From 9a00b8ccfef1d13088be2d76fefcb320c269732a Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Thu, 22 Jun 2017 13:24:59 +0200
Subject: Add extra support for symbol exporting in modularized projects

Since modules don't see each other's macros, we can use a single, keyword-
like macro for dll-exporting that is managed by the build system (so no
need for an "export" header). For example:

cxx.features.symexport = true

export __symexport void f ();
---
 build2/cxx/init.cxx | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

(limited to 'build2/cxx')

diff --git a/build2/cxx/init.cxx b/build2/cxx/init.cxx
index 2c59f2c..53ee2d2 100644
--- a/build2/cxx/init.cxx
+++ b/build2/cxx/init.cxx
@@ -55,8 +55,8 @@ namespace build2
         return var_pool.rw (rs).insert<bool> (v, variable_visibility::project);
       };
 
-      bool modules (false); auto& v_m (enter ("cxx.features.modules"));
       //bool concepts (false); auto& v_c (enter ("cxx.features.concepts"));
+      bool modules (false); auto& v_m (enter ("cxx.features.modules"));
 
       // Translate "latest" and "experimental" to the compiler/version-
       // appropriate option(s).
@@ -429,8 +429,16 @@ namespace build2
       if (!cast_false<bool> (rs["cxx.config.loaded"]))
         load_module (rs, rs, "cxx.config", loc, false, hints);
 
+      auto& vp (var_pool.rw (rs));
+
       bool modules (cast<bool> (rs["cxx.features.modules"]));
 
+      bool symexport (
+        modules &&
+        cast_false<bool> (
+          rs[vp.insert<bool> ("cxx.features.symexport",
+                              variable_visibility::project)]));
+
       config_module& cm (*rs.modules.lookup<config_module> ("cxx.config"));
 
       cc::data d {
@@ -451,6 +459,7 @@ namespace build2
         cm.tstd,
 
         modules,
+        symexport,
 
         cast_null<process_path> (rs["pkgconfig.path"]),
         cast<dir_paths> (rs[cm.x_sys_lib_dirs]),
-- 
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