This is actually two related bugs. The first problem is that sometimes running "ninja -C out\Default" will cause the "Regenerating ninja files" step to be run infinitely.

The second problem is that if you halt gn with Ctrl+C while it is generating .ninja files then it leaves the build directory in a bad state where subsequent builds will not generate the ninja files at all.

Both bugs are triggered by the same root cause - renaming an output directory and not running "gn gen" on it. This is presumably not supported behavior, but the failure mode should be more elegant, especially since the Ctrl+C issue can be reproduce in other ways.

Here is what the output looks like (Ctrl+C was typed during the third regenerating of ninja files):

  D:\src\chromium\src>ninja -C out\debug_analyze
  ninja: Entering directory `out\debug_analyze'
  [1/1] Regenerating ninja files
  [1/1] Regenerating ninja files
  [0/1] Regenerating ninja files
  ninja: error: rebuilding 'build.ninja': interrupted by user

  D:\src\chromium\src>ninja -C out\debug_analyze
  ninja: error: loading 'build.ninja': The system cannot find the file specified.

  ninja: Entering directory `out\debug_analyze'

The initial issue is because build.ninja contains the path to the original output directory, the .ninja files are generated there, but the dependency checking expects them to be in the new (renamed) directory, which is why the infinite regenerating happens.

The second issue is more general and therefore more important. If the "Regenerating ninja files" step is halted with Ctrl+C then the build.ninja file is often deleted and subsequent builds will fail. This can occur even without the unsupported directory renaming.
 

Deleted: out_dir_contents.zip 688 bytes

out_dir_contents.zip 688 bytes Download