Jim Meyering <jim <at> meyering.net> writes: > It adds a test to gl_REGEX that ensures that re_compiler_pattern > diagnoses [b-a] as invalid when using RE_SYNTAX_POSIX_EGREP.
Where does POSIX state that this is invalid? So far, I can only see that it is undefined, but have not found any hard requirements that it be a failure. http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html 9.3.5 RE Bracket Expression, step 7: "The starting range point and the ending range point shall be a collating element or collating symbol.... If the represented set of collating elements is empty, it is unspecified whether the expression matches nothing, or is treated as invalid." That said, forcing a hard failure is probably the best QoI implementation of undefined behavior. -- Eric Blake
