One of Autoconf's regression tests includes: # If Autoconf is too old, or the user has turned caching off, skip: AT_CHECK([aclocal || { ret=$?; test $ret -eq 63 && ret=77; exit $ret; }], [], [], [ignore])
The effect is to skip the rest of the test if aclocal's exit status is 63. This code was written in 2006, I can't find any documentation on what it means for aclocal to exit with code 63, and I also can't find any code in the current automake git repo that looks like it would make aclocal exit with code 63. (*automake* can exit with code 63 under some circumstances, but it really looks like aclocal never will.) Does anyone remember what situation this might have been trying to detect? Thanks, zw