From 0bd954eabb236bc9530220ffbc076967d35e33f4 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 23 Feb 2015 16:09:27 +0200
Subject: Don't create new target for alias/action/dir prerequisite

---
 build/b.cxx      |  4 ++--
 build/target.cxx | 17 ++++++++++++++++-
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/build/b.cxx b/build/b.cxx
index a71a866..1edce6b 100644
--- a/build/b.cxx
+++ b/build/b.cxx
@@ -182,10 +182,10 @@ main (int argc, char* argv[])
     rules[typeid (obj)].emplace ("cxx.gnu.compile", cxx_compile);
 
     dir_rule dir_r;
-    rules[typeid (dir)].emplace ("", dir_r);
+    rules[typeid (dir)].emplace ("dir", dir_r);
 
     path_rule path_r;
-    rules[typeid (path_target)].emplace ("", path_r);
+    rules[typeid (path_target)].emplace ("path", path_r);
 
     // Build.
     //
diff --git a/build/target.cxx b/build/target.cxx
index 197770c..50a7cc6 100644
--- a/build/target.cxx
+++ b/build/target.cxx
@@ -150,6 +150,21 @@ namespace build
       return nullptr;
   }
 
+  // dir target
+  //
+  static target*
+  search_alias (prerequisite& p)
+  {
+    // For an alias/action we don't want to silently create a target
+    // since it will do nothing and it most likely not what the author
+    // intended.
+    //
+    if (target* t = search_existing_target (p))
+      return t;
+
+    fail << "no explicit target for prerequisite " << p;
+  }
+
   // type info
   //
 
@@ -195,6 +210,6 @@ namespace build
     "dir",
     &target::static_type,
     &target_factory<dir>,
-    target::static_type.search
+    &search_alias
   };
 }
-- 
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