[d8] Fix the shared-library build

src/flag-definitions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file defines all of the flags.  It is separated into different section,
 // for Debug, Release, Logging and Profiling, etc.  To add a new flag, find the
 // correct section, and use one of the DEFINE_ macros, without a trailing ';'.
 //
 // This include does not have a guard, because it is a template-style include,
 // which can be included multiple times in different modes.  It expects to have
 // a mode defined before it's included.  The modes are FLAG_MODE_... below:
 
 #define DEFINE_IMPLICATION(whenflag, thenflag)              \
   DEFINE_VALUE_IMPLICATION(whenflag, thenflag, true)
 
 #define DEFINE_NEG_IMPLICATION(whenflag, thenflag)          \
   DEFINE_VALUE_IMPLICATION(whenflag, thenflag, false)
 
 #define DEFINE_NEG_NEG_IMPLICATION(whenflag, thenflag) \
   DEFINE_NEG_VALUE_IMPLICATION(whenflag, thenflag, false)
 
 // We want to declare the names of the variables for the header file.  Normally
 // this will just be an extern declaration, but for a readonly flag we let the
 // compiler make better optimizations by giving it the value.
 #if defined(FLAG_MODE_DECLARE)
-#define FLAG_FULL(ftype, ctype, nam, def, cmt) extern ctype FLAG_##nam;
+#define FLAG_FULL(ftype, ctype, nam, def, cmt) \
+  V8_EXPORT_PRIVATE extern ctype FLAG_##nam;
 #define FLAG_READONLY(ftype, ctype, nam, def, cmt) \
   static ctype const FLAG_##nam = def;
 
 // We want to supply the actual storage and value for the flag variable in the
 // .cc file.  We only do this for writable flags.
 #elif defined(FLAG_MODE_DEFINE)
-#define FLAG_FULL(ftype, ctype, nam, def, cmt) ctype FLAG_##nam = def;
+#ifdef USING_V8_SHARED
+#define FLAG_FULL(ftype, ctype, nam, def, cmt) \
+  V8_EXPORT_PRIVATE extern ctype FLAG_##nam;
+#else
+#define FLAG_FULL(ftype, ctype, nam, def, cmt) \
+  V8_EXPORT_PRIVATE ctype FLAG_##nam = def;
+#endif
 
 // We need to define all of our default values so that the Flag structure can
 // access them by pointer.  These are just used internally inside of one .cc,
 // for MODE_META, so there is no impact on the flags interface.
 #elif defined(FLAG_MODE_DEFINE_DEFAULTS)
 #define FLAG_FULL(ftype, ctype, nam, def, cmt) \
   static ctype const FLAGDEFAULT_##nam = def;
 
 // We want to write entries into our meta data table, for internal parsing and
 // printing / etc in the flag parser code.  We only do this for writable flags.
@@ skipping 1158 matching lines @@
 #undef DEFINE_ALIAS_FLOAT
 #undef DEFINE_ALIAS_ARGS
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 
 #undef COMMA