* lib/autotest/general.m4 (AT_DATA): Special case an empty data
file, since zsh botches empty here-docs.
* doc/autoconf.texi (Writing Testsuites)<AT_DATA>: Document that
empty contents is allowed.
* tests/autotest.at (AT_DATA): New test.
Reported by Ralf Wildenhues.
Signed-off-by: Eric Blake<address@hidden>
---
Independent of the doc patch about the zsh bug, it turned out
to be pretty easy to work around it in AT_DATA.
By testing the tests/ change independently from the rest of the
patch, I've confirmed that bash passes both before and after, while
zsh fails before but passes after the rest of the patch.
This does not protect against:
AT_DATA([file], [macro_that_expands_to_nothing])
but I suspect that is enough of a corner case to not worry about
unless we get a specific report of someone needing it.