Xiretza . authored Jan 01, 2022 and Allan McRae committed Jan 02, 2022

>From gcc(1):

-ffile-prefix-map=old=new
	[...] Specifying this option is equivalent to specifying all the
	individual -f*-prefix-map options. This can be used to make reproducible
	builds that are location independent.

Specifically, this additionally enables -fmacro-prefix-map=, which causes
prefix mapping to be applied to expansions of __FILE__ and similar macros.

Without this option, if source files are compiled by passing the
absolute file path to the compiler (as done by e.g. cmake), any
expansions of __FILE__ (e.g. from uses of assert()) will contain
$srcdir.

Signed-off-by: Allan McRae <allan@archlinux.org>