Manage FreeType symbol visibility using platform specific FT_EXPORT

third_party/freetype/include/freetype-custom-config/ftoption.h

 /***************************************************************************/
 /*                                                                         */
 /*  ftoption.h                                                             */
 /*                                                                         */
 /*    User-selectable configuration macros (specification only).           */
 /*                                                                         */
 /*  Copyright 1996-2017 by                                                 */
 /*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
 /*                                                                         */
 /*  This file is part of the FreeType project, and may only be used,       */
@@ skipping 291 matching lines @@
   /*         }                                                             */
   /*                                                                       */
   /*   You can provide your own implementation of FT_EXPORT and            */
   /*   FT_EXPORT_DEF here if you want.  If you leave them undefined, they  */
   /*   will be later automatically defined as `extern return_type' to      */
   /*   allow normal compilation.                                           */
   /*                                                                       */
   /*   Do not #undef these macros here since the build system might define */
   /*   them for certain configurations only.                               */
   /*                                                                       */
-/* #define FT_EXPORT(x)      extern x */
-/* #define FT_EXPORT_DEF(x)  x */
-
+#if defined(_WIN32)
+#define FT_EXPORT(x)     __declspec(dllexport) x
+#define FT_EXPORT_DEF(x) __declspec(dllexport) x

[bungeman-skia, 2017/03/10 17:02:56]

How are you getting away with using only dllexport and not dllimport? Are all
the trybots non-component builds? Usually on Windows one sees something more
like https://lists.nongnu.org/archive/html/freetype/2009-05/msg00004.html which
also takes into account that in a non-component build you don't want to export
anything (Chromium doesn't want to expose the FreeType symbols in a
non-component build if it can be avoided).

[drott, 2017/03/13 10:17:37]

Thanks for pointing this out. I am not very familiar with Windows linking, but
according to https://msdn.microsoft.com/en-us/library/aa271769(v=vs.60).aspx I
can get away without dllimport at the expense of an extra redirect thunk, if I
understood correctly. In the updated patch I try to match dllexport/dllimport if
it's a component build and don't add any extra qualifications when it's static
linkage. On non Windows, I add the gcc-style visibility attribute.

+#else
+#define FT_EXPORT(x)     __attribute__((visibility ("default"))) x
+#define FT_EXPORT_DEF(x) __attribute__((visibility ("default"))) x
+#endif
 
   /*************************************************************************/
   /*                                                                       */
   /* Glyph Postscript Names handling                                       */
   /*                                                                       */
   /*   By default, FreeType 2 is compiled with the `psnames' module.  This */
   /*   module is in charge of converting a glyph name string into a        */
   /*   Unicode value, or return a Macintosh standard glyph name for the    */
   /*   use with the TrueType `post' table.                                 */
   /*                                                                       */
@@ skipping 635 matching lines @@
 #error "Invalid CFF darkening parameters!"
 #endif
 
 FT_END_HEADER
 
 
 #endif /* FTOPTION_H_ */
 
 
 /* END */