C#: Begin move to .NET Core

We're targeting .NET 5 for now to make development easier while
.NET 6 is not yet released.

TEMPORARY REGRESSIONS
---------------------

Assembly unloading is not implemented yet. As such, many Godot
resources are leaked at exit. This will be re-implemented later
together with assembly hot-reloading.

5 files changed, 124 insertions, 701 deletions

diff --git a/modules/mono/build_scripts/build_assemblies.py b/modules/mono/build_scripts/build_assemblies.py
index dd96f40f6b..67c2f7f70e 100755
--- a/modules/mono/build_scripts/build_assemblies.py
+++ b/modules/mono/build_scripts/build_assemblies.py
@@ -203,6 +203,9 @@ def build_godot_api(msbuild_tool, module_dir, output_dir):
         "GodotSharpEditor.dll",
         "GodotSharpEditor.pdb",
         "GodotSharpEditor.xml",
+        "GodotPlugins.dll",
+        "GodotPlugins.pdb",
+        "GodotPlugins.runtimeconfig.json",
     ]
 
     for build_config in ["Debug", "Release"]:
@@ -223,6 +226,7 @@ def build_godot_api(msbuild_tool, module_dir, output_dir):
 
         core_src_dir = os.path.abspath(os.path.join(sln, os.pardir, "GodotSharp", "bin", build_config))
         editor_src_dir = os.path.abspath(os.path.join(sln, os.pardir, "GodotSharpEditor", "bin", build_config))
+        plugins_src_dir = os.path.abspath(os.path.join(sln, os.pardir, "GodotPlugins", "bin", build_config, "net5.0"))
 
         if not os.path.isdir(editor_api_dir):
             assert not os.path.isfile(editor_api_dir)
@@ -236,6 +240,8 @@ def build_godot_api(msbuild_tool, module_dir, output_dir):
             src_path = os.path.join(core_src_dir, filename)
             if not os.path.isfile(src_path):
                 src_path = os.path.join(editor_src_dir, filename)
+            if not os.path.isfile(src_path):
+                src_path = os.path.join(plugins_src_dir, filename)
 
             print(f"Copying assembly to {target_path}...")
             copy(src_path, target_path)
diff --git a/modules/mono/build_scripts/make_android_mono_config.py b/modules/mono/build_scripts/make_android_mono_config.py
deleted file mode 100644
index 3459244bc2..0000000000
--- a/modules/mono/build_scripts/make_android_mono_config.py
+++ /dev/null
@@ -1,55 +0,0 @@
-def generate_compressed_config(config_src, output_dir):
-    import os.path
-
-    # Source file
-    with open(os.path.join(output_dir, "android_mono_config.gen.cpp"), "w") as cpp:
-        with open(config_src, "rb") as f:
-            buf = f.read()
-            decompr_size = len(buf)
-            import zlib
-
-            # Use maximum zlib compression level to further reduce file size
-            # (at the cost of initial build times).
-            buf = zlib.compress(buf, zlib.Z_BEST_COMPRESSION)
-            compr_size = len(buf)
-
-            bytes_seq_str = ""
-            for i, buf_idx in enumerate(range(compr_size)):
-                if i > 0:
-                    bytes_seq_str += ", "
-                bytes_seq_str += str(buf[buf_idx])
-
-            cpp.write(
-                """/* THIS FILE IS GENERATED DO NOT EDIT */
-#include "android_mono_config.h"
-
-#ifdef ANDROID_ENABLED
-
-#include "core/io/compression.h"
-
-
-namespace {
-
-// config
-static const int config_compressed_size = %d;
-static const int config_uncompressed_size = %d;
-static const unsigned char config_compressed_data[] = { %s };
-} // namespace
-
-String get_godot_android_mono_config() {
-	Vector<uint8_t> data;
-	data.resize(config_uncompressed_size);
-	uint8_t* w = data.ptrw();
-	Compression::decompress(w, config_uncompressed_size, config_compressed_data,
-			config_compressed_size, Compression::MODE_DEFLATE);
-	String s;
-	if (s.parse_utf8((const char *)w, data.size()) != OK) {
-		ERR_FAIL_V(String());
-	}
-	return s;
-}
-
-#endif // ANDROID_ENABLED
-"""
-                % (compr_size, decompr_size, bytes_seq_str)
-            )
diff --git a/modules/mono/build_scripts/mono_android_config.xml b/modules/mono/build_scripts/mono_android_config.xml
deleted file mode 100644
index e79670afd2..0000000000
--- a/modules/mono/build_scripts/mono_android_config.xml
+++ /dev/null
@@ -1,28 +0,0 @@
-<configuration>
-	<dllmap wordsize="32" dll="i:cygwin1.dll" target="/system/lib/libc.so" />
-	<dllmap wordsize="64" dll="i:cygwin1.dll" target="/system/lib64/libc.so" />
-	<dllmap wordsize="32" dll="libc" target="/system/lib/libc.so" />
-	<dllmap wordsize="64" dll="libc" target="/system/lib64/libc.so" />
-	<dllmap wordsize="32" dll="intl" target="/system/lib/libc.so" />
-	<dllmap wordsize="64" dll="intl" target="/system/lib64/libc.so" />
-	<dllmap wordsize="32" dll="libintl" target="/system/lib/libc.so" />
-	<dllmap wordsize="64" dll="libintl" target="/system/lib64/libc.so" />
-	<dllmap dll="MonoPosixHelper" target="libMonoPosixHelper.so" />
-	<dllmap dll="System.Native" target="libmono-native.so" />
-	<dllmap wordsize="32" dll="i:msvcrt" target="/system/lib/libc.so" />
-	<dllmap wordsize="64" dll="i:msvcrt" target="/system/lib64/libc.so" />
-	<dllmap wordsize="32" dll="i:msvcrt.dll" target="/system/lib/libc.so" />
-	<dllmap wordsize="64" dll="i:msvcrt.dll" target="/system/lib64/libc.so" />
-	<dllmap wordsize="32" dll="sqlite" target="/system/lib/libsqlite.so" />
-	<dllmap wordsize="64" dll="sqlite" target="/system/lib64/libsqlite.so" />
-	<dllmap wordsize="32" dll="sqlite3" target="/system/lib/libsqlite.so" />
-	<dllmap wordsize="64" dll="sqlite3" target="/system/lib64/libsqlite.so" />
-	<dllmap wordsize="32" dll="liblog" target="/system/lib/liblog.so" />
-	<dllmap wordsize="64" dll="liblog" target="/system/lib64/liblog.so" />
-	<dllmap dll="i:kernel32.dll">
-		<dllentry dll="__Internal" name="CopyMemory" target="mono_win32_compat_CopyMemory"/>
-		<dllentry dll="__Internal" name="FillMemory" target="mono_win32_compat_FillMemory"/>
-		<dllentry dll="__Internal" name="MoveMemory" target="mono_win32_compat_MoveMemory"/>
-		<dllentry dll="__Internal" name="ZeroMemory" target="mono_win32_compat_ZeroMemory"/>
-	</dllmap>
-</configuration>
diff --git a/modules/mono/build_scripts/mono_configure.py b/modules/mono/build_scripts/mono_configure.py
index e69904c54b..071693d758 100644
--- a/modules/mono/build_scripts/mono_configure.py
+++ b/modules/mono/build_scripts/mono_configure.py
@@ -1,65 +1,5 @@
 import os
 import os.path
-import subprocess
-
-from SCons.Script import Dir, Environment
-
-if os.name == "nt":
-    from . import mono_reg_utils as monoreg
-
-
-android_arch_dirs = {
-    "armv7": "armeabi-v7a",
-    "arm64v8": "arm64-v8a",
-    "x86": "x86",
-    "x86_64": "x86_64",
-}
-
-
-def get_android_out_dir(env):
-    return os.path.join(
-        Dir("#platform/android/java/lib/libs").abspath,
-        "release" if env["target"] == "release" else "debug",
-        android_arch_dirs[env["android_arch"]],
-    )
-
-
-def find_name_in_dir_files(directory, names, prefixes=[""], extensions=[""]):
-    for extension in extensions:
-        if extension and not extension.startswith("."):
-            extension = "." + extension
-        for prefix in prefixes:
-            for curname in names:
-                if os.path.isfile(os.path.join(directory, prefix + curname + extension)):
-                    return curname
-    return ""
-
-
-def find_file_in_dir(directory, names, prefixes=[""], extensions=[""]):
-    for extension in extensions:
-        if extension and not extension.startswith("."):
-            extension = "." + extension
-        for prefix in prefixes:
-            for curname in names:
-                filename = prefix + curname + extension
-                if os.path.isfile(os.path.join(directory, filename)):
-                    return filename
-    return ""
-
-
-def copy_file(src_dir, dst_dir, src_name, dst_name=""):
-    from shutil import copy
-
-    src_path = os.path.join(Dir(src_dir).abspath, src_name)
-    dst_dir = Dir(dst_dir).abspath
-
-    if not os.path.isdir(dst_dir):
-        os.makedirs(dst_dir)
-
-    if dst_name:
-        copy(src_path, os.path.join(dst_dir, dst_name))
-    else:
-        copy(src_path, dst_dir)
 
 
 def is_desktop(platform):
@@ -71,504 +11,176 @@ def is_unix_like(platform):
 
 
 def module_supports_tools_on(platform):
-    return platform not in ["android", "javascript", "ios"]
-
-
-def find_wasm_src_dir(mono_root):
-    hint_dirs = [
-        os.path.join(mono_root, "src"),
-        os.path.join(mono_root, "../src"),
-    ]
-    for hint_dir in hint_dirs:
-        if os.path.isfile(os.path.join(hint_dir, "driver.c")):
-            return hint_dir
-    return ""
+    return is_desktop(platform)
 
 
 def configure(env, env_mono):
-    bits = env["bits"]
-    is_android = env["platform"] == "android"
-    is_javascript = env["platform"] == "javascript"
-    is_ios = env["platform"] == "ios"
-    is_ios_sim = is_ios and env["arch"] in ["x86", "x86_64"]
+    # is_android = env["platform"] == "android"
+    # is_javascript = env["platform"] == "javascript"
+    # is_ios = env["platform"] == "ios"
+    # is_ios_sim = is_ios and env["arch"] in ["x86", "x86_64"]
 
     tools_enabled = env["tools"]
-    mono_static = env["mono_static"]
-    copy_mono_root = env["copy_mono_root"]
-
-    mono_prefix = env["mono_prefix"]
-    mono_bcl = env["mono_bcl"]
-
-    mono_lib_names = ["mono-2.0-sgen", "monosgen-2.0"]
-
-    if is_android and not env["android_arch"] in android_arch_dirs:
-        raise RuntimeError("This module does not support the specified 'android_arch': " + env["android_arch"])
 
     if tools_enabled and not module_supports_tools_on(env["platform"]):
-        # TODO:
-        # Android: We have to add the data directory to the apk, concretely the Api and Tools folders.
         raise RuntimeError("This module does not currently support building for this platform with tools enabled")
 
-    if is_android and mono_static:
-        # FIXME: When static linking and doing something that requires libmono-native, we get a dlopen error as 'libmono-native'
-        # seems to depend on 'libmonosgen-2.0'. Could be fixed by re-directing to '__Internal' with a dllmap or in the dlopen hook.
-        raise RuntimeError("Statically linking Mono is not currently supported for this platform")
-
-    if not mono_static and (is_javascript or is_ios):
-        raise RuntimeError("Dynamically linking Mono is not currently supported for this platform")
-
-    if not mono_prefix and (os.getenv("MONO32_PREFIX") or os.getenv("MONO64_PREFIX")):
-        print(
-            "WARNING: The environment variables 'MONO32_PREFIX' and 'MONO64_PREFIX' are deprecated; use the"
-            " 'mono_prefix' SCons parameter instead"
-        )
-
-    # Although we don't support building with tools for any platform where we currently use static AOT,
-    # if these are supported in the future, we won't be using static AOT for them as that would be
-    # too restrictive for the editor. These builds would probably be made to only use the interpreter.
-    mono_aot_static = (is_ios and not is_ios_sim) and not env["tools"]
-
-    # Static AOT is only supported on the root domain
-    mono_single_appdomain = mono_aot_static
-
-    if mono_single_appdomain:
-        env_mono.Append(CPPDEFINES=["GD_MONO_SINGLE_APPDOMAIN"])
-
-    if (env["tools"] or env["target"] != "release") and not mono_single_appdomain:
+    if env["tools"] or env["target"] != "release":
         env_mono.Append(CPPDEFINES=["GD_MONO_HOT_RELOAD"])
 
-    if env["platform"] == "windows":
-        mono_root = mono_prefix
-
-        if not mono_root and os.name == "nt":
-            mono_root = monoreg.find_mono_root_dir(bits)
-
-        if not mono_root:
-            raise RuntimeError(
-                "Mono installation directory not found; specify one manually with the 'mono_prefix' SCons parameter"
-            )
-
-        print("Found Mono root directory: " + mono_root)
-
-        mono_lib_path = os.path.join(mono_root, "lib")
-
-        env.Append(LIBPATH=mono_lib_path)
-        env_mono.Prepend(CPPPATH=os.path.join(mono_root, "include", "mono-2.0"))
+    app_host_dir = find_dotnet_app_host_dir(env)
 
-        lib_suffixes = [".lib"]
+    def check_app_host_file_exists(file):
+        file_path = os.path.join(app_host_dir, file)
+        if not os.path.isfile(file_path):
+            raise RuntimeError("File not found: " + file_path)
 
-        if not env.msvc:
-            # MingW supports both '.a' and '.lib'
-            lib_suffixes.insert(0, ".a")
+    # TODO:
+    # All libnethost does for us is provide a function to find hostfxr.
+    # If we could handle that logic ourselves we could void linking it.
 
-        if mono_static:
-            if env.msvc:
-                mono_static_lib_name = "libmono-static-sgen"
-            else:
-                mono_static_lib_name = "libmonosgen-2.0"
+    # nethost file names:
+    #   static: libnethost.a/lib
+    #   shared: libnethost.a/dylib and nethost.dll
+    check_app_host_file_exists("libnethost.lib" if os.name == "nt" else "libnethost.a")
+    check_app_host_file_exists("nethost.h")
+    check_app_host_file_exists("hostfxr.h")
+    check_app_host_file_exists("coreclr_delegates.h")
 
-            mono_static_lib_file = find_file_in_dir(mono_lib_path, [mono_static_lib_name], extensions=lib_suffixes)
+    env.Append(LIBPATH=[app_host_dir])
+    env_mono.Prepend(CPPPATH=app_host_dir)
 
-            if not mono_static_lib_file:
-                raise RuntimeError("Could not find static mono library in: " + mono_lib_path)
+    libnethost_path = os.path.join(app_host_dir, "libnethost.lib" if os.name == "nt" else "libnethost.a")
 
-            if env.msvc:
-                env.Append(LINKFLAGS=mono_static_lib_file)
-
-                env.Append(LINKFLAGS="Mincore.lib")
-                env.Append(LINKFLAGS="msvcrt.lib")
-                env.Append(LINKFLAGS="LIBCMT.lib")
-                env.Append(LINKFLAGS="Psapi.lib")
-            else:
-                mono_static_lib_file_path = os.path.join(mono_lib_path, mono_static_lib_file)
-                env.Append(LINKFLAGS=["-Wl,-whole-archive", mono_static_lib_file_path, "-Wl,-no-whole-archive"])
+    if env["platform"] == "windows":
+        env_mono.Append(CPPDEFINES=["NETHOST_USE_AS_STATIC"])
 
-                env.Append(LIBS=["psapi"])
-                env.Append(LIBS=["version"])
+        if env.msvc:
+            env.Append(LINKFLAGS="libnethost.lib")
         else:
-            mono_lib_file = find_file_in_dir(mono_lib_path, mono_lib_names, extensions=lib_suffixes)
-
-            if not mono_lib_file:
-                raise RuntimeError("Could not find mono library in: " + mono_lib_path)
-
-            if env.msvc:
-                env.Append(LINKFLAGS=mono_lib_file)
-            else:
-                mono_lib_file_path = os.path.join(mono_lib_path, mono_lib_file)
-                env.Append(LINKFLAGS=mono_lib_file_path)
-
-            mono_bin_path = os.path.join(mono_root, "bin")
-
-            mono_dll_file = find_file_in_dir(mono_bin_path, mono_lib_names, prefixes=["", "lib"], extensions=[".dll"])
-
-            if not mono_dll_file:
-                raise RuntimeError("Could not find mono shared library in: " + mono_bin_path)
-
-            copy_file(mono_bin_path, "#bin", mono_dll_file)
+            env.Append(LINKFLAGS=["-Wl,-whole-archive", libnethost_path, "-Wl,-no-whole-archive"])
     else:
         is_apple = env["platform"] in ["macos", "ios"]
-        is_macos = is_apple and not is_ios
-
-        sharedlib_ext = ".dylib" if is_apple else ".so"
-
-        mono_root = mono_prefix
-        mono_lib_path = ""
-        mono_so_file = ""
-
-        if not mono_root and (is_android or is_javascript or is_ios):
-            raise RuntimeError(
-                "Mono installation directory not found; specify one manually with the 'mono_prefix' SCons parameter"
-            )
-
-        if not mono_root and is_macos:
-            # Try with some known directories under macOS
-            hint_dirs = ["/Library/Frameworks/Mono.framework/Versions/Current", "/usr/local/var/homebrew/linked/mono"]
-            for hint_dir in hint_dirs:
-                if os.path.isdir(hint_dir):
-                    mono_root = hint_dir
-                    break
-
-        # We can't use pkg-config to link mono statically,
-        # but we can still use it to find the mono root directory
-        if not mono_root and mono_static:
-            mono_root = pkgconfig_try_find_mono_root(mono_lib_names, sharedlib_ext)
-            if not mono_root:
-                raise RuntimeError(
-                    "Building with mono_static=yes, but failed to find the mono prefix with pkg-config; "
-                    + "specify one manually with the 'mono_prefix' SCons parameter"
-                )
-
-        if is_ios and not is_ios_sim:
-            env_mono.Append(CPPDEFINES=["IOS_DEVICE"])
-
-        if mono_root:
-            print("Found Mono root directory: " + mono_root)
-
-            mono_lib_path = os.path.join(mono_root, "lib")
-
-            env.Append(LIBPATH=[mono_lib_path])
-            env_mono.Prepend(CPPPATH=os.path.join(mono_root, "include", "mono-2.0"))
-
-            mono_lib = find_name_in_dir_files(mono_lib_path, mono_lib_names, prefixes=["lib"], extensions=[".a"])
-
-            if not mono_lib:
-                raise RuntimeError("Could not find mono library in: " + mono_lib_path)
-
-            env_mono.Append(CPPDEFINES=["_REENTRANT"])
-
-            if mono_static:
-                if not is_javascript:
-                    env.Append(LINKFLAGS=["-rdynamic"])
-
-                mono_lib_file = os.path.join(mono_lib_path, "lib" + mono_lib + ".a")
-
-                if is_apple:
-                    if is_macos:
-                        env.Append(LINKFLAGS=["-Wl,-force_load," + mono_lib_file])
-                    else:
-                        arch = env["arch"]
-
-                        def copy_mono_lib(libname_wo_ext):
-                            copy_file(
-                                mono_lib_path, "#bin", libname_wo_ext + ".a", "%s.ios.%s.a" % (libname_wo_ext, arch)
-                            )
-
-                        # Copy Mono libraries to the output folder. These are meant to be bundled with
-                        # the export templates and added to the Xcode project when exporting a game.
-                        copy_mono_lib("lib" + mono_lib)
-                        copy_mono_lib("libmono-native")
-                        copy_mono_lib("libmono-profiler-log")
-
-                        if not is_ios_sim:
-                            copy_mono_lib("libmono-ee-interp")
-                            copy_mono_lib("libmono-icall-table")
-                            copy_mono_lib("libmono-ilgen")
-                else:
-                    assert is_desktop(env["platform"]) or is_android or is_javascript
-                    env.Append(LINKFLAGS=["-Wl,-whole-archive", mono_lib_file, "-Wl,-no-whole-archive"])
-
-                if is_javascript:
-                    env.Append(LIBS=["mono-icall-table", "mono-native", "mono-ilgen", "mono-ee-interp"])
-
-                    wasm_src_dir = os.path.join(mono_root, "src")
-                    if not os.path.isdir(wasm_src_dir):
-                        raise RuntimeError("Could not find mono wasm src directory")
-
-                    # Ideally this should be defined only for 'driver.c', but I can't fight scons for another 2 hours
-                    env_mono.Append(CPPDEFINES=["CORE_BINDINGS"])
-
-                    env_mono.add_source_files(
-                        env.modules_sources,
-                        [
-                            os.path.join(wasm_src_dir, "driver.c"),
-                            os.path.join(wasm_src_dir, "zlib-helper.c"),
-                            os.path.join(wasm_src_dir, "corebindings.c"),
-                        ],
-                    )
-
-                    env.Append(
-                        LINKFLAGS=[
-                            "--js-library",
-                            os.path.join(wasm_src_dir, "library_mono.js"),
-                            "--js-library",
-                            os.path.join(wasm_src_dir, "binding_support.js"),
-                            "--js-library",
-                            os.path.join(wasm_src_dir, "dotnet_support.js"),
-                        ]
-                    )
-            else:
-                env.Append(LIBS=[mono_lib])
-
-            if is_macos:
-                env.Append(LIBS=["iconv", "pthread"])
-            elif is_android:
-                pass  # Nothing
-            elif is_ios:
-                pass  # Nothing, linking is delegated to the exported Xcode project
-            elif is_javascript:
-                env.Append(LIBS=["m", "rt", "dl", "pthread"])
-            else:
-                env.Append(LIBS=["m", "rt", "dl", "pthread"])
-
-            if not mono_static:
-                mono_so_file = find_file_in_dir(
-                    mono_lib_path, mono_lib_names, prefixes=["lib"], extensions=[sharedlib_ext]
-                )
-
-                if not mono_so_file:
-                    raise RuntimeError("Could not find mono shared library in: " + mono_lib_path)
-        else:
-            assert not mono_static
+        # is_macos = is_apple and not is_ios
 
-            # TODO: Add option to force using pkg-config
-            print("Mono root directory not found. Using pkg-config instead")
+        # if is_ios and not is_ios_sim:
+        #     env_mono.Append(CPPDEFINES=["IOS_DEVICE"])
 
-            env.ParseConfig("pkg-config monosgen-2 --libs")
-            env_mono.ParseConfig("pkg-config monosgen-2 --cflags")
+        if is_apple:
+            env.Append(LINKFLAGS=["-Wl,-force_load," + libnethost_path])
+        else:
+            env.Append(LINKFLAGS=["-Wl,-whole-archive", libnethost_path, "-Wl,-no-whole-archive"])
 
-            tmpenv = Environment()
-            tmpenv.AppendENVPath("PKG_CONFIG_PATH", os.getenv("PKG_CONFIG_PATH"))
-            tmpenv.ParseConfig("pkg-config monosgen-2 --libs-only-L")
 
-            for hint_dir in tmpenv["LIBPATH"]:
-                file_found = find_file_in_dir(hint_dir, mono_lib_names, prefixes=["lib"], extensions=[sharedlib_ext])
-                if file_found:
-                    mono_lib_path = hint_dir
-                    mono_so_file = file_found
-                    break
+def find_dotnet_app_host_dir(env):
+    dotnet_root = env["dotnet_root"]
 
-            if not mono_so_file:
-                raise RuntimeError("Could not find mono shared library in: " + str(tmpenv["LIBPATH"]))
+    if not dotnet_root:
+        dotnet_exe = find_executable("dotnet")
+        if dotnet_exe:
+            dotnet_exe_realpath = os.path.realpath(dotnet_exe)  # Eliminate symbolic links
+            dotnet_root = os.path.abspath(os.path.join(dotnet_exe_realpath, os.pardir))
+        else:
+            raise RuntimeError("Cannot find .NET Core Sdk")
 
-        if not mono_static:
-            libs_output_dir = get_android_out_dir(env) if is_android else "#bin"
-            copy_file(mono_lib_path, libs_output_dir, mono_so_file)
+    print("Found .NET Core Sdk root directory: " + dotnet_root)
 
-    if not tools_enabled:
-        if is_desktop(env["platform"]):
-            if not mono_root:
-                mono_root = (
-                    subprocess.check_output(["pkg-config", "mono-2", "--variable=prefix"]).decode("utf8").strip()
-                )
+    dotnet_cmd = os.path.join(dotnet_root, "dotnet.exe" if os.name == "nt" else "dotnet")
 
-            make_template_dir(env, mono_root)
-        elif is_android:
-            # Compress Android Mono Config
-            from . import make_android_mono_config
+    runtime_identifier = determine_runtime_identifier(env)
 
-            module_dir = os.getcwd()
-            config_file_path = os.path.join(module_dir, "build_scripts", "mono_android_config.xml")
-            make_android_mono_config.generate_compressed_config(config_file_path, "mono_gd/")
+    # TODO: In the future, if it can't be found this way, we want to obtain it
+    # from the runtime.{runtime_identifier}.Microsoft.NETCore.DotNetAppHost NuGet package.
+    app_host_search_version = "5.0"
+    app_host_version = find_app_host_version(dotnet_cmd, app_host_search_version)
+    if not app_host_version:
+        raise RuntimeError("Cannot find .NET app host for version: " + app_host_search_version)
 
-            # Copy the required shared libraries
-            copy_mono_shared_libs(env, mono_root, None)
-        elif is_javascript:
-            pass  # No data directory for this platform
-        elif is_ios:
-            pass  # No data directory for this platform
+    app_host_dir = os.path.join(
+        dotnet_root,
+        "packs",
+        "Microsoft.NETCore.App.Host." + runtime_identifier,
+        app_host_version,
+        "runtimes",
+        runtime_identifier,
+        "native",
+    )
 
-    if copy_mono_root:
-        if not mono_root:
-            mono_root = subprocess.check_output(["pkg-config", "mono-2", "--variable=prefix"]).decode("utf8").strip()
+    return app_host_dir
 
-        if tools_enabled:
-            # Only supported for editor builds.
-            copy_mono_root_files(env, mono_root, mono_bcl)
 
+def determine_runtime_identifier(env):
+    names_map = {
+        "windows": "win",
+        "macos": "osx",
+        "linuxbsd": "linux",
+        "server": "linux",  # FIXME: Is server linux only, or also macos?
+    }
 
-def make_template_dir(env, mono_root):
-    from shutil import rmtree
+    # .NET RID architectures: x86, x64, arm, or arm64
 
     platform = env["platform"]
-    target = env["target"]
-
-    template_dir_name = ""
-
-    assert is_desktop(platform)
-
-    template_dir_name = "data.mono.%s.%s.%s" % (platform, env["bits"], target)
-
-    output_dir = Dir("#bin").abspath
-    template_dir = os.path.join(output_dir, template_dir_name)
-
-    template_mono_root_dir = os.path.join(template_dir, "Mono")
-
-    if os.path.isdir(template_mono_root_dir):
-        rmtree(template_mono_root_dir)  # Clean first
 
-    # Copy etc/mono/
-
-    template_mono_config_dir = os.path.join(template_mono_root_dir, "etc", "mono")
-    copy_mono_etc_dir(mono_root, template_mono_config_dir, platform)
-
-    # Copy the required shared libraries
-
-    copy_mono_shared_libs(env, mono_root, template_mono_root_dir)
-
-
-def copy_mono_root_files(env, mono_root, mono_bcl):
-    from glob import glob
-    from shutil import copy
-    from shutil import rmtree
-
-    if not mono_root:
-        raise RuntimeError("Mono installation directory not found")
-
-    output_dir = Dir("#bin").abspath
-    editor_mono_root_dir = os.path.join(output_dir, "GodotSharp", "Mono")
-
-    if os.path.isdir(editor_mono_root_dir):
-        rmtree(editor_mono_root_dir)  # Clean first
-
-    # Copy etc/mono/
-
-    editor_mono_config_dir = os.path.join(editor_mono_root_dir, "etc", "mono")
-    copy_mono_etc_dir(mono_root, editor_mono_config_dir, env["platform"])
-
-    # Copy the required shared libraries
-
-    copy_mono_shared_libs(env, mono_root, editor_mono_root_dir)
+    if is_desktop(platform):
+        if env["arch"] in ["arm", "arm32"]:
+            rid = "arm"
+        elif env["arch"] == "arm64":
+            rid = "arm64"
+        else:
+            bits = env["bits"]
+            bit_arch_map = {"64": "x64", "32": "x86"}
+            rid = bit_arch_map[bits]
+        return "%s-%s" % (names_map[platform], rid)
+    else:
+        raise NotImplementedError()
 
-    # Copy framework assemblies
 
-    mono_framework_dir = mono_bcl or os.path.join(mono_root, "lib", "mono", "4.5")
-    mono_framework_facades_dir = os.path.join(mono_framework_dir, "Facades")
+def find_app_host_version(dotnet_cmd, search_version):
+    import subprocess
 
-    editor_mono_framework_dir = os.path.join(editor_mono_root_dir, "lib", "mono", "4.5")
-    editor_mono_framework_facades_dir = os.path.join(editor_mono_framework_dir, "Facades")
+    try:
+        lines = subprocess.check_output([dotnet_cmd, "--list-runtimes"]).splitlines()
 
-    if not os.path.isdir(editor_mono_framework_dir):
-        os.makedirs(editor_mono_framework_dir)
-    if not os.path.isdir(editor_mono_framework_facades_dir):
-        os.makedirs(editor_mono_framework_facades_dir)
+        for line_bytes in lines:
+            line = line_bytes.decode("utf-8")
+            if not line.startswith("Microsoft.NETCore.App "):
+                continue
 
-    for assembly in glob(os.path.join(mono_framework_dir, "*.dll")):
-        copy(assembly, editor_mono_framework_dir)
-    for assembly in glob(os.path.join(mono_framework_facades_dir, "*.dll")):
-        copy(assembly, editor_mono_framework_facades_dir)
+            parts = line.split(" ")
+            if len(parts) < 2:
+                continue
 
+            version = parts[1]
 
-def copy_mono_etc_dir(mono_root, target_mono_config_dir, platform):
-    from distutils.dir_util import copy_tree
-    from glob import glob
-    from shutil import copy
+            # Look for 6.0.0 or 6.0.0-*
+            if version.startswith(search_version + "."):
+                return version
+    except (subprocess.CalledProcessError, OSError):
+        pass
+    return ""
 
-    if not os.path.isdir(target_mono_config_dir):
-        os.makedirs(target_mono_config_dir)
 
-    mono_etc_dir = os.path.join(mono_root, "etc", "mono")
-    if not os.path.isdir(mono_etc_dir):
-        mono_etc_dir = ""
-        etc_hint_dirs = []
-        if platform != "windows":
-            etc_hint_dirs += ["/etc/mono", "/usr/local/etc/mono"]
-        if "MONO_CFG_DIR" in os.environ:
-            etc_hint_dirs += [os.path.join(os.environ["MONO_CFG_DIR"], "mono")]
-        for etc_hint_dir in etc_hint_dirs:
-            if os.path.isdir(etc_hint_dir):
-                mono_etc_dir = etc_hint_dir
-                break
-        if not mono_etc_dir:
-            raise RuntimeError("Mono installation etc directory not found")
+ENV_PATH_SEP = ";" if os.name == "nt" else ":"
 
-    copy_tree(os.path.join(mono_etc_dir, "2.0"), os.path.join(target_mono_config_dir, "2.0"))
-    copy_tree(os.path.join(mono_etc_dir, "4.0"), os.path.join(target_mono_config_dir, "4.0"))
-    copy_tree(os.path.join(mono_etc_dir, "4.5"), os.path.join(target_mono_config_dir, "4.5"))
-    if os.path.isdir(os.path.join(mono_etc_dir, "mconfig")):
-        copy_tree(os.path.join(mono_etc_dir, "mconfig"), os.path.join(target_mono_config_dir, "mconfig"))
 
-    for file in glob(os.path.join(mono_etc_dir, "*")):
-        if os.path.isfile(file):
-            copy(file, target_mono_config_dir)
+def find_executable(name):
+    is_windows = os.name == "nt"
+    windows_exts = os.environ["PATHEXT"].split(ENV_PATH_SEP) if is_windows else None
+    path_dirs = os.environ["PATH"].split(ENV_PATH_SEP)
 
+    search_dirs = path_dirs + [os.getcwd()]  # cwd is last in the list
 
-def copy_mono_shared_libs(env, mono_root, target_mono_root_dir):
-    from shutil import copy
+    for dir in search_dirs:
+        path = os.path.join(dir, name)
 
-    def copy_if_exists(src, dst):
-        if os.path.isfile(src):
-            copy(src, dst)
+        if is_windows:
+            for extension in windows_exts:
+                path_with_ext = path + extension
 
-    platform = env["platform"]
+                if os.path.isfile(path_with_ext) and os.access(path_with_ext, os.X_OK):
+                    return path_with_ext
+        else:
+            if os.path.isfile(path) and os.access(path, os.X_OK):
+                return path
 
-    if platform == "windows":
-        src_mono_bin_dir = os.path.join(mono_root, "bin")
-        target_mono_bin_dir = os.path.join(target_mono_root_dir, "bin")
-
-        if not os.path.isdir(target_mono_bin_dir):
-            os.makedirs(target_mono_bin_dir)
-
-        mono_posix_helper_file = find_file_in_dir(
-            src_mono_bin_dir, ["MonoPosixHelper"], prefixes=["", "lib"], extensions=[".dll"]
-        )
-        copy(
-            os.path.join(src_mono_bin_dir, mono_posix_helper_file),
-            os.path.join(target_mono_bin_dir, "MonoPosixHelper.dll"),
-        )
-
-        # For newer versions
-        btls_dll_path = os.path.join(src_mono_bin_dir, "libmono-btls-shared.dll")
-        if os.path.isfile(btls_dll_path):
-            copy(btls_dll_path, target_mono_bin_dir)
-    else:
-        target_mono_lib_dir = (
-            get_android_out_dir(env) if platform == "android" else os.path.join(target_mono_root_dir, "lib")
-        )
-
-        if not os.path.isdir(target_mono_lib_dir):
-            os.makedirs(target_mono_lib_dir)
-
-        lib_file_names = []
-        if platform == "macos":
-            lib_file_names = [
-                lib_name + ".dylib"
-                for lib_name in ["libmono-btls-shared", "libmono-native-compat", "libMonoPosixHelper"]
-            ]
-        elif is_unix_like(platform):
-            lib_file_names = [
-                lib_name + ".so"
-                for lib_name in [
-                    "libmono-btls-shared",
-                    "libmono-ee-interp",
-                    "libmono-native",
-                    "libMonoPosixHelper",
-                    "libmono-profiler-aot",
-                    "libmono-profiler-coverage",
-                    "libmono-profiler-log",
-                    "libMonoSupportW",
-                ]
-            ]
-
-        for lib_file_name in lib_file_names:
-            copy_if_exists(os.path.join(mono_root, "lib", lib_file_name), target_mono_lib_dir)
-
-
-def pkgconfig_try_find_mono_root(mono_lib_names, sharedlib_ext):
-    tmpenv = Environment()
-    tmpenv.AppendENVPath("PKG_CONFIG_PATH", os.getenv("PKG_CONFIG_PATH"))
-    tmpenv.ParseConfig("pkg-config monosgen-2 --libs-only-L")
-    for hint_dir in tmpenv["LIBPATH"]:
-        name_found = find_name_in_dir_files(hint_dir, mono_lib_names, prefixes=["lib"], extensions=[sharedlib_ext])
-        if name_found and os.path.isdir(os.path.join(hint_dir, "..", "include", "mono-2.0")):
-            return os.path.join(hint_dir, "..")
     return ""
diff --git a/modules/mono/build_scripts/mono_reg_utils.py b/modules/mono/build_scripts/mono_reg_utils.py
deleted file mode 100644
index 43c1ec8f8a..0000000000
--- a/modules/mono/build_scripts/mono_reg_utils.py
+++ /dev/null
@@ -1,112 +0,0 @@
-import os
-import platform
-
-if os.name == "nt":
-    import winreg
-
-
-def _reg_open_key(key, subkey):
-    try:
-        return winreg.OpenKey(key, subkey)
-    except OSError:
-        if platform.architecture()[0] == "32bit":
-            bitness_sam = winreg.KEY_WOW64_64KEY
-        else:
-            bitness_sam = winreg.KEY_WOW64_32KEY
-        return winreg.OpenKey(key, subkey, 0, winreg.KEY_READ | bitness_sam)
-
-
-def _reg_open_key_bits(key, subkey, bits):
-    sam = winreg.KEY_READ
-
-    if platform.architecture()[0] == "32bit":
-        if bits == "64":
-            # Force 32bit process to search in 64bit registry
-            sam |= winreg.KEY_WOW64_64KEY
-    else:
-        if bits == "32":
-            # Force 64bit process to search in 32bit registry
-            sam |= winreg.KEY_WOW64_32KEY
-
-    return winreg.OpenKey(key, subkey, 0, sam)
-
-
-def _find_mono_in_reg(subkey, bits):
-    try:
-        with _reg_open_key_bits(winreg.HKEY_LOCAL_MACHINE, subkey, bits) as hKey:
-            value = winreg.QueryValueEx(hKey, "SdkInstallRoot")[0]
-            return value
-    except OSError:
-        return None
-
-
-def _find_mono_in_reg_old(subkey, bits):
-    try:
-        with _reg_open_key_bits(winreg.HKEY_LOCAL_MACHINE, subkey, bits) as hKey:
-            default_clr = winreg.QueryValueEx(hKey, "DefaultCLR")[0]
-            if default_clr:
-                return _find_mono_in_reg(subkey + "\\" + default_clr, bits)
-            return None
-    except OSError:
-        return None
-
-
-def find_mono_root_dir(bits):
-    root_dir = _find_mono_in_reg(r"SOFTWARE\Mono", bits)
-    if root_dir is not None:
-        return str(root_dir)
-    root_dir = _find_mono_in_reg_old(r"SOFTWARE\Novell\Mono", bits)
-    if root_dir is not None:
-        return str(root_dir)
-    return ""
-
-
-def find_msbuild_tools_path_reg():
-    import subprocess
-
-    vswhere = os.getenv("PROGRAMFILES(X86)")
-    if not vswhere:
-        vswhere = os.getenv("PROGRAMFILES")
-    vswhere += r"\Microsoft Visual Studio\Installer\vswhere.exe"
-
-    vswhere_args = ["-latest", "-products", "*", "-requires", "Microsoft.Component.MSBuild"]
-
-    try:
-        lines = subprocess.check_output([vswhere] + vswhere_args).splitlines()
-
-        for line in lines:
-            parts = line.decode("utf-8").split(":", 1)
-
-            if len(parts) < 2 or parts[0] != "installationPath":
-                continue
-
-            val = parts[1].strip()
-
-            if not val:
-                raise ValueError("Value of `installationPath` entry is empty")
-
-            # Since VS2019, the directory is simply named "Current"
-            msbuild_dir = os.path.join(val, "MSBuild\\Current\\Bin")
-            if os.path.isdir(msbuild_dir):
-                return msbuild_dir
-
-            # Directory name "15.0" is used in VS 2017
-            return os.path.join(val, "MSBuild\\15.0\\Bin")
-
-        raise ValueError("Cannot find `installationPath` entry")
-    except ValueError as e:
-        print("Error reading output from vswhere: " + e.message)
-    except subprocess.CalledProcessError as e:
-        print(e.output)
-    except OSError as e:
-        print(e)
-
-    # Try to find 14.0 in the Registry
-
-    try:
-        subkey = r"SOFTWARE\Microsoft\MSBuild\ToolsVersions\14.0"
-        with _reg_open_key(winreg.HKEY_LOCAL_MACHINE, subkey) as hKey:
-            value = winreg.QueryValueEx(hKey, "MSBuildToolsPath")[0]
-            return value
-    except OSError:
-        return ""