it's not clear to me at the moment whether the code that was removed
(and which is now being re-added) is needed, but it's far from being a
no-op, and i don't want to risk breaking regex in this release.
to deal with the fact that the public headers may be used with pre-c99
compilers, __restrict is used in place of restrict, and defined
appropriately for any supported compiler. we also avoid the form
[restrict] since older versions of gcc rejected it due to a bug in the
original c99 standard, and instead use the form *restrict.
the "< 0" test was always false due to use of an unsigned type. this
resulted in infinite loops on 32-bit machines (adding -1U to a pointer
is the same as adding -1) and crashes on 64-bit machines (offsetting
the string pointer by 4gb-1b when an illegal sequence was hit).
the main practical results of this change are
1. the regex code is no longer subject to LGPL; it's now 2-clause BSD
2. most (all?) popular nonstandard regex extensions are supported
I hesitate to call this a "sync" since both the old and new code are
heavily modified. in one sense, the old code was "more severely"
modified, in that it was actively hostile to non-strictly-conforming
expressions. on the other hand, the new code has eliminated the
useless translation of the entire regex string to wchar_t prior to
compiling, and now only converts multibyte character literals as
needed.
in the future i may use this modified TRE as a basis for writing the
long-planned new regex engine that will avoid multibyte-to-wide
character conversion entirely by compiling multibyte bracket
expressions specific to UTF-8.
Rich Felker
Szabolcs Nagy