* guix/gexp.scm (assume-source-relative-file-name): New macro.
(local-file): Use assume-source-relative-file-name to look up a non-literal
file relative to the current source directory.
* doc/guix.texi (G-expressions): Document it.
* tests/gexp.scm ("local-file, non-literal source relative file name"):
New test.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
Change-Id: I18573c8c7a6c87e8351b34412f9d26bb23b068b4