Add basic ES6 class method support to TypedScopeCreator

Methods are added to the type's property map, but no checking of overrides is done yet, and 'super' is not yet supported.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=202241474

src/com/google/javascript/jscomp/NodeUtil.java

@@ -5239,6 +5239,8 @@ public static Node getBestLValue(Node n) {
     Node parent = n.getParent();
     if (isFunctionDeclaration(n) || isClassDeclaration(n)) {
       return n.getFirstChild();
+    } else if (n.isClassMembers()) {
+      return getBestLValue(parent);
     } else if (parent.isName()) {
       return parent;
     } else if (parent.isAssign()) {
@@ -5316,7 +5318,8 @@ static String getBestLValueName(@Nullable Node lValue) {
         return null;
       }
       String methodName = lValue.getString();
-      return className + ".prototype." + methodName;
+      String maybePrototype = lValue.isStaticMember() ? "." : ".prototype.";
+      return className + maybePrototype + methodName;
     }
     // TODO(sdh): Tighten this to simply require !lValue.isQuotedString()
     // Could get rid of the isJSIdentifier check, but may need to fix depot.

src/com/google/javascript/jscomp/TypedScopeCreator.java

@@ -1074,21 +1074,32 @@ private FunctionType createFunctionTypeFromNodes(
       boolean isFnLiteral = rValue != null && rValue.isFunction();
       Node fnRoot = isFnLiteral ? rValue : null;
       Node parametersNode = isFnLiteral ? rValue.getSecondChild() : null;
+      Node classRoot =
+          lvalueNode != null && lvalueNode.getParent().isClassMembers()
+              ? lvalueNode.getGrandparent()
+              : null;
 
       // Find the type of any overridden function.
       Node ownerNode = NodeUtil.getBestLValueOwner(lvalueNode);
       String ownerName = NodeUtil.getBestLValueName(ownerNode);
-      TypedVar ownerVar = null;
-      String propName = null;
       ObjectType ownerType = null;
-      if (ownerName != null) {
-        ownerVar = currentScope.getVar(ownerName);
+      if (ownerNode != null && classRoot != null) {
+        // Static members are owned by the constructor, non-statics are owned by the prototype.
+        ownerType = JSType.toMaybeFunctionType(classRoot.getJSType());
+        if (!lvalueNode.isStaticMember() && ownerType != null) {
+          ownerType = ((FunctionType) ownerType).getPrototype();
+          ownerName = ownerName + ".prototype";
+        }
+      } else if (ownerName != null) {
+        TypedVar ownerVar = currentScope.getVar(ownerName);
         if (ownerVar != null) {
           ownerType = ObjectType.cast(ownerVar.getType());
         }
-        if (name != null) {
-          propName = name.substring(ownerName.length() + 1);
-        }
+      }
+
+      String propName = null;
+      if (ownerName != null && name != null) {
+        propName = name.substring(ownerName.length() + 1);
       }
 
       ObjectType prototypeOwner = getPrototypeOwnerType(ownerType);
@@ -1549,6 +1560,8 @@ JSType getDeclaredType(JSDocInfo info, Node lValue, @Nullable Node rValue) {
           && shouldUseFunctionLiteralType(
               JSType.toMaybeFunctionType(rValue.getJSType()), info, lValue)) {
         return rValue.getJSType();
+      } else if (rValue != null && rValue.isClass()) {
+        return rValue.getJSType();
       } else if (info != null) {
         if (info.hasEnumParameterType()) {
           if (rValue != null && rValue.isObjectLit()) {
@@ -2321,9 +2334,10 @@ void visitPreorder(NodeTraversal t, Node n, Node parent) {
       if (n.isFunction()) {
         if (parent.getString().equals("constructor")) {
           // Constructor has already been analyzed, so pull that here.
-          n.setJSType(currentScope.getRootNode().getJSType());
+          setDeferredType(n, currentScope.getRootNode().getJSType());
+        } else {
+          defineFunctionLiteral(n);
         }
-        // TODO(sdh): handle non-constructor methods.
       }
     }
 
@@ -2335,7 +2349,20 @@ void visitPostorder(NodeTraversal t, Node n, Node parent) {
         // Declare bleeding class name in scope.  Pull the type off the AST.
         checkState(!n.getString().isEmpty()); // anonymous classes have EMPTY nodes, not NAME
         defineSlot(n, parent.getJSType(), false);
+      } else if (n.isMemberFunctionDef() && !"constructor".equals(n.getString())) {
+        defineMemberFunction(n);
+      }
+    }
+
+    void defineMemberFunction(Node n) {
+      // MEMBER_FUNCTION_DEF -> CLASS_MEMBERS -> CLASS
+      Node ownerNode = n.getGrandparent();
+      checkState(ownerNode.isClass());
+      ObjectType ownerType = ownerNode.getJSType().toMaybeFunctionType();
+      if (!n.isStaticMember()) {
+        ownerType = ((FunctionType) ownerType).getPrototype();
       }
+      ownerType.defineDeclaredProperty(n.getString(), n.getLastChild().getJSType(), n);
     }
   } // end ClassScopeBuilder
 

test/com/google/javascript/jscomp/NodeUtilTest.java

@@ -46,6 +46,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.function.Function;
 import javax.annotation.Nullable;
 import junit.framework.TestCase;
 
@@ -2348,6 +2349,23 @@ public void testGetBestLValue() {
     assertEquals("x", getFunctionLValue("var x = (y, function() {});"));
   }
 
+  public void testGetBestLValueName() {
+    Function<String, String> getBestName =
+        (js) -> NodeUtil.getBestLValueName(NodeUtil.getBestLValue(getFunctionNode(js)));
+    assertEquals("x", getBestName.apply("var x = function() {};"));
+    assertEquals("x", getBestName.apply("x = function() {};"));
+    assertEquals("x", getBestName.apply("function x() {};"));
+    assertEquals("x", getBestName.apply("var x = y ? z : function() {};"));
+    assertEquals("x", getBestName.apply("var x = y ? function() {} : z;"));
+    assertEquals("x", getBestName.apply("var x = y && function() {};"));
+    assertEquals("x", getBestName.apply("var x = y || function() {};"));
+    assertEquals("x", getBestName.apply("var x = (y, function() {});"));
+    assertEquals("C.prototype.d", getBestName.apply("C.prototype.d = function() {};"));
+    assertEquals("C.prototype.d", getBestName.apply("class C { d() {} };"));
+    assertEquals("C.d", getBestName.apply("C.d = function() {};"));
+    assertEquals("C.d", getBestName.apply("class C { static d() {} };"));
+  }
+
   public void testGetRValueOfLValue() {
     assertTrue(functionIsRValueOfAssign("x = function() {};"));
     assertTrue(functionIsRValueOfAssign("x += function() {};"));