commit 3cb0851989749a6ff630d4a7c978b44281feb41e
author Dan Willemsen <dwillemsen@google.com> Mon Jan 13 19:04:14 2020 -0800
committer Dan Willemsen <dwillemsen@google.com> Mon Jan 13 22:20:00 2020 -0800
tree 59d12222df2a60ac093088f790619dac71f4e849
parent 62c124ccbcc60b8c23fb07ed2f6ddced080324cf

Add better warning output for stale output files

I'm running into this warning in some unexpected cases, so provide some
extra information when it hits.

Test: ninja_tests (run by build_prebuilts.sh)
Change-Id: I294cf0d38dad3324d7fc697bff94356f07f3df13

src/build.cc

diff --git a/src/build.cc b/src/build.cc
index 5a7221d..ad5d409 100644
--- a/src/build.cc
+++ b/src/build.cc
@@ -603,13 +603,16 @@
     vector<Node*> nodes_cleaned;
 
     TimeStamp newest_input = 0;
+    Node* newest_input_node = nullptr;
     for (vector<Node*>::iterator i = edge->inputs_.begin();
          i != edge->inputs_.end() - edge->order_only_deps_; ++i) {
       TimeStamp input_mtime = (*i)->mtime();
       if (input_mtime == -1)
         return false;
-      if (input_mtime > newest_input)
+      if (input_mtime > newest_input) {
         newest_input = input_mtime;
+        newest_input_node = (*i);
+      }
     }
 
     for (vector<Node*>::iterator o = edge->outputs_.begin();
@@ -631,8 +634,10 @@
         } else if (!restat && new_mtime < newest_input) {
           if (!result->output.empty())
             result->output.append("\n");
-          result->output.append("ninja: Missing `restat`? An output file is older than the most recent input: ");
+          result->output.append("ninja: Missing `restat`? An output file is older than the most recent input:\n output: ");
           result->output.append((*o)->path());
+          result->output.append("\n  input: ");
+          result->output.append(newest_input_node->path());
           if (config_.old_output_should_err) {
             result->status = ExitFailure;
           }

src/build_test.cc

diff --git a/src/build_test.cc b/src/build_test.cc
index 2400f18..e7b0e55 100644
--- a/src/build_test.cc
+++ b/src/build_test.cc
@@ -2573,7 +2573,7 @@
   EXPECT_TRUE(builder.Build(&err));
   EXPECT_EQ("", err);
 
-  EXPECT_EQ("ninja: Missing `restat`? An output file is older than the most recent input: out", status_.last_output_);
+  EXPECT_EQ("ninja: Missing `restat`? An output file is older than the most recent input:\n output: out\n  input: in", status_.last_output_);
 
   builder.command_runner_.release();
 }
@@ -2609,7 +2609,7 @@
   EXPECT_FALSE(builder.Build(&err));
   EXPECT_EQ("subcommand failed", err);
 
-  EXPECT_EQ("ninja: Missing `restat`? An output file is older than the most recent input: out", status_.last_output_);
+  EXPECT_EQ("ninja: Missing `restat`? An output file is older than the most recent input:\n output: out\n  input: in", status_.last_output_);
 
   builder.command_runner_.release();
 }