On Wed, Nov 15, 2017 at 11:14:20AM -0800, Stefan Beller wrote:

quoted

I did manually disable HAVE_VARIADIC_MACROS and confirmed that the
result builds and passes the test suite (though I suspect that GIT_TRACE
is not well exercised by the suite).

GIT_TRACE is exercised in the test suite (though I am not sure if it counts
as well-exercised) in t7406-submodule-update.sh for example, which uses
GIT_TRACE to obtain information about thread parallelism used by Git, as
that is not observable otherwise, if we assume that performance tests in the
standard test suite are not feasible.

Hmm, yeah, that might cover it. What I'm worried about is that we missed
some case where NULL needed to become &trace_default_key. But I did look
for that in my review of the patch and didn't notice any spots. And the
coverage in t7406 should help.

quoted

After your patch, the GIT_TRACE=1 time remains the same but GIT_TRACE=0
drops to 1ms.

So does that mean we can use a lot more tracing now?

Yep, that's the intent.

-Peff