[boost] Re: [Boost.Regex] [PATCH] Fix GCC 3.3 warnings.

From: Gennaro Prota (gennaro_prota_at_[hidden])
Date: 2003-03-12 12:44:31

On 12 Mar 2003 13:25:36 +0100, larsbj_at_[hidden] (Lars Gullik Bjønnes)
wrote:

>
>With GCC 3.3. there are a couple of warnings in the regex lib.
>The warnings is about of the type of the array index.
>Warning about char being used as index.
>
>This patch fixes that. (by casting to unsigned int).

Actually you are casting to unsigned char. That's safe whether plain
chars are signed or not, because for 3.9.1/3 the range of nonnegative
values of a signed integer type is a subrange of the corresponding
unsigned integer type *and* you are converting only members of the
basic execution character set (guaranteed to be non-negative by
2.2/3).

For arbitrary characters (and plain char = signed char) though that's
not a reassuring practice.

Had I proposed the patch, I would have probably suggested adding 0 to
trigger integral promotion; e.g.:

  class_map[ 0 + '_'] |= char_class_underscore;

BTW I found the program confusing as to what kind of indexing is
intended for class_map (because if one wants to use arbitrary chars to
index an array one declares it as:

  T arr [CHAR_MAX - CHAR_MIN + 1];

and not as

  T arr [UCHAR_MAX + 1];

In either case, then I don't see why indexing by unsigned int, like in
do_update_ctype).

Also, the calls to memset look suspicious, but I've not investigated
further.

Genny.