switch to cmake and add c++ modules

i have to switch to cmake to get proper c++ modules support.

CMakeLists.txt

@@ -0,0 +1,23 @@
+cmake_minimum_required(VERSION 3.26)
+project(LearningProject CXX)
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+	string(CONCAT CMAKE_EXPERIMENTAL_CXX_SCANDEP_SOURCE
+		"<CMAKE_CXX_COMPILER> <DEFINES> <INCLUDES> <FLAGS> <SOURCE>"
+		" -MT <DYNDEP_FILE> -MD -MF <DEP_FILE>"
+		" ${flags_to_scan_deps} -fdep-file=<DYNDEP_FILE> -fdep-output=<OBJECT>"
+	)
+
+	set(CMAKE_EXPERIMENTAL_CXX_MODULE_MAP_FORMAT "gcc")
+	set(CMAKE_EXPERIMENTAL_CXX_MODULE_MAP_FLAG
+		"${compiler_flags_for_module_map} -fmodule-mapper=<MODULE_MAP_FILE>")
+endif()
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_EXPERIMENTAL_CXX_MODULE_DYNDEP 1)
+set(CMAKE_EXPERIMENTAL_CXX_MODULE_CMAKE_API "2182bf5c-ef0d-489a-91da-49dbc3090d2a")
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+add_subdirectory(src)
+

meson.build

@@ -1,2 +0,0 @@
-project('LearningProject', 'cpp')
-subdir('src')

src/CMakeLists.txt

@@ -0,0 +1,7 @@
+add_subdirectory(math)
+
+add_executable(hello hello.cc)
+add_executable(sqrt sqrt.cc)
+target_link_libraries(sqrt PRIVATE Math)
+add_executable(inheritance inheritance.cc)
+add_executable(enumerations enumerations.cc)

src/enumerations.cc

@@ -1,6 +1,6 @@
 #include <iostream>
 
-std::string generate_crewmate_string(std::string type);
+constexpr std::string generate_crewmate_string(std::string type);
 
 enum class CrewmateType {
 	Sus,
@@ -34,7 +34,7 @@ public:
 	}
 };
 
-std::string generate_crewmate_string(std::string type)
+constexpr std::string generate_crewmate_string(std::string type)
 {
 	return "Your crewmate type is " + type;
 }

src/math.cc

@@ -1,5 +0,0 @@
-#include "math.hh"
-double Math::square(double x)
-{
-	return x * x;
-}

src/math.hh

@@ -1,4 +0,0 @@
-class Math {
-public:
-	double static square(double x);
-};

src/math/CMakeLists.txt

@@ -0,0 +1,2 @@
+add_library(Math)
+target_sources(Math PUBLIC FILE_SET cxx_modules TYPE CXX_MODULES FILES math.cc)

src/math/math.cc

@@ -0,0 +1,12 @@
+module;
+export module Math;
+
+export class Math {
+public:
+	double static square(double x);
+};
+
+double Math::square(double x)
+{
+	return x * x;
+}

src/meson.build

@@ -1,4 +0,0 @@
-executable('hello', 'hello.cc')
-executable('sqrt', ['math.cc', 'sqrt.cc'])
-executable('inheritance', 'inheritance.cc')
-executable('enumerations', 'enumerations.cc')

src/sqrt.cc

@@ -1,4 +1,4 @@
-#include "math.hh"
+import Math;
 #include <iostream>
 
 void print_squared(double x);