[RFC] move COW basic_string and SSO basic_string to separate files

[Ville Voutilainen]

On Tue, 11 Dec 2018 at 18:15, Daniel Krügler <daniel.kruegler@gmail.com> wrote:
>
> Am Di., 11. Dez. 2018 um 15:31 Uhr schrieb Jonathan Wakely <jwakely@redhat.com>:
> >
> > Often when I'm poking around in <bits/basic_string.h> and/or
> > <bits/basic_string.tcc> I lose context and am not sure if I'm looking
> > at a member of the old string type or the new one. I've considered
> > putting comments above each member definition in the .tcc file saying
> > "COW" or "SSO" but asimpler solution might be to move the definitions
> > to separate files.
> >
> > This has the additional advantage of only having to parse the one
> > we're actually using in a given translation unit:
> >
> > #if _GLIBCXX_USE_CXX11_ABI
> > # include <bits/sso_string.h>
> > #else
> > # include <bits/cow_string.h>
> > #endif
> >
> > That's approx. 3500 fewer lines to preprocess per compilation.
> >
> > Are there advantages to having them both in one place? For example,
> > when fixing a bug, is it helpful to be able to find all occurrences of
> > a name in a single file, across both COW and SSO types? Since the
> > members are already spread across the .h and .tcc files, I think that
> > ship already sailed.
>
> I appreciate your suggested refactoring. As you say, assuming that
> searching in the same file would be sufficient to perform a fix in
> both places is an illusion. IMO it is much easier to work with the new
> code structure in two separate files.

Strongly in favor of a file split; the separate files become much less
macro-infested.