[glib/fix-gresource-export-msvc] glib-compile-resources: Fix exporting on Visual Studio

[Chun-wei Fan <fanchunwei src gnome org>]

commit d308fa9fccf179d9464a5dcbba28b63bdb2c68e9
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Wed Apr 29 19:04:36 2020 +0800

    glib-compile-resources: Fix exporting on Visual Studio
    
    Have the generated code append "__declspec(dllexport)" before "extern" if
    the generated code is being built on Windows on Visual Studio-style
    compilers when --internal is not being used, so that we also export the
    symbols from the generated code, if needed.
    
    On non-Windows or non-Visual Studio-style compilers, we use "extern" as
    we did before.

 gio/glib-compile-resources.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)
---
diff --git a/gio/glib-compile-resources.c b/gio/glib-compile-resources.c
index 9b82ebade..052404f53 100644
--- a/gio/glib-compile-resources.c
+++ b/gio/glib-compile-resources.c
@@ -1061,6 +1061,9 @@ main (int argc, char **argv)
       guint8 *data;
       gsize data_size;
       gsize i;
+      const char *export = "#if defined (G_OS_WIN32) && defined (_MSC_VER)\n"
+                           "__declspec(dllexport)\n"
+                           "#endif\n";
 
       if (!g_file_get_contents (binary_target, (char **)&data,
                                &data_size, NULL))
@@ -1081,6 +1084,9 @@ main (int argc, char **argv)
          return 1;
        }
 
+      if (internal)
+        export = "";
+
       g_fprintf (file,
               "#include <gio/gio.h>\n"
               "\n"
@@ -1140,30 +1146,36 @@ main (int argc, char **argv)
       g_fprintf (file,
               "\n"
               "static GStaticResource static_resource = { %s_resource_data.data, sizeof 
(%s_resource_data.data)%s, NULL, NULL, NULL };\n"
-              "%s GResource *%s_get_resource (void);\n"
+              "\n"
+              "%s%s\n"
+              "GResource *%s_get_resource (void);\n"
               "GResource *%s_get_resource (void)\n"
               "{\n"
               "  return g_static_resource_get_resource (&static_resource);\n"
               "}\n",
-              c_name, c_name, (external_data ? "" : " - 1 /* nul terminator */"), linkage, c_name, c_name);
+              c_name, c_name, (external_data ? "" : " - 1 /* nul terminator */"),
+              export, linkage, c_name, c_name);
 
 
       if (manual_register)
        {
          g_fprintf (file,
                   "\n"
-                  "%s void %s_unregister_resource (void);\n"
+                  "%s%s\n"
+                  "void %s_unregister_resource (void);\n"
                   "void %s_unregister_resource (void)\n"
                   "{\n"
                   "  g_static_resource_fini (&static_resource);\n"
                   "}\n"
                   "\n"
-                  "%s void %s_register_resource (void);\n"
+                  "%s%s\n"
+                  "void %s_register_resource (void);\n"
                   "void %s_register_resource (void)\n"
                   "{\n"
                   "  g_static_resource_init (&static_resource);\n"
                   "}\n",
-                  linkage, c_name, c_name, linkage, c_name, c_name);
+                  export, linkage, c_name, c_name,
+                  export, linkage, c_name, c_name);
        }
       else
        {