[www-patch] bugs.html rewrite, part 6: section about upgrading the compiler

[Volker Reichelt]

Hi again,

how about the following version:

The application binary interface (ABI) consists of two components: The first
defines how the elements of classes are laid out, how functions are called,
how function names are mangled etc. The second part deals with the internals
of the objects in libstdc++. Although we strive for a non-changing ABI, we
had to modify it with each major release (i.e. when the first or second part
of the version number changes). If you upgrade your compiler to a new major
release version, you must therefore recompile all libraries that contain C++
code, or you risk linker errors or malfunctioning programs. (Some of our
Java support libraries also contain Java code, so you might want to recompile
all libraries to be save.) However, it should not be necessary to recompile,
if you have changed to a bug-fix release of the same version of the compiler
(i.e. when only the third part of the version number changes); bug-fix
releases are careful to avoid ABI changes.

Regards,
Volker