Re: [cmake-developers] [CMake] [MSVC] Setting warning level on target feels like long-time bug

[Mateusz Loskot]

On Sun, 9 Dec 2018 at 14:09, Marc CHEVRIER  wrote:
>
> I think the discussion is shifting from the initial problem which was 
> unwanted warning « Command line warning D9025: overriding '/W3' with '/W4' ».

I disagree with your opinion.
Fixing just the warning would be a symptomatic treatment.

> Changing defaults is not a good idea from my point of view because relying on 
> defaults can be problematic if Microsoft decide to change the default 
> behaviour.

Although I think it is a long shot at something that is (highly)
unlikely to change, YAGNI consideration,
I understand CMake developers may be reluctant to change the long-time defaults.

> The real question is how to manage cleanly target specific flags overriding 
> global or directory defaults?

From end-user point of view (I have not checekd CMake implementation),
I'd either do not explicitly set -W defaults or strip any -W option
prior re-setting
with (possibly) new value passed to target_compile_options.

Best regards,
-- 
Mateusz Loskot, http://mateusz.loskot.net
-- 

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Re: [cmake-developers] [CMake] [MSVC] Setting warning level on target feels like long-time bug

[Mateusz Loskot]

On Sun, 9 Dec 2018 at 12:14, Craig Scott  wrote:
>
> From what I understand from a very limited quick search just now,
> it seems that /W3 is the default warning level for Visual Studio

Yes, it is the default level indeed.

> but CMake explicitly adds it as a default compiler flag in 
> CMAKE__FLAGS_INIT.
> This makes me wonder if it has always been the default, otherwise it isn't 
> clear why it was deemed necessary to add it.

Yes, I'd suspect it was added as 'just in case'  too eagerly.

> More to the point, unless there's a reason not to, perhaps we could consider 
> removing it from the default flags CMake sets.
> I think this would largely address the situation you're describing and 
> shouldn't actually change the behavior of existing projects.

Yes, it should be removed.
Unless I'm missing an important reason behind the explicit -W3.

No, "This has been the default since CMake began" [1], is not enough
rationale to keep it.

In the old times of manual editing of CMAKE_CXX_FLAGS, it was not a huge deal
- in fact, fiddling with CMAKE_CXX_FLAGS was quite canonical way of
doing things..
But with the advent of target_compile_options, the string call
requirement is just unacceptable.

[1] https://gitlab.kitware.com/cmake/cmake/issues/18317

> I've CC'ed the developer's list and suggest that follow-up discussion should 
> occur there.

FYI, I've just subscribed to the developer's list.

Best regards,
-- 
Mateusz Loskot, http://mateusz.loskot.net
-- 

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