withval=$with_encoding; with_tcencoding=${withval}
-fi
-
-
-    if test x"${with_tcencoding}" != x ; then
-
-cat >>confdefs.h <<_ACEOF
-#define TCL_CFGVAL_ENCODING "${with_tcencoding}"
-_ACEOF
 
+    if test "$tcl_ok" = "yes"; then
+	# The space is needed
+	THREADS_LIBS=" -lpthread"
     else
-
-$as_echo "#define TCL_CFGVAL_ENCODING \"iso8859-1\"" >>confdefs.h
-
-    fi
-
-
-#--------------------------------------------------------------------
-# Look for libraries that we will need when compiling the Tcl shell
-#--------------------------------------------------------------------
-
-
-    #--------------------------------------------------------------------
-    # On a few very rare systems, all of the libm.a stuff is
-    # already in libc.a.  Set compiler flags accordingly.
-    #--------------------------------------------------------------------
-
-    ac_fn_c_check_func "$LINENO" "sin" "ac_cv_func_sin"
-if test "x$ac_cv_func_sin" = xyes; then :
-  MATH_LIBS=""
-else
-  MATH_LIBS="-lm"
-fi
-
-
-    #--------------------------------------------------------------------
-    # Interactive UNIX requires -linet instead of -lsocket, plus it
-    # needs net/errno.h to define the socket-related error codes.
-    #--------------------------------------------------------------------
-
-    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for main in -linet" >&5
-$as_echo_n "checking for main in -linet... " >&6; }
-if ${ac_cv_lib_inet_main+:} false; then :
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for pthread_mutex_init in -lpthreads" >&5
+$as_echo_n "checking for pthread_mutex_init in -lpthreads... " >&6; }
+if ${ac_cv_lib_pthreads_pthread_mutex_init+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-linet  $LIBS"
+LIBS="-lpthreads  $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
-
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char pthread_mutex_init ();
 int
 main ()
 {
-return main ();
+return pthread_mutex_init ();
   ;
   return 0;
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_inet_main=yes
+  ac_cv_lib_pthreads_pthread_mutex_init=yes
 else
-  ac_cv_lib_inet_main=no
+  ac_cv_lib_pthreads_pthread_mutex_init=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_inet_main" >&5
-$as_echo "$ac_cv_lib_inet_main" >&6; }
-if test "x$ac_cv_lib_inet_main" = xyes; then :
-  LIBS="$LIBS -linet"
-fi
-
-    ac_fn_c_check_header_mongrel "$LINENO" "net/errno.h" "ac_cv_header_net_errno_h" "$ac_includes_default"
-if test "x$ac_cv_header_net_errno_h" = xyes; then :
-
-
-$as_echo "#define HAVE_NET_ERRNO_H 1" >>confdefs.h
-
-fi
-
-
-
-    #--------------------------------------------------------------------
-    #	Check for the existence of the -lsocket and -lnsl libraries.
-    #	The order here is important, so that they end up in the right
-    #	order in the command line generated by make.  Here are some
-    #	special considerations:
-    #	1. Use "connect" and "accept" to check for -lsocket, and
-    #	   "gethostbyname" to check for -lnsl.
-    #	2. Use each function name only once:  can't redo a check because
-    #	   autoconf caches the results of the last check and won't redo it.
-    #	3. Use -lnsl and -lsocket only if they supply procedures that
-    #	   aren't already present in the normal libraries.  This is because
-    #	   IRIX 5.2 has libraries, but they aren't needed and they're
-    #	   bogus:  they goof up name resolution if used.
-    #	4. On some SVR4 systems, can't use -lsocket without -lnsl too.
-    #	   To get around this problem, check for both libraries together
-    #	   if -lsocket doesn't work by itself.
-    #--------------------------------------------------------------------
-
-    tcl_checkBoth=0
-    ac_fn_c_check_func "$LINENO" "connect" "ac_cv_func_connect"
-if test "x$ac_cv_func_connect" = xyes; then :
-  tcl_checkSocket=0
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_pthreads_pthread_mutex_init" >&5
+$as_echo "$ac_cv_lib_pthreads_pthread_mutex_init" >&6; }
+if test "x$ac_cv_lib_pthreads_pthread_mutex_init" = xyes; then :
+  _ok=yes
 else
-  tcl_checkSocket=1
+  tcl_ok=no
 fi
 
-    if test "$tcl_checkSocket" = 1; then
-	ac_fn_c_check_func "$LINENO" "setsockopt" "ac_cv_func_setsockopt"
-if test "x$ac_cv_func_setsockopt" = xyes; then :
-
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for setsockopt in -lsocket" >&5
-$as_echo_n "checking for setsockopt in -lsocket... " >&6; }
-if ${ac_cv_lib_socket_setsockopt+:} false; then :
+	if test "$tcl_ok" = "yes"; then
+	    # The space is needed
+	    THREADS_LIBS=" -lpthreads"
+	else
+	    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for pthread_mutex_init in -lc" >&5
+$as_echo_n "checking for pthread_mutex_init in -lc... " >&6; }
+if ${ac_cv_lib_c_pthread_mutex_init+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lsocket  $LIBS"
+LIBS="-lc  $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -4366,57 +4297,40 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 #ifdef __cplusplus
 extern "C"
 #endif
-char setsockopt ();
+char pthread_mutex_init ();
 int
 main ()
 {
-return setsockopt ();
+return pthread_mutex_init ();
   ;
   return 0;
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_socket_setsockopt=yes
+  ac_cv_lib_c_pthread_mutex_init=yes
 else
-  ac_cv_lib_socket_setsockopt=no
+  ac_cv_lib_c_pthread_mutex_init=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_socket_setsockopt" >&5
-$as_echo "$ac_cv_lib_socket_setsockopt" >&6; }
-if test "x$ac_cv_lib_socket_setsockopt" = xyes; then :
-  LIBS="$LIBS -lsocket"
-else
-  tcl_checkBoth=1
-fi
-
-fi
-
-    fi
-    if test "$tcl_checkBoth" = 1; then
-	tk_oldLibs=$LIBS
-	LIBS="$LIBS -lsocket -lnsl"
-	ac_fn_c_check_func "$LINENO" "accept" "ac_cv_func_accept"
-if test "x$ac_cv_func_accept" = xyes; then :
-  tcl_checkNsl=0
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_c_pthread_mutex_init" >&5
+$as_echo "$ac_cv_lib_c_pthread_mutex_init" >&6; }
+if test "x$ac_cv_lib_c_pthread_mutex_init" = xyes; then :
+  tcl_ok=yes
 else
-  LIBS=$tk_oldLibs
+  tcl_ok=no
 fi
 
-    fi
-    ac_fn_c_check_func "$LINENO" "gethostbyname" "ac_cv_func_gethostbyname"
-if test "x$ac_cv_func_gethostbyname" = xyes; then :
-
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for gethostbyname in -lnsl" >&5
-$as_echo_n "checking for gethostbyname in -lnsl... " >&6; }
-if ${ac_cv_lib_nsl_gethostbyname+:} false; then :
+	    if test "$tcl_ok" = "no"; then
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for pthread_mutex_init in -lc_r" >&5
+$as_echo_n "checking for pthread_mutex_init in -lc_r... " >&6; }
+if ${ac_cv_lib_c_r_pthread_mutex_init+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lnsl  $LIBS"
+LIBS="-lc_r  $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -4426,32 +4340,61 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 #ifdef __cplusplus
 extern "C"
 #endif
-char gethostbyname ();
+char pthread_mutex_init ();
 int
 main ()
 {
-return gethostbyname ();
+return pthread_mutex_init ();
   ;
   return 0;
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_nsl_gethostbyname=yes
+  ac_cv_lib_c_r_pthread_mutex_init=yes
 else
-  ac_cv_lib_nsl_gethostbyname=no
+  ac_cv_lib_c_r_pthread_mutex_init=no
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_nsl_gethostbyname" >&5
-$as_echo "$ac_cv_lib_nsl_gethostbyname" >&6; }
-if test "x$ac_cv_lib_nsl_gethostbyname" = xyes; then :
-  LIBS="$LIBS -lnsl"
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_c_r_pthread_mutex_init" >&5
+$as_echo "$ac_cv_lib_c_r_pthread_mutex_init" >&6; }
+if test "x$ac_cv_lib_c_r_pthread_mutex_init" = xyes; then :
+  tcl_ok=yes
+else
+  tcl_ok=no
 fi
 
+		if test "$tcl_ok" = "yes"; then
+		    # The space is needed
+		    THREADS_LIBS=" -pthread"
+		else
+		    { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: Don't know how to find pthread lib on your system - you must edit the LIBS in the Makefile..." >&5
+$as_echo "$as_me: WARNING: Don't know how to find pthread lib on your system - you must edit the LIBS in the Makefile..." >&2;}
+		fi
+	    fi
+	fi
+    fi
+
+    # Does the pthread-implementation provide
+    # 'pthread_attr_setstacksize' ?
+
+    ac_saved_libs=$LIBS
+    LIBS="$LIBS $THREADS_LIBS"
+    for ac_func in pthread_attr_setstacksize pthread_atfork
+do :
+  as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
+ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
+if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
+_ACEOF
+
 fi
+done
 
+    LIBS=$ac_saved_libs
 
 
 # Add the threads support libraries
diff --git a/unix/configure.ac b/unix/configure.ac
index e14d85e..5b982e8 100644
--- a/unix/configure.ac
+++ b/unix/configure.ac
@@ -120,12 +120,6 @@ if test -z "$no_pipe" && test -n "$GCC"; then
 fi
 
 #------------------------------------------------------------------------
-# Threads support
-#------------------------------------------------------------------------
-
-SC_ENABLE_THREADS
-
-#------------------------------------------------------------------------
 # Embedded configuration information, encoding to use for the values, TIP #59
 #------------------------------------------------------------------------
 
diff --git a/unix/tcl.m4 b/unix/tcl.m4
index 4acbed0..70f3c3d 100644
--- a/unix/tcl.m4
+++ b/unix/tcl.m4
@@ -593,113 +593,6 @@ AC_DEFUN([SC_ENABLE_FRAMEWORK], [
 ])
 
 #------------------------------------------------------------------------
-# SC_ENABLE_THREADS --
-#
-#	Specify if thread support should be enabled
-#
-# Arguments:
-#	none
-#
-# Results:
-#
-#	Adds the following arguments to configure:
-#		--enable-threads
-#
-#	Sets the following vars:
-#		THREADS_LIBS	Thread library(s)
-#
-#	Defines the following vars:
-#		TCL_THREADS
-#		_REENTRANT
-#		_THREAD_SAFE
-#------------------------------------------------------------------------
-
-AC_DEFUN([SC_ENABLE_THREADS], [
-    AC_ARG_ENABLE(threads,
-	AC_HELP_STRING([--enable-threads],
-	    [build with threads (default: on)]),
-	[tcl_ok=$enableval], [tcl_ok=yes])
-
-    if test "${TCL_THREADS}" = 1; then
-	tcl_threaded_core=1;
-    fi
-
-    if test "$tcl_ok" = "yes" -o "${TCL_THREADS}" = 1; then
-	TCL_THREADS=1
-	# USE_THREAD_ALLOC tells us to try the special thread-based
-	# allocator that significantly reduces lock contention
-	AC_DEFINE(USE_THREAD_ALLOC, 1,
-	    [Do we want to use the threaded memory allocator?])
-	AC_DEFINE(_REENTRANT, 1, [Do we want the reentrant OS API?])
-	if test "`uname -s`" = "SunOS" ; then
-	    AC_DEFINE(_POSIX_PTHREAD_SEMANTICS, 1,
-		    [Do we really want to follow the standard? Yes we do!])
-	fi
-	AC_DEFINE(_THREAD_SAFE, 1, [Do we want the thread-safe OS API?])
-	AC_CHECK_LIB(pthread,pthread_mutex_init,tcl_ok=yes,tcl_ok=no)
-	if test "$tcl_ok" = "no"; then
-	    # Check a little harder for __pthread_mutex_init in the same
-	    # library, as some systems hide it there until pthread.h is
-	    # defined.  We could alternatively do an AC_TRY_COMPILE with
-	    # pthread.h, but that will work with libpthread really doesn't
-	    # exist, like AIX 4.2.  [Bug: 4359]
-	    AC_CHECK_LIB(pthread, __pthread_mutex_init,
-		tcl_ok=yes, tcl_ok=no)
-	fi
-
-	if test "$tcl_ok" = "yes"; then
-	    # The space is needed
-	    THREADS_LIBS=" -lpthread"
-	else
-	    AC_CHECK_LIB(pthreads, pthread_mutex_init,
-		tcl_ok=yes, tcl_ok=no)
-	    if test "$tcl_ok" = "yes"; then
-		# The space is needed
-		THREADS_LIBS=" -lpthreads"
-	    else
-		AC_CHECK_LIB(c, pthread_mutex_init,
-		    tcl_ok=yes, tcl_ok=no)
-		if test "$tcl_ok" = "no"; then
-		    AC_CHECK_LIB(c_r, pthread_mutex_init,
-			tcl_ok=yes, tcl_ok=no)
-		    if test "$tcl_ok" = "yes"; then
-			# The space is needed
-			THREADS_LIBS=" -pthread"
-		    else
-			TCL_THREADS=0
-			AC_MSG_WARN([Don't know how to find pthread lib on your system - you must disable thread support or edit the LIBS in the Makefile...])
-		    fi
-		fi
-	    fi
-	fi
-
-	# Does the pthread-implementation provide
-	# 'pthread_attr_setstacksize' ?
-
-	ac_saved_libs=$LIBS
-	LIBS="$LIBS $THREADS_LIBS"
-	AC_CHECK_FUNCS(pthread_attr_setstacksize pthread_atfork)
-	LIBS=$ac_saved_libs
-    else
-	TCL_THREADS=0
-    fi
-    # Do checking message here to not mess up interleaved configure output
-    AC_MSG_CHECKING([for building with threads])
-    if test "${TCL_THREADS}" = 1; then
-	AC_DEFINE(TCL_THREADS, 1, [Are we building with threads enabled?])
-	if test "${tcl_threaded_core}" = 1; then
-	    AC_MSG_RESULT([yes (threaded core)])
-	else
-	    AC_MSG_RESULT([yes])
-	fi
-    else
-	AC_MSG_RESULT([no])
-    fi
-
-    AC_SUBST(TCL_THREADS)
-])
-
-#------------------------------------------------------------------------
 # SC_ENABLE_SYMBOLS --
 #
 #	Specify if debugging symbols should be used.
@@ -2350,13 +2243,21 @@ AC_DEFUN([SC_BUGGY_STRTOD], [
 #
 #	Search for the libraries needed to link the Tcl shell.
 #	Things like the math library (-lm) and socket stuff (-lsocket vs.
-#	-lnsl) are dealt with here.
+#	-lnsl) or thread library (-lpthread) are dealt with here.
 #
 # Arguments:
 #	None.
 #
 # Results:
 #
+#	Sets the following vars:
+#		THREADS_LIBS	Thread library(s)
+#
+#	Defines the following vars:
+#		TCL_THREADS
+#		_REENTRANT
+#		_THREAD_SAFE
+#
 #	Might append to the following vars:
 #		LIBS
 #		MATH_LIBS
@@ -2414,6 +2315,52 @@ AC_DEFUN([SC_TCL_LINK_LIBS], [
     fi
     AC_CHECK_FUNC(gethostbyname, , [AC_CHECK_LIB(nsl, gethostbyname,
 	    [LIBS="$LIBS -lnsl"])])
+
+    AC_DEFINE(_REENTRANT, 1, [Do we want the reentrant OS API?])
+    AC_DEFINE(_THREAD_SAFE, 1, [Do we want the thread-safe OS API?])
+    AC_CHECK_LIB(pthread,pthread_mutex_init,tcl_ok=yes,tcl_ok=no)
+    if test "$tcl_ok" = "no"; then
+	# Check a little harder for __pthread_mutex_init in the same
+	# library, as some systems hide it there until pthread.h is
+	# defined.  We could alternatively do an AC_TRY_COMPILE with
+	# pthread.h, but that will work with libpthread really doesn't
+	# exist, like AIX 4.2.  [Bug: 4359]
+	AC_CHECK_LIB(pthread, __pthread_mutex_init,
+		tcl_ok=yes, tcl_ok=no)
+    fi
+
+    if test "$tcl_ok" = "yes"; then
+	# The space is needed
+	THREADS_LIBS=" -lpthread"
+    else
+	AC_CHECK_LIB(pthreads, pthread_mutex_init,
+	_ok=yes, tcl_ok=no)
+	if test "$tcl_ok" = "yes"; then
+	    # The space is needed
+	    THREADS_LIBS=" -lpthreads"
+	else
+	    AC_CHECK_LIB(c, pthread_mutex_init,
+		    tcl_ok=yes, tcl_ok=no)
+	    if test "$tcl_ok" = "no"; then
+		AC_CHECK_LIB(c_r, pthread_mutex_init,
+			tcl_ok=yes, tcl_ok=no)
+		if test "$tcl_ok" = "yes"; then
+		    # The space is needed
+		    THREADS_LIBS=" -pthread"
+		else
+		    AC_MSG_WARN([Don't know how to find pthread lib on your system - you must edit the LIBS in the Makefile...])
+		fi
+	    fi
+	fi
+    fi
+
+    # Does the pthread-implementation provide
+    # 'pthread_attr_setstacksize' ?
+
+    ac_saved_libs=$LIBS
+    LIBS="$LIBS $THREADS_LIBS"
+    AC_CHECK_FUNCS(pthread_attr_setstacksize pthread_atfork)
+    LIBS=$ac_saved_libs
 ])
 
 #--------------------------------------------------------------------
diff --git a/unix/tclSelectNotfy.c b/unix/tclSelectNotfy.c
index cf21b85..4bdfaef 100644
--- a/unix/tclSelectNotfy.c
+++ b/unix/tclSelectNotfy.c
@@ -81,7 +81,7 @@ typedef struct ThreadSpecificData {
     int numFdBits;		/* Number of valid bits in checkMasks (one
 				 * more than highest fd for which
 				 * Tcl_WatchFile has been called). */
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
     int onList;			/* True if it is in this list */
     unsigned int pollState;	/* pollState is used to implement a polling
 				 * handshake between each thread and the
@@ -112,7 +112,7 @@ typedef struct ThreadSpecificData {
 
 static Tcl_ThreadDataKey dataKey;
 
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 /*
  * The following static indicates the number of threads that have initialized
  * notifiers.
@@ -193,7 +193,7 @@ static Tcl_ThreadId notifierThread;
  * Static routines defined in this file.
  */
 
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 static TCL_NORETURN void NotifierThreadProc(ClientData clientData);
 #if defined(HAVE_PTHREAD_ATFORK)
 static int	atForkInit = 0;
@@ -206,7 +206,7 @@ static int	FileHandlerEventProc(Tcl_Event *evPtr, int flags);
  * Import of Windows API when building threaded with Cygwin.
  */
 
-#if defined(TCL_THREADS) && defined(__CYGWIN__)
+#if defined(__CYGWIN__)
 typedef struct {
     void *hwnd;
     unsigned int *message;
@@ -285,7 +285,7 @@ Tcl_InitNotifier(void)
     } else {
 	ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
 
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 	tsdPtr->eventReady = 0;
 
 	/*
@@ -370,7 +370,7 @@ Tcl_FinalizeNotifier(
 	tclNotifierHooks.finalizeNotifierProc(clientData);
 	return;
     } else {
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 	ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
 
 	pthread_mutex_lock(&notifierInitMutex);
@@ -587,7 +587,7 @@ Tcl_DeleteFileHandler(
     }
 }
 
-#if defined(TCL_THREADS) && defined(__CYGWIN__)
+#if defined(__CYGWIN__)
 
 static DWORD __stdcall
 NotifierProc(
@@ -640,7 +640,7 @@ Tcl_WaitForEvent(
 	FileHandler *filePtr;
 	int mask;
 	Tcl_Time vTime;
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 	int waitForFiles;
 #   ifdef __CYGWIN__
 	MSG msg;
@@ -675,7 +675,7 @@ Tcl_WaitForEvent(
 		tclScaleTimeProcPtr(&vTime, tclTimeClientData);
 		timePtr = &vTime;
 	    }
-#ifndef TCL_THREADS
+#if defined(TCL_THREADS) && !TCL_THREADS
 	    timeout.tv_sec = timePtr->sec;
 	    timeout.tv_usec = timePtr->usec;
 	    timeoutPtr = &timeout;
@@ -694,7 +694,7 @@ Tcl_WaitForEvent(
 #endif /* !TCL_THREADS */
 	}
 
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 	/*
 	 * Start notifier thread and place this thread on the list of
 	 * interested threads, signal the notifier thread, and wait for a
@@ -885,14 +885,14 @@ Tcl_WaitForEvent(
 	    }
 	    filePtr->readyMask = mask;
 	}
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 	pthread_mutex_unlock(&notifierMutex);
 #endif /* TCL_THREADS */
 	return 0;
     }
 }
 
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 
 /*
  *----------------------------------------------------------------------
diff --git a/unix/tclUnixCompat.c b/unix/tclUnixCompat.c
index ea6067e..2d2e53b 100644
--- a/unix/tclUnixCompat.c
+++ b/unix/tclUnixCompat.c
@@ -47,7 +47,7 @@
  * library calls.
  */
 
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 
 typedef struct {
     struct passwd pwd;
@@ -182,7 +182,7 @@ struct passwd *
 TclpGetPwNam(
     const char *name)
 {
-#if !defined(TCL_THREADS)
+#if defined(TCL_THREADS) && !TCL_THREADS
     return getpwnam(name);
 #else
     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
@@ -262,7 +262,7 @@ struct passwd *
 TclpGetPwUid(
     uid_t uid)
 {
-#if !defined(TCL_THREADS)
+#if defined(TCL_THREADS) && !TCL_THREADS
     return getpwuid(uid);
 #else
     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
@@ -365,7 +365,7 @@ struct group *
 TclpGetGrNam(
     const char *name)
 {
-#if !defined(TCL_THREADS)
+#if defined(TCL_THREADS) && !TCL_THREADS
     return getgrnam(name);
 #else
     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
@@ -445,7 +445,7 @@ struct group *
 TclpGetGrGid(
     gid_t gid)
 {
-#if !defined(TCL_THREADS)
+#if defined(TCL_THREADS) && !TCL_THREADS
     return getgrgid(gid);
 #else
     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
@@ -548,7 +548,7 @@ struct hostent *
 TclpGetHostByName(
     const char *name)
 {
-#if !defined(TCL_THREADS) || defined(HAVE_MTSAFE_GETHOSTBYNAME)
+#if (defined(TCL_THREADS) && !TCL_THREADS) || defined(HAVE_MTSAFE_GETHOSTBYNAME)
     return gethostbyname(name);
 #else
     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
@@ -618,7 +618,7 @@ TclpGetHostByAddr(
     int length,
     int type)
 {
-#if !defined(TCL_THREADS) || defined(HAVE_MTSAFE_GETHOSTBYADDR)
+#if (defined(TCL_THREADS) && !TCL_THREADS) || defined(HAVE_MTSAFE_GETHOSTBYADDR)
     return gethostbyaddr(addr, length, type);
 #else
     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
diff --git a/unix/tclUnixFCmd.c b/unix/tclUnixFCmd.c
index 88b9d1c..2b2a613 100644
--- a/unix/tclUnixFCmd.c
+++ b/unix/tclUnixFCmd.c
@@ -256,7 +256,7 @@ Realpath(
 #endif /* PURIFY */
 
 #ifndef NO_REALPATH
-#if defined(__APPLE__) && defined(TCL_THREADS) && \
+#if defined(__APPLE__) && (!defined(TCL_THREADS) || TCL_THREADS) && \
 	defined(MAC_OS_X_VERSION_MIN_REQUIRED) && \
 	MAC_OS_X_VERSION_MIN_REQUIRED < 1030
 /*
diff --git a/unix/tclUnixInit.c b/unix/tclUnixInit.c
index 630460a..78d591a 100644
--- a/unix/tclUnixInit.c
+++ b/unix/tclUnixInit.c
@@ -316,7 +316,7 @@ static int		MacOSXGetLibraryPath(Tcl_Interp *interp,
 #endif /* HAVE_COREFOUNDATION */
 #if defined(__APPLE__) && (defined(TCL_LOAD_FROM_MEMORY) || ( \
 	defined(MAC_OS_X_VERSION_MIN_REQUIRED) && ( \
-	(defined(TCL_THREADS) && MAC_OS_X_VERSION_MIN_REQUIRED < 1030) || \
+	((!defined(TCL_THREADS) || TCL_THREADS) && MAC_OS_X_VERSION_MIN_REQUIRED < 1030) || \
 	(defined(__LP64__) && MAC_OS_X_VERSION_MIN_REQUIRED < 1050) || \
 	(defined(HAVE_COREFOUNDATION) && MAC_OS_X_VERSION_MIN_REQUIRED < 1050)\
 	)))
diff --git a/unix/tclUnixNotfy.c b/unix/tclUnixNotfy.c
index b7df740..ccae39b 100644
--- a/unix/tclUnixNotfy.c
+++ b/unix/tclUnixNotfy.c
@@ -18,7 +18,7 @@
  */
 
 #ifdef NOTIFIER_SELECT
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 static TCL_NORETURN void NotifierThreadProc(ClientData clientData);
 #if defined(HAVE_PTHREAD_ATFORK)
 static void	AtForkChild(void);
@@ -28,7 +28,7 @@ static void	AtForkChild(void);
 static int	FileHandlerEventProc(Tcl_Event *evPtr, int flags);
 
 #ifdef NOTIFIER_SELECT
-#if TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 /*
  *----------------------------------------------------------------------
  *
@@ -107,7 +107,7 @@ Tcl_AlertNotifier(
 	return;
     } else {
 #ifdef NOTIFIER_SELECT
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 	ThreadSpecificData *tsdPtr = clientData;
 
 	pthread_mutex_lock(&notifierMutex);
@@ -198,7 +198,7 @@ Tcl_ServiceModeHook(
 	return;
     } else if (mode == TCL_SERVICE_ALL) {
 #ifdef NOTIFIER_SELECT
-#if TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 	StartNotifierThread("Tcl_ServiceModeHook");
 #endif
 #endif /* NOTIFIER_SELECT */
@@ -280,7 +280,7 @@ FileHandlerEventProc(
 }
 
 #ifdef NOTIFIER_SELECT
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 /*
  *----------------------------------------------------------------------
  *
diff --git a/unix/tclUnixPort.h b/unix/tclUnixPort.h
index fec27d0..e4277a3 100644
--- a/unix/tclUnixPort.h
+++ b/unix/tclUnixPort.h
@@ -610,10 +610,8 @@ extern char **		environ;
 #	    undef HAVE_COPYFILE
 #	endif
 #	if MAC_OS_X_VERSION_MAX_ALLOWED < 1030
-#	    ifdef TCL_THREADS
-		/* prior to 10.3, realpath is not threadsafe, c.f. bug 711232 */
-#		define NO_REALPATH 1
-#	    endif
+	    /* prior to 10.3, realpath is not threadsafe, c.f. bug 711232 */
+#	    define NO_REALPATH 1
 #	    undef HAVE_LANGINFO
 #	endif
 #   endif /* MAC_OS_X_VERSION_MAX_ALLOWED */
@@ -686,7 +684,7 @@ typedef int socklen_t;
 
 #define TclpExit	exit
 
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 #   include <pthread.h>
 #endif /* TCL_THREADS */
 
diff --git a/unix/tclUnixThrd.c b/unix/tclUnixThrd.c
index 120d5d5..76228a3 100644
--- a/unix/tclUnixThrd.c
+++ b/unix/tclUnixThrd.c
@@ -13,7 +13,7 @@
 
 #include "tclInt.h"
 
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 
 #ifndef TCL_NO_DEPRECATED
 typedef struct {
@@ -74,7 +74,7 @@ TclpThreadCreate(
     int flags)			/* Flags controlling behaviour of the new
 				 * thread. */
 {
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
     pthread_attr_t attr;
     pthread_t theThread;
     int result;
@@ -152,7 +152,7 @@ Tcl_JoinThread(
 				 * thread we wait upon will be written into.
 				 * May be NULL. */
 {
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
     int result;
     unsigned long retcode, *retcodePtr = &retcode;
 
@@ -166,7 +166,7 @@ Tcl_JoinThread(
 #endif
 }
 
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 /*
  *----------------------------------------------------------------------
  *
@@ -210,7 +210,7 @@ TclpThreadExit(
 Tcl_ThreadId
 Tcl_GetCurrentThread(void)
 {
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
     return (Tcl_ThreadId) pthread_self();
 #else
     return (Tcl_ThreadId) 0;
@@ -239,7 +239,7 @@ Tcl_GetCurrentThread(void)
 void
 TclpInitLock(void)
 {
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
     pthread_mutex_lock(&initLock);
 #endif
 }
@@ -265,7 +265,7 @@ TclpInitLock(void)
 void
 TclFinalizeLock(void)
 {
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
     /*
      * You do not need to destroy mutexes that were created with the
      * PTHREAD_MUTEX_INITIALIZER macro. These mutexes do not need any
@@ -296,7 +296,7 @@ TclFinalizeLock(void)
 void
 TclpInitUnlock(void)
 {
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
     pthread_mutex_unlock(&initLock);
 #endif
 }
@@ -325,7 +325,7 @@ TclpInitUnlock(void)
 void
 TclpMasterLock(void)
 {
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
     pthread_mutex_lock(&masterLock);
 #endif
 }
@@ -351,7 +351,7 @@ TclpMasterLock(void)
 void
 TclpMasterUnlock(void)
 {
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
     pthread_mutex_unlock(&masterLock);
 #endif
 }
@@ -378,7 +378,7 @@ TclpMasterUnlock(void)
 Tcl_Mutex *
 Tcl_GetAllocMutex(void)
 {
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
     pthread_mutex_t **allocLockPtrPtr = &allocLockPtr;
     return (Tcl_Mutex *) allocLockPtrPtr;
 #else
@@ -386,7 +386,7 @@ Tcl_GetAllocMutex(void)
 #endif
 }
 
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 
 /*
  *----------------------------------------------------------------------
@@ -659,7 +659,7 @@ char *
 TclpInetNtoa(
     struct in_addr addr)
 {
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
     ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
     unsigned char *b = (unsigned char*) &addr.s_addr;
 
@@ -671,7 +671,7 @@ TclpInetNtoa(
 }
 #endif /* TCL_NO_DEPRECATED */
 
-#ifdef TCL_THREADS
+#if !defined(TCL_THREADS) || TCL_THREADS
 /*
  * Additions by AOL for specialized thread memory allocator.
  */
diff --git a/unix/tclUnixThrd.h b/unix/tclUnixThrd.h
deleted file mode 100644
index f03b530..0000000
--- a/unix/tclUnixThrd.h
+++ /dev/null
@@ -1,19 +0,0 @@
-/*
- * tclUnixThrd.h --
- *
- *      This header file defines things for thread support.
- *
- * Copyright (c) 1998 Sun Microsystems, Inc.
- *
- * See the file "license.terms" for information on usage and redistribution
- * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
- */
-
-#ifndef _TCLUNIXTHRD
-#define _TCLUNIXTHRD
-
-#ifdef TCL_THREADS
-
-
-#endif /* TCL_THREADS */
-#endif /* _TCLUNIXTHRD */