cmake cannot find libraries installed with vcpkg

Question

I want to use vcpkg in a CMake project in Windows, because I need boost and xerces that are both handled by this package manager.

I've the following CMakeLists.txt:

cmake_minimum_required (VERSION 3.12.0)

project (myproj)

set (CMAKE_PREFIX_PATH ${XERCES_ROOT})
set (Boost_USE_STATIC_LIBS ON)
set (Boost_USE_MULTITHREADED ON)
unset (Boost_INCLUDE_DIR CACHE)
unset (Boost_LIBRARY_DIRS CACHE)

# set (CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/../../cmake/modules)
find_package (Boost COMPONENTS filesystem regex REQUIRED)
find_package (XercesC CONFIG REQUIRED)

set (CMAKE_INCLUDE_CURRENT_DIR ON)
message (STATUS "binary dir is ${CMAKE_BINARY_DIR}")
include_directories (${CMAKE_BINARY_DIR}/${PROJECT_NAME}/)
include_directories (${CMAKE_CURRENT_SOURCE_DIR}/..)
include_directories (${Boost_INCLUDE_DIRS})
include_directories (${XercesC_INCLUDE_DIRS})

set (PROJECT_SRC
  code.cpp
  )

add_library (${PROJECT_NAME} SHARED ${PROJECT_SRC})
add_dependencies (${PROJECT_NAME} UPDATE_RESOURCES)
target_link_libraries (${PROJECT_NAME} ${Boost_LIBRARIES} XercesC::XercesC)

Boost and xerces-c are installed with vcpkg. Since I'm using Visual Studio Code I'm setting vcpkg variables in settings.json:

  "cmake.configureSettings": {
    "CMAKE_TOOLCHAIN_FILE" : "some/path/vcpkg/scripts/buildsystems/vcpkg.cmake",
    "VCPKG_TARGET_TRIPLET": "x64-windows"
  }

When I run che CMake I obtain following errors:

[cmake] CMake Error at C:/Program Files/CMake/share/cmake-3.14/Modules/FindBoost.cmake:2132 (message):
[cmake]   Unable to find the requested Boost libraries.
[cmake] 
[cmake]   Unable to find the Boost header files.  Please set BOOST_ROOT to the root
[cmake]   directory containing Boost or BOOST_INCLUDEDIR to the directory containing
[cmake]   Boost's headers.
[cmake] Call Stack (most recent call first):
[cmake]   D:/projects/vcpkg/scripts/buildsystems/vcpkg.cmake:233 (_find_package)
[cmake]   src/myroject/CMakeLists.txt:24 (find_package)
[cmake] 
[cmake] 
[cmake] CMake Error at D:/Projects/vcpkg/installed/x64-windows/share/xercesc/vcpkg-cmake-wrapper.cmake:1 (_find_package):
[cmake]   Could not find a package configuration file provided by "XercesC" with any
[cmake]   of the following names:
[cmake] 
[cmake]     XercesCConfig.cmake
[cmake]     xercesc-config.cmake
[cmake] 
[cmake]   Add the installation prefix of "XercesC" to CMAKE_PREFIX_PATH or set
[cmake]   "XercesC_DIR" to a directory containing one of the above files.  If
[cmake]   "XercesC" provides a separate development package or SDK, be sure it has
[cmake]   been installed.
[cmake] Call Stack (most recent call first):
[cmake]   D:/Projects/vcpkg/scripts/buildsystems/vcpkg.cmake:189 (include)
[cmake]   src/ZLA/CMakeLists.txt:25 (find_package)
[cmake] 
[cmake] 
[cmake] Configuring incomplete, errors occurred!
[cmake] See also "D:/Projects/zla/build/vscode/CMakeFiles/CMakeOutput.log".
[cms-driver] Error during CMake configure: [cmake-server] Configuration failed.

At the moment I've installed xerces with vcpkg commands, while boost is currently not installed, but I was expecting that during the execution of the cmake command, vcpkg will download and build needed build packages.

I've tried also the command line:

 cmake -DCMAKE_TOOLCHAIN_FILE=D:/Projects/vcpkg/scripts/buildsystems/vcpkg.cmake -DVCPKG_TARGET_TRIPLET=x64-windows ../

but the result is the same.

What I'm doing wrong? How can I use vcpkg successfully?

Answer 1

In theory it's as simple as (assuming vcpkg as installed in C:/vcpkg as it is for github actions);

1. Install your "foo" package with vcpkg install foo
2. Make sure your CMakeLists.txt finds and uses the package with;

find_package(FOO)
# Use these instead of the package doesn't have proper cmake package support.
# find_path(FOO_INCLUDE_DIRS foo.h)
# find_library(FOO_LIBRARYS foo)
include_directories(${FOO_INCLUDE_DIRS})
target_link_libraries(myprogram ${FOO_LIBRARIES})                                     

1. Run cmake with -DCMAKE_TOOLCHAIN_FILE=C:/vcpkg/scripts/buildsystems/vcpkg.cmake

But... this didn't work for me until I added --triplet x64-windows to the vcpkg install command.

The DCMAKE_TOOLCHAIN_FILE sets the various CMAKE_(SYSTEM_)?(PREFIX|LIBRARY|INCLUDE|FRAMEWORK)_PATH variables to enable the find_*() cmake functions to work, but note that these paths include the VCPKG_TARGET_TRIPLET. In my case the package install with vcpkg install <foo> defaulted to x86-windows but then invoking cmake with -DCMAKE_TOOLCHAIN_FILE=C:/.... defaulted to x64-windows so it couldn't find the the package.

Currently vcpkg defaults to the older x86 target, but modern Visual Studio (as used by githup actions) defaults to x64. The fix was to install the package with vcpkg -triplet x64-windows install <foo>. It took me way too long going down too many red-herring rabbit holes to discover this.