[CMake] Ignoring Visual Studio 2015 warnings in .inl files

[Niels Dekker - address until 2018]

On 02 Oct 2015 10:53 PM, compix (Wladimir) wrote:
> I'm trying to ignore warnings in VS2015 in .inl files with
> set(CMAKE_CXX_FLAGS "/w")
> set(CMAKE_C_FLAGS "/w")
>
> Unfortunately it doesn't work.
> I'd be glad if anyone could help me out.

First of all, it is often preferable to fix warnings, instead of 
ignoring them. Of course...  :-)

Then it appears that with VS2010 - VS2015, adding "/w" to 
CMAKE_CXX_FLAGS may trigger another warning, "warning D9025: 
overriding '/W1' with '/w'". For details, you may check 
http://public.kitware.com/pipermail/vtkusers/2015-September/092255.html However, 
that issue does not occur when you replace your "/w" by "/W0".

ITK and VTK basically use the following two CMake commands to disable 
MSVC warnings:

   string(REGEX REPLACE "(^| )[/-]W[0-4]( |$)" " "
     CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W0")

For example, look at macro(itk_module_warnings_disable) in 
https://github.com/InsightSoftwareConsortium/ITK/blob/master/CMake/ITKModuleMacros.cmake#L327

Keep in mind that doing so disables all warnings in a project. If you 
want to disable only warnings from header files, you can do #pragma 
warning(push, 0) before the #include statement, and #pragma 
warning(pop) afterwards. But of course, that's just Visual C++, not CMake!

Good luck!

Niels
-- 
Niels Dekker
Scientific programmer
LKEB, Division of Image Processing
Leiden University Medical Center