Pass in the Truffle runtime implementation name

* Creating a nested Engine is not well supported, and can lead to errors
  if experimental options are set in system properties.

Author: eregon

src/launcher/java/org/truffleruby/launcher/RubyLauncher.java

@@ -13,6 +13,7 @@
 import org.graalvm.nativeimage.ProcessProperties;
 import org.graalvm.options.OptionCategory;
 import org.graalvm.polyglot.Context;
+import org.graalvm.polyglot.Engine;
 import org.graalvm.polyglot.PolyglotException;
 import org.graalvm.polyglot.Source;
 import org.truffleruby.shared.options.CommandLineOptions;
@@ -57,7 +58,7 @@ protected void validateArguments(Map<String, String> polyglotOptions) {
 
     @Override
     protected void printVersion() {
-        System.out.println(TruffleRuby.getVersionString(isAOT()));
+        System.out.println(TruffleRuby.getVersionString(getImplementationNameFromEngine(), isAOT()));
         System.out.println();
         printPolyglotVersions();
     }
@@ -271,7 +272,7 @@ private String setRubyLauncher() {
 
     private static void printPreRunInformation(CommandLineOptions config) {
         if ((boolean) config.getOption(OptionsCatalog.SHOW_VERSION)) {
-            System.out.println(TruffleRuby.getVersionString(isAOT()));
+            System.out.println(TruffleRuby.getVersionString(getImplementationNameFromEngine(), isAOT()));
         }
 
         if ((boolean) config.getOption(OptionsCatalog.SHOW_COPYRIGHT)) {
@@ -290,6 +291,12 @@ private static void printPreRunInformation(CommandLineOptions config) {
         }
     }
 
+    private static String getImplementationNameFromEngine() {
+        try (Engine engine = Engine.create()) {
+            return engine.getImplementationName();
+        }
+    }
+
     // To update this, use:
     // ruby --help | ruby -e 'puts STDIN.readlines.map{|line|"out.println(#{line.chomp.inspect});"}'
     // replace ruby by truffleruby for the first line, and remove unsupported flags.

src/main/java/org/truffleruby/core/CoreLibrary.java

@@ -24,6 +24,7 @@
 import java.util.concurrent.ConcurrentMap;
 
 import com.oracle.truffle.api.CompilerDirectives;
+import com.oracle.truffle.api.Truffle;
 import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import com.oracle.truffle.api.TruffleOptions;
@@ -711,7 +712,7 @@ private void initializeConstants() {
         setConstant(objectClass, "RUBY_ENGINE_VERSION", frozenUSASCIIString(TruffleRuby.getEngineVersion()));
         setConstant(objectClass, "RUBY_PLATFORM", frozenUSASCIIString(RubyLanguage.PLATFORM));
         setConstant(objectClass, "RUBY_RELEASE_DATE", frozenUSASCIIString(BuildInformationImpl.INSTANCE.getCompileDate()));
-        setConstant(objectClass, "RUBY_DESCRIPTION", frozenUSASCIIString(TruffleRuby.getVersionString(TruffleOptions.AOT)));
+        setConstant(objectClass, "RUBY_DESCRIPTION", frozenUSASCIIString(TruffleRuby.getVersionString(Truffle.getRuntime().getName(), TruffleOptions.AOT)));
         setConstant(objectClass, "RUBY_COPYRIGHT", frozenUSASCIIString(TruffleRuby.RUBY_COPYRIGHT));
 
         // BasicObject knows itself

src/shared/java/org/truffleruby/shared/TruffleRuby.java

@@ -27,12 +27,7 @@ public class TruffleRuby {
     public static final String RUBY_COPYRIGHT = "truffleruby - Copyright (c) 2013-2019 Oracle and/or its affiliates";
     public static final boolean PRE_INITIALIZE_CONTEXTS = System.getProperty("polyglot.engine.PreinitializeContexts") != null;
 
-    public static String getVersionString(boolean isAOT) {
-        final String implementationName;
-        try (Engine engine = Engine.create()) {
-            implementationName = engine.getImplementationName();
-        }
-
+    public static String getVersionString(String implementationName, boolean isAOT) {
         final String vm;
         if (isAOT) {
             vm = implementationName + " Native";