Fix the current parser detection

Since `RUBY_DESCRIPTION` contains the branch name, `/prism/i` can
match unexpectedly.  Extract the feature lists between revision
and platform infos.

.github/workflows/parse_y.yml

@@ -78,7 +78,9 @@ jobs:
 
       - run: make
 
-      - run: make TESTRUN_SCRIPT='-e "exit !RUBY_DESCRIPTION.include?(%[+PRISM])"' run
+      - run: make TESTRUN_SCRIPT='-renvutil -v -e "exit EnvUtil.current_parser == %[parse.y]"' run
+        env:
+          RUNOPT0: -I$(tooldir)/lib
 
       - name: make ${{ matrix.test_task }}
         run: make -s ${{ matrix.test_task }} RUN_OPTS="$RUN_OPTS" SPECOPTS="$SPECOPTS"

tool/lib/envutil.rb

@@ -226,7 +226,6 @@ module EnvUtil
     args = [args] if args.kind_of?(String)
     # use the same parser as current ruby
     if args.none? { |arg| arg.start_with?("--parser=") }
-      current_parser = RUBY_DESCRIPTION =~ /prism/i ? "prism" : "parse.y"
       args = ["--parser=#{current_parser}"] + args
     end
     pid = spawn(child_env, *precommand, rubybin, *args, opt)
@@ -276,6 +275,12 @@ module EnvUtil
   end
   module_function :invoke_ruby
 
+  def current_parser
+    features = RUBY_DESCRIPTION[%r{\)\K [-+*/%._0-9a-zA-Z ]*(?=\[[-+*/%._0-9a-zA-Z]+\]\z)}]
+    features&.split&.include?("+PRISM") ? "prism" : "parse.y"
+  end
+  module_function :current_parser
+
   def verbose_warning
     class << (stderr = "".dup)
       alias write concat