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From: Pedro Alves <palves@redhat.com>
To: Tom Tromey <tromey@adacore.com>
Cc: gdb-patches@sourceware.org
Subject: Re: [PATCH 2/2] Avoid copying in lookup_name_info
Date: Tue, 31 Mar 2020 20:23:52 +0100	[thread overview]
Message-ID: <3b48b922-0320-504a-36a4-3c14f6d789d7@redhat.com> (raw)
In-Reply-To: <87wo70baqu.fsf@tromey.com>

On 3/31/20 8:11 PM, Tom Tromey wrote:
>>>>>> "Pedro" == Pedro Alves <palves@redhat.com> writes:
> 
> Pedro> I think it would be better for this overload to take a
> Pedro> gdb::string_view instead of a const std::string& .  That
> Pedro> way, it still works if you only have a string_view handy.
> Pedro> As is, there's no way to created a lookup_name_info starting
> Pedro> with a string_view without copying.  WDYT?
> 
> The issue is that there's a trick in the implementation:
> 
>   /* Like the "name" method but guarantees that the returned string is
>      \0-terminated.  */
>   const char *c_str () const
>   {
>     /* Actually this is always guaranteed due to how the class is
>        constructed.  */
>     return m_name.data ();
>   }
> 
> This is needed in some spots.
> 
> However, if we take a string_view at construction, then we'd be
> violating the string_view contract, or we'd need to make a copy -- but
> the former is bad, and the latter is the goal the patch.

I see.  I agree with leaving it as is then.

Thanks,
Pedro Alves



      parent reply	other threads:[~2020-03-31 19:23 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-20 20:49 [PATCH 0/2] Avoid copying in name lookup Tom Tromey
2020-03-20 20:49 ` [PATCH 1/2] Avoid some copying in psymtab.c Tom Tromey
2020-03-31 17:46   ` Pedro Alves
2020-03-31 19:35     ` Tom Tromey
2020-03-20 20:49 ` [PATCH 2/2] Avoid copying in lookup_name_info Tom Tromey
2020-03-23 17:51   ` Christian Biesinger
2020-03-31 13:28     ` Tom Tromey
2020-03-31 18:18   ` Pedro Alves
2020-03-31 19:11     ` Tom Tromey
2020-03-31 19:15       ` Tom Tromey
2020-03-31 19:28         ` Pedro Alves
2020-03-31 19:35           ` Tom Tromey
2020-03-31 19:23       ` Pedro Alves [this message]

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