29538c89cd
This fixes an issue where at least in Xcode 11.0, `make` uses
`/var/tmp` as a fallback for temporary files unless `TMPDIR` is set:
```
$ strings "$(xcrun -f make)" | grep -B 3 fopen
TMPDIR
/var/tmp/
GmXXXXXX
fopen (temporary file)
```
Given that Homebrew filtered `TMPDIR`, and the `/var/tmp` directory may
not be writable for non-root users, this would cause Homebrew’s
build environment to error out:
```
$ brew ruby -e 'puts ENV["TMPDIR"]; puts `: | make -f -`'
```
```
Ignoring bigdecimal-2.0.0 because its extensions are not built. Try: gem pristine bigdecimal --version 2.0.0
[…]
Ignoring zlib-1.1.0 because its extensions are not built. Try: gem pristine zlib --version 1.1.0
make: *** fopen (temporary file): Permission denied. Stop.
```
In practice, this would break `brew audit`, `brew style`, and other
commands, which would run `make` to build native gem extensions.
This commit sets `TMPDIR` to `${HOMEBREW_TEMP}` in the gem environment, which
mirrors the behaviour we already have in other places.
We choose `HOMEBREW_TEMP` because that’s user-controlled but also falls
back to `/tmp` in case `TMPDIR` is not set in the user’s environment.
Thanks to Bo Anderson for helping find the bug.
CC: Bo Anderson <mail@boanderson.me>
Library
This directory contains all the code run by the official brew and brew cask commands in Homebrew and all formulae (package descriptions) in taps (repositories containing formulae) in Taps subdirectories.