We have recently noticed that our CI does not always notice variables
that may be used uninitialized. While it is expected that compiler
warnings aren't perfect, this one was a but puzzling because it was
rather obvious that the variable can be uninitialized.

Many compiler warnings unfortunately depend on the optimization level
used by the compiler. While `-O0` for example will disable a lot of
warnings altogether because optimization passes go away, `-O2`, which is
our default optimization level used in CI, may optimize specific code
away or even double down on undefined behaviour. Interestingly, this
specific instance that triggered the investigation does get noted by GCC
when using `-Og`.

While we could adapt all jobs to compile with `-Og` now, that would
potentially mask other warnings that only get diagnosed with `-O2`.
Instead, only adapt the "pedantic" job to compile with `-Og`.

Signed-off-by: Patrick Steinhardt <redacted>
---
 ci/run-build-and-tests.sh | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/ci/run-build-and-tests.sh b/ci/run-build-and-tests.sh
index 98dda42045..e78e19e4a6 100755
--- a/ci/run-build-and-tests.sh
+++ b/ci/run-build-and-tests.sh

@@ -44,6 +44,15 @@ pedantic)
 	# Don't run the tests; we only care about whether Git can be
 	# built.
 	export DEVOPTS=pedantic
+	# Warnings generated by compilers are unfortunately specific to the
+	# optimization level. With `-O0`, many warnings won't be shown at all,
+	# whereas the optimizations performed by our default optimization level
+	# `-O2` will mask others. We thus use `-Og` here just so that we have
+	# at least one job with a different optimization level so that we can
+	# overall surface more warnings.
+	cat >config.mak <<-EOF
+	export CFLAGS=-Og
+	EOF
 	run_tests=
 	;;
 esac

-- 
2.45.2.409.g7b0defb391.dirty