4 files changed, 21 insertions, 12 deletions
diff --git a/build/config/module b/build/config/module
index 4ab3e7e..58d9814 100644
--- a/build/config/module
+++ b/build/config/module
@@ -12,8 +12,9 @@ namespace build
 {
   namespace config
   {
-    void
-    init (scope&, scope&, const location&);
+    extern "C" void
+    config_init (
+      scope&, scope&, const location&, std::unique_ptr<module>&, bool);
   }
 }
 
diff --git a/build/config/module.cxx b/build/config/module.cxx
index 7ac9071..237547c 100644
--- a/build/config/module.cxx
+++ b/build/config/module.cxx
@@ -23,16 +23,23 @@ namespace build
     //
     static const path config_file ("build/config.build");
 
-    void
-    init (scope& root, scope& base, const location& l)
+    extern "C" void
+    config_init (scope& root,
+                 scope& base,
+                 const location& l,
+                 std::unique_ptr<module>&,
+                 bool first)
     {
-      //@@ TODO: avoid multiple inits (generally, for modules).
-      //
-
       tracer trace ("config::init");
 
       if (&root != &base)
-        fail (l) << "config module must be initialized in project root scope";
+        fail (l) << "config module must be initialized in bootstrap.build";
+
+      if (!first)
+      {
+        warn (l) << "multiple config module initializations";
+        return;
+      }
 
       const dir_path& out_root (root.path ());
       level4 ([&]{trace << "for " << out_root;});
diff --git a/build/config/operation.cxx b/build/config/operation.cxx
index ecd805f..78ad9e8 100644
--- a/build/config/operation.cxx
+++ b/build/config/operation.cxx
@@ -8,8 +8,9 @@
 
 #include <butl/filesystem>
 
-#include <build/scope>
 #include <build/file>
+#include <build/scope>
+#include <build/target>
 #include <build/context>
 #include <build/diagnostics>
 
diff --git a/build/config/utility b/build/config/utility
index 8ab6afe..e1d81a7 100644
--- a/build/config/utility
+++ b/build/config/utility
@@ -31,9 +31,9 @@ namespace build
     required (scope& root, const char* name, const char* default_value);
 
     // Set, if necessary, an optional config.* variable. In particular,
-    // an unspecified variable is set to NULL which is used to to
-    // distinguish between the "configured as unspecified" and "not
-    // yet configured" cases.
+    // an unspecified variable is set to NULL which is used to distinguish
+    // between the "configured as unspecified" and "not yet configured"
+    // cases.
     //
     // Return the pointer to the value, which can be NULL.
     //