[CMake] Visual Studio Warning Level

[Hendrik Sattler]

Am Saturday 22 November 2008 15:17:12 schrieb Vladimir Prus:
> Michael Jackson wrote:
> > On Nov 22, 2008, at 8:01 AM, Vladimir Prus wrote:
> >> Bill Hoffman wrote:
> >>> Robert Dailey wrote:
> >>>> Hi,
> >>>>
> >>>> I've done some googling on how to set warning levels for visual
> >>>> studio
> >>>> projects generated with CMake and I can't say I really enjoy the
> >>>> proposed solutions I've found. Literally this should be a single
> >>>> function call like:
> >>>>
> >>>> cmake_warning_level( 4 )
> >>>>
> >>>> I expected something simple like above, but instead I found
> >>>> solutions
> >>>> that involved over 10 lines of code and very complex logic. This is
> >>>> really starting to discourage me from using CMake. I won't jump
> >>>> the gun,
> >>>> though, and I'll assume that I just haven't found that magically
> >>>> simple
> >>>> solution yet. Help is greatly appreciated!
> >>>
> >>> CMake does not yet have a feature to flag type of mapping layer like
> >>> that.  It is on the road map for the future.  It could be and is done
> >>> with macros or functions in projects currently.  I am pretty sure the
> >>> boost CMake files have macros that do this.  Anyone have a macro for
> >>> this to post?
> >>
> >> Boost.Build allows you to write:
> >>
> >>        bjam warnings=all
> >>
> >> and this will lead to /W4 on msvc (and to suitable options on other
> >> compilers)
> >>
> >> I don't think boost's CMake setup has this specific option, and
> >> generally,
> >> lacks most of advanced Boost.Build mechanisms necessary to portably
> >> specify build properties.
> >>
> >> - Volodya
> >
> > Vladimar,
> >     Could you please enumerate the advanced options that are missing
> > from boost's cmake setup so that I can start working on implementing
> > those options. (Cross Posting to Boost-CMake as that may become the
> > more appropriate place for this )
>
> It might be a little bit hard to summarize several years of development,
> and a pile of code ;-)
>
> The key components (relevant to the original question of setting compiler
> options more-or-less portably) are:
>
> 1. Mechanism to map from portable build features to compiler options --
> e.g. setting certain flag when the compiler is gcc and target-os=windows
> and link=shared.
>
> 2. Mechanisms to refine features a specific target is built with depending
> on requested features (e.g. on msvc, disable all warnings)
>
> > What are the equivalents in gcc to /w4, /w3, /w2, /w1?
>
> Here's the relevant code:
>
>         toolset.flags gcc.compile OPTIONS <warnings>off : -w ;
>         toolset.flags gcc.compile OPTIONS <warnings>on  : -Wall ;
>         toolset.flags gcc.compile OPTIONS <warnings>all : -Wall -pedantic ;

All warnings on gcc are: -O3 -g -W -Wall -pedantic -std=<somevalue>

On msvc you usually want to disable some very useless warnings (like that 
funny proposal to replace "unsafe" POSIX functions with microsoft-only "safe" 
functions) and that is not handled by /w? as some other warnings may still be 
useful.

On gcc, when using the -pedantic option, you should also set the standards 
version that your program complies to or you will get lots of useless 
warnings/errors. To get some warnings, you need optimisation turned on and 
also use -g or you will never see them.
That may still not be all warnings, depending on OS and on versions of gcc.

I don't see how this could be handled by a simply integer.

HS