[CMake] set CMAKE_INSTALL_PREFIX in CMakeLists

[David Cole]

If we want this unintentional behavior to continue working as is into
the future, we should add a test for this behavior and make the test
fail if the value of CMAKE_INSTALL_PREFIX is not as expected at the
bottom of CMakeLists...

Anybody want to add some code to the test suite to validate this
particular idiosyncrasy?


On Tuesday, November 30, 2010, S Roderick <kiwi.net at mac.com> wrote:
> 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
>
>