GNU Emacs has long been using signed types (typically ptrdiff_t) to count
objects. This has the advantage that signed integer overflow can be detected
automatically on some platforms (unfortunately, size_t arithmetic silently wraps
around). I would like to change the Gnulib modules that GNU Emacs uses, to use
this style. The main effect on these modules' non-Emacs users would be:
* They accept ptrdiff_t counts, not size_t counts. Normally sizes are computed
by new functions like xwgrowalloc. When the caller computes sizes by hand, it is
the caller's responsibility to check for integer overflow.
* They report errors via xwalloc_die, not xalloc_die.
I've also changed the modules that GNU grep uses, as a test that this idea works
on non-Emacs applications.
As this is a nontrivial change, I'll post the Gnulib patches first without
installing them, for discussion.
