1 files changed, 24 insertions, 25 deletions

diff --git a/src/graph.cc b/src/graph.cc
index 43ba45a..041199a 100644
--- a/src/graph.cc
+++ b/src/graph.cc
@@ -298,37 +298,34 @@ bool DependencyScan::RecomputeOutputDirty(const Edge* edge,
     return false;
   }
 
-  BuildLog::LogEntry* entry = 0;
-
   // Dirty if we're missing the output.
   if (!output->exists()) {
     EXPLAIN("output %s doesn't exist", output->path().c_str());
     return true;
   }
 
-  // Dirty if the output is older than the input.
-  if (most_recent_input && output->mtime() < most_recent_input->mtime()) {
-    TimeStamp output_mtime = output->mtime();
-
-    // If this is a restat rule, we may have cleaned the output with a restat
-    // rule in a previous run and stored the most recent input mtime in the
-    // build log.  Use that mtime instead, so that the file will only be
-    // considered dirty if an input was modified since the previous run.
-    bool used_restat = false;
-    if (edge->GetBindingBool("restat") && build_log() &&
-        (entry = build_log()->LookupByOutput(output->path()))) {
-      output_mtime = entry->mtime;
-      used_restat = true;
-    }
+  BuildLog::LogEntry* entry = 0;
 
-    if (output_mtime < most_recent_input->mtime()) {
-      EXPLAIN("%soutput %s older than most recent input %s "
-              "(%" PRId64 " vs %" PRId64 ")",
-              used_restat ? "restat of " : "", output->path().c_str(),
-              most_recent_input->path().c_str(),
-              output_mtime, most_recent_input->mtime());
-      return true;
-    }
+  // If this is a restat rule, we may have cleaned the output in a
+  // previous run and stored the command start time in the build log.
+  // We don't want to consider a restat rule's outputs as dirty unless
+  // an input changed since the last run, so we'll skip checking the
+  // output file's actual mtime and simply check the recorded mtime from
+  // the log against the most recent input's mtime (see below)
+  bool used_restat = false;
+  if (edge->GetBindingBool("restat") && build_log() &&
+      (entry = build_log()->LookupByOutput(output->path()))) {
+    used_restat = true;
+  }
+
+  // Dirty if the output is older than the input.
+  if (!used_restat && most_recent_input && output->mtime() < most_recent_input->mtime()) {
+    EXPLAIN("output %s older than most recent input %s "
+            "(%" PRId64 " vs %" PRId64 ")",
+            output->path().c_str(),
+            most_recent_input->path().c_str(),
+            output->mtime(), most_recent_input->mtime());
+    return true;
   }
 
   if (build_log()) {
@@ -346,7 +343,9 @@ bool DependencyScan::RecomputeOutputDirty(const Edge* edge,
         // May also be dirty due to the mtime in the log being older than the
         // mtime of the most recent input.  This can occur even when the mtime
         // on disk is newer if a previous run wrote to the output file but
-        // exited with an error or was interrupted.
+        // exited with an error or was interrupted. If this was a restat rule,
+        // then we only check the recorded mtime against the most recent input
+        // mtime and ignore the actual output's mtime above.
         EXPLAIN("recorded mtime of %s older than most recent input %s (%" PRId64 " vs %" PRId64 ")",
                 output->path().c_str(), most_recent_input->path().c_str(),
                 entry->mtime, most_recent_input->mtime());