Subject: Re: [PATCH v2 2/2] sha1dc: optionally use sha1collisiondetection as a submodule

From: Junio C Hamano <[email-masked]>
Date: Mon, 22 May 2017 11:48:01 +0900

Junio C Hamano <[email-masked]> writes:

> But when somebody (like me?) feels strongly enough, such a change
> can always come on top of this patch, so let's have this
> manual-configuration-only version as our first step.

Just so that I have something I can come back to, here it is with a
log message.

-- >8 --
Subject: [PATCH] sha1collisiondetection: automatically enable when submodule is populated

If a user wants to experiment with the version of collision
detecting sha1 from the submodule, the user needed to not just
populate the submodule but also needed to turn the knob.

A Makefile trick is easy enough to do so, so let's do this.  When
somebody with a copy of the submodule populated wants not to use it,
that can be done by overriding it in config.mak or from the command
line, e.g. "make DC_SHA1_SUBMODULE= all".

Signed-off-by: Junio C Hamano <[email-masked]>
---
 Makefile | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Makefile b/Makefile
index 6baad1669e..8d33936a12 100644
--- a/Makefile
+++ b/Makefile
@@ -989,6 +989,10 @@ EXTLIBS =
 
 GIT_USER_AGENT = git/$(GIT_VERSION)
 
+ifeq ($(wildcard sha1collisiondetection/lib/sha1.h),sha1collisiondetection/lib/sha1.h)
+DC_SHA1_SUBMODULE = auto
+endif
+
 include config.mak.uname
 -include config.mak.autogen
 -include config.mak
-- 
2.13.0-440-g3ce6d2d5b8