Homebrew 0.9.3

Superenv

Superenv is an attempt to improve build-reliability and end-build-quality. It is:

• The user’s PATH is ignored. Thus, only tools we authorize can be used during builds[^1].
• PATH is reconstructed. For example: /usr/local/Library/$ENV/4.3:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin.
• /usr/local/Library/$ENV/4.3 (superbin[^2]) contains wrapper-scripts for cc, etc.
• We unset all build-related ENV variables.
• Build systems now pick their preferred compilers from superbin.
• Superbin scripts are smart. They forcibly insert all the include-paths and library-paths that Homebrew formulae need to compile, and remove flags that break builds.

Because we are working with a practically virgin environment, we are essentially giving build-systems the kind of environments that the developers are used to building with. This makes them more reliable. By stepping into the toolchain between the build-system and the compiler, we have complete control over the toolchain. We can prevent a good deal of breakage, and ensure that Homebrew uses the same executables that the compiler sees (and not those bundled with the system).

So:

• We no longer worry about MacPorts/Fink being installed†
• We no longer worry about system duplicates†
• We override common tools and fix them—we no longer have to do so with workarounds in affected formula, waiting for a fix from Apple.
• Builds are forcibly optimized how we want, and debug info forcibly removed.

† (nearly as much, anyway)

[^1]: Formula can opt-into re-adding the user’s PATH again. Some formulae need this.

[^2]: Indeed; this is selected based on Xcode version.