From 4b507ea962169a8d19e4b37b940448eba97d87a4 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Sun, 24 Jan 2016 10:47:42 +0200
Subject: If base target type doesn't use extensions, don't use them in derived

---
 build2/parser.cxx | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

(limited to 'build2')

diff --git a/build2/parser.cxx b/build2/parser.cxx
index c632c80..b28f4f6 100644
--- a/build2/parser.cxx
+++ b/build2/parser.cxx
@@ -937,9 +937,13 @@ namespace build2
       dt->factory = &derived_factory;
 
       // Override extension derivation function: we most likely don't want
-      // to use the same default as our base (think cli: file).
+      // to use the same default as our base (think cli: file). But, if our
+      // base doesn't use extensions, then most likely neither do we (think
+      // foo: alias).
       //
-      dt->extension = &target_extension_var<derived_ext_var, nullptr>;
+      dt->extension = /*bt->extension == nullptr
+        ? nullptr
+        :*/ &target_extension_var<derived_ext_var, nullptr>;
 
       target_type& rdt (*dt); // Save a non-const reference to the object.
 
-- 
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