[CMake] CMake 3.6.0-rc4 now ready for testing!

[Hendrik Sattler]

Zitat von Brad King <brad.king at kitware.com>:

> On 06/29/2016 05:05 PM, Hendrik Sattler wrote:
>>> * The "InstallRequiredSystemLibraries" module learned a new
>>>  "CMAKE_INSTALL_UCRT_LIBRARIES" option to enable app-local deployment
>>>  of the Windows Universal CRT libraries with Visual Studio 2015.
>>
>> Maybe the help should note that this is only needed when targeting
>> WindowsXP.
>
> It is also useful for deploying to Windows 7 machines that have
> not had updates installed to provide the UCRT libraries.  I've
> updated the documentation to show Windows XP as an example:
>
>  InstallRequiredSystemLibraries: Document UCRT option use case
>  https://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=dab3ccf2

Thanks.

>>> * A "CMAKE_TRY_COMPILE_PLATFORM_VARIABLES" variable was added for
>>>  use by toolchain files to specify platform-specific variables that
>>>  must be propagated by the "try_compile()" command into test
>>>  projects.
>>
>> Can someone please add an example to the help.
>
> Done:
>
>  Help: Document CMAKE_TRY_COMPILE_PLATFORM_VARIABLES example
>  https://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=c05d240e
>
>> E.g. I tried to make the initial try_compile() to respect my
>> CMAKE_CXX_FLAGS_INIT variable that gets defined in my toolchain file...
>
> CMAKE_CXX_FLAGS_INIT is not documented for use in a toolchain file.
> It is used internally by platform modules.
>
>> I really have to use CXXFLAGS environment variable which feels clumsy.
>> It's that really the only reliable way to define compiler arguments
>> like -mcpu= for all compiler invocations?
>
> It is one way.  Another way is to set the cache entry directly:
>
>   set(CMAKE_CXX_FLAGS "-mcpu=..." CACHE STRING "C++ flags")
>
> Note that CMAKE_CXX_FLAGS is propagated by try_compile automatically.
> The above two approaches are actually just trying to get a toolchain
> file to have a say in the initial CMAKE_CXX_FLAGS cache entry value
> of the main project.

The the following code in CMakeCXXInformation.cmake does nothing
--------------------snip--------------------
# add the flags to the cache based
# on the initial values computed in the platform/*.cmake files
# use _INIT variables so that this only happens the first time
# and you can set these flags in the cmake cache
set(CMAKE_CXX_FLAGS_INIT "$ENV{CXXFLAGS} ${CMAKE_CXX_FLAGS_INIT}")
# avoid just having a space as the initial value for the cache
if(CMAKE_CXX_FLAGS_INIT STREQUAL " ")
   set(CMAKE_CXX_FLAGS_INIT)
endif()
set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS_INIT}" CACHE STRING
      "Flags used by the compiler during all build types.")
--------------------snip--------------------

So each and every toolchain file shall also take care of the  
environment variable?
How about CMAKE_CXX_FLAGS_INIT set by other module files? Ok, only 3  
real users in CMake's module folder.

And VERY IMPORTANT: the toolchain file MUST make those variables CACHE  
variables, else it will not work (at least CMAKE_CXX_FLAGS is only  
propagated, then).

Thanks...

Hendrik