How to compile wxWidgets using custom version of required 3rd party libraries - cmake

Question

Let's say I have libTiff, libpng, zlib and libjpeg. How do I tell wxWidgets to use those instead of builtin or installed ones on the system?
I'm quite new to wxWidgets and trying to add it as a dependency to my CMake project, which in return already depends and builds (using ExternalProject) the above mentioned libraries. I do not want to mix versions (which is bound to happen if I use builtin or ones already installed on the system). I also want to keep all the dependencies separate from what is already present on the system for easier distribution.
I have checked setup.h.in where the preprocessor macros are defined (here: wxUSE_ZLIB, wxUSE_LIBJPEG, wxUSE_LIBTIFF and wxUSE_LIBPNG). I also see that inside <root of wxWidgets git repo>/build/cmake/lib/ I have various *.cmake include files that handle different 3rd party dependencies.
I am however confused what I need to pass to my cmake command in order to configure wxWidgets to use versions of the libraries mentioned above from a specific location. I have defined PNG_LIBRARIES, JPEG_LIBRARIES etc. (pointing at where the *.lib (on Windows) or *.so (on Linux) files are. In addition I have defined the ..._INCLUDE_DIRS accordingly.
Currently this is the state of my external project description (the ... are placeholders of valid paths)
ExternalProject_Add(wxWidgets
PREFIX ${CMAKE_CURRENT_BINARY_DIR}/deps/wxwidgets
INSTALL_DIR ...
DOWNLOAD_DIR ""
TMP_DIR ...
STAMP_DIR ...
LOG_DIR ...
BINARY_DIR ...
SOURCE_DIR ...
INSTALL_COMMAND "${CMAKE_COMMAND}" -E echo "Skipping install step for dependency libzmq"
INSTALL_PREFIX ...
BUILD_ALWAYS OFF
# For build configurations see https://wiki.wxwidgets.org/WxWidgets_Build_Configurations
# Also setup.h.in and <wxWidgets_root>/build/cmake/libs
CMAKE_ARGS
"-DCMAKE_BUILD_TYPE=Release"
"-DBUILD=release"
"-DSHARED=1"
"-DMONOLITHIC=1"
"-DwxBUILD_TESTS=OFF"
"-DwxBUILD_DEMOS=OFF"
"-DwxBUILD_BENCHMARKS=OFF"
"-DwxUSE_GUI=1" # <---- forces dependency requirement for PNG, ZLIB, JPEG, TIFF
"-DwxUSE_OPENGL=1"
"-DwxUSE_ZLIB=sys"
"-DZLIB_LIBRARY=${ZLIB_LIBRARIES}" # <---- from another ExternalProject
"-DZLIB_INCLUDE_DIRS=${ZLIB_INCLUDE_DIRS}" # <---- from another ExternalProject
"-DwxUSE_LIBJPEG=sys"
"-DJPEG_LIBRARY=${JPEG_LIBRARIES}" # <---- from another ExternalProject
"-DJPEG_INCLUDE_DIR=${JPEG_INCLUDE_DIRS}" # <---- from another ExternalProject
"-DwxUSE_LIBPNG=sys"
"-DPNG_LIBRARY=${PNG_LIBRARIES}" # <---- from another ExternalProject
"-DPNG_PNG_INCLUDE_DIR=${PNG_INCLUDE_DIRS}" # <---- from another ExternalProject
"-DwxUSE_LIBTIFF=builtin" # TODO Add libTiff to external project dependencies and use here
)
What I basically did is initially put stuff on OFF. wxWidgets's configuration is smart enough to warn me that (since I included wxUSE_GUI, which requires those libs) the respective libraries are missing and it will use builtin instead. From there I found out which variables it is actually looking for and by setting wxUSE_... to sys for the respective library. For now I am getting closer to configuring the build:
1>------ Rebuild All started: Project: ZERO_CHECK, Configuration: Debug x64 ------
1>Checking Build System
2>------ Rebuild All started: Project: wxWidgets, Configuration: Debug x64 ------
2>Creating directories for 'wxWidgets'
2>Building Custom Rule C:/Users/.../Documents/.../CMakeLists.txt
2>No download step for 'wxWidgets'
2>No update step for 'wxWidgets'
2>No patch step for 'wxWidgets'
2>Performing configure step for 'wxWidgets'
2>-- Selecting Windows SDK version 10.0.17763.0 to target Windows 10.0.19042.
2>-- cotire 1.8.0 loaded.
2>-- Found ZLIB: C:/Users/.../CMakeBuilds/ef5b5ada-ee42-7735-988a-ae37c735ccff/build/deps/build/zlib/Debug/zlibd.lib (found version "1.2.11")
2>-- Found JPEG: C:/Users/rcr-aa/CMakeBuilds/ef5b5ada-ee42-7735-988a-ae37c735ccff/build/deps/build/jpeg/Debug/jpeg.lib (found version "90")
2>-- Found PNG: C:/Users/.../CMakeBuilds/ef5b5ada-ee42-7735-988a-ae37c735ccff/build/deps/build/png/Debug/libpng16d.lib (found version "1.6.38.git")
2>-- Which libraries should wxWidgets use?
2> wxUSE_STL: OFF (use C++ STL classes)
2> wxUSE_REGEX: builtin (enable support for wxRegEx class)
2> wxUSE_ZLIB: sys (use zlib for LZW compression)
2> wxUSE_EXPAT: builtin (use expat for XML parsing)
2> wxUSE_LIBJPEG: sys (use libjpeg (JPEG file format))
2> wxUSE_LIBPNG: sys (use libpng (PNG image format))
2> wxUSE_LIBTIFF: builtin (use libtiff (TIFF file format))
2> wxUSE_LIBLZMA: OFF (use liblzma for LZMA compression)
2>
2>-- Configured wxWidgets 3.1.6 for Windows-10.0.19042
2> Min OS Version required at runtime: Windows Vista / Windows Server 2008 (x64 Edition)
2> Which GUI toolkit should wxWidgets use? msw
2> Should wxWidgets be compiled into single library? OFF
2> Should wxWidgets be linked as a shared library? ON
2> Should wxWidgets support Unicode? ON
2> What wxWidgets compatibility level should be used? 3.0
2>-- Configuring done
While looking around I also checked the *.cmake files for the libraries I want to use a custom version of to confirm what needs to be set. An example for zlib can be seen below:
#############################################################################
# Name: build/cmake/lib/zlib.cmake
# Purpose: Use external or internal zlib
# Author: Tobias Taschner
# Created: 2016-09-21
# Copyright: (c) 2016 wxWidgets development team
# Licence: wxWindows licence
#############################################################################
if(wxUSE_ZLIB STREQUAL "builtin")
# TODO: implement building zlib via its CMake file, using
# add_subdirectory or ExternalProject_Add
wx_add_builtin_library(wxzlib
src/zlib/adler32.c
src/zlib/compress.c
src/zlib/crc32.c
src/zlib/deflate.c
src/zlib/gzclose.c
src/zlib/gzlib.c
src/zlib/gzread.c
src/zlib/gzwrite.c
src/zlib/infback.c
src/zlib/inffast.c
src/zlib/inflate.c
src/zlib/inftrees.c
src/zlib/trees.c
src/zlib/uncompr.c
src/zlib/zutil.c
)
if(WIN32)
# Define this to get rid of many warnings about using open(),
# read() and other POSIX functions in zlib code. This is much
# more convenient than having to modify it to avoid them.
target_compile_definitions(wxzlib PRIVATE _CRT_NONSTDC_NO_WARNINGS)
endif()
set(ZLIB_LIBRARIES wxzlib) # <----------- set via -DZLIB_LIBRARIES in my ExternalProject
set(ZLIB_INCLUDE_DIRS ${wxSOURCE_DIR}/src/zlib) # <----------- set via -DZLIB_INCLUDE_DIRS in my ExternalProject
elseif(wxUSE_ZLIB)
find_package(ZLIB REQUIRED)
endif()
My biggest problem here is that I apparently have to set the configuration for each and every 3rd party dependency (in my case set every other dependency to builtin)
2>CMake Error at build/cmake/functions.cmake:591 (add_library):
2> Cannot find source file:
2>
2> C:/Users/.../Documents/.../deps/wxwidgets/3rdparty/pcre/src/pcre2_auto_possess.c
2>
2> Tried extensions .c .C .c++ .cc .cpp .cxx .cu .mpp .m .M .mm .ixx .cppm .h
2> .hh .h++ .hm .hpp .hxx .in .txx .f .F .for .f77 .f90 .f95 .f03 .hip .ispc
2>Call Stack (most recent call first):
2> build/cmake/lib/regex.cmake:13 (wx_add_builtin_library)
2> build/cmake/lib/CMakeLists.txt:28 (include)
2>
2>
2>CMake Error at build/cmake/functions.cmake:591 (add_library):
2> Cannot find source file:
2>
2> C:/Users/.../Documents/.../deps/wxwidgets/src/expat/expat/lib/xmlparse.c
2>
2> Tried extensions .c .C .c++ .cc .cpp .cxx .cu .mpp .m .M .mm .ixx .cppm .h
2> .hh .h++ .hm .hpp .hxx .in .txx .f .F .for .f77 .f90 .f95 .f03 .hip .ispc
2>Call Stack (most recent call first):
2> build/cmake/lib/expat.cmake:13 (wx_add_builtin_library)
2> build/cmake/lib/CMakeLists.txt:28 (include)
2>
2>
2>CMake Error at build/cmake/functions.cmake:591 (add_library):
2> Cannot find source file:
2>
2> C:/Users/.../Documents/.../deps/wxwidgets/src/tiff/libtiff/tif_win32.c
2>
2> Tried extensions .c .C .c++ .cc .cpp .cxx .cu .mpp .m .M .mm .ixx .cppm .h
2> .hh .h++ .hm .hpp .hxx .in .txx .f .F .for .f77 .f90 .f95 .f03 .hip .ispc
2>Call Stack (most recent call first):
2> build/cmake/lib/tiff.cmake:19 (wx_add_builtin_library)
2> build/cmake/lib/CMakeLists.txt:28 (include)
2>
2>
2>CMake Error at build/cmake/functions.cmake:591 (add_library):
2> No SOURCES given to target: wxregex
2>Call Stack (most recent call first):
2> build/cmake/lib/regex.cmake:13 (wx_add_builtin_library)
2> build/cmake/lib/CMakeLists.txt:28 (include)
2>
2>
2>CMake Error at build/cmake/functions.cmake:591 (add_library):
2> No SOURCES given to target: wxexpat
2>Call Stack (most recent call first):
2> build/cmake/lib/expat.cmake:13 (wx_add_builtin_library)
2> build/cmake/lib/CMakeLists.txt:28 (include)
2>
2>
2>CMake Error at build/cmake/functions.cmake:591 (add_library):
2> No SOURCES given to target: wxtiff
2>Call Stack (most recent call first):
2> build/cmake/lib/tiff.cmake:19 (wx_add_builtin_library)
2> build/cmake/lib/CMakeLists.txt:28 (include)
2>
2>
2>CMake Generate step failed. Build files cannot be regenerated correctly.
2>C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\IDE\VC\VCTargets\Microsoft.CppCommon.targets(209,5): error MSB6006: "cmd.exe" exited with code 1.
2>Done building project "wxWidgets.vcxproj" -- FAILED.
Since I am not familiar with wxWidgets I would like to ask if I can just set all the rest of the dependencies to builtin.

Answer 1

First of all, you have to set things up so that the existing libraries can be found, either by CMake (using its find_package()) or configure (which uses pkg-config).
Second, with CMake, I believe that you need to explicit set options such as wxUSE_LIBPNG to sys. When building using configure, this is already the default, as configure will look for the system libraries first, and only fall back on the built-in ones if system ones are not found, but you can also use its command line options such as --with-libpng=sys to force using the system libraries (and fail the configuration if they're not found).