Add CMake function to copy DLL and PDB to tests/examples binary directories when building for Windows

Author: Anton Pantyukhin

cmake/silent_copy.cmake

@@ -0,0 +1,27 @@
+# Script which does not fail when some of the files to be copied are missing.
+#
+# Usage: cmake -P silent_copy.cmake [files]... [dest]
+
+math(EXPR dir_idx "${CMAKE_ARGC} - 1")
+set(first_file_idx ${dir_idx})
+
+foreach(i RANGE ${dir_idx})
+    if ("${CMAKE_ARGV${i}}" STREQUAL "-P")
+        math(EXPR first_file_idx "${i} + 2")
+        break()
+    endif()
+endforeach()
+
+if(first_file_idx GREATER_EQUAL dir_idx)
+    return()
+endif()
+
+math(EXPR last_file_idx "${dir_idx} - 1")
+set(dest ${CMAKE_ARGV${dir_idx}})
+set(files "")
+
+foreach(i RANGE ${first_file_idx} ${last_file_idx})
+    list(APPEND files "${CMAKE_ARGV${i}}")
+endforeach()
+
+execute_process(COMMAND ${CMAKE_COMMAND} -E copy_if_different ${files} "${dest}" ERROR_QUIET)

cmake/utils.cmake

@@ -6,3 +6,45 @@ macro(set_if_undefined variable)
         set("${variable}" ${ARGN})
     endif()
 endmacro()
+
+# win_copy_deps_to_target_dir(<target> [<target-dep>]...)
+#
+# Creates custom command to copy runtime dependencies to target's directory after building the target.
+# Function does nothing if platform is not Windows or current project is built as stand-alone (top-level)
+# project. Additionally, it ignores all dependencies except shared libraries.
+# On CMake 3.21 or newer, function uses TARGET_RUNTIME_DLLS generator expression to obtain list of runtime
+# dependencies. Specified dependencies (if any) are still used to find and copy PDB files for debug builds.
+function(win_copy_deps_to_target_dir target)
+    if(NOT WIN32 OR "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}")
+        return()
+    endif()
+
+    set(has_runtime_dll_genex NO)
+
+    if(CMAKE_MAJOR_VERSION GREATER 3 OR CMAKE_MINOR_VERSION GREATER_EQUAL 21)
+        set(has_runtime_dll_genex YES)
+
+        add_custom_command(TARGET ${target} POST_BUILD
+            COMMAND ${CMAKE_COMMAND} -P "${mylib_SOURCE_DIR}/cmake/silent_copy.cmake"
+                "$<TARGET_RUNTIME_DLLS:${target}>" "$<TARGET_FILE_DIR:${target}>"
+            COMMAND_EXPAND_LISTS)
+    endif()
+
+    foreach(dep ${ARGN})
+        get_target_property(dep_type ${dep} TYPE)
+
+        if(dep_type STREQUAL "SHARED_LIBRARY")
+            if(NOT has_runtime_dll_genex)
+                add_custom_command(TARGET ${target} POST_BUILD
+                    COMMAND ${CMAKE_COMMAND} -P "${mylib_SOURCE_DIR}/cmake/silent_copy.cmake" 
+                        "$<TARGET_FILE:${dep}>" "$<TARGET_PDB_FILE:${dep}>" "$<TARGET_FILE_DIR:${target}>"
+                    COMMAND_EXPAND_LISTS)
+            else()
+                add_custom_command(TARGET ${target} POST_BUILD
+                    COMMAND ${CMAKE_COMMAND} -P "${mylib_SOURCE_DIR}/cmake/silent_copy.cmake"
+                        "$<TARGET_PDB_FILE:${dep}>" "$<TARGET_FILE_DIR:${target}>"
+                    COMMAND_EXPAND_LISTS)
+            endif()
+        endif()
+    endforeach()
+endfunction()

examples/add/CMakeLists.txt

@@ -1,5 +1,6 @@
 cmake_minimum_required(VERSION 3.14)
 project(mylib-add LANGUAGES CXX)
+include("../../cmake/utils.cmake")
 
 find_package(mylib REQUIRED)
 
@@ -9,3 +10,4 @@ source_group(TREE "${CMAKE_CURRENT_SOURCE_DIR}" FILES ${sources})
 add_executable(mylib-add)
 target_sources(mylib-add PRIVATE ${sources})
 target_link_libraries(mylib-add PRIVATE mylib::mylib)
+win_copy_deps_to_target_dir(mylib-add mylib::mylib)

examples/add/main.cpp

@@ -1,6 +1,10 @@
 #include <mylib/mylib.h>
 
+#include <iostream>
+
 int main(int, char*[])
 {
+    auto sum = mylib::add(1, 1);
+    std::cout << sum << std::endl;
     return 0;
 }

tests/CMakeLists.txt

@@ -1,5 +1,6 @@
 cmake_minimum_required(VERSION 3.14)
 project(mylib-tests)
+include("../cmake/utils.cmake")
 
 #----------------------------------------------------------------------------------------------------------------------
 # general settings and options
@@ -21,6 +22,10 @@ FetchContent_Declare(googletest URL https://github.com/google/googletest/archive
 set(gtest_force_shared_crt ON CACHE BOOL "" FORCE) # do not override parent project's runtime settings on Windows
 set(INSTALL_GTEST OFF)
 
+# For simplicity, always build googletest as static library. This prevents mylib-tests executable from
+# complaining about missing googletest DLLs on Windows.
+set(BUILD_SHARED_LIBS OFF)
+
 FetchContent_MakeAvailable(googletest)
 
 #----------------------------------------------------------------------------------------------------------------------
@@ -49,5 +54,7 @@ target_link_libraries(mylib-tests
         mylib::mylib
         gtest_main)
 
+win_copy_deps_to_target_dir(mylib-tests mylib::mylib)
+
 include(GoogleTest)
 gtest_discover_tests(mylib-tests)