From c28bb7c4038916d359228317d4ef5fe17dabce61 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 18 Nov 2019 15:11:53 +0200
Subject: Add couple of sanity checks

---
 libbuild2/cc/compile-rule.cxx | 11 ++++++++---
 libbuild2/rule.cxx            |  2 +-
 libbuild2/target.cxx          |  3 +--
 libbuild2/target.ixx          |  4 ++++
 4 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/libbuild2/cc/compile-rule.cxx b/libbuild2/cc/compile-rule.cxx
index 6e21a7e..da958f4 100644
--- a/libbuild2/cc/compile-rule.cxx
+++ b/libbuild2/cc/compile-rule.cxx
@@ -779,7 +779,7 @@ namespace build2
         // t.prerequisite_targets since we used standard search() and match()
         // above.
         //
-        const file& src (*md.src.search (t).is_a<file> ());
+        const file& src (*md.src.load (memory_order_relaxed)->is_a<file> ());
 
         // Figure out if __symexport is used. While normally it is specified
         // on the project root (which we cached), it can be overridden with
@@ -892,8 +892,13 @@ namespace build2
 
         // Finally the source file.
         //
-        if (dd.expect (src.path ()) != nullptr)
-          l4 ([&]{trace << "source file mismatch forcing update of " << t;});
+        {
+          const path& p (src.path ());
+          assert (!p.empty ()); // Sanity check.
+
+          if (dd.expect (p) != nullptr)
+            l4 ([&]{trace << "source file mismatch forcing update of " << t;});
+        }
 
         // If any of the above checks resulted in a mismatch (different
         // compiler, options, or source file) or if the depdb is newer than
diff --git a/libbuild2/rule.cxx b/libbuild2/rule.cxx
index d69e817..776f022 100644
--- a/libbuild2/rule.cxx
+++ b/libbuild2/rule.cxx
@@ -71,7 +71,7 @@ namespace build2
         if (p->empty ())
         {
           // Since we cannot come up with an extension, ask the target's
-          // derivation function to treat this as prerequisite (just like in
+          // derivation function to treat this as a prerequisite (just like in
           // search_existing_file()).
           //
           if (pt->derive_extension (true) == nullptr)
diff --git a/libbuild2/target.cxx b/libbuild2/target.cxx
index 23e6c9c..2ca3de8 100644
--- a/libbuild2/target.cxx
+++ b/libbuild2/target.cxx
@@ -700,8 +700,7 @@ namespace build2
       p += ee;
     }
 
-    path (move (p));
-    return path_;
+    return path (move (p));
   }
 
   // Search functions.
diff --git a/libbuild2/target.ixx b/libbuild2/target.ixx
index f304250..49f87cf 100644
--- a/libbuild2/target.ixx
+++ b/libbuild2/target.ixx
@@ -504,6 +504,10 @@ namespace build2
   inline const path& path_target::
   path () const
   {
+    // You may be wondering why don't we spin the transition out? The reason
+    // is it shouldn't matter since were we called just a moment earlier, we
+    // would have seen it.
+    //
     return path_state_.load (memory_order_acquire) == 2 ? path_ : empty_path;
   }
 
-- 
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