Cleanup TruffleRuby.graalvm_home it is always nil now

* Specifically it is nil in JVM & Native standalones.
* Legacy GraalVMs with languages inside are no longer supported.
* The method is kept since this is public API.

Author: eregon

doc/user/truffleruby-additions.md

@@ -38,8 +38,6 @@ TruffleRuby provides these non-standard methods and classes that provide additio
 
 * `TruffleRuby.full_memory_barrier` ensures lack of reordering of loads or stores before the barrier with loads or stores after the barrier.
 
-* `TruffleRuby.graalvm_home` returns the GraalVM home or `nil` if running outside of GraalVM (e.g., Native standalone).
-
 * `TruffleRuby.synchronized(object) { }` will run the block while holding an implicit lock per object instance.
 
 ### Atomic References

spec/truffle/launcher_spec.rb

@@ -341,8 +341,8 @@ def should_print_full_java_command(options, env: {})
       out.should include("--jvm")
     end
 
-    if TruffleRuby.graalvm_home or !TruffleRuby.native?
-      # These options are only shown in GraalVM, they are not available in a native standalone
+    unless TruffleRuby.native?
+      # This is only shown in JVM standalones
       out.should include("--polyglot")
     end
   end
@@ -417,53 +417,4 @@ def should_print_full_java_command(options, env: {})
       out.should == 'bar'
     end
   end
-
-  guard -> {
-    # GraalVM with both --jvm and --native
-    defined?(::TruffleRuby) and TruffleRuby.graalvm_home and TruffleRuby.native?
-  } do
-    describe "runtime configuration flags" do
-      before :each do
-        @trufflerubyopt = ENV['TRUFFLERUBYOPT']
-        # remove --native/--jvm from $TRUFFLERUBYOPT as they can conflict with command line arguments for these specs
-        ENV['TRUFFLERUBYOPT'] = @trufflerubyopt.to_s.gsub(/--(native|jvm)\b/, '')
-      end
-
-      after :each do
-        ENV['TRUFFLERUBYOPT'] = @trufflerubyopt
-      end
-
-      ['RUBYOPT', 'TRUFFLERUBYOPT'].each do |var|
-        it "should recognize ruby --vm options in #{var} when switching to JVM" do
-          env = { var => "--jvm #{@ignore_jvm_thread_warnings} --vm.Dfoo=bar" } # ignoring the original value of RUBYOPT/TRUFFLERUBYOPT on purpose here
-          out = ruby_exe('puts RUBY_DESCRIPTION; puts Truffle::System.get_java_property("foo")', env: env, args: @redirect)
-          check_status_and_empty_stderr
-          out = out.lines.map(&:chomp)
-          out[0].should =~ /(GraalVM CE|Oracle GraalVM) JVM/
-          out[1].should == 'bar'
-        end
-      end
-
-      it "uses --native by default" do
-        out = ruby_exe(nil, options: "--version", args: @redirect)
-        check_status_and_empty_stderr
-        out.should =~ /(GraalVM CE|Oracle GraalVM) Native/
-      end
-
-      it "switches to JVM with --jvm as a Ruby argument" do
-        out = ruby_exe(nil, options: "--jvm #{@ignore_jvm_thread_warnings} --version", args: @redirect)
-        check_status_and_empty_stderr
-        out.should =~ /(GraalVM CE|Oracle GraalVM) JVM/
-      end
-
-      it "keeps --jvm as an application argument if given as an application argument" do
-        script = fixture(__FILE__, "argv.rb")
-        out = ruby_exe(nil, options: "-v", args: "#{script} --jvm 1 2 #{@redirect}")
-        check_status_and_empty_stderr
-        out = out.lines.map(&:chomp)
-        out[0].should =~ /(GraalVM CE|Oracle GraalVM) Native/
-        out.should.include?('["--jvm", "1", "2"]')
-      end
-    end
-  end
 end

src/main/java/org/truffleruby/extra/TruffleRubyNodes.java

@@ -17,7 +17,6 @@
 import com.oracle.truffle.api.nodes.Node;
 import com.oracle.truffle.api.object.DynamicObjectLibrary;
 import com.oracle.truffle.api.profiles.InlinedBranchProfile;
-import com.oracle.truffle.api.strings.TruffleString;
 import org.truffleruby.Layouts;
 import org.truffleruby.RubyContext;
 import org.truffleruby.RubyLanguage;
@@ -26,7 +25,6 @@
 import org.truffleruby.builtins.CoreMethodArrayArgumentsNode;
 import org.truffleruby.builtins.CoreMethodNode;
 import org.truffleruby.annotations.CoreModule;
-import org.truffleruby.core.encoding.Encodings;
 import org.truffleruby.core.mutex.MutexOperations;
 import org.truffleruby.core.proc.RubyProc;
 
@@ -48,21 +46,9 @@ public abstract class TruffleRubyNodes {
     public abstract static class GraalvmHomeNode extends CoreMethodArrayArgumentsNode {
 
         @Specialization
-        Object graalvmHome(
-                @Cached TruffleString.FromJavaStringNode fromJavaStringNode) {
-            String value = getProperty("org.graalvm.home");
-            if (value == null) {
-                return nil;
-            } else {
-                return createString(fromJavaStringNode, value, Encodings.UTF_8);
-            }
-        }
-
-        @TruffleBoundary
-        private static String getProperty(String key) {
-            return System.getProperty(key);
+        Object graalvmHome() {
+            return nil;
         }
-
     }
 
     @CoreMethod(names = "jit?", onSingleton = true)