From ca0f9c71be279aee845bf5328ac0af8c02c8849e Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 17 Apr 2019 13:42:37 +0200
Subject: Incorporate ad hoc prerequisite mtime into out-of-date determination

---
 build2/cc/link-rule.cxx | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

(limited to 'build2/cc/link-rule.cxx')

diff --git a/build2/cc/link-rule.cxx b/build2/cc/link-rule.cxx
index 28d4fc6..443f91d 100644
--- a/build2/cc/link-rule.cxx
+++ b/build2/cc/link-rule.cxx
@@ -1633,13 +1633,34 @@ namespace build2
       bool binless (md.binless);
       assert (ot != otype::e || !binless); // Sanity check.
 
-      // Update prerequisites. We determine if any relevant ones render us
-      // out-of-date manually below.
+      // Determine if we are out-of-date.
+      //
+      bool update (false);
+      bool scratch (false);
+      timestamp mt (binless ? timestamp_unreal : t.load_mtime ());
+
+      // Update prerequisites. We determine if any relevant non-ad hoc ones
+      // render us out-of-date manually below.
       //
-      // Note that straight_execute_prerequisites() blanks out all the ad hoc
+      // Note that execute_prerequisites() blanks out all the ad hoc
       // prerequisites so we don't need to worry about them from now on.
       //
-      target_state ts (straight_execute_prerequisites (a, t));
+      target_state ts;
+
+      if (optional<target_state> s =
+          execute_prerequisites (a,
+                                 t,
+                                 mt,
+                                 [] (const target&, size_t) {return false;}))
+        ts = *s;
+      else
+      {
+        // An ad hoc prerequisite renders us out-of-date. Let's update from
+        // scratch for good measure.
+        //
+        scratch = update = true;
+        ts = target_state::changed;
+      }
 
       // (Re)generate pkg-config's .pc file. While the target itself might be
       // up-to-date from a previous run, there is no guarantee that .pc exists
@@ -1661,11 +1682,6 @@ namespace build2
         return ts;
       }
 
-      // Determine if we are out-of-date.
-      //
-      bool update (false);
-      timestamp mt (t.load_mtime ());
-
       // Open the dependency database (do it before messing with Windows
       // manifests to diagnose missing output directory).
       //
@@ -2120,7 +2136,6 @@ namespace build2
       // target (interrupted update) then force the target update. Also note
       // this situation in the "from scratch" flag.
       //
-      bool scratch (false);
       if (dd.writing () || dd.mtime > mt)
         scratch = update = true;
 
-- 
cgit v1.1