[CMake] set CMAKE_INSTALL_PREFIX in CMakeLists

[S Roderick]

On Nov 30, 2010, at 13:40 , David Cole wrote:

> It probably works "accidentally" if you do the set before the project command.

That is what we do, and it definitely works for us. Set it _before_ the PROJECT() statement.

> 
> Unfortunately, the project command has significant side effects.
> Setting a default (cached) value for CMAKE_INSTALL_PREFIX might be one
> of those...
> 
> 
> On Tuesday, November 30, 2010, Tyler Roscoe <tyler at cryptio.net> wrote:
>> On Thu, Nov 25, 2010 at 02:01:31PM +0100, Marcel Loose wrote:
>>>>>> On 24-11-2010 at 17:45, in message
>>> <20101124164507.GG23449 at cryptio.net>, Tyler
>>> Roscoe <tyler at cryptio.net> wrote:
>>>> On Wed, Nov 24, 2010 at 12:11:56PM +0100, Micha Renner wrote:
>>>>> 
>>>>>>   SET(CMAKE_INSTALL_PREFIX "/foo/bar" CACHE PATH "Foo install
>>> prefix")
>>>>>> 
>>>>>> So, without the test to
>>> CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT,
>>>>>> and without the FORCE option.
>>>>> 
>>>>> No, as I mentioned, there was an article of one the
>>> CMake-maintainers
>>>>> who recommended this.
>>>> 
>>>> Micha is correct. CMAKE_INSTALL_PREFIX is set before your
>>> CMakeLists.txt
>>>> is processed, so the above will never do anything.
>>>> 
>>>> tyler
>>> 
>>> Well, I tested this before I posted my reply. It does work the way I
>>> describe it. Try it yourself.
>> 
>> It doesn't work for me:
>> 
>> [tylermr at tpb006:~/cmake-test-install-prefix]$ cmake --version
>> cmake version 2.8.3
>> 
>> [tylermr at tpb006:~/cmake-test-install-prefix]$ cat CMakeLists.txt
>> cmake_minimum_required(VERSION 2.8)
>> project(p)
>> 
>> set (CMAKE_INSTALL_PREFIX "foo" CACHE PATH "docstring")
>> message ("CMAKE_INSTALL_PREFIX = ${CMAKE_INSTALL_PREFIX}")
>> 
>> [tylermr at tpb006:~/cmake-test-install-prefix]$ mkdir b && cd b && cmake ..
>> -- The C compiler identification is GNU
>> -- The CXX compiler identification is GNU
>> -- Check for working C compiler: /usr/bin/gcc
>> -- Check for working C compiler: /usr/bin/gcc -- works
>> -- Detecting C compiler ABI info
>> -- Detecting C compiler ABI info - done
>> -- Check for working CXX compiler: /usr/bin/c++
>> -- Check for working CXX compiler: /usr/bin/c++ -- works
>> -- Detecting CXX compiler ABI info
>> -- Detecting CXX compiler ABI info - done
>> CMAKE_INSTALL_PREFIX = /usr/local
>> -- Configuring done
>> -- Generating done
>> -- Build files have been written to: /tpb006/tylermr/cmake-test-install-prefix/b