Adds ability to optionalize class getters

src/compiler/binder.ts

@@ -2101,7 +2101,8 @@ namespace ts {
                 case SyntaxKind.Constructor:
                     return declareSymbolAndAddToSymbolTable(<Declaration>node, SymbolFlags.Constructor, /*symbolExcludes:*/ SymbolFlags.None);
                 case SyntaxKind.GetAccessor:
-                    return bindPropertyOrMethodOrAccessor(<Declaration>node, SymbolFlags.GetAccessor, SymbolFlags.GetAccessorExcludes);
+                    return bindPropertyOrMethodOrAccessor(<Declaration>node, SymbolFlags.GetAccessor | ((<AccessorDeclaration>node).questionToken ? SymbolFlags.Optional : SymbolFlags.None),
+                        SymbolFlags.GetAccessorExcludes);
                 case SyntaxKind.SetAccessor:
                     return bindPropertyOrMethodOrAccessor(<Declaration>node, SymbolFlags.SetAccessor, SymbolFlags.SetAccessorExcludes);
                 case SyntaxKind.FunctionType:

src/compiler/checker.ts

@@ -4588,7 +4588,12 @@ namespace ts {
                         error(getter, Diagnostics._0_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions, symbolToString(symbol));
                     }
                 }
-                links.type = type;
+                if (getter) {
+                    links.type = addOptionality(type, /*optional*/ !!getter.questionToken);
+                }
+                else {
+                    links.type = type;
+                }
             }
             return links.type;
         }
@@ -24280,7 +24285,7 @@ namespace ts {
             else if (isInAmbientContext(accessor)) {
                 return grammarErrorOnNode(accessor.name, Diagnostics.An_accessor_cannot_be_declared_in_an_ambient_context);
             }
-            else if (accessor.body === undefined && !(getModifierFlags(accessor) & ModifierFlags.Abstract)) {
+            else if (accessor.body === undefined && !hasQuestionToken(accessor) && !(getModifierFlags(accessor) & ModifierFlags.Abstract)) {
                 return grammarErrorAtPos(getSourceFileOfNode(accessor), accessor.end - 1, ";".length, Diagnostics._0_expected, "{");
             }
             else if (accessor.body && getModifierFlags(accessor) & ModifierFlags.Abstract) {

src/compiler/declarationEmitter.ts

@@ -1393,6 +1393,9 @@ namespace ts {
                 emitJsDocComments(accessors.setAccessor);
                 emitClassMemberDeclarationFlags(getModifierFlags(node) | (accessors.setAccessor ? 0 : ModifierFlags.Readonly));
                 writeTextOfNode(currentText, node.name);
+                if (hasQuestionToken(accessors.getAccessor)) {
+                    write("?");
+                }
                 if (!hasModifier(node, ModifierFlags.Private)) {
                     accessorWithTypeAnnotation = node;
                     let type = getTypeAnnotationFromAccessor(node);

src/compiler/parser.ts

@@ -4263,12 +4263,12 @@ namespace ts {
             return finishNode(node);
         }
 
-        function tryParseAccessorDeclaration(fullStart: number, decorators: NodeArray<Decorator>, modifiers: NodeArray<Modifier>): AccessorDeclaration {
+        function tryParseAccessorDeclaration(fullStart: number, decorators: NodeArray<Decorator>, modifiers: NodeArray<Modifier>, allowQuestionToken: boolean): AccessorDeclaration {
             if (parseContextualModifier(SyntaxKind.GetKeyword)) {
-                return parseAccessorDeclaration(SyntaxKind.GetAccessor, fullStart, decorators, modifiers);
+                return parseAccessorDeclaration(SyntaxKind.GetAccessor, fullStart, decorators, modifiers, allowQuestionToken);
             }
             else if (parseContextualModifier(SyntaxKind.SetKeyword)) {
-                return parseAccessorDeclaration(SyntaxKind.SetAccessor, fullStart, decorators, modifiers);
+                return parseAccessorDeclaration(SyntaxKind.SetAccessor, fullStart, decorators, modifiers, /* allowQuestionToken */ false);
             }
 
             return undefined;
@@ -4285,7 +4285,7 @@ namespace ts {
             const decorators = parseDecorators();
             const modifiers = parseModifiers();
 
-            const accessor = tryParseAccessorDeclaration(fullStart, decorators, modifiers);
+            const accessor = tryParseAccessorDeclaration(fullStart, decorators, modifiers, /* allowQuestionToken */ false);
             if (accessor) {
                 return accessor;
             }
@@ -5193,11 +5193,14 @@ namespace ts {
             return parseInitializer(/*inParameter*/ false);
         }
 
-        function parseAccessorDeclaration(kind: SyntaxKind, fullStart: number, decorators: NodeArray<Decorator>, modifiers: NodeArray<Modifier>): AccessorDeclaration {
+        function parseAccessorDeclaration(kind: SyntaxKind, fullStart: number, decorators: NodeArray<Decorator>, modifiers: NodeArray<Modifier>, allowQuestionToken: boolean): AccessorDeclaration {
             const node = <AccessorDeclaration>createNode(kind, fullStart);
             node.decorators = decorators;
             node.modifiers = modifiers;
             node.name = parsePropertyName();
+            if (allowQuestionToken) {
+                node.questionToken = parseOptionalToken(SyntaxKind.QuestionToken);
+            }
             fillSignature(SyntaxKind.ColonToken, /*yieldContext*/ false, /*awaitContext*/ false, /*requireCompleteParameterList*/ false, node);
             node.body = parseFunctionBlockOrSemicolon(/*isGenerator*/ false, /*isAsync*/ false);
             return addJSDocComment(finishNode(node));
@@ -5373,7 +5376,7 @@ namespace ts {
             const decorators = parseDecorators();
             const modifiers = parseModifiers(/*permitInvalidConstAsModifier*/ true);
 
-            const accessor = tryParseAccessorDeclaration(fullStart, decorators, modifiers);
+            const accessor = tryParseAccessorDeclaration(fullStart, decorators, modifiers, /* allowQuestionToken */ true);
             if (accessor) {
                 return accessor;
             }

src/compiler/utilities.ts

@@ -1411,6 +1411,7 @@ namespace ts {
                 case SyntaxKind.Parameter:
                 case SyntaxKind.MethodDeclaration:
                 case SyntaxKind.MethodSignature:
+                case SyntaxKind.GetAccessor:
                 case SyntaxKind.ShorthandPropertyAssignment:
                 case SyntaxKind.PropertyAssignment:
                 case SyntaxKind.PropertyDeclaration:

tests/baselines/reference/optionalClassGetters.errors.txt

@@ -0,0 +1,102 @@
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(1,15): error TS2349: Cannot invoke an expression whose type lacks a call signature. Type '{ readonly a: void; }' has no compatible call signatures.
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(2,10): error TS1005: '(' expected.
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(2,11): error TS1136: Property assignment expected.
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(2,14): error TS1005: ',' expected.
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(3,16): error TS1005: ':' expected.
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(3,17): error TS1005: ',' expected.
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(4,5): error TS1128: Declaration or statement expected.
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(5,1): error TS1128: Declaration or statement expected.
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(11,10): error TS1005: '(' expected.
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(11,12): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(11,24): error TS1005: '=>' expected.
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(12,1): error TS1128: Declaration or statement expected.
+tests/cases/conformance/types/namedTypes/optionalClassGetters.ts(34,14): error TS2532: Object is possibly 'undefined'.
+
+
+==== tests/cases/conformance/types/namedTypes/optionalClassGetters.ts (13 errors) ====
+    const test1 = {
+                  ~
+        get a?() { // Object literal getters may not be marked optional
+    ~~~~~~~~~~~~
+!!! error TS2349: Cannot invoke an expression whose type lacks a call signature. Type '{ readonly a: void; }' has no compatible call signatures.
+             ~
+!!! error TS1005: '(' expected.
+              ~
+!!! error TS1136: Property assignment expected.
+                 ~
+!!! error TS1005: ',' expected.
+            return 2;
+                   ~
+!!! error TS1005: ':' expected.
+                    ~
+!!! error TS1005: ',' expected.
+        }
+        ~
+!!! error TS1128: Declaration or statement expected.
+    }
+    ~
+!!! error TS1128: Declaration or statement expected.
+
+    class Foo {
+        get a? () {
+            return 1;
+        }
+        set a? (v: number) { } // Setters may not be marked optional
+             ~
+!!! error TS1005: '(' expected.
+               ~
+!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
+                           ~
+!!! error TS1005: '=>' expected.
+    }
+    ~
+!!! error TS1128: Declaration or statement expected.
+
+    class Bar {
+        get a() {
+            return 1;
+        }
+        get b?(): string;  // Body of optional getter can be omitted
+        get c?() {
+            return 'foo';
+        }
+        get d?() {
+            return 'bar';
+        }
+    }
+
+    function test2(x: Bar) {
+        x.a;
+        x.b;
+        x.c;
+        x.d;
+        let a1 = x.a;
+        let b1 = x.b;
+        let c1 = x.c.toString();
+                 ~~~
+!!! error TS2532: Object is possibly 'undefined'.
+        let d1 = x.d && x.d.toString();
+    }
+
+    class Base {
+        get f?(): number;
+    }
+
+    class Derived extends Base {
+        get f(): number { return 1; }
+    }
+
+    class Person {
+        firstName: string;
+        lastName: string;
+
+        get fullName?() {
+            return this.firstName + ' ' + this.lastName;
+        }
+    }
+
+    const person: Person = {
+        firstName: 'foo',
+        lastName: 'bar'
+    }
+