From: "François Dumont" <frs.dumont@gmail.com>
To: Jonathan Wakely <jwakely@redhat.com>
Cc: libstdc++ <libstdc++@gcc.gnu.org>
Subject: Re: [committed 03/12] libstdc++: Add macros for the inline namespace std::_V2
Date: Mon, 16 May 2022 19:04:10 +0200 [thread overview]
Message-ID: <885f26d0-3208-cbe0-6429-69d2862cbfbf@gmail.com> (raw)
In-Reply-To: <CACb0b4kOvaTHX7EpcEhb1nfvw4XKXpRkZxpL_bAt5y5TfsnB-Q@mail.gmail.com>
On 16/05/22 18:19, Jonathan Wakely wrote:
> On Mon, 16 May 2022 at 05:28, François Dumont via Libstdc++
> <libstdc++@gcc.gnu.org> wrote:
>> Based on what you told me recently maybe this patch is better. It does
>> not change the link errors.
> We need to be a little careful about just removing those macros.
>
> For definitions that use qualified names, the macros are not needed.
> For example:
>
> namespace std { inline namespace __8 {
> struct foo {
> void bar(); // #1
> };
> } }
>
> namespace std {
> void foo::bar() { } // #2
> }
>
> The definition at #2 works correctly, because name lookup for 'foo'
> finds std::__8::foo, so it's a definition of the member declared at
> #1.
>
> But if we have a definition using an unqualified name, that doesn't
> work the same. For example:
>
> namespace std { inline namespace __8 {
> void func(); // #3
> } }
>
> namespace std {
> void func() { } // #4
> }
>
> The definition at #4 doesn't need to do any name lookup, so it just
> defines (and declares) a new function directly in namespace std. This
> means we have std::__8::func declared at #3 and std::func declared at
> #4, and so trying to call std::func() would be ambiguous.
>
> So we don't need to _add_ the macros to files where the symbols are
> already being defined correctly (which is why your recent patch was
> not needed). And we can remove them from _some_ source files. But if
> we remove all source files, some of those removals would be wrong.
>
And thanks for this explanation too, I wasn't considering all use cases
indeed.
So no rush to do any cleanup, good.
next prev parent reply other threads:[~2022-05-16 17:04 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-13 12:40 [committed 01/12] libstdc++: Disable Doxygen GROUP_NESTED_COMPOUNDS config option Jonathan Wakely
2022-05-13 12:40 ` [committed 02/12] libstdc++: Fix typo in doxygen @headerfile command Jonathan Wakely
2022-05-13 12:40 ` [committed 03/12] libstdc++: Add macros for the inline namespace std::_V2 Jonathan Wakely
2022-05-14 15:36 ` François Dumont
2022-05-16 4:27 ` François Dumont
2022-05-16 16:19 ` Jonathan Wakely
2022-05-16 17:04 ` François Dumont [this message]
2022-05-16 16:13 ` Jonathan Wakely
2022-05-16 16:59 ` François Dumont
2022-05-13 12:40 ` [committed 04/12] libstdc++: Improve doxygen docs for std::pointer_traits Jonathan Wakely
2022-05-13 12:40 ` [committed 05/12] libstdc++: Improve doxygen docs for <system_error> Jonathan Wakely
2022-05-13 12:40 ` [committed 06/12] libstdc++: Improve doxygen docs for <atomic> Jonathan Wakely
2022-05-13 12:40 ` [committed 07/12] libstdc++: Improve doxygen docs for <regex> Jonathan Wakely
2022-05-13 12:40 ` [committed 08/12] libstdc++: Improve doxygen docs for std::allocator Jonathan Wakely
2022-05-13 12:40 ` [committed 09/12] libstdc++: Improve doxygen docs for algorithms and more Jonathan Wakely
2022-05-13 12:40 ` [committed 10/12] libstdc++: Improve doxygen docs for <thread> and <future> Jonathan Wakely
2022-05-13 12:40 ` [committed 11/12] libstdc++: Improve doxygen docs for some of <memory> Jonathan Wakely
2022-05-13 12:40 ` [committed 12/12] libstdc++: Improve doxygen docs for <mutex> Jonathan Wakely
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