I just tried to compile package abiword-2.2.9-3 with a prerelease of the
GNU C compiler version 4.1. It said

1.

xap_UnixPSGraphics.cpp:1213: warning: operation on "cursor" may be undefined.

The source code is

                g_snprintf(reinterpret_cast<char *>(&hexbuf[0]), sizeof(hexbuf), "%.2X", ( static_cast<UT_Byte>( ( static_cast<float>(*cursor++) * static_cast<float>(1) +
                                                                                  static_cast<float>(*cursor++) * static_cast<float>(1) +
                                                                                  static_cast<float>(*cursor++) * static_cast<float>(1) ) /
                                                                                  static_cast<float>(3.0) )) );

I agree with the compiler - this code seems to be undefined. 

There are no guarantees in C that arguments are evaluated left to right.
Suggest code rework.

BTW, the email address of the author [ jeff@abisource.com ] seems to
be broken.