MacOS clang via Homebrew broken under Mojave `wchar.h`

Question

Unsurprisingly the new update of OSX Mojave broke my llvm installation in Homebrew, these are the steps I tried:

xcode-select --install # Complained, so I in         


        

Answer 1

This is a well known issue of the latest macos. Try to set this environment variable, it must fix this issue.

export LIBCLANG_SYSTEM_INCLUDE_DIR="/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include"

Answer 2

Here's how I solved it, given I have paper deadlines and this is the least of my worries:

1. Disabled SIP on my Mac
2. Symlinked /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include to /usr/include as is expected in POSIX environments.
3. Re-enabled SIP.

Now I got to make a note to re-do this everytime a new OSX update comes out. This has not broken anything wrt Xcode, clang (from brew) etc so I'll keep it. Be advised though, this might break your stuff.

Answer 3

I did something dumb but it did fix the problem... Not sure if it will work for your computer though.

Here is what I did: I originally installed c++ using Homebrew on my MacBook on Mojave... so I had to manually install the Xcode CommandLineTools using the installer found at /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg . Then I copied the "c++" folder contents from to folder /Library/Developer/CommandLineTools/usr/include/c++/v1 to the folder where I want the missing file to be, at /usr/local/Cellar/gcc/8.2.0/include/c++/8.2.0 , while replacing files with the same names.

The trick worked, since now the missing file "wchar.h" is right where it should be... I could have simlinked, in hindsight. Cheers!