Re: [boost] vc_8 and 1.33.1 [regex]

From: George M. Garner Jr. (gmgarner_at_[hidden])
Date: 2005-12-11 14:49:39

John,

I think that the problem is at regex_traits_defaults.hpp line 191:

static const character_pointer_range<charT>* ranges_end = ranges + 
(sizeof(ranges)/sizeof(ranges[0]));

Your algorithm doesn't allow for compiler data alignment. With 8-byte data 
alignment (now the default with VC8) sizeof(ranges) == ((19*4)/8+1)*8 == 80. 
The compiler warning is correct  get_default_class_id() may return a value 
between -1 and 20.  Add 1 to this return value and you get a range of 0-21 
which exceeds the size of masks in
lookup_classname_imp().

Note that similar code at win32_regex_traits.hpp line 536 is not affected 
because the size of masks is 8-byte aligned (for now at least).  64-bit 
compilers require 8-byte alignment so I assume that this code will not 
compile correctly on those platforms as well.

If you must use this construct ("sizeof(ranges)/sizeof(ranges[0]") then 
static assert that this formula yields the same size as your array.

I see that there are a few other non-trivial warnings in my build of the 
regex library.  My examples were not intended to be exhaustive but to 
illustrate the utility of incorporating this into boost's QA.

Regards,

George.