From 30afe1d6895c4dd597634869732a35aeaae47af1 Mon Sep 17 00:00:00 2001
From: Evan Martin <martine@danga.com>
Date: Sat, 4 Dec 2010 15:06:27 -0800
Subject: [PATCH] show referencing node in 'file missing' message

---
 build.cc      | 5 ++++-
 build_test.cc | 3 ++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/build.cc b/build.cc
index 919e4ac..6282b5f 100644
--- a/build.cc
+++ b/build.cc
@@ -14,7 +14,10 @@ bool Plan::AddSubTarget(Node* node, vector<Node*>* stack, string* err) {
   Edge* edge = node->in_edge_;
   if (!edge) {  // Leaf node.
     if (node->dirty_) {
-      *err = "'" + node->file_->path_ + "' missing "
+      string referenced;
+      if (!stack->empty())
+        referenced = ", needed by '" + stack->back()->file_->path_ + "',";
+      *err = "'" + node->file_->path_ + "'" + referenced + " missing "
              "and no known rule to make it";
     }
     return false;
diff --git a/build_test.cc b/build_test.cc
index 26d1080..81f2fbe 100644
--- a/build_test.cc
+++ b/build_test.cc
@@ -350,7 +350,8 @@ TEST_F(BuildTest, MissingInput) {
   string err;
   Dirty("in1");
   EXPECT_FALSE(builder_.AddTarget("cat1", &err));
-  EXPECT_EQ("'in1' missing and no known rule to make it", err);
+  EXPECT_EQ("'in1', needed by 'cat1', missing and no known rule to make it",
+            err);
 }
 
 TEST_F(BuildTest, MissingTarget) {
-- 
2.7.4