Bug fix for format library

From: Fred Jackson (yg-boost-users_at_[hidden])
Date: 2002-11-04 04:31:25

I found a bug in the format library and fixed it.

  strm << boost::format("%64.64s") % "hello";

gave an access violation.  It was caused by passing an
argument greater than the string length to std::string::erase.
I added a check so as not to try to erase text that is not there.

Here is a diff of my small fix.
< is feed_args.hpp from the boost_1_29_0 distribution.
> is my fixed file.

158c158,162
<     if (specs.truncate_ >= 0)
---
>     // @@@@@ fjackson 20021022 Added test to make sure we don't call
>     // std::string::erase with an arg greater than the length - this
>     // caused an access violation, noted on outputting a short string
>     // with a %64.64 format specifier.
>     if (specs.truncate_ >= 0 && specs.truncate_ < res.length())