Clang "Error: Process completed with exit code 1."

Builds done when I submit a pull request to the Adafruit_GFX library fail with “Error: Process completed with exit code 1.” but no indication of what caused the failure. The code builds and runs locally. I’ve tried:

  1. Convert to unix line endings.
  2. Move to a different branch.

It still fails, and I’ve no indication why. Any suggestions on what I could look at?

Thanks.