Add public functions to modify Arity

Author: wildmaples

src/main/java/org/truffleruby/core/proc/RubyProc.java

@@ -74,6 +74,22 @@ public RubyProc(
         this.declarationContext = declarationContext;
     }
 
+    public RubyProc withSharedMethodInfo(SharedMethodInfo newSharedMethodInfo, RubyClass newRubyClass, Shape newShape) {
+        return new RubyProc(
+                newRubyClass,
+                newShape,
+                type,
+                newSharedMethodInfo,
+                callTargets,
+                callTarget,
+                declarationFrame,
+                declarationVariables,
+                method,
+                block,
+                frameOnStackMarker,
+                declarationContext);
+    }
+
     @Override
     public void getAdjacentObjects(Set<Object> reachable) {
         ObjectGraph.getObjectsInFrame(declarationFrame, reachable);

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

@@ -91,6 +91,18 @@ public SharedMethodInfo convertMethodMissingToMethod(RubyModule declaringModule,
                 newArgs);
     }
 
+    public SharedMethodInfo withArity(Arity newArity) {
+        return new SharedMethodInfo(
+                sourceSection,
+                lexicalScope,
+                newArity,
+                backtraceName,
+                blockDepth,
+                parseName,
+                notes,
+                argumentDescriptors);
+    }
+
     public SourceSection getSourceSection() {
         return sourceSection;
     }