From d19e3a5b21f28c07886801616e02e08eab64a7d8 Mon Sep 17 00:00:00 2001 From: Ronald Wampler Date: Thu, 7 Jul 2016 16:45:54 -0400 Subject: [PATCH 1/2] Makefile: add NEEDS_LIBRT to optionally link with librt We unconditionally link with librt, when HAVE_CLOCK_GETTIME is defined. But clock_gettime() has been available in most libc implementations for some time now (e.g., for glibc since version 2.17) and no longer requires linking with librt. Furthermore, commit a6c3c63 (configure.ac: check for clock_gettime() and CLOCK_MONOTONIC) will automatically determined which library (libc or librt) is required for linking when checking for clock_gettime(). The assumption to unconditionally link with librt was OK, since either almost every Unix-like system provides a version of librt for backwards compatibility or other systems, namely Windows or OS X, never provided clock_gettime(). However, in the latest release of OS X (macOS Sierra), this function has been added to OS X libc version. As a result, when running the configuration script, HAVE_CLOCK_GETTIME is set and since librt is not present, it causes a linker error. This patches requires those not building via the configuration scripts to define NEEDS_LIBRT in addition to HAVE_CLOCK_GETTIME, if needed. Signed-off-by: Ronald Wampler Signed-off-by: Junio C Hamano --- Makefile | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/Makefile b/Makefile index e11e626d05..949925e946 100644 --- a/Makefile +++ b/Makefile @@ -351,9 +351,12 @@ all:: # Define GMTIME_UNRELIABLE_ERRORS if your gmtime() function does not # return NULL when it receives a bogus time_t. # -# Define HAVE_CLOCK_GETTIME if your platform has clock_gettime in librt. +# Define HAVE_CLOCK_GETTIME if your platform has clock_gettime. # -# Define HAVE_CLOCK_MONOTONIC if your platform has CLOCK_MONOTONIC in librt. +# Define HAVE_CLOCK_MONOTONIC if your platform has CLOCK_MONOTONIC. +# +# Define NEEDS_LIBRT if your platform requires linking with librt (glibc version +# before 2.17) for clock_gettime and CLOCK_MONOTONIC. # # Define USE_PARENS_AROUND_GETTEXT_N to "yes" if your compiler happily # compiles the following initialization: @@ -1465,13 +1468,16 @@ endif ifdef HAVE_CLOCK_GETTIME BASIC_CFLAGS += -DHAVE_CLOCK_GETTIME - EXTLIBS += -lrt endif ifdef HAVE_CLOCK_MONOTONIC BASIC_CFLAGS += -DHAVE_CLOCK_MONOTONIC endif +ifdef NEEDS_LIBRT + EXTLIBS += -lrt +endif + ifdef HAVE_BSD_SYSCTL BASIC_CFLAGS += -DHAVE_BSD_SYSCTL endif From 52fcec75ce3a010ef4b2bbd1161da5e5fe301ec7 Mon Sep 17 00:00:00 2001 From: Eric Wong Date: Sun, 10 Jul 2016 22:16:44 +0000 Subject: [PATCH 2/2] config.mak.uname: define NEEDS_LIBRT under Linux, for now My Debian wheezy LTS system is still on glibc 2.13; and LTS distros may use older glibc, still, so lets not unnecessarily break things out-of-the-box. We seem to assume Linux is using glibc in our Makefiles anyways, so I don't think this will introduce new breakage for users of alternative libc implementations. Signed-off-by: Eric Wong Signed-off-by: Junio C Hamano --- config.mak.uname | 2 ++ 1 file changed, 2 insertions(+) diff --git a/config.mak.uname b/config.mak.uname index a88f13989a..22958a8d6f 100644 --- a/config.mak.uname +++ b/config.mak.uname @@ -36,6 +36,8 @@ ifeq ($(uname_S),Linux) HAVE_DEV_TTY = YesPlease HAVE_CLOCK_GETTIME = YesPlease HAVE_CLOCK_MONOTONIC = YesPlease + # -lrt is needed for clock_gettime on glibc <= 2.16 + NEEDS_LIBRT = YesPlease HAVE_GETDELIM = YesPlease SANE_TEXT_GREP=-a endif