From 6e2e56e8f70faed666a83797cebb96e844650a79 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 8 Apr 2015 16:16:17 +0200
Subject: Add note to generated config.build about inherited configuration

---
 build/config/operation.cxx | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/build/config/operation.cxx b/build/config/operation.cxx
index ef83e47..e62d313 100644
--- a/build/config/operation.cxx
+++ b/build/config/operation.cxx
@@ -66,9 +66,9 @@ namespace build
     }
 
     static void
-    save_config (scope& r)
+    save_config (scope& root)
     {
-      const path& out_root (r.path ());
+      const path& out_root (root.path ());
       path f (out_root / config_file);
 
       if (verb >= 1)
@@ -84,10 +84,22 @@ namespace build
 
         ofs.exceptions (ofstream::failbit | ofstream::badbit);
 
+        ofs << "# Created automatically by the config module, but" << endl
+            << "# feel free to edit." << endl
+            << "#" << endl;
+
+        if (auto v = root.ro_variables ()["amalgamation"])
+        {
+          const path& d (v.as<const path&> ());
+
+          ofs << "# Base configuration inherited from " << d << "/ ." << endl
+              << "#" << endl;
+        }
+
         // Save all the variables in the config namespace that are set
         // on the project's root scope.
         //
-        for (auto p (r.variables.find_namespace ("config"));
+        for (auto p (root.variables.find_namespace ("config"));
              p.first != p.second;
              ++p.first)
         {
-- 
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