Makefile & test-tool: replace "DC_SHA1" variable with a "define"

Address the root cause of technical debt we've been carrying since
sha1collisiondetection was made the default in [1]. In a preceding
commit we narrowly fixed a bug where the "DC_SHA1" variable would be
unset (in combination with "NO_APPLE_COMMON_CRYPTO=" on OSX), even
though we had the sha1collisiondetection library enabled.

But the only reason we needed to have such a user-exposed knob went
away with [1], and it's been doing nothing useful since then. We don't
care if you define DC_SHA1=*, we only care that you don't ask for any
other SHA-1 implementation. If it turns out that you didn't, we'll use
sha1collisiondetection, whether you had "DC_SHA1" set or not.

As a result of this being confusing we had e.g. [2] for cmake and the
recent [3] for ci/lib.sh setting "DC_SHA1" explicitly, even though
this was always a NOOP.

A much simpler way to do this is to stop having the Makefile and
CMakeLists.txt set "DC_SHA1" to be picked up by the test-lib.sh, let's
instead add a trivial "test-tool sha1-is-sha1dc". It returns zero if
we're using sha1collisiondetection, non-zero otherwise.

1. e6b07da2780 (Makefile: make DC_SHA1 the default, 2017-03-17)
2. c4b2f41b5f5 (cmake: support for testing git with ctest, 2020-06-26)
3. 1ad5c3df35a (ci: use DC_SHA1=YesPlease on osx-clang job for CI,
   2022-10-20)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/ci/lib.sh b/ci/lib.sh
index 1808e3b1ce..24d20a5d64 100755
--- a/ci/lib.sh
+++ b/ci/lib.sh
@@ -260,7 +260,7 @@ macos-latest)
 	else
 		MAKEFLAGS="$MAKEFLAGS PYTHON_PATH=$(which python2)"
 		MAKEFLAGS="$MAKEFLAGS NO_APPLE_COMMON_CRYPTO=NoThanks"
-		MAKEFLAGS="$MAKEFLAGS DC_SHA1=YesPlease NO_OPENSSL=NoThanks"
+		MAKEFLAGS="$MAKEFLAGS NO_OPENSSL=NoThanks"
 	fi
 	;;
 esac