build: Remove --gemfile option from rbwasm command line

This option was used to specify the path to the `Gemfile` by overriding
gemfile path after launching rbwasm command through Bundler. But it does
not work because Bundler caches a lot of information and cannot
invalidate all of them in-process. So we should cd to the directory
containing the Gemfile and run the command there to avoid the need to
switch the Gemfile path.

This issue was revealed when trying to install remote gems, which was
reuired to work around installation issue around bundled power_assert
gem in the Ruby build system.

Author: kateinoigakukun

lib/ruby_wasm/cli.rb

@@ -116,10 +116,6 @@ def build(args)
             options[:format] = format
           end
 
-          opts.on("--gemfile GEMFILE", "Gemfile") do |gemfile|
-            options[:gemfile] = gemfile
-          end
-
           opts.on("--print-ruby-cache-key", "Print Ruby cache key") do
             options[:print_ruby_cache_key] = true
           end
@@ -289,12 +285,7 @@ def derive_packager(options)
           level = options[:print_ruby_cache_key] ? :silent : Bundler.ui.level
           old_level = Bundler.ui.level
           Bundler.ui.level = level
-          if options[:gemfile]
-            Bundler::SharedHelpers.set_env "BUNDLE_GEMFILE", options[:gemfile]
-            definition = Bundler.definition(true) # unlock=true to re-evaluate "BUNDLE_GEMFILE"
-          else
-            definition = Bundler.definition
-          end
+          definition = Bundler.definition
         ensure
           Bundler.ui.level = old_level
         end

rakelib/packaging.rake

@@ -51,8 +51,9 @@ namespace :npm do
           # Share ./build and ./rubies in the same workspace
           "RUBY_WASM_ROOT" => base_dir
         }
+        cwd = nil
         if gemfile_path = pkg[:gemfile]
-          build_command.push "--gemfile", gemfile_path
+          cwd = File.dirname(gemfile_path)
         else
           # Explicitly disable rubygems integration since Bundler finds
           # Gemfile in the repo root directory.
@@ -61,15 +62,17 @@ namespace :npm do
         dist_dir = File.join(pkg_dir, "dist")
         mkdir_p dist_dir
         if pkg[:target] == "wasm32-unknown-wasi"
-          sh env,
-             *build_command,
-             "--no-stdlib",
-             "-o",
-             File.join(dist_dir, "ruby.wasm")
-          sh env,
-             *build_command,
-             "-o",
-             File.join(dist_dir, "ruby.debug+stdlib.wasm")
+          Dir.chdir(cwd || base_dir) do
+            sh env,
+               *build_command,
+               "--no-stdlib",
+               "-o",
+               File.join(dist_dir, "ruby.wasm")
+            sh env,
+               *build_command,
+               "-o",
+               File.join(dist_dir, "ruby.debug+stdlib.wasm")
+          end
           sh wasi_sdk.wasm_opt,
              "--strip-debug",
              File.join(dist_dir, "ruby.wasm"),
@@ -81,7 +84,9 @@ namespace :npm do
              "-o",
              File.join(dist_dir, "ruby+stdlib.wasm")
         elsif pkg[:target] == "wasm32-unknown-emscripten"
-          sh env, *build_command, "-o", "/dev/null"
+          Dir.chdir(cwd || base_dir) do
+            sh env, *build_command, "-o", "/dev/null"
+          end
         end
       end