tests: make GIT_TEST_GETTEXT_POISON a boolean

Change the GIT_TEST_GETTEXT_POISON variable from being "non-empty?" to
being a more standard boolean variable.

Since it needed to be checked in both C code and shellscript (via test
-n) it was one of the remaining shellscript-like variables. Now that
we have "env--helper" we can change that.

There's a couple of tricky edge cases that arise because we're using
git_env_bool() early, and the config-reading "env--helper".

If GIT_TEST_GETTEXT_POISON is set to an invalid value die_bad_number()
will die, but to do so it would usually call gettext(). Let's detect
the special case of GIT_TEST_GETTEXT_POISON and always emit that
message in the C locale, lest we infinitely loop.

As seen in the updated tests in t0017-env-helper.sh there's also a
caveat related to "env--helper" needing to read the config for trace2
purposes.

Since the C_LOCALE_OUTPUT prerequisite is lazy and relies on
"env--helper" we could get invalid results if we failed to read the
config (e.g. because we'd loop on includes) when combined with
e.g. "test_i18ngrep" wanting to check with "env--helper" if
GIT_TEST_GETTEXT_POISON was true or not.

I'm crossing my fingers and hoping that a test similar to the one I
removed in the earlier "config tests: simplify include cycle test"
change in this series won't happen again, and testing for this
explicitly in "env--helper"'s own tests.

This change breaks existing uses of
e.g. GIT_TEST_GETTEXT_POISON=YesPlease, which we've documented in
po/README and other places. As noted in [1] we might want to consider
also accepting "YesPlease" in "env--helper" as a special-case.

But as the lack of uproar over 6cdccfce1e ("i18n: make GETTEXT_POISON
a runtime option", 2018-11-08) demonstrates the audience for this
option is a really narrow set of git developers, who shouldn't have
much trouble modifying their test scripts, so I think it's better to
deal with that minor headache now and make all the relevant GIT_TEST_*
variables boolean in the same way than carry the "YesPlease"
special-case forward.

1. https://public-inbox.org/git/xmqqtvckm3h8.fsf@gitster-ct.c.googlers.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/config.c b/config.c
index 374cb33005..b985d60fa4 100644
--- a/config.c
+++ b/config.c
@@ -956,6 +956,15 @@ static void die_bad_number(const char *name, const char *value)
 	if (!value)
 		value = "";
 
+	if (!strcmp(name, "GIT_TEST_GETTEXT_POISON"))
+		/*
+		 * We explicitly *don't* use _() here since it would
+		 * cause an infinite loop with _() needing to call
+		 * use_gettext_poison(). This is why marked up
+		 * translations with N_() above.
+		 */
+		die(bad_numeric, value, name, error_type);
+
 	if (!(cf && cf->name))
 		die(_(bad_numeric), value, name, _(error_type));