[bug-gawk] Attribute((pure)) with impure function causes test failures

[Neil Cahill]

With the gawk-3.1.6 source bz2, gawk compiles incorrectly on my Gentoo system with gcc-4.4.5 -O2 -fno-inline.  This causes 4 tests to fail (eg. datanonl.awk), all related to character classes like /[[:alpha:]]/ not being recognized.

I tracked this down to the following function:

/* regex_internal.c */
static unsigned char
internal_function __attribute((pure))
re_string_fetch_byte_case(...)

This function modifies a value pstr->cur_idx which is also used in a macro (re_string_eoi).  Calling the macro after calling the function can mean an old value of cur_idx is used.  This happens in regcomp.c in the function parse_bracket_symbol, which caused those character classes to go unrecognized.

A simple fix is to remove the pure attribute from the function.  This seems to be present in 3.1.8 as well, as both exhibited the same problem.

Neil Cahill.