commit 08e362e7bbc48e1d9155095059ec11a162d936e9
author Bruce Dawson <brucedawson@chromium.org> Fri Jan 12 01:42:08 2018 +0000
committer Commit Bot <commit-bot@chromium.org> Fri Jan 12 01:42:08 2018 +0000
tree 7df96c90c86d024c97e1272660e591538f9db620
parent 3d7411fe4b2162a3be1fd55417f791bc347534d4

Print args.gn if gn clean fails to write it

For mysterious reasons "gn clean" sometimes fails to write args.gn,
which is a surprisingly frustrating bit of data loss. This change gets
gn to do the most that it can in this case - print args.gn to the
console.

I tested by forcing a failure to write args.gn and verified that the
printout looked good and was usable.

Bug: 627656
Change-Id: Ifbd6ddd8c851da13e482e8a0f617b218e29ede08
Reviewed-on: https://chromium-review.googlesource.com/862697
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#528842}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: b7c2c4ec1b901041af24793d679e3acaec4b750d

tools/gn/command_clean.cc

diff --git a/tools/gn/command_clean.cc b/tools/gn/command_clean.cc
index 70def6d..f4b64af 100644
--- a/tools/gn/command_clean.cc
+++ b/tools/gn/command_clean.cc
@@ -105,7 +105,11 @@
   if (!args_contents.empty()) {
     if (base::WriteFile(gn_args_file, args_contents.data(),
                         static_cast<int>(args_contents.size())) == -1) {
-      Err(Location(), std::string("Failed to write args.gn.")).PrintToStdout();
+      // Print the previous contents of args.gn since otherwise it is lost for
+      // good which can be quite frustrating.
+      Err(Location(),
+          "Failed to write args.gn. Old contents was:\n\n" + args_contents)
+          .PrintToStdout();
       return 1;
     }
   }