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Diffstat (limited to 'm4/btrfs_detect_cstd.m4')
| -rw-r--r-- | m4/btrfs_detect_cstd.m4 | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/m4/btrfs_detect_cstd.m4 b/m4/btrfs_detect_cstd.m4 new file mode 100644 index 00000000..f0c45d97 --- /dev/null +++ b/m4/btrfs_detect_cstd.m4 @@ -0,0 +1,20 @@ +dnl We prefer -std=gnu90 but gcc versions prior to 4.5.0 don't support +dnl it. AX_CHECK_COMPILE_FLAG is the right way to determine whether a +dnl particular version of gcc supports a flag, but it requires autoconf +dnl 2.64. Since (for now) we still want to support older releases +dnl that ship with autoconf 2.63, we the also-deprecated AX_GCC_VERSION +dnl macro there. +AC_DEFUN([BTRFS_DETECT_CSTD], +[ + m4_version_prereq([2.64], [ + AX_CHECK_COMPILE_FLAG([-std=gnu90], + [BTRFS_CSTD_FLAGS=-std=gnu90], + [BTRFS_CSTD_FLAGS=-std=gnu89]) + ], [ + AX_GCC_VERSION([4], [5], [0], + [BTRFS_CSTD_FLAGS=-std=gnu90], + [BTRFS_CSTD_FLAGS=-std=gnu89]) + ]) + AC_SUBST([BTRFS_CSTD_FLAGS]) +]) dnl BTRFS_DETECT_CSTD + |