add build time dependency to static lib

the header only fmt lib is used to show this

CMakeLists.txt

@@ -5,7 +5,7 @@ cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 # Note: update this to your new project's name and version
 project(
   Greeter
-  VERSION 1.0
+  VERSION 1.1
   LANGUAGES CXX
 )
 
@@ -18,6 +18,14 @@ if(PROJECT_SOURCE_DIR STREQUAL PROJECT_BINARY_DIR)
   )
 endif()
 
+# ---- Project settings ----
+
+if(NOT DEFINED CMAKE_CXX_STANDARD)
+  set(CMAKE_CXX_STANDARD 17)
+  set(CMAKE_CXX_STANDARD_REQUIRED ON)
+  set(CMAKE_CXX_EXTENSIONS NO)
+endif()
+
 # ---- Add dependencies via CPM ----
 # see https://github.com/TheLartians/CPM.cmake for more info
 
@@ -27,7 +35,18 @@ include(cmake/CPM.cmake)
 CPMAddPackage(
   NAME PackageProject.cmake
   GITHUB_REPOSITORY TheLartians/PackageProject.cmake
-  VERSION 1.4
+  VERSION 1.4.1
+)
+
+# NOTE: If fmt is not imported, this is needed to prevent: CMake Error: install(EXPORT
+# "GreeterTargets" ...) includes target "Greeter" which requires target "fmt" that is not in any
+# export set.  see too https://gitlab.kitware.com/cmake/cmake/-/issues/15415
+set(FMT_VERSION 7.1.3)
+CPMAddPackage(
+  NAME fmt
+  GIT_TAG ${FMT_VERSION}
+  GITHUB_REPOSITORY fmtlib/fmt
+  # XXX OPTION "FMT_INSTALL YES"
 )
 
 # ---- Add source files ----
@@ -40,17 +59,20 @@ file(GLOB_RECURSE sources CONFIGURE_DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/source/
 # ---- Create library ----
 
 # Note: for header-only libraries change all PUBLIC flags to INTERFACE and create an interface
-# target: add_library(Greeter INTERFACE) set_target_properties(Greeter PROPERTIES
-# INTERFACE_COMPILE_FEATURES cxx_std_17)
+# target:
+add_library(Greeter)
+target_compile_features(Greeter PUBLIC cxx_std_17)
 
-add_library(Greeter ${headers} ${sources})
-
-set_target_properties(Greeter PROPERTIES CXX_STANDARD 17)
+target_sources(Greeter PRIVATE ${headers} ${sources})
 
 # being a cross-platform target, we enforce standards conformance on MSVC
-target_compile_options(Greeter PUBLIC "$<$<BOOL:${MSVC}>:/permissive->")
+if(MSVC)
+  target_compile_options(Greeter PUBLIC /permissive)
+endif()
 
-# Link dependencies (if required) target_link_libraries(Greeter PUBLIC cxxopts)
+# Link dependencies (if required)
+target_link_libraries(Greeter PRIVATE $<BUILD_INTERFACE:fmt::fmt-header-only>)
+# XXX target_link_libraries(Greeter PUBLIC fmt::fmt)
 
 target_include_directories(
   Greeter PUBLIC $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
@@ -72,5 +94,5 @@ packageProject(
   INCLUDE_DIR ${PROJECT_SOURCE_DIR}/include
   INCLUDE_DESTINATION include/${PROJECT_NAME}-${PROJECT_VERSION}
   VERSION_HEADER "${VERSION_HEADER_LOCATION}"
-  DEPENDENCIES ""
+  # XXX DEPENDENCIES "fmt ${FMT_VERSION}"
 )

all/CMakeLists.txt

@@ -7,6 +7,9 @@ project(BuildAll LANGUAGES CXX)
 
 include(../cmake/tools.cmake)
 
+# needed to generate test target
+enable_testing()
+
 add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/../standalone ${CMAKE_BINARY_DIR}/standalone)
 add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/../test ${CMAKE_BINARY_DIR}/test)
 add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/../documentation ${CMAKE_BINARY_DIR}/documentation)

include/greeter/greeter.h

@@ -26,6 +26,9 @@ namespace greeter {
      * @return a string containing the greeting
      */
     std::string greet(LanguageCode lang = LanguageCode::EN) const;
+
+    /// @brief Return an iso date string
+    std::string getIsoDate() const;
   };
 
 }  // namespace greeter

source/greeter.cpp

@@ -1,8 +1,9 @@
+#include <fmt/chrono.h>
 #include <greeter/greeter.h>
 
 using namespace greeter;
 
-Greeter::Greeter(std::string _name) : name(_name) {}
+Greeter::Greeter(std::string _name) : name(std::move(_name)) {}
 
 std::string Greeter::greet(LanguageCode lang) const {
   switch (lang) {
@@ -17,3 +18,8 @@ std::string Greeter::greet(LanguageCode lang) const {
       return "Bonjour " + name + "!";
   }
 }
+
+std::string Greeter::getIsoDate() const {
+  using namespace std::literals::chrono_literals;
+  return fmt::format("{:%H:%M:%S}", 3h + 15min + 30s);
+}

test/CMakeLists.txt

@@ -1,6 +1,10 @@
 cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
 
-project(GreeterTests LANGUAGES CXX)
+project(
+  GreeterTests
+  VERSION 1.1
+  LANGUAGES CXX
+)
 
 # ---- Options ----
 
@@ -22,7 +26,7 @@ CPMAddPackage(
 )
 
 if(TEST_INSTALLED_VERSION)
-  find_package(Greeter REQUIRED)
+  find_package(Greeter ${PROJECT_VERSION} REQUIRED)
 else()
   CPMAddPackage(NAME Greeter SOURCE_DIR ${CMAKE_CURRENT_LIST_DIR}/..)
 endif()
@@ -46,9 +50,9 @@ set_target_properties(GreeterTests PROPERTIES CXX_STANDARD 17)
 # enable compiler warnings
 if(NOT TEST_INSTALLED_VERSION)
   if(CMAKE_CXX_COMPILER_ID MATCHES "Clang" OR CMAKE_CXX_COMPILER_ID MATCHES "GNU")
-    target_compile_options(Greeter PUBLIC -Wall -pedantic -Wextra -Werror)
+    target_compile_options(Greeter PRIVATE -Wall -pedantic -Wextra -Werror)
   elseif(MSVC)
-    target_compile_options(Greeter PUBLIC /W4 /WX)
+    target_compile_options(Greeter PRIVATE /W4 /WX)
     target_compile_definitions(GreeterTests PUBLIC DOCTEST_CONFIG_USE_STD_HEADERS)
   endif()
 endif()
@@ -65,7 +69,7 @@ doctest_discover_tests(GreeterTests)
 
 # ---- code coverage ----
 
-if(ENABLE_TEST_COVERAGE)
+if(ENABLE_TEST_COVERAGE AND NOT TEST_INSTALLED_VERSION)
   target_compile_options(Greeter PUBLIC -O0 -g -fprofile-arcs -ftest-coverage)
   target_link_options(Greeter PUBLIC -fprofile-arcs -ftest-coverage)
 endif()

test/source/greeter.cpp

@@ -16,6 +16,11 @@ TEST_CASE("Greeter") {
 }
 
 TEST_CASE("Greeter version") {
-  static_assert(std::string_view(GREETER_VERSION) == std::string_view("1.0"));
-  CHECK(std::string(GREETER_VERSION) == std::string("1.0"));
-}
+  static_assert(std::string_view(GREETER_VERSION) == std::string_view("1.1"));
+  CHECK(std::string(GREETER_VERSION) == std::string("1.1"));
+}
+
+TEST_CASE("Greeter date") {
+  const greeter::Greeter greeter("Tests");
+  CHECK(greeter.getIsoDate() == std::string("03:15:30"));
+}