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Re: {PATCH] New C++ warning -Wcatch-value
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