build wit-bindgen if needed

Author: kateinoigakukun

lib/ruby_wasm/build_system/toolchain.rb

@@ -1,3 +1,5 @@
+require_relative "./toolchain/wit_bindgen"
+
 module RubyWasm
   class Toolchain < ::Rake::TaskLib
     attr_reader :name

lib/ruby_wasm/build_system/toolchain/wit_bindgen.rb

@@ -0,0 +1,29 @@
+module RubyWasm
+  class WitBindgen < ::Rake::TaskLib
+    attr_reader :bin_path
+
+    def initialize(build_dir:, revision: "bb33644b4fd21ecf43761f63c472cdfffe57e300")
+      @build_dir = build_dir
+      @tool_dir = File.join(@build_dir, "toolchain", "wit-bindgen")
+      @bin_path = File.join(@tool_dir, "bin", "wit-bindgen")
+      @revision = revision
+    end
+
+    def define_task
+      file @bin_path do
+        RubyWasm::Toolchain.check_executable("cargo")
+        sh *[
+          "cargo", "install",
+          "--git", "https://github.com/bytecodealliance/wit-bindgen",
+          "--rev", @revision, "--root", @tool_dir,
+          "wit-bindgen-cli",
+        ]
+      end
+      @task ||= task "wit-bindgen:install" => @bin_path
+    end
+
+    def install_task
+      @task
+    end
+  end
+end

tasks/check.rake

@@ -1,23 +1,24 @@
 namespace :check do
-  task :bindgen_c do
-    RubyWasm::Toolchain.check_executable("wit-bindgen")
+  wit_bindgen = RubyWasm::WitBindgen.new(build_dir: "build")
+  wit_bindgen.define_task
+  task :bindgen_c => wit_bindgen.install_task do
     wits = [
       ["ext/witapi/bindgen/rb-abi-guest.wit", "--export"],
       ["ext/js/bindgen/rb-js-abi-host.wit", "--import"],
     ]
     wits.each do |wit|
       path, mode = wit
-      sh "wit-bindgen c #{mode} #{path} --out-dir #{File.dirname(path)}"
+      sh "#{wit_bindgen.bin_path} c #{mode} #{path} --out-dir #{File.dirname(path)}"
     end
   end
 
-  task :bindgen_js do
-    sh *%w(
-      wit-bindgen js
-      --import ext/witapi/bindgen/rb-abi-guest.wit
-      --export ext/js/bindgen/rb-js-abi-host.wit
-      --out-dir packages/npm-packages/ruby-wasm-wasi/src/bindgen
-    )
+  task :bindgen_js => wit_bindgen.install_task do
+    sh *[
+      wit_bindgen.bin_path, "js",
+      "--import", "ext/witapi/bindgen/rb-abi-guest.wit",
+      "--export", "ext/js/bindgen/rb-js-abi-host.wit",
+      "--out-dir", "packages/npm-packages/ruby-wasm-wasi/src/bindgen",
+    ]
   end
 
   desc "Check wit-bindgen'ed sources are up-to-date"