From 107681258b57390ade604c4f4a8dc1e30cfae7ef Mon Sep 17 00:00:00 2001
From: Andreas Schuh <andreas.schuh.84@gmail.com>
Date: Mon, 17 Mar 2014 21:20:24 +0000
Subject: [PATCH] Fix VS linker warning regarding locally defined
 FLAGS_tryfromenv symbol.

---
 src/gflags.cc           |  8 ++++++--
 src/gflags_declare.h.in | 26 ++++++++++++++++----------
 test/gflags_unittest.cc |  5 +++++
 3 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/src/gflags.cc b/src/gflags.cc
index 0f1f0b0..2e0b89c 100644
--- a/src/gflags.cc
+++ b/src/gflags.cc
@@ -109,6 +109,11 @@
 #include "mutex.h"
 #include "util.h"
 
+// Export the following flags only if the gflags library is a DLL
+#ifndef GFLAGS_SHARED_LIBS
+#  undef  GFLAGS_DLL_DEFINE_FLAG
+#  define GFLAGS_DLL_DEFINE_FLAG
+#endif
 
 // Special flags, type 1: the 'recursive' flags.  They set another flag's val.
 DEFINE_string(flagfile,   "", "load flags from file");
@@ -395,8 +400,7 @@ const char* FlagValue::TypeName() const {
     assert(false);
     return "";
   }
-  // Directly indexing the strigns in the 'types' string, each of them
-  // is 7 bytes long.
+  // Directly indexing the strings in the 'types' string, each of them is 7 bytes long.
   return &types[type_ * 7];
 }
 
diff --git a/src/gflags_declare.h.in b/src/gflags_declare.h.in
index 99a7c2d..a9b7b6a 100644
--- a/src/gflags_declare.h.in
+++ b/src/gflags_declare.h.in
@@ -72,18 +72,24 @@
 #  endif
 #endif
 
-// We always want to export defined variables, dll or no
-#if defined(_MSC_VER)
-#  define GFLAGS_DLL_DEFINE_FLAG __declspec(dllexport)
-#else
-#  define GFLAGS_DLL_DEFINE_FLAG
+// By default, we always want to export defined variables, assuming
+// that the DEFINE_FLAG macros are used within shared modules.
+#ifndef GFLAGS_DLL_DEFINE_FLAG
+#  if defined(_MSC_VER)
+#    define GFLAGS_DLL_DEFINE_FLAG __declspec(dllexport)
+#  else
+#    define GFLAGS_DLL_DEFINE_FLAG
+#  endif
 #endif
 
-// We always want to import declared variables, dll or no
-#if defined(_MSC_VER)
-#  define GFLAGS_DLL_DECLARE_FLAG __declspec(dllimport)
-#else
-#  define GFLAGS_DLL_DECLARE_FLAG
+// By default, we always want to export defined variables, assuming
+// that the DECLARE_FLAG macros are used within shared modules.
+#ifndef GFLAGS_DLL_DECLARE_FLAG
+#  if defined(_MSC_VER)
+#    define GFLAGS_DLL_DECLARE_FLAG __declspec(dllimport)
+#  else
+#    define GFLAGS_DLL_DECLARE_FLAG
+#  endif
 #endif
 
 // Export/import of STL class instantiations
diff --git a/test/gflags_unittest.cc b/test/gflags_unittest.cc
index 185d562..8f3096b 100644
--- a/test/gflags_unittest.cc
+++ b/test/gflags_unittest.cc
@@ -35,6 +35,11 @@
 #include "config_for_unittests.h"
 #include <gflags/gflags.h>
 
+#ifndef GFLAGS_SHARED_LIBS
+#  undef  GFLAGS_DLL_DECLARE_FLAG
+#  define GFLAGS_DLL_DECLARE_FLAG
+#endif
+
 #include <math.h>       // for isinf() and isnan()
 #include <stdio.h>
 #include <stdlib.h>