@matheusbsbs / matheus-bagliano / commits / d19e3a5b21

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

Ronald Wampler committed Jul 7, 2016 at 16:45 UTC d19e3a5b21f28c07886801616e02e08eab64a7d8
1 file changed +9 -3
Makefile
+9 -3
@@ -351,9 +351,12 @@ all::
351 # Define GMTIME_UNRELIABLE_ERRORS if your gmtime() function does not
352 # return NULL when it receives a bogus time_t.
353 #
354 -# Define HAVE_CLOCK_GETTIME if your platform has clock_gettime in librt.
354 +# Define HAVE_CLOCK_GETTIME if your platform has clock_gettime.
355 #
356 -# Define HAVE_CLOCK_MONOTONIC if your platform has CLOCK_MONOTONIC in librt.
356 +# Define HAVE_CLOCK_MONOTONIC if your platform has CLOCK_MONOTONIC.
357 +#
358 +# Define NEEDS_LIBRT if your platform requires linking with librt (glibc version
359 +# before 2.17) for clock_gettime and CLOCK_MONOTONIC.
360 #
361 # Define USE_PARENS_AROUND_GETTEXT_N to "yes" if your compiler happily
362 # compiles the following initialization:
@@ -1465,13 +1468,16 @@ endif
1468
1469 ifdef HAVE_CLOCK_GETTIME
1470 BASIC_CFLAGS += -DHAVE_CLOCK_GETTIME
1468 - EXTLIBS += -lrt
1471 endif
1472
1473 ifdef HAVE_CLOCK_MONOTONIC
1474 BASIC_CFLAGS += -DHAVE_CLOCK_MONOTONIC
1475 endif
1476
1477 +ifdef NEEDS_LIBRT
1478 + EXTLIBS += -lrt
1479 +endif
1480 +
1481 ifdef HAVE_BSD_SYSCTL
1482 BASIC_CFLAGS += -DHAVE_BSD_SYSCTL
1483 endif