cmake: Add root CMakeLists.txt file

Github-Pull: #5
Rebased-From: bc25dda

CMakeLists.txt

@@ -0,0 +1,99 @@
+# Copyright (c) 2023 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+# IMPORTANT: Changes which affect binary results may not be quietly gated
+#            by CMake version.
+#
+# Debian 10 Buster, https://wiki.debian.org/LTS, EOL 2024:
+#  - CMake 3.13.4, https://packages.debian.org/buster/cmake
+#
+# Ubuntu 22.04 Jammy, https://wiki.ubuntu.com/Releases, EOL 2032:
+#  - CMake 3.22.1, https://packages.ubuntu.com/jammy/cmake
+#
+# Visual Studio 17 2022, https://visualstudio.microsoft.com:
+#  - CMake 3.24
+#
+# All policies known to the running version of CMake and introduced
+# in the 3.24 version or earlier will be set to use NEW behavior.
+# All policies introduced in later versions will be unset.
+# See: https://cmake.org/cmake/help/latest/manual/cmake-policies.7.html
+cmake_minimum_required(VERSION 3.13...3.24)
+
+project("Bitcoin Core"
+  VERSION 24.99.0
+  DESCRIPTION "Bitcoin client software"
+  HOMEPAGE_URL "https://bitcoincore.org/"
+  LANGUAGES CXX C ASM
+)
+
+# Configurable options.
+# When adding a new option, end the <help_text> with a full stop for consistency.
+include(CMakeDependentOption)
+cmake_dependent_option(CXX20 "Enable compilation in C++20 mode." OFF "NOT MSVC" ON)
+
+if(CXX20)
+  set(CMAKE_CXX_STANDARD 20)
+else()
+  set(CMAKE_CXX_STANDARD 17)
+endif()
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+set(configure_warnings)
+if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.14)
+  include(CheckPIESupported)
+  check_pie_supported(OUTPUT_VARIABLE check_pie_output LANGUAGES CXX)
+  if(NOT CMAKE_CXX_LINK_PIE_SUPPORTED)
+    list(APPEND configure_warnings "PIE link options are not supported for executable targets: ${check_pie_output}.")
+  endif()
+else()
+  list(APPEND configure_warnings "No PIE options will be passed to a linker for executable targets.")
+endif()
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+
+message("\n")
+message("Configure summary")
+message("=================")
+get_directory_property(definitions COMPILE_DEFINITIONS)
+string(REPLACE ";" " " definitions "${definitions}")
+message("Preprocessor defined macros ........... ${definitions}")
+message("C compiler ............................ ${CMAKE_C_COMPILER}")
+message("CFLAGS ................................ ${CMAKE_C_FLAGS}")
+message("C++ compiler .......................... ${CMAKE_CXX_COMPILER}")
+message("CXXFLAGS .............................. ${CMAKE_CXX_FLAGS}")
+get_directory_property(common_compile_options COMPILE_OPTIONS)
+string(REPLACE ";" " " common_compile_options "${common_compile_options}")
+message("Common compile options ................ ${common_compile_options}")
+get_directory_property(common_link_options LINK_OPTIONS)
+string(REPLACE ";" " " common_link_options "${common_link_options}")
+message("Common link options ................... ${common_link_options}")
+if(DEFINED CMAKE_BUILD_TYPE)
+  message("Build type:")
+  message(" - CMAKE_BUILD_TYPE ................... ${CMAKE_BUILD_TYPE}")
+  string(TOUPPER "${CMAKE_BUILD_TYPE}" build_type)
+  message(" - CFLAGS ............................. ${CMAKE_C_FLAGS_${build_type}}")
+  message(" - CXXFLAGS ........................... ${CMAKE_CXX_FLAGS_${build_type}}")
+  message(" - LDFLAGS for executables ............ ${CMAKE_EXE_LINKER_FLAGS_${build_type}}")
+  message(" - LDFLAGS for shared libraries ....... ${CMAKE_SHARED_LINKER_FLAGS_${build_type}}")
+else()
+  message("Available configurations .............. ${CMAKE_CONFIGURATION_TYPES}")
+  message("Debug configuration:")
+  message(" - CFLAGS ............................. ${CMAKE_C_FLAGS_DEBUG}")
+  message(" - CXXFLAGS ........................... ${CMAKE_CXX_FLAGS_DEBUG}")
+  message(" - LDFLAGS for executables ............ ${CMAKE_EXE_LINKER_FLAGS_DEBUG}")
+  message(" - LDFLAGS for shared libraries ....... ${CMAKE_SHARED_LINKER_FLAGS_DEBUG}")
+  message("Release configuration:")
+  message(" - CFLAGS ............................. ${CMAKE_C_FLAGS_RELEASE}")
+  message(" - CXXFLAGS ........................... ${CMAKE_CXX_FLAGS_RELEASE}")
+  message(" - LDFLAGS for executables ............ ${CMAKE_EXE_LINKER_FLAGS_RELEASE}")
+  message(" - LDFLAGS for shared libraries ....... ${CMAKE_SHARED_LINKER_FLAGS_RELEASE}")
+endif()
+message("\n")
+if(configure_warnings)
+    message("  ******\n")
+    foreach(warning IN LISTS configure_warnings)
+      message(WARNING "${warning}")
+    endforeach()
+    message("  ******\n")
+endif()