[CMake] (no subject)

[Matt Wilbur]

With a bit of thought and source code reading, I sorted this out.  Let me know if you'd like me to post my answer to my own question.

Matt

> On Jan 1, 2014, at 11:13 AM, Matt Wilbur <wilburm at gmail.com> wrote:
> 
> Hello CMakers,
> 
> I’m seeing behavior with find_path that seems to be inconsistent with the cmake documentation.  According to the documentation (as I understand it), when NO_DEFAULT_PATH is set, the CMAKE_FIND_ROOT_PATH should have no impact on where find_path looks.  However it seems to be having a big impact when the CMAKE_TOOLCHAIN_FILE is used.  
> 
> You’ll see between Experiment 2 and Experiment 3 below, where the only difference is setting 
> 
> set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
> 
> and this means the difference between success and failure of find_path, even though CMAKE_FIND_ROOT_PATH should have no impact if NO_DEFAULT_PATH is used.
> 
> Furthermore CMAKE_FIND_ROOT_PATH_MODE_INCLUDE seems to have this impact only when cross-compiling, not when 
> 
> Thoughts?  Is this behavior seem odd to anyone else?
> 
> Matt
> 
> 
> Experiment 1:
> 
> CMakeLists.txt:
> 
> cmake_minimum_required(VERSION 2.8)
> set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
> find_path(ZLIB_INCLUDE_DIR NAMES zlib.h PATHS /home/vagrant/Projects/cmake-test/zlib-1.2.8 NO_DEFAULT_PATH)
> message("Found: ${ZLIB_INCLUDE_DIR}”)
> 
> Output from cmake:
> 
> cmake ..
> 
> -- The C compiler identification is GNU 4.6.3
> -- The CXX compiler identification is GNU 4.6.3
> -- Check for working C compiler: /usr/bin/cc
> -- Check for working C compiler: /usr/bin/cc -- 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
> Found: /home/vagrant/Projects/cmake-test/zlib-1.2.8
> -- Configuring done
> -- Generating done
> -- Build files have been written to: /home/vagrant/Projects/another-cmake-test/build
> 
> Experiment 2:
> 
> CMakeLists.txt:  same as above
> 
> Toolchain file: 
> 
> # this one is important
> SET(CMAKE_SYSTEM_NAME Linux)
> 
> # specify the cross compiler
> set(CMAKE_C_COMPILER /opt/freescale-2010.09/bin/powerpc-linux-gnu-gcc)
> set(CMAKE_CXX_COMPILER /opt/freescale-2010.09/bin/powerpc-linux-gnu-g++)
> 
> # where is the target environment
> set(CMAKE_FIND_ROOT_PATH /opt/freescale-2010.09)
> 
> # search for programs in the build host directories
> SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
> # for libraries and headers in the target directories
> SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
> SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
> 
> Output from cmake:
> 
> -- The C compiler identification is GNU 4.5.1
> -- The CXX compiler identification is GNU 4.5.1
> -- Check for working C compiler: /opt/freescale-2010.09/bin/powerpc-linux-gnu-gcc
> -- Check for working C compiler: /opt/freescale-2010.09/bin/powerpc-linux-gnu-gcc -- works
> -- Detecting C compiler ABI info
> -- Detecting C compiler ABI info - done
> -- Check for working CXX compiler: /opt/freescale-2010.09/bin/powerpc-linux-gnu-g++
> -- Check for working CXX compiler: /opt/freescale-2010.09/bin/powerpc-linux-gnu-g++ -- works
> -- Detecting CXX compiler ABI info
> -- Detecting CXX compiler ABI info - done
> Found: ZLIB_INCLUDE_DIR-NOTFOUND
> -- Configuring done
> -- Generating done
> -- Build files have been written to: /home/vagrant/Projects/another-cmake-test/build
> 
> Experiment 3:
> 
> CMakeLists.txt:
> 
> cmake_minimum_required(VERSION 2.8)
> 
> find_path(ZLIB_INCLUDE_DIR NAMES zlib.h PATHS /home/vagrant/Projects/cmake-test/zlib-1.2.8 NO_DEFAULT_PATH)
> message("Found: ${ZLIB_INCLUDE_DIR}”)
> 
> Toolchain file:
> 
>  this one is important
> SET(CMAKE_SYSTEM_NAME Linux)
> 
> # specify the cross compiler
> set(CMAKE_C_COMPILER /opt/freescale-2010.09/bin/powerpc-linux-gnu-gcc)
> set(CMAKE_CXX_COMPILER /opt/freescale-2010.09/bin/powerpc-linux-gnu-g++)
> 
> # where is the target environment
> set(CMAKE_FIND_ROOT_PATH /opt/freescale-2010.09)
> 
> # search for programs in the build host directories
> SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
> # for libraries and headers in the target directories
> SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
> 
> Output from cmake:
> 
> cmake -DCMAKE_TOOLCHAIN_FILE=../TC-powerpc-e500v2.cmake ..
> 
> -- The C compiler identification is GNU 4.5.1
> -- The CXX compiler identification is GNU 4.5.1
> -- Check for working C compiler: /opt/freescale-2010.09/bin/powerpc-linux-gnu-gcc
> -- Check for working C compiler: /opt/freescale-2010.09/bin/powerpc-linux-gnu-gcc -- works
> -- Detecting C compiler ABI info
> -- Detecting C compiler ABI info - done
> -- Check for working CXX compiler: /opt/freescale-2010.09/bin/powerpc-linux-gnu-g++
> -- Check for working CXX compiler: /opt/freescale-2010.09/bin/powerpc-linux-gnu-g++ -- works
> -- Detecting CXX compiler ABI info
> -- Detecting CXX compiler ABI info - done
> Found: /home/vagrant/Projects/cmake-test/zlib-1.2.8
> -- Configuring done
> -- Generating done
> -- Build files have been written to: /home/vagrant/Projects/another-cmake-test/build
> --
> 
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