cmake tweating

- setting compiler flags via interface library. There are flags for the
  library and the tests
- showing which version of external lib (catch2) is being fetched

CMakeLists.txt

@@ -14,6 +14,8 @@ set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_CXX_STANDARD_REQUIRED ON) # ensure -std=c++...
 set(CMAKE_CXX_EXTENSIONS OFF) # avoid -std=g++...
 
+include(cmake/compile_flags.cmake)
+
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 

cmake/compile_flags.cmake

@@ -0,0 +1,5 @@
+add_library(options_compile_flags INTERFACE)
+target_compile_options(options_compile_flags INTERFACE -Wall -Wextra -Wpedantic)
+
+add_library(options_tests_compile_flags INTERFACE)
+target_compile_options(options_tests_compile_flags INTERFACE -Wall -Wextra -Wpedantic)

src/CMakeLists.txt

@@ -1,8 +1,4 @@
 # if either tests or example should be built - then add some extra flags
-if(USE_TESTS OR USE_EXAMPLE)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS_DEBUG} -Wall -Wextra -Wunused-variable")
-endif()
-
 add_subdirectory(options)
 
 if(USE_TESTS)

src/example/CMakeLists.txt

@@ -1,2 +1,2 @@
 add_executable(example example.cpp)
-target_link_libraries(example PRIVATE options)
+target_link_libraries(example PRIVATE options options_compile_flags)

src/options/CMakeLists.txt

@@ -1,2 +1,3 @@
 add_library(options STATIC Converters.cpp Option.cpp Options.cpp)
 target_include_directories(options PUBLIC ..)
+target_link_libraries(options PRIVATE options_compile_flags)

src/tests/CMakeLists.txt

@@ -1,16 +1,17 @@
 include(FetchContent)
 
+set(CATCH2_GIT_TAG v3.5.2)
 FetchContent_Declare(
     Catch2
     GIT_REPOSITORY https://github.com/catchorg/Catch2.git
-    GIT_TAG v3.5.2
+    GIT_TAG ${CATCH2_GIT_TAG}
     GIT_SHALLOW TRUE)
 
-message(STATUS "Making Catch2 available...")
+message(STATUS "Making Catch2 ${CATCH2_GIT_TAG} available...")
 FetchContent_MakeAvailable(Catch2)
 message(STATUS "Catch2 ready")
 
 enable_testing()
 
 add_executable(${PROJECT_NAME}_tests Option_Test.cpp Options_Test.cpp)
-target_link_libraries(${PROJECT_NAME}_tests PRIVATE options Catch2WithMain)
+target_link_libraries(${PROJECT_NAME}_tests PRIVATE options options_tests_compile_flags Catch2WithMain)