xmake v2.3.4 发布，更加完善的工具链支持

$ xmake f -p windows --toolchain=clang

$ xmake f -p cross --toolchain=llvm --sdk="C:\Program Files\LLVM"
$ xmake

$ xmake f -p cross --toolchain=gnu-rm --sdk=/xxx/cc-arm-none-eabi-9-2019-q4-major
$ xmake

$ xmake show -l toolchains
xcode         Xcode IDE
vs            VisualStudio IDE
yasm          The Yasm Modular Assembler
clang         A C language family frontend for LLVM
go            Go Programming Language Compiler
dlang         D Programming Language Compiler
sdcc          Small Device C Compiler
cuda          CUDA Toolkit
ndk           Android NDK
rust          Rust Programming Language Compiler
llvm          A collection of modular and reusable compiler and toolchain technologies
cross         Common cross compilation toolchain
nasm          NASM Assembler
gcc           GNU Compiler Collection
mingw         Minimalist GNU for Windows
gnu-rm        GNU Arm Embedded Toolchain
envs          Environment variables toolchain
fasm          Flat Assembler

$ xmake f --toolchain=clang
$ xmake

$ xmake f --toolchain=gcc
$ xmake

toolchain("myclang")
    set_kind("standalone")
    set_toolset("cc", "clang")
    set_toolset("cxx", "clang", "clang++")
    set_toolset("ld", "clang++", "clang")
    set_toolset("sh", "clang++", "clang")
    set_toolset("ar", "ar")
    set_toolset("ex", "ar")
    set_toolset("strip", "strip")
    set_toolset("mm", "clang")
    set_toolset("mxx", "clang", "clang++")
    set_toolset("as", "clang")

    -- ...

target("test")
    set_kind("binary")
    add_files("src/*.c")
    set_toolchains("clang", "yasm")

target("test")
    set_kind("binary")
    set_toolset("cxx", "clang")
    set_toolset("ld", "clang++")

$ xmake g --theme=ninja

set_policy("check.auto_ignore_flags", false)

target("test")
    set_policy("check.auto_ignore_flags", false)

$ xmake l core.project.policy.policies
{ 
  "check.auto_map_flags" = { 
    type = "boolean",
    description = "Enable map gcc flags to the current compiler and linker automatically.",
    default = true 
  },
  "build.across_targets_in_parallel" = { 
    type = "boolean",
    description = "Enable compile the source files for each target in parallel.",
    default = true 
  },
  "check.auto_ignore_flags" = { 
    type = "boolean",
    description = "Enable check and ignore unsupported flags automatically.",
    default = true 
  } 
}

warning: add_ldflags("-static") is ignored, please pass `{force = true}` or call `set_policy("check.auto_ignore_flags", false)` if you want to set it.

add_ldflags("-static", {force = true})

set_policy("check.auto_ignore_flags", false)
target("test")
    add_ldflags("-static")

add_cxflags("-O0")

set_policy("check.auto_map_flags", false)

set_policy("build.across_targets_in_parallel", false)

add_rules("mode.releasedbg")

if is_mode("releasedbg") then
    set_symbols("debug")
    set_optimize("fastest")
    set_strip("all")
end

add_rules("mode.minsizerel")

if is_mode("minsizerel") then
    set_symbols("hidden")
    set_optimize("smallest")
    set_strip("all")
end

$ xmake show
The information of xmake:
    version: 2.3.3+202006011009
    host: macosx/x86_64
    programdir: /Users/ruki/.local/share/xmake
    programfile: /Users/ruki/.local/bin/xmake
    globaldir: /Users/ruki/.xmake
    tmpdir: /var/folders/32/w9cz0y_14hs19lkbs6v6_fm80000gn/T/.xmake501/200603
    workingdir: /Users/ruki/projects/personal/tbox
    packagedir: /Users/ruki/.xmake/packages
    packagedir(cache): /Users/ruki/.xmake/cache/packages/2006

The information of project: tbox
    version: 1.6.5
    plat: macosx
    arch: x86_64
    mode: release
    buildir: build
    configdir: /Users/ruki/projects/personal/tbox/.xmake/macosx/x86_64
    projectdir: /Users/ruki/projects/personal/tbox
    projectfile: /Users/ruki/projects/personal/tbox/xmake.lua

$ xmake show -l toolchains
xcode         Xcode IDE
vs            VisualStudio IDE
yasm          The Yasm Modular Assembler
clang         A C language family frontend for LLVM
...

$ xmake show --target=tbox
The information of target(tbox):
    kind: static
    targetfile: build/macosx/x86_64/release/libtbox.a
    rules: mode.release, mode.debug, mode.profile, mode.coverage
    options: info, float, wchar, exception, force-utf8, deprecated, xml, zip, hash, regex, coroutine, object, charset, database
    packages: mbedtls, polarssl, openssl, pcre2, pcre, zlib, mysql, sqlite3
    links: pthread
    syslinks: pthread, dl, m, c
    cxflags: -Wno-error=deprecated-declarations, -fno-strict-aliasing, -Wno-error=expansion-to-defined, -fno-stack-protector
    defines: __tb_small__, __tb_prefix__="tbox"
    mxflags: -Wno-error=deprecated-declarations, -fno-strict-aliasing, -Wno-error=expansion-to-defined
    headerfiles: src/(tbox/**.h)|**/impl/**.h, src/(tbox/prefix/**/prefix.S), src/(tbox/math/impl/*.h), src/(tbox/utils/impl/*.h), build/macosx/x86_64/release/tbox.config.h
    includedirs: src, build/macosx/x86_64/release
    at: /Users/ruki/projects/personal/tbox/src/tbox/xmake.lua
    sourcebatch(cc): with rule(c.build)
      -> src/tbox/string/static_string.c
         -> build/.objs/tbox/macosx/x86_64/release/src/tbox/string/static_string.c.o
         -> build/.deps/tbox/macosx/x86_64/release/src/tbox/string/static_string.c.o.d
      -> src/tbox/platform/sched.c
         -> build/.objs/tbox/macosx/x86_64/release/src/tbox/platform/sched.c.o
         -> build/.deps/tbox/macosx/x86_64/release/src/tbox/platform/sched.c.o.d
      -> src/tbox/stream/stream.c
         -> build/.objs/tbox/macosx/x86_64/release/src/tbox/stream/stream.c.o
         -> build/.deps/tbox/macosx/x86_64/release/src/tbox/stream/stream.c.o.d
      -> src/tbox/utils/base32.c
         -> build/.objs/tbox/macosx/x86_64/release/src/tbox/utils/base32.c.o
         -> build/.deps/tbox/macosx/x86_64/release/src/tbox/utils/base32.c.o.d

$ xmake show -l modes

$ xmake show -l rules

$ xmake show --help