i18n: make GETTEXT_POISON a runtime option

Change the GETTEXT_POISON compile-time + runtime GIT_GETTEXT_POISON
test parameter to only be a GIT_TEST_GETTEXT_POISON=<non-empty?>
runtime parameter, to be consistent with other parameters documented
in "Running tests with special setups" in t/README.

When I added GETTEXT_POISON in bb946bba76 ("i18n: add GETTEXT_POISON
to simulate unfriendly translator", 2011-02-22) I was concerned with
ensuring that the _() function would get constant folded if NO_GETTEXT
was defined, and likewise that GETTEXT_POISON would be compiled out
unless it was defined.

But as the benchmark in my [1] shows doing a one-off runtime
getenv("GIT_TEST_[...]") is trivial, and since GETTEXT_POISON was
originally added the GIT_TEST_* env variables have become the common
idiom for turning on special test setups.

So change GETTEXT_POISON to work the same way. Now the
GETTEXT_POISON=YesPlease compile-time option is gone, and running the
tests with GIT_TEST_GETTEXT_POISON=[YesPlease|] can be toggled on/off
without recompiling.

This allows for conditionally amending tests to test with/without
poison, similar to what 859fdc0c3c ("commit-graph: define
GIT_TEST_COMMIT_GRAPH", 2018-08-29) did for GIT_TEST_COMMIT_GRAPH. Do
some of that, now we e.g. always run the t0205-gettext-poison.sh test.

I did enough there to remove the GETTEXT_POISON prerequisite, but its
inverse C_LOCALE_OUTPUT is still around, and surely some tests using
it can be converted to e.g. always set GIT_TEST_GETTEXT_POISON=.

Notes on the implementation:

 * We still compile a dedicated GETTEXT_POISON build in Travis
   CI. Perhaps this should be revisited and integrated into the
   "linux-gcc" build, see ae59a4e44f ("travis: run tests with
   GIT_TEST_SPLIT_INDEX", 2018-01-07) for prior art in that area. Then
   again maybe not, see [2].

 * We now skip a test in t0000-basic.sh under
   GIT_TEST_GETTEXT_POISON=YesPlease that wasn't skipped before. This
   test relies on C locale output, but due to an edge case in how the
   previous implementation of GETTEXT_POISON worked (reading it from
   GIT-BUILD-OPTIONS) wasn't enabling poison correctly. Now it does,
   and needs to be skipped.

 * The getenv() function is not reentrant, so out of paranoia about
   code of the form:

       printf(_("%s"), getenv("some-env"));

   call use_gettext_poison() in our early setup in git_setup_gettext()
   so we populate the "poison_requested" variable in a codepath that's
   won't suffer from that race condition.

 * We error out in the Makefile if you're still saying
   GETTEXT_POISON=YesPlease to prompt users to change their
   invocation.

 * We should not print out poisoned messages during the test
   initialization itself to keep it more readable, so the test library
   hides the variable if set in $GIT_TEST_GETTEXT_POISON_ORIG during
   setup. See [3].

See also [4] for more on the motivation behind this patch, and the
history of the GETTEXT_POISON facility.

1. https://public-inbox.org/git/871s8gd32p.fsf@evledraar.gmail.com/
2. https://public-inbox.org/git/20181102163725.GY30222@szeder.dev/
3. https://public-inbox.org/git/20181022202241.18629-2-szeder.dev@gmail.com/
4. https://public-inbox.org/git/878t2pd6yu.fsf@evledraar.gmail.com/

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

9 files changed, 40 insertions, 19 deletions

diff --git a/t/README b/t/README
index 8847489..25c4ba3 100644
--- a/t/README
+++ b/t/README
@@ -301,6 +301,12 @@ that cannot be easily covered by a few specific test cases. These
 could be enabled by running the test suite with correct GIT_TEST_
 environment set.
 
+GIT_TEST_GETTEXT_POISON=<non-empty?> turns all strings marked for
+translation into gibberish if non-empty (think "test -n"). Used for
+spotting those tests that need to be marked with a C_LOCALE_OUTPUT
+prerequisite when adding more strings for translation. See "Testing
+marked strings" in po/README for details.
+
 GIT_TEST_SPLIT_INDEX=<boolean> forces split-index mode on the whole
 test suite. Accept any boolean values that are accepted by git-config.
 
diff --git a/t/lib-gettext.sh b/t/lib-gettext.sh
index eec757f..755f421 100644
--- a/t/lib-gettext.sh
+++ b/t/lib-gettext.sh
@@ -12,7 +12,7 @@ export GIT_TEXTDOMAINDIR GIT_PO_PATH
 
 . "$GIT_BUILD_DIR"/git-sh-i18n
 
-if test_have_prereq GETTEXT && ! test_have_prereq GETTEXT_POISON
+if test_have_prereq GETTEXT && test_have_prereq C_LOCALE_OUTPUT
 then
 	# is_IS.UTF-8 on Solaris and FreeBSD, is_IS.utf8 on Debian
 	is_IS_locale=$(locale -a 2>/dev/null |
diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
index 4d23373..b656600 100755
--- a/t/t0000-basic.sh
+++ b/t/t0000-basic.sh
@@ -274,7 +274,7 @@ test_expect_success 'pretend we have a mix of all possible results' "
 	EOF
 "
 
-test_expect_success 'test --verbose' '
+test_expect_success C_LOCALE_OUTPUT 'test --verbose' '
 	test_must_fail run_sub_test_lib_test \
 		test-verbose "test verbose" --verbose <<-\EOF &&
 	test_expect_success "passing test" true
diff --git a/t/t0205-gettext-poison.sh b/t/t0205-gettext-poison.sh
index 438e778..a06269f 100755
--- a/t/t0205-gettext-poison.sh
+++ b/t/t0205-gettext-poison.sh
@@ -5,13 +5,15 @@
 
 test_description='Gettext Shell poison'
 
+GIT_TEST_GETTEXT_POISON=YesPlease
+export GIT_TEST_GETTEXT_POISON
 . ./lib-gettext.sh
 
-test_expect_success GETTEXT_POISON 'sanity: $GIT_INTERNAL_GETTEXT_SH_SCHEME" is poison' '
+test_expect_success 'sanity: $GIT_INTERNAL_GETTEXT_SH_SCHEME" is poison' '
     test "$GIT_INTERNAL_GETTEXT_SH_SCHEME" = "poison"
 '
 
-test_expect_success GETTEXT_POISON 'gettext: our gettext() fallback has poison semantics' '
+test_expect_success 'gettext: our gettext() fallback has poison semantics' '
     printf "# GETTEXT POISON #" >expect &&
     gettext "test" >actual &&
     test_cmp expect actual &&
@@ -20,7 +22,7 @@ test_expect_success GETTEXT_POISON 'gettext: our gettext() fallback has poison s
     test_cmp expect actual
 '
 
-test_expect_success GETTEXT_POISON 'eval_gettext: our eval_gettext() fallback has poison semantics' '
+test_expect_success 'eval_gettext: our eval_gettext() fallback has poison semantics' '
     printf "# GETTEXT POISON #" >expect &&
     eval_gettext "test" >actual &&
     test_cmp expect actual &&
diff --git a/t/t3406-rebase-message.sh b/t/t3406-rebase-message.sh
index 0392e36..2bdcf83 100755
--- a/t/t3406-rebase-message.sh
+++ b/t/t3406-rebase-message.sh
@@ -77,7 +77,7 @@ test_expect_success 'rebase -n overrides config rebase.stat config' '
 #     "Does not point to a valid commit: invalid-ref"
 #
 # NEEDSWORK: This "grep" is fine in real non-C locales, but
-# GETTEXT_POISON poisons the refname along with the enclosing
+# GIT_TEST_GETTEXT_POISON poisons the refname along with the enclosing
 # error message.
 test_expect_success 'rebase --onto outputs the invalid ref' '
 	test_must_fail git rebase --onto invalid-ref HEAD HEAD 2>err &&
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index 826987c..72b9b37 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -254,9 +254,9 @@ test_expect_success 'checkout to detach HEAD (with advice declined)' '
 test_expect_success 'checkout to detach HEAD' '
 	git config advice.detachedHead true &&
 	git checkout -f renamer && git clean -f &&
-	git checkout renamer^ 2>messages &&
-	test_i18ngrep "HEAD is now at 7329388" messages &&
-	(test_line_count -gt 1 messages || test -n "$GETTEXT_POISON") &&
+	GIT_TEST_GETTEXT_POISON= git checkout renamer^ 2>messages &&
+	grep "HEAD is now at 7329388" messages &&
+	test_line_count -gt 1 messages &&
 	H=$(git rev-parse --verify HEAD) &&
 	M=$(git show-ref -s --verify refs/heads/master) &&
 	test "z$H" = "z$M" &&
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 175f83d..3c6b185 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -1697,7 +1697,8 @@ test_expect_success 'sourcing the completion script clears cached commands' '
 	verbose test -z "$__git_all_commands"
 '
 
-test_expect_success !GETTEXT_POISON 'sourcing the completion script clears cached merge strategies' '
+test_expect_success 'sourcing the completion script clears cached merge strategies' '
+	GIT_TEST_GETTEXT_POISON= &&
 	__git_compute_merge_strategies &&
 	verbose test -n "$__git_merge_strategies" &&
 	. "$GIT_BUILD_DIR/contrib/completion/git-completion.bash" &&
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 78d8c37..2f42b36 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -755,16 +755,16 @@ test_cmp_bin() {
 
 # Use this instead of test_cmp to compare files that contain expected and
 # actual output from git commands that can be translated.  When running
-# under GETTEXT_POISON this pretends that the command produced expected
+# under GIT_TEST_GETTEXT_POISON this pretends that the command produced expected
 # results.
 test_i18ncmp () {
-	test -n "$GETTEXT_POISON" || test_cmp "$@"
+	! test_have_prereq C_LOCALE_OUTPUT || test_cmp "$@"
 }
 
 # Use this instead of "grep expected-string actual" to see if the
 # output from a git command that can be translated either contains an
 # expected string, or does not contain an unwanted one.  When running
-# under GETTEXT_POISON this pretends that the command produced expected
+# under GIT_TEST_GETTEXT_POISON this pretends that the command produced expected
 # results.
 test_i18ngrep () {
 	eval "last_arg=\${$#}"
@@ -779,7 +779,7 @@ test_i18ngrep () {
 		error "bug in the test script: too few parameters to test_i18ngrep"
 	fi
 
-	if test -n "$GETTEXT_POISON"
+	if test_have_prereq !C_LOCALE_OUTPUT
 	then
 		# pretend success
 		return 0
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 897e6fc..edee38a 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -95,6 +95,16 @@ PAGER=cat
 TZ=UTC
 export LANG LC_ALL PAGER TZ
 EDITOR=:
+
+# GIT_TEST_GETTEXT_POISON should not influence git commands executed
+# during initialization of test-lib and the test repo. Back it up,
+# unset and then restore after initialization is finished.
+if test -n "$GIT_TEST_GETTEXT_POISON"
+then
+	GIT_TEST_GETTEXT_POISON_ORIG=$GIT_TEST_GETTEXT_POISON
+	unset GIT_TEST_GETTEXT_POISON
+fi
+
 # A call to "unset" with no arguments causes at least Solaris 10
 # /usr/xpg4/bin/sh and /bin/ksh to bail out.  So keep the unsets
 # deriving from the command substitution clustered with the other
@@ -1104,13 +1114,15 @@ test -n "$USE_LIBPCRE1" && test_set_prereq LIBPCRE1
 test -n "$USE_LIBPCRE2" && test_set_prereq LIBPCRE2
 test -z "$NO_GETTEXT" && test_set_prereq GETTEXT
 
+if test -n "$GIT_TEST_GETTEXT_POISON_ORIG"
+then
+	GIT_TEST_GETTEXT_POISON=$GIT_TEST_GETTEXT_POISON_ORIG
+	unset GIT_TEST_GETTEXT_POISON_ORIG
+fi
+
 # Can we rely on git's output in the C locale?
-if test -n "$GETTEXT_POISON"
+if test -z "$GIT_TEST_GETTEXT_POISON"
 then
-	GIT_GETTEXT_POISON=YesPlease
-	export GIT_GETTEXT_POISON
-	test_set_prereq GETTEXT_POISON
-else
 	test_set_prereq C_LOCALE_OUTPUT
 fi