Bring back the "external dependencies" build

For now we only test with external dependencies on macOS. mio and
whereami are not available in brew so we'll still fetch them with CMake.

Doctest needed to be added to brew deps.

Author: MiKom

.github/workflows/build-external.yml

@@ -37,12 +37,13 @@ jobs:
                                                                 # We remove the pinned CMake if it's installed so commands below can succeed
                                                                 # TODO: remove when not needed anymore
           brew tap KDAB/tap
-          brew install fmt spdlog KDBindings mosquitto
+          brew install doctest fmt spdlog KDBindings mosquitto
 
       - name: Configure project
         run: >
           cmake -S . -B ./build -DCMAKE_BUILD_TYPE=Debug -G Ninja
           -DKDUTILS_BUILD_TESTS=ON
+          -DKDUTILS_USE_EXTERNAL_DEPENDENCIES=ON
           -DBUILD_SHARED_LIBS=${{ matrix.shared }}
 
       - name: Check if external dependencies were used

CMakeLists.txt

@@ -10,11 +10,17 @@
 
 cmake_minimum_required(VERSION 3.16)
 
+option(KDUTILS_USE_EXTERNAL_DEPENDENCIES
+       "Assume all project dependencies are available on the system. Don't fetch through vcpkg." OFF
+)
+
 # vcpkg manifest mode
-include(cmake/KDUtilsFunctions.cmake)
-kdutils_check_submodule_exists(vcpkg vcpkg)
-if(NOT DEFINED CMAKE_TOOLCHAIN_FILE)
-    set(CMAKE_TOOLCHAIN_FILE ${CMAKE_SOURCE_DIR}/vcpkg/scripts/buildsystems/vcpkg.cmake)
+if(NOT KDUTILS_USE_EXTERNAL_DEPENDENCIES)
+    if(NOT DEFINED CMAKE_TOOLCHAIN_FILE)
+        include(cmake/KDUtilsFunctions.cmake)
+        kdutils_check_submodule_exists(vcpkg vcpkg)
+        set(CMAKE_TOOLCHAIN_FILE ${CMAKE_SOURCE_DIR}/vcpkg/scripts/buildsystems/vcpkg.cmake)
+    endif()
 endif()
 
 option(KDUTILS_BUILD_EXAMPLES "Build examples" ON)

cmake/dependencies.cmake

@@ -8,12 +8,37 @@
 # Contact KDAB at <info@kdab.com> for commercial licensing options.
 #
 
+include(FetchContent)
+
 message(STATUS "Looking for KDUtils dependencies")
 
 find_package(spdlog REQUIRED)
 find_package(KDBindings REQUIRED)
-find_package(whereami REQUIRED)
-find_package(mio REQUIRED)
+
+# Following two packages are still acquired via fetchcontent because they aren't
+# available in brew on macOS so the non-vcpkg build would be hard to set up there
+
+# whereami library
+find_package(whereami QUIET)
+if(NOT TARGET whereami::whereami)
+    fetchcontent_declare(
+        whereami
+        GIT_REPOSITORY https://github.com/gpakosz/whereami
+        GIT_TAG e4b7ba1be0e9fd60728acbdd418bc7195cdd37e7 # master at 5/July/2021
+    )
+    fetchcontent_makeavailable(whereami)
+endif()
+
+# mio header-only lib (provides memory mapping for files)
+find_package(mio QUIET)
+if(NOT TARGET mio::mio)
+    fetchcontent_declare(
+        mio
+        GIT_REPOSITORY https://github.com/mandreyel/mio.git
+        GIT_TAG 8b6b7d878c89e81614d05edca7936de41ccdd2da # March 3rd 2023
+    )
+    fetchcontent_makeavailable(mio)
+endif()
 
 if(KDUTILS_BUILD_MQTT_SUPPORT)
     find_package(mosquitto REQUIRED)

src/KDUtils/CMakeLists.txt

@@ -47,7 +47,7 @@ add_library(
 target_link_libraries(
     KDUtils
     PUBLIC spdlog::spdlog
-    PRIVATE mio::mio whereami::whereami
+    PRIVATE mio::mio
 )
 
 if(ANDROID)
@@ -59,6 +59,13 @@ target_include_directories(
     PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/../> $<INSTALL_INTERFACE:include/>
 )
 
+if(NOT TARGET whereami::whereami)
+    target_include_directories(KDUtils PRIVATE ${whereami_SOURCE_DIR}/src)
+    target_sources(KDUtils PRIVATE ${whereami_SOURCE_DIR}/src/whereami.c)
+else()
+    target_link_libraries(KDUtils PRIVATE whereami::whereami)
+endif()
+
 set_target_properties(
     KDUtils
     PROPERTIES ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib"