Improve toolchain configs, add_toolchains("name[configs]")

[waruqi]

• Fastly switch toolchain configs
  • set_toolchains("mingw[clang]"), it is equivalent to set_toolchains("mingw", {clang = true})
  • xmake f --toolchain=mingw[clang]
• Add add_configs in toolchains to define and check toolchain configs
• Add clang support for llvm-mingw toolchain
  • xmake f --toolchain=mingw[clang] --sdk=/xxx/llvm-mingw
  • set_toolchains("mingw[clang]@llvm-mingw")
• Add gcc support for old version ndk toolchain
  • xmake f -p android --toolchain=ndk[gcc] --ndk=/xxxx

Simplify toolchain configs

1. only toolchain name
e.g. clang, gcc

2. toolchain@package
e.g. "clang@llvm-10", "@muslcc", zig

3. toolchain[configs]@package
e.g. "mingw[clang]@llvm-mingw", "msvc[vs=2025,..]"

• 如何使用 llvm-mingw 的 clang？并且如何使用 xmake.lua 配置？ #6903
• 请教一下旧版本的 NDK 如何指定用 GCC 而不是 LLVM 编译 #6879

[waruqi]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a significant improvement to toolchain configuration by allowing a more concise syntax, such as toolchain[config]. The changes are well-integrated into the core logic, affecting toolchain parsing, project loading, and platform handling. Support for clang in the llvm-mingw toolchain and gcc in the ndk toolchain are also valuable additions.

My review has identified a couple of bugs in the new configuration parsing logic within toolchain.parsename that could lead to incorrect behavior with complex config strings. I've provided a detailed comment with a suggested fix. Additionally, I've pointed out an opportunity to refactor duplicated code in toolchain.load and toolchain.load_withinfo to improve maintainability. With these adjustments, this will be a solid and robust enhancement.

[gemini-code-assist]

There are a couple of issues in the parsing logic for toolchain configs:

1. The gsub pattern on line 631 is greedy. "%[(.*)%]" will cause incorrect parsing if there are multiple [...] sections in the config string. For example, with toolchain[config1=[a,b],config2=[c,d]], the pattern will match a,b],config2=[c,d. You should use a non-greedy pattern like "%[([^]]*)%]" to correctly handle this.

2. When parsing a list-like value (e.g., sdk=[1,2]), the code on line 644 splits a string like "[1:2]" by the colon, which results in {"[1", "2]"}. The surrounding brackets should be removed before splitting the string. You could use v:sub(2, -2) to strip them.

Here's a suggested implementation that addresses both issues:

        if toolchain_name_raw and configs_str then
            configs_str = configs_str:gsub("%%[([^\]]*)%%]", function (w)
                return w:replace(",", ":")
            end)
            requirestr = configs_str
            toolchain_name = toolchain_name_raw
            local splitinfo = configs_str:split(",", {plain = true})
            for _, v in ipairs(splitinfo) do
                local parts = v:split("=", {plain = true})
                local k = parts[1]
                v = parts[2]
                requireconfs = requireconfs or {}
                if v then
                    if v:find(":", 1 ,true) then
                        if v:startswith("[") and v:endswith("]") then
                            v = v:sub(2, -2)
                        end
                        requireconfs[k] = v:split(":", {plain = true})
                    else
                        requireconfs[k] = option.boolean(v)
                    end
                else
                    requireconfs[k] = true
                end
            end
        end

[gemini-code-assist]

The logic for parsing the toolchain name and initializing the configs table is duplicated here and in toolchain.load_withinfo (lines 777-786). To improve maintainability and reduce redundancy, you could extract this common logic into a private helper function.

For example, you could create a function toolchain._prepare_load_params(name, opt):

function toolchain._prepare_load_params(name, opt)
    opt = opt or {}
    local parseinfo = toolchain.parsename(name)
    local name = parseinfo.name
    local configs = parseinfo.requireconfs or {}
    table.join2(configs, opt)
    configs.packages = opt.packages or parseinfo.packages
    configs.plat = opt.plat or config.get("plat") or os.host()
    configs.arch = opt.arch or config.get("arch") or os.arch()
    return name, configs, parseinfo
end

Then both toolchain.load and toolchain.load_withinfo can be simplified by calling this helper.