Re: Emacs and glibc malloc API change

[Paul Eggert]

Richard Stallman wrote:
>    > So far as we know, recent Emacs should work even after the proposed glibc 
> change
>    > is installed. For example, if you build Emacs 24.5 on a system with the new
>    > glibc, it should still work.
>
> How is that?

Emac's 'configure' script probes the system for its malloc API. If 'configure' 
sees the special glibc malloc API, it normally uses that API; otherwise it falls 
back on a couple of alternatives that do not involve a special malloc API. One 
alternative is to use the standard malloc API without GNU extensions; another is 
to use a malloc implementation that Emacs provides, a modified copy of older 
glibc code that mostly supports the glibc malloc API. Currently the second 
alternative is what Emacs 'configure' will choose on a hypothetical new glibc 
that would lack the special malloc API.

Even without any glibc change, the current approach was reaching its limits. For 
example, even though Cygwin is based on glibc, its malloc doesn't work with 
Emacs and so Emacs 'configure' has special-case code for Cygwin that jumps 
through hoops that almost no one understands. Removing all this gorp from Emacs 
will be a win in the long run, though it'll take some work to code and test. But 
in the meantime Emacs should still work without change.