config.mak.uname: add hint on uname_R for MacOS X

I always have to scratch my head every time I see this cryptic
pattern "[15678]\."; leave a short note to remind the maintainer
and the reviewers.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/config.mak.uname b/config.mak.uname
index f8e12c96260730aa34a76f306d7fba578152ca15..fde196f63ab4b6f6a31dfe490c93b65f059ef756 100644 (file)
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -86,6 +86,10 @@ ifeq ($(uname_S),Darwin)
        NEEDS_CRYPTO_WITH_SSL = YesPlease
        NEEDS_SSL_WITH_CRYPTO = YesPlease
        NEEDS_LIBICONV = YesPlease
+       # Note: $(uname_R) gives us the underlying Darwin version.
+       # - MacOS 10.0.* and MacOS 10.1.0 = Darwin 1.*
+       # - MacOS 10.x.* = Darwin (x+4).* for (1 <= x)
+       # i.e. "begins with [15678] and a dot" means "10.4.* or older".
        ifeq ($(shell expr "$(uname_R)" : '[15678]\.'),2)
                OLD_ICONV = UnfortunatelyYes
                NO_APPLE_COMMON_CRYPTO = YesPlease