Add cppfront rule

tests/projects/cppfront/console/.gitignore

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+# Xmake cache
+.xmake/
+build/
+
+# MacOS Cache
+.DS_Store
+
+

tests/projects/cppfront/console/src/main.cpp2

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+main: () -> int =
+    println("Hello world!\n");
+
+println: (msg: _) -> int = {
+    std::cout << msg;
+    return 0;
+}

tests/projects/cppfront/console/xmake.lua

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+add_rules("mode.debug", "mode.release")
+
+add_requires("cppfront")
+
+target("test")
+    add_rules("cppfront")
+    set_kind("binary")
+    add_files("src/*.cpp2")
+    add_packages("cppfront")
+

xmake/rules/cppfront/xmake.lua

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+--!A cross-platform build utility based on Lua
+--
+-- Licensed under the Apache License, Version 2.0 (the "License");
+-- you may not use this file except in compliance with the License.
+-- You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+--
+-- Copyright (C) 2015-present, TBOOX Open Source Group.
+--
+-- @author      ruki
+-- @file        xmake.lua
+--
+
+-- define rule: cppfront.build
+rule("cppfront.build")
+    set_extensions(".cpp2")
+    on_load(function (target)
+        -- only cppfront source files? we need to patch cxx source kind for linker
+        local sourcekinds = target:sourcekinds()
+        if #sourcekinds == 0 then
+            table.insert(sourcekinds, "cxx")
+        end
+        local cppfront = target:pkg("cppfront")
+        if cppfront and cppfront:installdir() then
+            local includedir = path.join(cppfront:installdir(), "include")
+            if os.isdir(includedir) then
+                target:add("includedirs", includedir)
+            end
+        end
+    end)
+    on_buildcmd_file(function (target, batchcmds, sourcefile_cpp2, opt)
+
+        -- get cppfront
+        import("lib.detect.find_tool")
+        local cppfront = assert(find_tool("cppfront", {check = "-h"}), "cppfront not found!")
+
+        -- get c++ source file for cpp2
+        local sourcefile_cpp = target:autogenfile((sourcefile_cpp2:gsub(".cpp2$", ".cpp")))
+        local basedir = path.directory(sourcefile_cpp)
+
+        -- add objectfile
+        local objectfile = target:objectfile(sourcefile_cpp)
+        table.insert(target:objectfiles(), objectfile)
+
+        -- add commands
+        local argv = {"-o", path(sourcefile_cpp), path(sourcefile_cpp2)}
+        batchcmds:show_progress(opt.progress, "${color.build.object}compiling.cpp2 %s", sourcefile_cpp2)
+        batchcmds:mkdir(basedir)
+        batchcmds:vrunv(cppfront.program, argv)
+        batchcmds:compile(sourcefile_cpp, objectfile, {configs = {languages = "c++20"}})
+
+        -- add deps
+        batchcmds:add_depfiles(sourcefile_cpp2)
+        batchcmds:set_depmtime(os.mtime(objectfile))
+        batchcmds:set_depcache(target:dependfile(objectfile))
+    end)
+
+
+-- define rule: cppfront
+rule("cppfront")
+
+    -- add build rules
+    add_deps("cppfront.build")
+
+    -- set compiler runtime, e.g. vs runtime
+    add_deps("utils.compiler.runtime")
+
+    -- inherit links and linkdirs of all dependent targets by default
+    add_deps("utils.inherit.links")
+
+    -- support `add_files("src/*.o")` and `add_files("src/*.a")` to merge object and archive files to target
+    add_deps("utils.merge.object", "utils.merge.archive")
+
+    -- we attempt to extract symbols to the independent file and
+    -- strip self-target binary if `set_symbols("debug")` and `set_strip("all")` are enabled
+    add_deps("utils.symbols.extract")
+