Ensure InternalMethod#capturedBlock is always nil or a RubyProc

Author: eregon

src/main/java/org/truffleruby/language/methods/InternalMethod.java

@@ -19,6 +19,7 @@
 import org.truffleruby.core.module.RubyModule;
 import org.truffleruby.core.proc.RubyProc;
 import org.truffleruby.language.LexicalScope;
+import org.truffleruby.language.Nil;
 import org.truffleruby.language.Visibility;
 import org.truffleruby.language.objects.ObjectGraphNode;
 
@@ -94,7 +95,7 @@ public InternalMethod(
                 null,
                 callTarget,
                 null,
-                null);
+                Nil.INSTANCE);
     }
 
     public InternalMethod(
@@ -119,7 +120,7 @@ public InternalMethod(
                 null,
                 callTarget,
                 callTargetSupplier,
-                null);
+                Nil.INSTANCE);
     }
 
     public InternalMethod(
@@ -170,6 +171,7 @@ private InternalMethod(
         assert declaringModule != null;
         assert lexicalScope != null;
         assert !sharedMethodInfo.isBlock() : sharedMethodInfo;
+        assert capturedBlock instanceof Nil || capturedBlock instanceof RubyProc : capturedBlock;
         this.sharedMethodInfo = sharedMethodInfo;
         this.lexicalScope = lexicalScope;
         this.declarationContext = declarationContext;

src/main/java/org/truffleruby/language/methods/LiteralMethodDefinitionNode.java

@@ -14,6 +14,7 @@
 import com.oracle.truffle.api.instrumentation.Tag;
 import org.truffleruby.collections.CachedSupplier;
 import org.truffleruby.core.module.RubyModule;
+import org.truffleruby.language.Nil;
 import org.truffleruby.language.RubyContextSourceNode;
 import org.truffleruby.language.RubyNode;
 import org.truffleruby.language.Visibility;
@@ -83,7 +84,7 @@ public Object execute(VirtualFrame frame) {
                 null,
                 null,
                 callTargetSupplier,
-                null);
+                Nil.INSTANCE);
 
         addMethodNode.executeAddMethod(module, method, visibility);
 

src/main/java/org/truffleruby/language/methods/ModuleBodyDefinitionNode.java

@@ -53,7 +53,7 @@ public InternalMethod createMethod(VirtualFrame frame, LexicalScope staticLexica
         if (captureBlock) {
             capturedBlock = RubyArguments.getBlock(frame);
         } else {
-            capturedBlock = null;
+            capturedBlock = nil;
         }
 
         final LexicalScope parentLexicalScope = RubyArguments.getMethod(frame).getLexicalScope();

src/main/java/org/truffleruby/language/yield/YieldExpressionNode.java

@@ -70,7 +70,7 @@ public final Object execute(VirtualFrame frame) {
 
             block = RubyArguments.getMethod(frame).getCapturedBlock();
 
-            if (block == null) {
+            if (block == nil) {
                 noCapturedBlock.enter();
                 throw new RaiseException(getContext(), coreExceptions().noBlockToYieldTo(this));
             }