Thanks PF, I think this makes more sense now! I was assuming that cmake always prefers CMAKE_PREFIX_PATH over builtin paths. But as you clarified, that only applies to libraries that provide find_package support.
This is actually quite unfortunate. Then I don't see an easy way to enforce usage of specific libs. As an example, if I want to enforce a patched libtiff (that does not itself provide find_package support) the only "safe" way is to replace the system libtiff. Otherwise any package might just find the system version first without me even knowing. This actually opens quite a can of worms :-( All the best, Mario On 23.03.2018 00:52, P F wrote: > Are you setting `CMAKE_INSTALL_PREFIX`? This path is searched before the > `CMAKE_PREFIX_PATH` is searched. > > Also the find_package paths listed in the documentation are only for > libraries that provide find_package support. Zlib does not, so it cmake > fallsback on the > FindZLIB.cmake module to do the searching which the search order can be > entirely up to the author of the module. You can see how FindZLIB.cmake > searches here: > > https://github.com/Kitware/CMake/blob/master/Modules/FindZLIB.cmake#L72 > > Of course, if its not correctly searching the `CMAKE_PREFIX_PATH` then this > should be considered a bug. > >> On Mar 22, 2018, at 11:54 AM, Mario Emmenlauer <ma...@emmenlauer.de >> <mailto:ma...@emmenlauer.de>> wrote: >> >> >> Dear Stephen, >> >> thanks a lot for your support! I've tested and your suggestion works! >> >> But, it does not fully resolve my pain :-( I'm slightly scared now >> because I assumed that cmake would prefer CMAKE_PREFIX_PATH over system >> libraries. In my understanding, the documentation says CMAKE_PREFIX_PATH >> is searched first (1). That aspect is quite crucial to me, because I have >> patched versions of more than 30 standard libraries in CMAKE_PREFIX_PATH. >> If I can not rely that cmake would use the patched versions, then I >> may end up having an "interesting" mix of system and patched libraries >> in my executable :-( >> >> (1) https://cmake.org/cmake/help/v3.0/command/find_package.html >> >> Thanks a lot and all the best, >> >> Mario >> >> >> On 22.03.2018 17:43, Stephen McDowell wrote: >>> Hi Mario, >>> >>> Very sorry, I should have looked more closely! CMAKE_MODULE_PATH is for >>> libraries that install their own CMake scripts. You are correct, Zlib only >>> installs a >>> pkg-config script. However, FindZLIB.cmake doesn’t appear to use that at >>> all (aka I don’t believe you /need/ to be setting PKG_CONFIG_PATH). You >>> should be >>> able to get away with setting *ZLIB_ROOT*. So for you I think it would >>> look like >>> >>> cmake .. -DZLIB_ROOT=/data/thirdparty >>> >>> FindZLIB.cmake will proceed to look for ZLIB_ROOT/include/zlib.h and look >>> in ZLIB_ROOT/lib for the library. >>> >>> The XXX_ROOT is typically available for any built-in CMake FindXXX.cmake >>> modules (see hint at bottom: >>> https://cmake.org/cmake/help/v3.0/module/FindZLIB.html ). >>> These FindXXX.cmake modules are for this exact scenario: there is a >>> library that many users want access to that does not install cmake scripts >>> (typically >>> because the library uses a different build system such as autotools). >>> >>> - - - - - >>> >>> If you are still having trouble, this is what I used to test this. I >>> didn’t actually write code that uses it, but I suspect if you *remove* >>> setting of >>> CMAKE_PREFIX_PATH (I think that’s where your conflict originates from) and >>> just specify ZLIB_ROOT your problem will be solved (I hope!). >>> >>> With a very crude CMakeLists.txt: >>> >>> cmake_minimum_required(VERSION 3.0 FATAL_ERROR) >>> project("find_zlib") >>> >>> find_package(ZLIB) >>> if (ZLIB_FOUND) >>> message(FATAL_ERROR "Found Zlib:\n- ZLIB_INCLUDE_DIRS: >>> ${ZLIB_INCLUDE_DIRS}\n- ZLIB_LIBRARIES: ${ZLIB_LIBRARIES}") >>> else() >>> message(FATAL_ERROR "Did not find Zlib :/") >>> endif() >>> >>> *Without* setting ZLIB_ROOT: >>> >>> $ cmake .. >>> -- Found ZLIB: /usr/lib/libz.dylib (found version "1.2.8") >>> CMake Error at CMakeLists.txt:6 (message): >>> Found Zlib: >>> - ZLIB_INCLUDE_DIRS: /usr/include >>> - ZLIB_LIBRARIES: /usr/lib/libz.dylib >>> >>> That’s the default Zlib that comes with OS X. However, if I specify >>> ZLIB_ROOT: >>> >>> $ cmake .. -DZLIB_ROOT=/usr/local/Cellar/zlib/1.2.11/ >>> -- Found ZLIB: /usr/local/Cellar/zlib/1.2.11/lib/libz.dylib (found >>> version "1.2.11") >>> CMake Error at CMakeLists.txt:6 (message): >>> Found Zlib: >>> - ZLIB_INCLUDE_DIRS: /usr/local/Cellar/zlib/1.2.11/include >>> - ZLIB_LIBRARIES: /usr/local/Cellar/zlib/1.2.11/lib/libz.dylib >>> >>> Let us know if it works or if you still need help! >>> >>> -Stephen Viele Gruesse, Mario Emmenlauer -- BioDataAnalysis GmbH, Mario Emmenlauer Tel. Buero: +49-89-74677203 Balanstr. 43 mailto: memmenlauer * biodataanalysis.de D-81669 München http://www.biodataanalysis.de/ -- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. 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