[Bug libstdc++/57704] New: std::char_traits<char>::lt is not standards-compliant

[tudorb at fb dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57704

            Bug ID: 57704
           Summary: std::char_traits<char>::lt is not standards-compliant
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tudorb at fb dot com

Created attachment 30356
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30356&action=edit
simple example to illustrate the bug

The C++11 standard says in 21.2.3.1 (struct char_traits<char>):

"The two-argument members eq and lt shall be defined identically to the
built-in operators == and < for type unsigned char."

However, this is not the case if char is signed (tested using gcc 4.1.2, 4.6.2,
and 4.7.1 on x86_64, but the trunk version of char_traits.h is the same);
char_traits<char>::lt compares the two values as char, not as unsigned char.

The attached program should print 1 twice when this bug is fixed.