From a1280406b012a7a5e4f145e9b39bc96efc7cebd6 Mon Sep 17 00:00:00 2001
From: Nick Terrell <terrelln@fb.com>
Date: Fri, 19 May 2017 18:01:59 -0700
Subject: [PATCH] [libzstd] Allow users to define custom visibility

---
 lib/common/zstd_errors.h | 10 ++++++----
 lib/dictBuilder/zdict.h  | 10 ++++++----
 lib/zstd.h               | 10 ++++++----
 3 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/lib/common/zstd_errors.h b/lib/common/zstd_errors.h
index de0fc8984..e067acf6e 100644
--- a/lib/common/zstd_errors.h
+++ b/lib/common/zstd_errors.h
@@ -19,10 +19,12 @@ extern "C" {
 
 
 /* =====   ZSTDERRORLIB_API : control library symbols visibility   ===== */
-#if defined(__GNUC__) && (__GNUC__ >= 4)
-#  define ZSTDERRORLIB_VISIBILITY __attribute__ ((visibility ("default")))
-#else
-#  define ZSTDERRORLIB_VISIBILITY
+#ifndef ZSTDERRORLIB_VISIBILITY
+#  if defined(__GNUC__) && (__GNUC__ >= 4)
+#    define ZSTDERRORLIB_VISIBILITY __attribute__ ((visibility ("default")))
+#  else
+#    define ZSTDERRORLIB_VISIBILITY
+#  endif
 #endif
 #if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)
 #  define ZSTDERRORLIB_API __declspec(dllexport) ZSTDERRORLIB_VISIBILITY
diff --git a/lib/dictBuilder/zdict.h b/lib/dictBuilder/zdict.h
index 9b53de346..5ef2a3f5b 100644
--- a/lib/dictBuilder/zdict.h
+++ b/lib/dictBuilder/zdict.h
@@ -20,10 +20,12 @@ extern "C" {
 
 
 /* =====   ZDICTLIB_API : control library symbols visibility   ===== */
-#if defined(__GNUC__) && (__GNUC__ >= 4)
-#  define ZDICTLIB_VISIBILITY __attribute__ ((visibility ("default")))
-#else
-#  define ZDICTLIB_VISIBILITY
+#ifndef ZDICTLIB_VISIBILITY
+#  if defined(__GNUC__) && (__GNUC__ >= 4)
+#    define ZDICTLIB_VISIBILITY __attribute__ ((visibility ("default")))
+#  else
+#    define ZDICTLIB_VISIBILITY
+#  endif
 #endif
 #if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)
 #  define ZDICTLIB_API __declspec(dllexport) ZDICTLIB_VISIBILITY
diff --git a/lib/zstd.h b/lib/zstd.h
index d96a535f3..b0aae3f73 100644
--- a/lib/zstd.h
+++ b/lib/zstd.h
@@ -19,10 +19,12 @@ extern "C" {
 
 
 /* =====   ZSTDLIB_API : control library symbols visibility   ===== */
-#if defined(__GNUC__) && (__GNUC__ >= 4)
-#  define ZSTDLIB_VISIBILITY __attribute__ ((visibility ("default")))
-#else
-#  define ZSTDLIB_VISIBILITY
+#ifndef ZSTDLIB_VISIBILITY
+#  if defined(__GNUC__) && (__GNUC__ >= 4)
+#    define ZSTDLIB_VISIBILITY __attribute__ ((visibility ("default")))
+#  else
+#    define ZSTDLIB_VISIBILITY
+#  endif
 #endif
 #if defined(ZSTD_DLL_EXPORT) && (ZSTD_DLL_EXPORT==1)
 #  define ZSTDLIB_API __declspec(dllexport) ZSTDLIB_VISIBILITY