[CMake] Visual Studio Warning Level

[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 ;

> What are the 
> equivalents on icc, or any other compiler? What does bjam do?

You would have to consult definitions for other compilers.

> It is easy enough to add some macros to the boost cmake files.
> 
> macro(set_warning_level warning_level)
> 
> if (MSVC)
> 
> elseif (GCC)
> 
> endif()
> 
> macro(set_warning_level warning_level)

Such a code would have to be modified for every new compiler.

- Volodya