* configure.in (XCFLAGS): use -fvisibility=hidden if possible.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@28709 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

26 files changed, 200 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index ff6bf8b426..b46b8bc609 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,6 @@
-Thu Jul 22 06:26:48 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Thu Jul 22 06:38:18 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* configure.in (XCFLAGS): use -fvisibility=hidden if possible.
 
 	* configure.in (RMDIR): use --ignore-fail-on-non-empty if possible.
 
diff --git a/common.mk b/common.mk
index c06f27596d..66dab00f5b 100644
--- a/common.mk
+++ b/common.mk
@@ -680,6 +680,8 @@ newline.$(OBJEXT): {$(VPATH)}newline.c {$(VPATH)}defines.h \
   {$(VPATH)}intern.h {$(VPATH)}missing.h {$(VPATH)}st.h \
   {$(VPATH)}transcode_data.h {$(VPATH)}ruby.h {$(VPATH)}config.h
 
+$(OBJS):  {$(VPATH)}config.h {$(VPATH)}missing.h
+
 INSNS2VMOPT = --srcdir="$(srcdir)"
 
 {$(VPATH)}minsns.inc: $(srcdir)/template/minsns.inc.tmpl
diff --git a/configure.in b/configure.in
index 64af34bc26..f05d85e5e2 100644
--- a/configure.in
+++ b/configure.in
@@ -269,6 +269,7 @@ if test "$GCC" = yes; then
     linker_flag=-Wl,
     : ${optflags=-O3}
     AS_CASE(["$target_os"], [linux*|darwin*], [: ${debugflags=-ggdb}])
+    RUBY_APPEND_OPTIONS(XCFLAGS, ["-include ruby/config.h" "-include ruby/missing.h"])
 else
     linker_flag=
 fi
@@ -414,6 +415,9 @@ if test "$GCC:${warnflags+set}:no" = yes::no; then
                              [wflag=-Wall])
     RUBY_TRY_CFLAGS($wflag, [warnflags="$wflag${warnflags+ $warnflags}"])
 fi
+if test "$GCC" = yes; then
+    RUBY_TRY_CFLAGS(-fvisibility=hidden, RUBY_APPEND_OPTION(XCFLAGS, -fvisibility=hidden))
+fi
 
 test -z "${ac_env_CFLAGS_set}" -a -n "${cflags+set}" && eval CFLAGS="\"$cflags $ARCH_FLAG\""
 test -z "${ac_env_CXXFLAGS_set}" -a -n "${cxxflags+set}" && eval CXXFLAGS="\"$cxxflags $ARCH_FLAG\""
@@ -2160,8 +2164,6 @@ AS_CASE("$enable_shared", [yes], [
 	LIBRUBY_DLDFLAGS="$LIBRUBY_DLDFLAGS "'-install_name '${libprefix}'/$(LIBRUBY_SO)'
 	LIBRUBY_DLDFLAGS="$LIBRUBY_DLDFLAGS "'-current_version $(MAJOR).$(MINOR).$(TEENY)'
 	LIBRUBY_DLDFLAGS="$LIBRUBY_DLDFLAGS "'-compatibility_version $(ruby_version)'
-	LIBRUBY_DLDFLAGS="$LIBRUBY_DLDFLAGS "'-Wl,-unexported_symbol,_Init_*'
-	LIBRUBY_DLDFLAGS="$LIBRUBY_DLDFLAGS "'-Wl,-unexported_symbol,*_threadptr_*'
 	LIBRUBY_DLDFLAGS="$LIBRUBY_DLDFLAGS "' $(XLDFLAGS)'
 	LIBRUBY_SO='lib$(RUBY_SO_NAME).dylib'
 	LIBRUBY_ALIASES='lib$(RUBY_BASE_NAME).$(MAJOR).$(MINOR).dylib lib$(RUBY_INSTALL_NAME).dylib'
diff --git a/cont.c b/cont.c
index 6065d34eff..962ea03664 100644
--- a/cont.c
+++ b/cont.c
@@ -1428,6 +1428,10 @@ Init_Cont(void)
     rb_define_method(rb_cFiber, "resume", rb_fiber_m_resume, -1);
 }
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 void
 ruby_Init_Continuation_body(void)
 {
@@ -1446,3 +1450,7 @@ ruby_Init_Fiber_as_Coroutine(void)
     rb_define_method(rb_cFiber, "alive?", rb_fiber_alive_p, 0);
     rb_define_singleton_method(rb_cFiber, "current", rb_fiber_s_current, 0);
 }
+
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
diff --git a/debug.h b/debug.h
index d5670651a4..cf904b6fcd 100644
--- a/debug.h
+++ b/debug.h
@@ -15,6 +15,10 @@
 #include "ruby/ruby.h"
 #include "node.h"
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 #define dpv(h,v) ruby_debug_print_value(-1, 0, h, v)
 #define dp(v)    ruby_debug_print_value(-1, 0, "", v)
 #define dpi(i)   ruby_debug_print_id(-1, 0, "", i)
@@ -33,4 +37,8 @@ void  ruby_debug_gc_check_func(void);
 void ruby_set_debug_option(const char *str);
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #endif /* RUBY_DEBUG_H */
diff --git a/dln.h b/dln.h
index 47ff3eaf59..abbd6d85a3 100644
--- a/dln.h
+++ b/dln.h
@@ -28,6 +28,10 @@
 # define _(args) ()
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 DEPRECATED(char *dln_find_exe(const char*,const char*));
 DEPRECATED(char *dln_find_file(const char*,const char*));
 char *dln_find_exe_r(const char*,const char*,char*,size_t);
@@ -38,4 +42,9 @@ extern char *dln_argv0;
 #endif
 
 void *dln_load(const char*);
+
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #endif
diff --git a/encoding.c b/encoding.c
index 79b90be10c..76dfac790b 100644
--- a/encoding.c
+++ b/encoding.c
@@ -23,6 +23,17 @@
 #endif
 #include "ruby/util.h"
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+int rb_enc_register(const char *name, rb_encoding *encoding);
+void rb_enc_set_base(const char *name, const char *orig);
+void rb_encdb_declare(const char *name);
+int rb_encdb_replicate(const char *name, const char *orig);
+int rb_encdb_dummy(const char *name);
+int rb_encdb_alias(const char *alias, const char *orig);
+#pragma GCC visibility pop
+#endif
+
 static ID id_encoding;
 VALUE rb_cEncoding;
 static VALUE rb_encoding_list;
diff --git a/include/ruby/defines.h b/include/ruby/defines.h
index 7bb2788aaf..45b19bdc58 100644
--- a/include/ruby/defines.h
+++ b/include/ruby/defines.h
@@ -49,6 +49,10 @@ extern "C" {
 #define ANYARGS
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 #define xmalloc ruby_xmalloc
 #define xmalloc2 ruby_xmalloc2
 #define xcalloc ruby_xcalloc
@@ -311,6 +315,10 @@ void rb_ia64_flushrs(void);
     RUBY_ALIAS_FUNCTION_TYPE(VALUE, prot, name, args)
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
diff --git a/include/ruby/encoding.h b/include/ruby/encoding.h
index 88f5e52101..2527427b1b 100644
--- a/include/ruby/encoding.h
+++ b/include/ruby/encoding.h
@@ -22,6 +22,10 @@ extern "C" {
 #include <stdarg.h>
 #include "ruby/oniguruma.h"
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 #define ENCODING_INLINE_MAX 1023
 #define ENCODING_SHIFT (FL_USHIFT+10)
 #define ENCODING_MASK (((VALUE)ENCODING_INLINE_MAX)<<ENCODING_SHIFT)
@@ -312,6 +316,10 @@ void rb_econv_binmode(rb_econv_t *ec);
 #define ECONV_AFTER_OUTPUT                      0x00020000
 /* end of flags for rb_econv_convert */
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
diff --git a/include/ruby/intern.h b/include/ruby/intern.h
index 98a194d2a6..46b4fe7752 100644
--- a/include/ruby/intern.h
+++ b/include/ruby/intern.h
@@ -28,6 +28,10 @@ extern "C" {
 #endif
 #include "ruby/st.h"
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 /*
  * Functions and variables that are used by more than one source file of
  * the kernel.
@@ -841,6 +845,10 @@ VALUE rb_time_succ(VALUE);
 void rb_frame_pop(void);
 int rb_frame_method_id_and_class(ID *idp, VALUE *klassp);
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
diff --git a/include/ruby/io.h b/include/ruby/io.h
index f0f83fc329..ba166f8c9a 100644
--- a/include/ruby/io.h
+++ b/include/ruby/io.h
@@ -27,6 +27,10 @@ extern "C" {
 #include <stdio_ext.h>
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 typedef struct rb_io_t {
     int fd;                     /* file descriptor */
     FILE *stdio_file;		/* stdio ptr for read/write if available */
@@ -165,6 +169,10 @@ void rb_io_read_check(rb_io_t*);
 int rb_io_read_pending(rb_io_t*);
 DEPRECATED(void rb_read_check(FILE*));
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
diff --git a/include/ruby/missing.h b/include/ruby/missing.h
index 5b147de6db..f4a5556ddf 100644
--- a/include/ruby/missing.h
+++ b/include/ruby/missing.h
@@ -49,6 +49,10 @@ struct timezone {
 #define RUBY_EXTERN extern
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 #ifndef HAVE_ACOSH
 RUBY_EXTERN double acosh(double);
 RUBY_EXTERN double asinh(double);
@@ -169,6 +173,10 @@ RUBY_EXTERN int signbit(double x);
 RUBY_EXTERN int ffs(int);
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
diff --git a/include/ruby/oniguruma.h b/include/ruby/oniguruma.h
index 41628ed4af..2674b010e7 100644
--- a/include/ruby/oniguruma.h
+++ b/include/ruby/oniguruma.h
@@ -97,6 +97,10 @@ extern "C" {
 #define ONIG_EXTERN   extern
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 /* PART: character encoding */
 
 #ifndef ONIG_ESCAPE_UCHAR_COLLISION
@@ -789,6 +793,10 @@ const char* onig_version P_((void));
 ONIG_EXTERN
 const char* onig_copyright P_((void));
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #ifdef __cplusplus
 #if 0
 { /* satisfy cc-mode */
diff --git a/include/ruby/re.h b/include/ruby/re.h
index c60ab96016..4039ba1800 100644
--- a/include/ruby/re.h
+++ b/include/ruby/re.h
@@ -24,6 +24,10 @@ extern "C" {
 
 #include "ruby/regex.h"
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 typedef struct re_pattern_buffer Regexp;
 
 struct rmatch_offset {
@@ -55,6 +59,11 @@ VALUE rb_reg_regsub(VALUE, VALUE, struct re_registers *, VALUE);
 long rb_reg_adjust_startpos(VALUE, VALUE, long, int);
 void rb_match_busy(VALUE);
 VALUE rb_reg_quote(VALUE);
+regex_t *rb_reg_prepare_re(VALUE re, VALUE str);
+
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
 
 #if defined(__cplusplus)
 #if 0
diff --git a/include/ruby/regex.h b/include/ruby/regex.h
index a63e2f6a4c..aeb6418d0a 100644
--- a/include/ruby/regex.h
+++ b/include/ruby/regex.h
@@ -24,6 +24,10 @@ extern "C" {
 #include "oniguruma.h"
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 #ifndef ONIG_RUBY_M17N
 
 ONIG_EXTERN OnigEncoding    OnigEncDefaultCharEncoding;
@@ -32,6 +36,10 @@ ONIG_EXTERN OnigEncoding    OnigEncDefaultCharEncoding;
 
 #endif /* ifndef ONIG_RUBY_M17N */
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 936493c028..c01d617ba3 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -73,6 +73,10 @@ extern "C" {
 
 #include "defines.h"
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 #if defined(HAVE_ALLOCA_H)
 #include <alloca.h>
 #else
@@ -1447,6 +1451,10 @@ int ruby_vsnprintf(char *str, size_t n, char const *fmt, va_list ap);
 #define close ruby_close
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
diff --git a/include/ruby/st.h b/include/ruby/st.h
index 27e47b816c..53e82618f1 100644
--- a/include/ruby/st.h
+++ b/include/ruby/st.h
@@ -33,6 +33,10 @@ extern "C" {
 # include <inttypes.h>
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 #if SIZEOF_LONG == SIZEOF_VOIDP
 typedef unsigned long st_data_t;
 #elif SIZEOF_LONG_LONG == SIZEOF_VOIDP
@@ -125,6 +129,10 @@ st_index_t st_hash_end(st_index_t h);
 st_index_t st_hash_start(st_index_t h);
 #define st_hash_start(h) ((st_index_t)(h))
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
diff --git a/include/ruby/util.h b/include/ruby/util.h
index 0c1e1c4ebc..ee8e726572 100644
--- a/include/ruby/util.h
+++ b/include/ruby/util.h
@@ -40,6 +40,10 @@ extern "C" {
 #endif
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 #define scan_oct(s,l,e) (int)ruby_scan_oct(s,l,e)
 unsigned long ruby_scan_oct(const char *, size_t, size_t *);
 #define scan_hex(s,l,e) (int)ruby_scan_hex(s,l,e)
@@ -80,6 +84,10 @@ double ruby_strtod(const char *, char **);
 
 void ruby_each_words(const char *, void (*)(const char*, int, void*), void *);
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
diff --git a/include/ruby/version.h b/include/ruby/version.h
index 32b09b3f52..101b5d9c63 100644
--- a/include/ruby/version.h
+++ b/include/ruby/version.h
@@ -36,6 +36,11 @@ extern "C" {
 } /* satisfy cc-mode */
 #endif
 #endif
+
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 /*
  * Interfaces from extension libraries.
  *
@@ -50,6 +55,11 @@ RUBY_EXTERN const int  ruby_patchlevel;
 RUBY_EXTERN const char ruby_description[];
 RUBY_EXTERN const char ruby_copyright[];
 RUBY_EXTERN const char ruby_engine[];
+
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
diff --git a/include/ruby/vm.h b/include/ruby/vm.h
index ac8e599e90..072d7d6f19 100644
--- a/include/ruby/vm.h
+++ b/include/ruby/vm.h
@@ -19,6 +19,10 @@ extern "C" {
 #endif
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 /* Place holder.
  *
  * We will prepare VM creation/control APIs on 1.9.2 or later.
@@ -32,6 +36,10 @@ typedef struct rb_vm_struct ruby_vm_t;
 /* core API */
 int ruby_vm_destruct(ruby_vm_t *vm);
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
diff --git a/include/ruby/win32.h b/include/ruby/win32.h
index 47a85270a5..b9299883bc 100644
--- a/include/ruby/win32.h
+++ b/include/ruby/win32.h
@@ -8,6 +8,10 @@ extern "C" {
 #endif
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 /*
  *  Copyright (c) 1993, Intergraph Corporation
  *
@@ -662,6 +666,10 @@ in asynchronous_func_t.
 typedef uintptr_t (*asynchronous_func_t)(uintptr_t self, int argc, uintptr_t* argv);
 uintptr_t rb_w32_asynchronize(asynchronous_func_t func, uintptr_t self, int argc, uintptr_t* argv, uintptr_t intrval);
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #if defined(__cplusplus)
 #if 0
 { /* satisfy cc-mode */
diff --git a/iseq.h b/iseq.h
index d09cdd5414..bc821ec00c 100644
--- a/iseq.h
+++ b/iseq.h
@@ -12,6 +12,10 @@
 #ifndef RUBY_COMPILE_H
 #define RUBY_COMPILE_H
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 /* compile.c */
 VALUE rb_iseq_compile_node(VALUE self, NODE *node);
 int rb_iseq_translate_threaded_code(rb_iseq_t *iseq);
@@ -101,4 +105,8 @@ struct iseq_compile_data {
 #define DEFINED_ZSUPER INT2FIX(9)
 #define DEFINED_FUNC   INT2FIX(10)
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #endif /* RUBY_COMPILE_H */
diff --git a/regenc.h b/regenc.h
index 9974165258..16fe9db813 100644
--- a/regenc.h
+++ b/regenc.h
@@ -39,6 +39,10 @@
 #endif
 #include "ruby/oniguruma.h"
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 typedef struct {
   OnigCodePoint from;
   OnigCodePoint to;
@@ -208,4 +212,8 @@ extern int ONIG_ENC_REGISTER(const char *, OnigEncodingType*);
 #define ENC_ALIAS(name, orig)
 #define ENC_DUMMY(name)
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #endif /* ONIGURUMA_REGENC_H */
diff --git a/regint.h b/regint.h
index 6c5ae7ba57..c0c0e99815 100644
--- a/regint.h
+++ b/regint.h
@@ -225,6 +225,10 @@
 
 #include "regenc.h"
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 #ifdef MIN
 #undef MIN
 #endif
@@ -838,4 +842,8 @@ typedef int (*ONIGENC_INIT_PROPERTY_LIST_FUNC_TYPE)(void);
 
 extern int onigenc_property_list_init P_((ONIGENC_INIT_PROPERTY_LIST_FUNC_TYPE));
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #endif /* ONIGURUMA_REGINT_H */
diff --git a/regparse.h b/regparse.h
index 18f7e6bd8f..fbe5a251a6 100644
--- a/regparse.h
+++ b/regparse.h
@@ -31,6 +31,10 @@
 
 #include "regint.h"
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 /* node type */
 #define NT_STR         0
 #define NT_CCLASS      1
@@ -351,4 +355,8 @@ extern int onig_print_names(FILE*, regex_t*);
 #endif
 #endif
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #endif /* ONIGURUMA_REGPARSE_H */
diff --git a/transcode_data.h b/transcode_data.h
index d0f3d0f764..8e85ce6db4 100644
--- a/transcode_data.h
+++ b/transcode_data.h
@@ -14,6 +14,10 @@
 #ifndef RUBY_TRANSCODE_DATA_H
 #define RUBY_TRANSCODE_DATA_H 1
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility push(default)
+#endif
+
 #define WORDINDEX_SHIFT_BITS 2
 #define WORDINDEX2INFO(widx)      ((widx) << WORDINDEX_SHIFT_BITS)
 #define INFO2WORDINDEX(info)      ((info) >> WORDINDEX_SHIFT_BITS)
@@ -106,4 +110,8 @@ struct rb_transcoder {
 void rb_declare_transcoder(const char *enc1, const char *enc2, const char *lib);
 void rb_register_transcoder(const rb_transcoder *);
 
+#if defined __GNUC__ && __GNUC__ >= 4
+#pragma GCC visibility pop
+#endif
+
 #endif /* RUBY_TRANSCODE_DATA_H */