Re: [PATCH v3] i18n: make GETTEXT_POISON a runtime option

On Thu, Nov 01, 2018 at 07:31:15PM +0000, Ævar Arnfjörð Bjarmason wrote:

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.
   This is probably the wrong thing to do and should be followed-up
   with something similar to ae59a4e44f ("travis: run tests with
   GIT_TEST_SPLIT_INDEX", 2018-01-07) to re-use an existing test setup
   for running in the GIT_TEST_GETTEXT_POISON mode.

I'm of two minds about this.  Sure, now it's not a compile time
option, so we can spare a dedicated compilation, and sparing resources
is good, of course.

However, checking test failures in the 'linux-gcc' build job is always
a bit of a hassle, because it's not enough to look at the output of
the failed test, but I also have to check which one of the two test
runs failed (i.e. the "regular" or one with all the GIT_TEST_* knobs
turned on).  Adding a second test run with GIT_TEST_GETTEXT_POISON
enabled to an other build job (e.g. 'linux-clang') would then bring
this hassle to that build job as well.

Furthermore, occasionally a build job is slower than usual (whatever
the reason might be), which can be an issue when running the test
suite twice, as it can exceed the time limit.

Anyway, we can think about this later.

In any case, GIT_TEST_GETTEXT_POISON definitely should not be enabled
in the same "catch-all" test run with all other GIT_TEST_* variables,
because it would mess up any translated error messages that might pop
up in a test failure, and then we wouldn't have any idea about what
went wrong.

 * 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.

See also [3] 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/87woq7b58k.fsf@evledraar.gmail.com/
3. https://public-inbox.org/git/878t2pd6yu.fsf@evledraar.gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason <redacted>
---

Now:

 * The new i18n helper is gone. We just use "test -n" semantics for
   $GIT_TEST_GETTEXT_POISON

 * We error out in the Makefile if you're still saying
   GETTEXT_POISON=YesPlease.

   This makes more sense than just making it a synonym since now this
   also needs to be defined at runtime.

OK, I think erroring out is better than silently ignoring
GETTEXT_POISON=YesPlease.  However, the commit message only mentions
that GETTEXT_POISON is gone, but perhaps this should be mentioned
there as well.

 * The caveat with avoiding test_lazy_prereq is gone (although there's
   still some unrelated bug there worth looking into).

 * We call use_gettext_poison() really early to avoid any reentrancy
   issue with getenv().

OK, makes sense.

 	verbose test -n "$__git_merge_strategies" &&
 	. "$GIT_BUILD_DIR/contrib/completion/git-completion.bash" &&

Why do these two helper functions call test_have_prereq (a function
that doesn't even fit on my screen) instead of a simple

  test -n "$GIT_TEST_GETTEXT_POISON"

GIT_TEST_GETTEXT_POISON=1 will influence even those git commands that
are executed during initialization of test-lib and the test repo:

  $ GIT_TEST_GETTEXT_POISON=1 ./t0000-basic.sh -v
  # GETTEXT POISON #expecting success: 
  <....>

It should say:

  Initialized empty Git repository in <... path ...>
  expecting success:

See https://public-inbox.org/git/20181022202241.18629-2-szeder.dev@gmail.com/
for a bit of code that you might find worthy to steal.