eb7b42003a
GCC releases prior to 4.5.0 don't support -std=gnu90 so btrfs-progs won't build at all on older distros. We can detect whether the compiler supports -std=gnu90 and fall back to -std=gnu89 if it doesn't. AX_CHECK_COMPILE_FLAG is the right way to do this, but it depends on autoconf 2.64. AX_GCC_VERSION has been deprecated, so we'll use that only for earlier autoconf versions so we can drop it when we drop support for older autoconf releases. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
21 lines
731 B
Plaintext
21 lines
731 B
Plaintext
dnl We prefer -std=gnu90 but gcc versions prior to 4.5.0 don't support
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dnl it. AX_CHECK_COMPILE_FLAG is the right way to determine whether a
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dnl particular version of gcc supports a flag, but it requires autoconf
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dnl 2.64. Since (for now) we still want to support older releases
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dnl that ship with autoconf 2.63, we the also-deprecated AX_GCC_VERSION
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dnl macro there.
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AC_DEFUN([BTRFS_DETECT_CSTD],
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[
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m4_version_prereq([2.64], [
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AX_CHECK_COMPILE_FLAG([-std=gnu90],
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[BTRFS_CSTD_FLAGS=-std=gnu90],
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[BTRFS_CSTD_FLAGS=-std=gnu89])
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], [
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AX_GCC_VERSION([4], [5], [0],
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[BTRFS_CSTD_FLAGS=-std=gnu90],
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[BTRFS_CSTD_FLAGS=-std=gnu89])
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])
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AC_SUBST([BTRFS_CSTD_FLAGS])
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]) dnl BTRFS_DETECT_CSTD
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