[CMake] set CMAKE_INSTALL_PREFIX in CMakeLists

[David Cole]

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

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
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