Verify EnsoContext can be GCed after cleaning up ContextUtils rule

engine/runtime-compiler/src/main/scala/org/enso/compiler/pass/resolve/TypeSignatures.scala

@@ -252,7 +252,7 @@ case object TypeSignatures extends IRPass {
     }
   }
 
-  val anyIr = Name.Qualified(
+  def anyIr = Name.Qualified(
     List(
       Name.Literal("Standard", isMethod = false, identifiedLocation = null),
       Name.Literal("Base", isMethod     = false, identifiedLocation = null),

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/runtime/ContextGCTest.java

@@ -0,0 +1,45 @@
+package org.enso.interpreter.runtime;
+
+import static org.junit.Assert.assertEquals;
+
+import org.enso.test.utils.ContextUtils;
+import org.junit.Rule;
+import org.junit.Test;
+
+public class ContextGCTest {
+  @Rule public final ContextUtils ctx = ContextUtils.createDefault();
+
+  @Test
+  public void simpleEval() throws Exception {
+    var fourtyTwo =
+        ctx.evalModule(
+            """
+            from Standard.Base import all
+
+            main = 6 * 7
+            """);
+    assertEquals(42, fourtyTwo.asInt());
+  }
+
+  @Test
+  public void multiValue() throws Exception {
+    var arr =
+        ctx.evalModule(
+            """
+            from Standard.Base import all
+
+            type T
+
+            Integer.from (_:T) = 42
+            Text.from (_:T) = "Meaning"
+
+            main =
+                conv t -> Integer&Text = t
+                v = conv T
+                [v, v:Text, v:Integer]
+
+            """);
+    assertEquals(42, arr.getArrayElement(2).asInt());
+    assertEquals("Meaning", arr.getArrayElement(1).asString());
+  }
+}

engine/runtime/src/main/java/org/enso/interpreter/runtime/data/EnsoMultiType.java

@@ -8,6 +8,7 @@
 import com.oracle.truffle.api.nodes.Node;
 import java.util.Arrays;
 import java.util.HashSet;
+import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import org.enso.interpreter.runtime.EnsoContext;
 
@@ -19,8 +20,8 @@
  * <p>Think twice before opening this type to public!
  */
 final class EnsoMultiType {
-  private static final ConcurrentHashMap<EnsoMultiType, EnsoMultiType> ALL_TYPES =
-      new ConcurrentHashMap<>();
+  private static final EnsoContext.Extra<Map> ALL_TYPES =
+      new EnsoContext.Extra<>(Map.class, (_) -> new ConcurrentHashMap());
 
   @CompilerDirectives.CompilationFinal(dimensions = 1)
   private final Type[] types;
@@ -41,9 +42,11 @@ private static boolean checkNonNull(Type[] types) {
   }
 
   @CompilerDirectives.TruffleBoundary
-  static EnsoMultiType findOrCreateSlow(Type[] types, int from, int to) {
+  @SuppressWarnings("unchecked")
+  static EnsoMultiType findOrCreateSlow(EnsoContext ctx, Type[] types, int from, int to) {
     var mt = new EnsoMultiType(Arrays.copyOfRange(types, from, to));
-    return ALL_TYPES.computeIfAbsent(mt, java.util.function.Function.identity());
+    var registry = ALL_TYPES.get(ctx);
+    return (EnsoMultiType) registry.computeIfAbsent(mt, java.util.function.Function.identity());
   }
 
   final int typesLength() {

engine/runtime/src/main/java/org/enso/interpreter/runtime/data/EnsoMultiValue.java

@@ -179,7 +179,8 @@ final EnsoMultiType cachedMultiType(
 
     @Specialization(replaces = "cachedMultiType")
     final EnsoMultiType createMultiType(Type[] types, int from, int to) {
-      return EnsoMultiType.findOrCreateSlow(types, from, to);
+      var ctx = EnsoContext.get(this);
+      return EnsoMultiType.findOrCreateSlow(ctx, types, from, to);
     }
 
     @TruffleBoundary

lib/java/test-utils/src/main/java/org/enso/test/utils/ContextUtils.java

@@ -1,11 +1,15 @@
 package org.enso.test.utils;
 
+import static org.junit.Assert.fail;
+
 import com.oracle.truffle.api.interop.InteropLibrary;
 import com.oracle.truffle.api.interop.TruffleObject;
 import com.oracle.truffle.api.library.ExportLibrary;
 import com.oracle.truffle.api.library.ExportMessage;
 import com.oracle.truffle.api.nodes.Node;
 import java.io.ByteArrayOutputStream;
+import java.lang.ref.Reference;
+import java.lang.ref.WeakReference;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.Objects;
@@ -127,8 +131,10 @@ public void resetOut() {
   @Override
   public void close() {
     if (context != null) {
+      var ref = new WeakReference<>(ensoContext());
       context.close();
       context = null;
+      assertGC("EnsoContext can be GCed when context is closed", true, ref);
     }
     resetOut();
   }
@@ -458,7 +464,7 @@ private CustomStatement(Statement base, Description description) {
     /** Evaluates jUnit {@link org.junit.Test}. */
     @Override
     public void evaluate() throws Throwable {
-      try (var ctx = currentCtx()) {
+      try {
         if (alwaysExecuteInContext) {
           executeInContext(
               () -> {
@@ -509,4 +515,23 @@ boolean isExecutable() {
       return true;
     }
   }
+
+  private static void assertGC(String msg, boolean expectGC, Reference<?> ref) {
+    for (var i = 1; i < Integer.MAX_VALUE / 2; i *= 2) {
+      if (ref.get() == null) {
+        break;
+      }
+      System.gc();
+    }
+    var obj = ref.get();
+    if (expectGC) {
+      if (obj != null) {
+        fail(msg + " ref still alive: " + obj);
+      }
+    } else {
+      if (obj == null) {
+        fail(msg + " ref has been cleaned: " + obj);
+      }
+    }
+  }
 }