This is the mail archive of the
mailing list for the GCC project.
Re: [PATCH 00/89] Compile-time gimple-checking
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Richard Sandiford <rdsandiford at googlemail dot com>, David Malcolm <dmalcolm at redhat dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 23 Apr 2014 16:19:35 +0200
- Subject: Re: [PATCH 00/89] Compile-time gimple-checking
- Authentication-results: sourceware.org; auth=none
- References: <1398099480-49147-1-git-send-email-dmalcolm at redhat dot com> <877g6hhjti dot fsf at talisman dot default> <1398186366 dot 26834 dot 95 dot camel at surprise> <87lhuxfb0n dot fsf at talisman dot default> <ac354302-43e9-4ecb-9706-662814a77982 at email dot android dot com>
On Tue, Apr 22, 2014 at 9:42 PM, Richard Biener
> On April 22, 2014 8:56:56 PM CEST, Richard Sandiford <firstname.lastname@example.org> wrote:
>>David Malcolm <email@example.com> writes:
>>> Alternatively we could change the is-a.h API to eliminate this
>>> discrepancy, and keep the typedefs; giving something like the
>>> static void
>>> dump_gimple_switch (pretty_printer *buffer, gimple_switch gs, int
>>> int flags)
>>> [...later, within pp_gimple_stmt_1:]
>>> case GIMPLE_SWITCH:
>>> dump_gimple_switch (buffer, as_a <gimple_switch> (gs), spc,
>>> which is concise, readable, and avoid the change in pointerness
>>> to the "gimple" typedef; the local decls above would look like this:
>>> gimple some_stmt; /* note how this doesn't have a star... */
>>> gimple_assign assign_stmt; /* ...and neither do these */
>>> gimple_cond assign_stmt;
>>> gimple_phi phi;
>>> I think this last proposal is my preferred API, but it requires the
>>> change to is-a.h
>>> Attached is a proposed change to the is-a.h API that elimintates the
>>> discrepancy, allowing the use of typedefs with is-a.h (doesn't yet
>>> compile, but hopefully illustrates the idea). Note how it changes
>>> API to match C++'s dynamic_cast<> operator i.e. you do
>>> Q* q = dyn_cast<Q*> (p);
>>> Q* q = dyn_cast<Q> (p);
>>Thanks for being flexible. :-) I like this version too FWIW, for the
>>reason you said: it really does look like a proper C++ cast.
> Indeed. I even wasn't aware it is different Than a c++ cast...
It would be nice if you can change that with a separate patch posted
in a separate thread to be more visible.
Also I see you introduce a const_FOO class with every FOO one.
I wonder whether, now that we have C++, can address const-correctness
in a less awkward way than with a typedef. Can you try to go back
in time and see why we did with that in the first place? ISTR that
it was "oh, if we were only using C++ we wouldn't need to jump through
>>If we ever decide to get rid of the typedefs (maybe at the same time as
>>using "auto") then the choice might be different, but that would be a
>>more systematic and easily-automated change than this one.