Revert [3eaa6c984a] (Enh [http://core.tcl.tk/tcl/info/2959069|2959069]), as it turns out that -fvisibility=hidden only affects definitions and not declarations.

Therefore explicitely declaring each MODULE_SCOPE function as  __attribute__((__visibility__("hidden")) is much better. 
Suggested by Stuart Cassoff (Thanks!).

3 files changed, 24 insertions, 119 deletions

diff --git a/unix/configure b/unix/configure
index a3888e3..d098588 100755
--- a/unix/configure
+++ b/unix/configure
@@ -1449,9 +1449,9 @@ echo "$as_me: error: ${with_tclconfig} directory doesn't contain tclConfig.sh" >
 			`ls -dr ${srcdir}/../tcl[8-9].[0-9] 2>/dev/null` \
 			`ls -dr ${srcdir}/../tcl[8-9].[0-9]* 2>/dev/null` ; do
 		    if test -f "$i/unix/tclConfig.sh" ; then
-		    ac_cv_c_tclconfig="`(cd $i/unix; pwd)`"
-		    break
-		fi
+			ac_cv_c_tclconfig="`(cd $i/unix; pwd)`"
+			break
+		    fi
 		done
 	    fi
 
@@ -4335,80 +4335,6 @@ if test "${tcl_cv_cc_visibility_hidden+set}" = set; then
   echo $ECHO_N "(cached) $ECHO_C" >&6
 else
 
-	    if test "$SHARED_BUILD" = 1; then
-
-		hold_cflags=$CFLAGS; CFLAGS="$CFLAGS -fvisibility=hidden -Werror"
-		cat >conftest.$ac_ext <<_ACEOF
-/* confdefs.h.  */
-_ACEOF
-cat confdefs.h >>conftest.$ac_ext
-cat >>conftest.$ac_ext <<_ACEOF
-/* end confdefs.h.  */
-
-int
-main ()
-{
-#if !defined(__GNUC__) || __GNUC__ < 4
-#error visibility hidden is not supported for this compiler
-#endif
-
-  ;
-  return 0;
-}
-_ACEOF
-rm -f conftest.$ac_objext
-if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
-  (eval $ac_compile) 2>conftest.er1
-  ac_status=$?
-  grep -v '^ *+' conftest.er1 >conftest.err
-  rm -f conftest.er1
-  cat conftest.err >&5
-  echo "$as_me:$LINENO: \$? = $ac_status" >&5
-  (exit $ac_status); } &&
-	 { ac_try='test -z "$ac_c_werror_flag"
-			 || test ! -s conftest.err'
-  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
-  (eval $ac_try) 2>&5
-  ac_status=$?
-  echo "$as_me:$LINENO: \$? = $ac_status" >&5
-  (exit $ac_status); }; } &&
-	 { ac_try='test -s conftest.$ac_objext'
-  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
-  (eval $ac_try) 2>&5
-  ac_status=$?
-  echo "$as_me:$LINENO: \$? = $ac_status" >&5
-  (exit $ac_status); }; }; then
-  tcl_cv_cc_visibility_hidden=yes
-else
-  echo "$as_me: failed program was:" >&5
-sed 's/^/| /' conftest.$ac_ext >&5
-
-tcl_cv_cc_visibility_hidden=no
-fi
-rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
-		CFLAGS=$hold_cflags
-
-else
-
-		tcl_cv_cc_visibility_hidden=no
-
-fi
-
-
-fi
-echo "$as_me:$LINENO: result: $tcl_cv_cc_visibility_hidden" >&5
-echo "${ECHO_T}$tcl_cv_cc_visibility_hidden" >&6
-    if test $tcl_cv_cc_visibility_hidden = yes; then
-
-	CFLAGS="$CFLAGS -fvisibility=hidden"
-
-cat >>confdefs.h <<\_ACEOF
-#define MODULE_SCOPE extern
-_ACEOF
-
-
-else
-
 	hold_cflags=$CFLAGS; CFLAGS="$CFLAGS -Werror"
 	cat >conftest.$ac_ext <<_ACEOF
 /* confdefs.h.  */
@@ -4459,7 +4385,10 @@ fi
 rm -f conftest.err conftest.$ac_objext \
       conftest$ac_exeext conftest.$ac_ext
 	CFLAGS=$hold_cflags
-	if test $tcl_cv_cc_visibility_hidden = yes; then
+fi
+echo "$as_me:$LINENO: result: $tcl_cv_cc_visibility_hidden" >&5
+echo "${ECHO_T}$tcl_cv_cc_visibility_hidden" >&6
+    if test $tcl_cv_cc_visibility_hidden = yes; then
 
 
 cat >>confdefs.h <<\_ACEOF
@@ -4475,9 +4404,6 @@ _ACEOF
 fi
 
 
-fi
-
-
     # Step 0.d: Disable -rpath support?
 
     echo "$as_me:$LINENO: checking if rpath support is requested" >&5
@@ -5995,7 +5921,6 @@ cat >>confdefs.h <<\_ACEOF
 #define MODULE_SCOPE __private_extern__
 _ACEOF
 
-		tcl_cv_cc_visibility_hidden=yes
 
 fi
 
diff --git a/unix/tcl.m4 b/unix/tcl.m4
index 070946a..8c29334 100644
--- a/unix/tcl.m4
+++ b/unix/tcl.m4
@@ -111,9 +111,9 @@ AC_DEFUN([SC_PATH_TCLCONFIG], [
 			`ls -dr ${srcdir}/../tcl[[8-9]].[[0-9]] 2>/dev/null` \
 			`ls -dr ${srcdir}/../tcl[[8-9]].[[0-9]]* 2>/dev/null` ; do
 		    if test -f "$i/unix/tclConfig.sh" ; then
-		    ac_cv_c_tclconfig="`(cd $i/unix; pwd)`"
-		    break
-		fi
+			ac_cv_c_tclconfig="`(cd $i/unix; pwd)`"
+			break
+		    fi
 		done
 	    fi
 	])
@@ -271,11 +271,10 @@ AC_DEFUN([SC_PATH_TKCONFIG], [
 #
 # Results:
 #
-#	Subst the following vars:
+#	Substitutes the following vars:
 #		TCL_BIN_DIR
 #		TCL_SRC_DIR
 #		TCL_LIB_FILE
-#
 #------------------------------------------------------------------------
 
 AC_DEFUN([SC_LOAD_TCLCONFIG], [
@@ -439,11 +438,11 @@ AC_DEFUN([SC_LOAD_TKCONFIG], [
 #	extension can't assume that an executable Tcl shell exists at
 #	build time.
 #
-# Arguments
+# Arguments:
 #	none
 #
-# Results
-#	Subst's the following values:
+# Results:
+#	Substitutes the following vars:
 #		TCLSH_PROG
 #------------------------------------------------------------------------
 
@@ -484,11 +483,11 @@ AC_DEFUN([SC_PROG_TCLSH], [
 #	when running tests from an extension build directory. It is not
 #	correct to use the TCLSH_PROG in cases like this.
 #
-# Arguments
+# Arguments:
 #	none
 #
-# Results
-#	Subst's the following values:
+# Results:
+#	Substitutes the following values:
 #		BUILD_TCLSH
 #------------------------------------------------------------------------
 
@@ -790,7 +789,6 @@ AC_DEFUN([SC_ENABLE_SYMBOLS], [
 #
 #	Defines the following vars:
 #		HAVE_LANGINFO	Triggers use of nl_langinfo if defined.
-#
 #------------------------------------------------------------------------
 
 AC_DEFUN([SC_ENABLE_LANGINFO], [
@@ -1045,34 +1043,17 @@ AC_DEFUN([SC_CONFIG_CFLAGS], [
 
     AC_CACHE_CHECK([if compiler supports visibility "hidden"],
 	tcl_cv_cc_visibility_hidden, [
-	    AS_IF([test "$SHARED_BUILD" = 1], [
-		hold_cflags=$CFLAGS; CFLAGS="$CFLAGS -fvisibility=hidden -Werror"
-		AC_TRY_COMPILE(,[#if !defined(__GNUC__) || __GNUC__ < 4
-#error visibility hidden is not supported for this compiler
-#endif
-		], tcl_cv_cc_visibility_hidden=yes,
-		    tcl_cv_cc_visibility_hidden=no)
-		CFLAGS=$hold_cflags
-	    ], [
-		tcl_cv_cc_visibility_hidden=no
-	    ])
-    ])
-    AS_IF([test $tcl_cv_cc_visibility_hidden = yes], [
-	CFLAGS="$CFLAGS -fvisibility=hidden"
-	AC_DEFINE(MODULE_SCOPE, [extern], [No need to mark inidividual symbols as hidden])
-    ], [
 	hold_cflags=$CFLAGS; CFLAGS="$CFLAGS -Werror"
 	AC_TRY_LINK([
 	    extern __attribute__((__visibility__("hidden"))) void f(void);
 	    void f(void) {}], [f();], tcl_cv_cc_visibility_hidden=yes,
 	    tcl_cv_cc_visibility_hidden=no)
-	CFLAGS=$hold_cflags
-	AS_IF([test $tcl_cv_cc_visibility_hidden = yes], [
-	    AC_DEFINE(MODULE_SCOPE,
-		[extern __attribute__((__visibility__("hidden")))],
-		[Compiler support for module scope symbols])
-	    AC_DEFINE(HAVE_HIDDEN, [1], [Compiler support for module scope symbols])
-	])
+	CFLAGS=$hold_cflags])
+    AS_IF([test $tcl_cv_cc_visibility_hidden = yes], [
+	AC_DEFINE(MODULE_SCOPE,
+	    [extern __attribute__((__visibility__("hidden")))],
+	    [Compiler support for module scope symbols])
+	AC_DEFINE(HAVE_HIDDEN, [1], [Compiler support for module scope symbols])
     ])
 
     # Step 0.d: Disable -rpath support?
@@ -1645,7 +1626,6 @@ AC_DEFUN([SC_CONFIG_CFLAGS], [
 	    AS_IF([test "$tcl_cv_cc_visibility_hidden" != yes], [
 		AC_DEFINE(MODULE_SCOPE, [__private_extern__],
 		    [Compiler support for module scope symbols])
-		tcl_cv_cc_visibility_hidden=yes
 	    ])
 	    CC_SEARCH_FLAGS=""
 	    LD_SEARCH_FLAGS=""
diff --git a/win/tcl.m4 b/win/tcl.m4
index 52c001f..625c329 100644
--- a/win/tcl.m4
+++ b/win/tcl.m4
@@ -247,7 +247,7 @@ AC_DEFUN([SC_PATH_TKCONFIG], [
 #
 # Results:
 #
-#	Subst the following vars:
+#	Substitutes the following vars:
 #		TCL_BIN_DIR
 #		TCL_SRC_DIR
 #		TCL_LIB_FILE