[CMake] project directive overwrites CMAKE_INSTALL_PREFIX?

[Chris Johnson]

This looks like a bug to me.  I have a very simple test case where
CMAKE_INSTALL_PREFIX is set correctly if I do so after the project()
statement, and fails to be set correctly if I do it before the project()
statement.

On Fri, Dec 5, 2014 at 2:06 PM, Chris Johnson <cxjohnson at gmail.com> wrote:

> Strangely, running "cmake -DCMAKE_INSTALL_PREFIX=/some/path" does NOT
> rewrite the cmake_install.cmake, but does rewrite the CMakeCache.txt and
> other files.  The result is a bad install path won't go away until one
> manually removes the cmake_install.cmake file(s).
>
> On Thu, Dec 4, 2014 at 9:48 PM, J Decker <d3ck0r at gmail.com> wrote:
>
>> I find it's better to define CMAKE_INSTALL_PREFIX on the command line
>> when building
>>
>> I do have this bit of code...
>>
>> IF(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
>>   SET(CMAKE_INSTALL_PREFIX
>>     ${CMAKE_BINARY_DIR}/../${CMAKE_BUILD_TYPE}_out CACHE PATH "Install
>> default 'out' in this directory." FORCE
>>     )
>> ENDIF(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
>>
>>
>> which keeps it from overwriting an already set value (from the command
>> line); and make sure it's in the cache so cmake-gui can edit it...
>>
>> (if  project() does something with cmake_isnstall_prefix might also be a
>> bug)
>>
>> On Thu, Dec 4, 2014 at 7:27 PM, Chris Johnson <cxjohnson at gmail.com>
>> wrote:
>>
>>> I have a global include file used by all of the CMakeLists.txt files in
>>> my project. In it, I set the value of CMAKE_INSTALL_PREFIX, as well as a
>>> number of other variables and functions.
>>>
>>> In my CMakeLists.txt file, I had this:
>>>
>>> cmake_minimum_require(VERSION 2.8.4)
>>> include(global.inc)
>>> project(whatever)
>>>
>>> When I run cmake, the value of CMAKE_INSTALL_PREFIX is lost! Instead, in
>>> the resulting cmake_install.cmake file has been defaulted back to
>>> /usr/local which is completely wrong.
>>>
>>> However, if I change the order to this:
>>>
>>> cmake_minimum_require(VERSION 2.8.4)
>>> project(whatever)
>>> include(global.inc)
>>>
>>> It appears to work.
>>>
>>> I find nothing in the documentation saying that the project() directive
>>> will set CMAKE_INSTALL_PREFIX.
>>>
>>> Even more strangely, if I run cmake a second time with the first
>>> configuration (include before project), it will rewrite cmake_install.cmake
>>> with the correct value.
>>> ​ ​
>>> That is, the behavior of cmake appears to be different based on whether
>>> the build directory is empty or already contains cmake_install.cmake and
>>> CMakeCache.txt files
>>> ​, even though they contain the wrong path value for
>>> CMAKE_INSTALL_PREFIX.​
>>>
>>> What is going on here?
>>>
>>>
>>>
>>>
>>>
>>>
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>>
>>
>
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