[CMake] Forcing CMake to never search install path

[Michael Hertling]

On 05/20/2011 12:08 AM, Clifford Yapp wrote:
> Michael,
> 
> At first glance those would be what I need (although it is not clear
> if I need to specify bin/lib/include for  CMAKE_SYSTEM_IGNORE_PATH as
> well as CMAKE_IGNORE_PATH.)  I have tested both out, and unfortunately
> they do not seem to exclude the CMAKE_INSTALL_PREFIX path when I
> supply it - I still get find results even after appending the install
> path to  CMAKE_SYSTEM_IGNORE_PATH.  I also tried
> 
> get_filename_component(PATH_NORMALIZED ${CMAKE_INSTALL_PREFIX}/lib ABSOLUTE)
> 
> to make it easier for Find to ignore the path, but that didn't seem to
> help.  I've tried forcing the results into the Cache as well.  Is
> there something else I need to do?
> 
> Thanks,
> CY

On *nix, I experimented with the following CMakeLists.txt:

CMAKE_MINIMUM_REQUIRED(VERSION 2.8 FATAL_ERROR)
PROJECT(IGNORE C)
SET(CMAKE_VERBOSE_MAKEFILE ON)
FIND_LIBRARY(XYZ_LIBRARY xyz)
MESSAGE("XYZ_LIBRARY: ${XYZ_LIBRARY}")
MESSAGE("CMAKE_PREFIX_PATH: ${CMAKE_PREFIX_PATH}")
MESSAGE("CMAKE_SYSTEM_PREFIX_PATH: ${CMAKE_SYSTEM_PREFIX_PATH}")
FILE(WRITE ${CMAKE_BINARY_DIR}/xyz.c "void xyz(void){}\n")
ADD_LIBRARY(xyz STATIC xyz.c)
INSTALL(TARGETS xyz ARCHIVE DESTINATION lib)

First of all, I built from within an empty build directory with

cmake <SRCDIR> -DCMAKE_INSTALL_PREFIX=/dev/shm/xyz; make install

and got /dev/shm/xyz/lib/libxyz.a as expected. Subsequently, a

rm CMakeCache.txt; cmake <SRCDIR> -DCMAKE_INSTALL_PREFIX=/dev/shm/xyz

finds /dev/shm/xyz/lib/libxyz.a because CMAKE_INSTALL_PREFIX is
mentioned in CMAKE_SYSTEM_PREFIX_PATH - also expected - but a

rm CMakeCache.txt; cmake <SRCDIR> -DCMAKE_INSTALL_PREFIX=/dev/shm/xyz
-DCMAKE_IGNORE_PATH=/dev/shm/xyz/lib

as well as a

rm CMakeCache.txt; cmake <SRCDIR> -DCMAKE_INSTALL_PREFIX=/dev/shm/xyz
-DCMAKE_SYSTEM_IGNORE_PATH=/dev/shm/xyz/lib

shows that the library is not found anymore, although CMAKE_SYSTEM_
IGNORE_PATH isn't meant to be set by the project. Therefore, I would
conclude that these variables act according to their documentation. If
this isn't the case w.r.t. your issue, could you provide a minimal but
complete example which demonstrates these variables' failure? Possibly,
it might be considered as a bug.

Regards,

Michael

> On Thu, May 19, 2011 at 7:47 AM, Michael Hertling <mhertling at online.de> wrote:
>>
>> Have you already tried the CMAKE_[SYSTEM_]IGNORE_PATH variables? At
>> the first glance, they provide exactly the functionality you need.