User Environment

User environment variables and make.conf settings get passed on to ebuilds. This can be useful — it's how CFLAGS and friends work, for example — but it can also result in nasty build-breaking variables like LANG and LC_ALL getting through. Currently no sanitisation is performed upon the environment.

Filtering Variables

Certain variables will really really upset certain build systems. A good example is the locale variables (LC_ALL et al), which if set to certain values will cause sed or grep expressions involving the likes of [A-Z] to fail. The easiest thing to do here is to unset or sanitise the offending variables inside pkg_setup.

The simplest way to unset all locale-related variables is:

pkg_setup() {
	# Unset all locale related variables, they can make the
	# build fail.

	eval unset ${!LC_*} LANG

Not Filtering Variables

On the other hand, it is extremely important that certain user preferences are honoured as far as possible. A good example is CFLAGS, which must be respected (selective filtering is fine, but outright ignoring is not). Ignoring CFLAGS when compiling can cause serious problems:

Some packages do this by accident. For example, one might see CFLAGS=-Wall in To fix this, either sed in the user's CFLAGS, or (the better solution) change the variable to AM_CFLAGS, which will automatically be merged with the user's settings. LDFLAGS also should be respected.