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From: Jason Merrill <jason@redhat.com>
To: Volker Reichelt <v.reichelt@netcologne.de>
Cc: gcc-patches List <gcc-patches@gcc.gnu.org>,
	Martin Sebor <msebor@gmail.com>
Subject: Re: {PATCH] New C++ warning -Wcatch-value
Date: Wed, 31 May 2017 20:55:00 -0000	[thread overview]
Message-ID: <CADzB+2ke4weniKcY-ZdR1W_tSEsXjobVpdvmg12J-Z5nKsL+6w@mail.gmail.com> (raw)
In-Reply-To: <tkrat.211d2cf50f51b06c@netcologne.de>

On Tue, May 30, 2017 at 2:14 AM, Volker Reichelt
<v.reichelt@netcologne.de> wrote:
> On 24 May, Jason Merrill wrote:
>> On Mon, May 15, 2017 at 3:58 PM, Martin Sebor <msebor@gmail.com> wrote:
>>>> So how about the following then? I stayed with the catch part and added
>>>> a parameter to the warning to let the user decide on the warnings she/he
>>>> wants to get: -Wcatch-value=n.
>>>> -Wcatch-value=1 only warns for polymorphic classes that are caught by
>>>> value (to avoid slicing), -Wcatch-value=2 warns for all classes that
>>>> are caught by value (to avoid copies). And finally -Wcatch-value=3
>>>> warns for everything not caught by reference to find typos (like pointer
>>>> instead of reference) and bad coding practices.
>>>
>>> It seems reasonable to me.  I'm not too fond of multi-level
>>> warnings since few users take advantage of anything but the
>>> default, but this case is simple and innocuous enough that
>>> I don't think it can do harm.
>>
>>>> Bootstrapped and regtested on x86_64-pc-linux-gnu.
>>>> OK for trunk?
>>
>> OK.
>
> Committed.
>
>>>> If so, would it make sense to add -Wcatch-value=1 to -Wextra or even -Wall?
>>>> I would do this in a seperate patch, becuase I haven't checked what that
>>>> would mean for the testsuite.
>>>
>>> I can't think of a use case for polymorphic slicing that's not
>>> harmful so unless there is a common one that escapes me, I'd say
>>> -Wall.
>>
>> Agreed.  But then you'll probably want to allow -Wno-catch-value to turn it off.
>
> So how about the following then?
> Bootstrapped and regtested on x86_64-pc-linux-gnu.
> OK for trunk?

OK, thanks.

Jason

  reply	other threads:[~2017-05-31 20:37 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-01  8:38 Volker Reichelt
2017-05-03  3:34 ` Martin Sebor
2017-05-07 20:28   ` Volker Reichelt
2017-05-08  3:18     ` Martin Sebor
2017-05-08 13:14       ` Jason Merrill via gcc-patches
2017-05-14 15:30       ` Volker Reichelt
2017-05-15 20:03         ` Martin Sebor
2017-05-24 20:13           ` Jason Merrill
2017-05-30  6:22             ` Volker Reichelt
2017-05-31 20:55               ` Jason Merrill [this message]
2017-06-05 10:55           ` Volker Reichelt
2017-06-05 19:08             ` Jason Merrill

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