How to update the location of installed library on windows? - c++

Question

I previously installed zlib library by "cmake ..", "make" and "make install". By calling function "find_package(zlib)" in CMakeLists.txt, the default installed location is found to be "C:\Program Files (x86)\zlib" . The content of CMakeLists.txt is written as:
cmake_minimum_required(VERSION 2.4.4)
project(zlib C)
find_package(ZLIB)
message(STATUS "Found")
message(STATUS " ${ZLIB_INCLUDE_DIRS}")
Now I reinstall this library by "cmake -G "MinGW Makefiles" -DCMAKE_INSTALL_PREFIX:PATH=D:/TEST_ZLIB/ ..", getting the result as bellow
E:\Code\cpp\zlib-1.2.11\build>make install
[ 41%] Built target zlib
[ 46%] Built target minigzip64
[ 85%] Built target zlibstatic
[ 90%] Built target example
[ 95%] Built target minigzip
[100%] Built target example64
Install the project...
-- Install configuration: ""
-- Installing: D:/TEST_ZLIB/lib/libzlib.dll.a
-- Installing: D:/TEST_ZLIB/bin/libzlib.dll
-- Installing: D:/TEST_ZLIB/lib/libzlibstatic.a
-- Installing: D:/TEST_ZLIB/include/zconf.h
-- Installing: D:/TEST_ZLIB/include/zlib.h
-- Installing: D:/TEST_ZLIB/share/man/man3/zlib.3
-- Installing: D:/TEST_ZLIB/share/pkgconfig/zlib.pc
However, function find_package(zlib) still reports the previous location:
E:\Code\cpp\test_cmake\build>cmake ..
-- Found
-- C:/Program Files (x86)/zlib/include
-- Configuring done
-- Generating done
-- Build files have been written to: E:/Code/cpp/test_cmake/build
How can I update the location of this library? Any help would be deeply appreciated.

Answer 1

Result of find_package() call is cached, so running it the second time doesn't search actually, but uses the cached value.
CMake cache is contained in CMakeCache.txt file located in the binary directory. So you have 3 possibilities for force find_package to search again:
Remove the whole binary directory.
Next invocation of cmake will be "fresh": it will search for compiler, all needed packages, and so on.
Remove CMakeCache.txt file from the binary directory.
Next invocation of cmake will be "fresh", same as in the first case.
From CMakeCache.txt remove the lines, corresponded to your package.
E.g., for force find_package(ZLIB) to search again, you may remove all entries contained substring "zlib" (case-insensitive).
Next invocation of cmake will use cached settings for compiler, other packages, but search ZLIB again.
The 3d variant requires slightly more actions, but it will result with faster cmake call.
The 1st and 2nd variants are easy to perform and their effects are almost identical. They both result in "slow" cmake call, which would need to perform all checks again. But you may be sure that you won't leave cached setting in inconsistent case.
When troubleshooting, always choose 1st or 2nd variants!