[PATCH] Makefile: avoid a fork in Cygwin version check

From: Jonathan Nieder <jrnieder@gmail.com>
Date: Apr 5, 2010, 15:11 UTC
Message-ID: <20100405151059.GB13761@progeny.tock>
In-Reply-To: <4BB9F756.7030701@redhat.com>

From: Eric Blake <eblake@redhat.com>

It is nice to use fewer processes, since forking is so expensive on cygwin. So use a case statement instead of expr.

But does that work to have unbalanced ) in a makefile $(shell)? On the other hand, this is already in a chunk guarded by $(uname_S) being cygwin, and we know that cygwin shells understand:

	case '$(uname_R)' in (1.[1-6].*) echo old;; esac

even though it is not portable to other shells, like NetBSD ash.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
Eric Blake wrote:

>> Eric Blake wrote:

>>> ifeq ($(shell case '$(uname_R)' in (1.[1-6].*) echo old;; esac),old)

[...]

> Junio mentioned he had already queued your first version of the patch;
> are you going to re-submit it with this tweak?

Since the patch to future-proof the version check has already hit master, here’s the change as an independent patch against master.

 Makefile |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/Makefile b/Makefile
index e210a42..767fb66 100644
--- a/Makefile
+++ b/Makefile
@@ -831,7 +831,7 @@ ifeq ($(uname_S),SunOS)
 	BASIC_CFLAGS += -D__EXTENSIONS__ -D__sun__ -DHAVE_ALLOCA_H
 endif
 ifeq ($(uname_O),Cygwin)
-	ifeq ($(shell expr "$(uname_R)" : '1\.[1-6]\.'),4)
+	ifeq ($(shell case '$(uname_R)' in (1.[1-6].*) echo old;; esac),old)
 		NO_D_TYPE_IN_DIRENT = YesPlease
 		NO_D_INO_IN_DIRENT = YesPlease
 		NO_STRCASESTR = YesPlease

-- 
1.7.0.3