[cmake-developers] CMAKE_INSTALL_PREFIX vs CMAKE_SYSROOT ?

[Stephen Kelly]

Brad King wrote:

> On 7/4/2013 4:29 AM, Stephen Kelly wrote:
>> I can't think of anything that can be done with CMAKE_FIND_ROOT_PATH
>> which can't be done with CMAKE_PREFIX_PATH (with a bit more repetition on
>> the command line, I think). Should we enumerate the use cases to consider
>> documenting it obsolete?
> 
> One could have several roots in which target-arch packages
> are installed.  CMAKE_FIND_ROOT_PATH can list all of them.
> The others are not lists.

I don't understand. CMAKE_PREFIX_PATH is a list.

> 
>> If the install prefix is outside the sysroot,
> 
> This seems like a reasonable use case that should have full support.
> Isn't your "Goals" example exactly this?

Yes, it is.

> 
>>> We already have
>>> 
>>>  $ENV{DESTDIR}${CMAKE_INSTALL_PREFIX}/${install_dest}
>> 
>> Goals:
>> * Install to /opt/kf5 on the target
>> * Install to $HOME/dev/kf5 on the host
>> 
>> What values should be used for CMAKE_INSTALL_PREFIX and DESTDIR?
> 
> It appears we need several values:
> 
> * Prefix on host for host-arch binaries ($HOME/host/kf5? not above)
> * Prefix on host for target-arch binaries ($HOME/dev/kf5 above)
> * Prefix on target for target-arch binaries (/opt/kf5 above)
> * Toolchain sysroot on host (CMAKE_SYSROOT)
> 
> Without teaching CMake which targets belong to which category I
> do not see how this can be done without project-specific values.

Even if we simplify and only install one target library (and build nothing 
for the host), I don't know what values are appropriate. If I set 

 CMAKE_INSTALL_PREFIX -> /opt/kf5
 DESTDIR -> $HOME/dev/kf5

then the library will end up in 

 $HOME/dev/kf5/opt/kf5/lib

instead of 

 $HOME/dev/kf5/lib

right? 

Should the latter be supported?

Thanks,

Steve.