I just upgraded & updated my homebrew and now if I run brew doctor, I get the following errors and it fails to run. May I deleted the unexpected header files or is there a better solution?
Warning: Your XQuartz (2.7.6) is outdated
Please install XQuartz 2.7.7:
https://xquartz.macosforge.org
Warning: Unbrewed header files were found in /usr/local/include. If you didn't put them there on purpose they could cause problems when building Homebrew formulae, and may need to be deleted.
Unexpected header files: /usr/local/include/node/ares.h /usr/local/include/node/ares_version.h /usr/local/include/node/eio-emul.h /usr/local/include/node/ev-emul.h /usr/local/include/node/node.h /usr/local/include/node/node_buffer.h /usr/local/include/node/node_object_wrap.h /usr/local/include/node/node_version.h /usr/local/include/node/uv-private/eio.h /usr/local/include/node/uv-private/ev.h /usr/local/include/node/uv-private/ngx-queue.h /usr/local/include/node/uv-private/tree.h /usr/local/include/node/uv-private/uv-unix.h /usr/local/include/node/uv-private/uv-win.h /usr/local/include/node/uv.h /usr/local/include/node/v8-debug.h /usr/local/include/node/v8-preparser.h /usr/local/include/node/v8-profiler.h /usr/local/include/node/v8-testing.h /usr/local/include/node/v8.h /usr/local/include/node/v8stdint.h
Basically, you just need to upgrade the XQuartz in your system and ignore all the other warnings.
You may build some software that utilise X11 components, so just go to https://xquartz.macosforge.org/, download and install the latest version.
It is obvious that you install node.js without using homebrew so that the header files are added into /use/local/include/ not via homebrew and confuse it. Unless you encounter some kind of problems as mentioned in the warning message, you can just ignore them.