diff options
Diffstat (limited to 'configure.ac')
| -rw-r--r-- | configure.ac | 28 |
1 files changed, 19 insertions, 9 deletions
diff --git a/configure.ac b/configure.ac index 281b2c088..6576b4c03 100644 --- a/configure.ac +++ b/configure.ac @@ -39,15 +39,25 @@ AM_MAINTAINER_MODE(enable) AC_CONFIG_MACRO_DIR([m4]) -dnl FIXME: Several AC_RUN_IFELSE programs can return several values -dnl (one for each format to be detected), but the Autoconf manual says: -dnl "This exit status might be that of a failed compilation, or it might -dnl be that of a failed program execution." Unfortunately, we cannot -dnl know whether a non-zero exit status comes from a failed compilation, -dnl so that the detection may be incorrect. To avoid this problem, write -dnl a test program for each possible format? Alternatively, the test -dnl program could output the result of the format detection to a file -dnl and return with the 0 exit status if it could do that successfully. +dnl Some AC_RUN_IFELSE programs need to be able to return several values +dnl (e.g., in a format detection, one for each possible format). But the +dnl Autoconf manual says: "This exit status might be that of a failed +dnl compilation, or it might be that of a failed program execution." +dnl Unfortunately, we cannot know whether a non-zero exit status comes +dnl from a failed compilation, so that the detection may be incorrect. +dnl Since failures generally occur with a small exit status, the value 77 +dnl is reserved for skipped tests by Autoconf, and values larger than 125 +dnl have special meanings in POSIX[*], good candidates for success are 0 +dnl and values from 80 to 125. +dnl https://tldp.org/LDP/abs/html/exitcodes.html suggests the range 64-113 +dnl but note that /usr/include/sysexits.h now allocates previously unused +dnl exit codes from 64 - 78 (for various kinds of errors). +dnl +dnl Alternatively, the test program could output the result to a file and +dnl return with the 0 exit status if it could do that successfully. +dnl +dnl [*] 2.8.2 Exit Status for Commands +dnl https://pubs.opengroup.org/onlinepubs/9699919799//utilities/V3_chap02.html#tag_18_08_02 test_CFLAGS=${CFLAGS+set} |