Rename strictOptionalProperties -> exactOptionalPropertyTypes and remove it from the strict family

src/compiler/checker.ts

@@ -343,12 +343,12 @@ namespace ts {
         const strictFunctionTypes = getStrictOptionValue(compilerOptions, "strictFunctionTypes");
         const strictBindCallApply = getStrictOptionValue(compilerOptions, "strictBindCallApply");
         const strictPropertyInitialization = getStrictOptionValue(compilerOptions, "strictPropertyInitialization");
-        const strictOptionalProperties = getStrictOptionValue(compilerOptions, "strictOptionalProperties");
         const noImplicitAny = getStrictOptionValue(compilerOptions, "noImplicitAny");
         const noImplicitThis = getStrictOptionValue(compilerOptions, "noImplicitThis");
         const useUnknownInCatchVariables = getStrictOptionValue(compilerOptions, "useUnknownInCatchVariables");
         const keyofStringsOnly = !!compilerOptions.keyofStringsOnly;
         const freshObjectLiteralFlag = compilerOptions.suppressExcessPropertyErrors ? 0 : ObjectFlags.FreshLiteral;
+        const exactOptionalPropertyTypes = compilerOptions.exactOptionalPropertyTypes;
 
         const checkBinaryExpression = createCheckBinaryExpression();
         const emitResolver = createResolver();
@@ -739,7 +739,7 @@ namespace ts {
         const undefinedType = createIntrinsicType(TypeFlags.Undefined, "undefined");
         const undefinedWideningType = strictNullChecks ? undefinedType : createIntrinsicType(TypeFlags.Undefined, "undefined", ObjectFlags.ContainsWideningType);
         const optionalType = createIntrinsicType(TypeFlags.Undefined, "undefined");
-        const missingType = strictOptionalProperties ? createIntrinsicType(TypeFlags.Undefined, "undefined") : undefinedType;
+        const missingType = exactOptionalPropertyTypes ? createIntrinsicType(TypeFlags.Undefined, "undefined") : undefinedType;
         const nullType = createIntrinsicType(TypeFlags.Null, "null");
         const nullWideningType = strictNullChecks ? nullType : createIntrinsicType(TypeFlags.Null, "null", ObjectFlags.ContainsWideningType);
         const stringType = createIntrinsicType(TypeFlags.String, "string");
@@ -13884,7 +13884,7 @@ namespace ts {
                 if (includes & TypeFlags.AnyOrUnknown) {
                     return includes & TypeFlags.Any ? includes & TypeFlags.IncludesWildcard ? wildcardType : anyType : unknownType;
                 }
-                if (strictOptionalProperties && includes & TypeFlags.Undefined) {
+                if (exactOptionalPropertyTypes && includes & TypeFlags.Undefined) {
                     const missingIndex = binarySearch(typeSet, missingType, getTypeId, compareValues);
                     if (missingIndex >= 0 && containsType(typeSet, undefinedType)) {
                         orderedRemoveItemAt(typeSet, missingIndex);
@@ -20356,15 +20356,15 @@ namespace ts {
         }
 
         function removeMissingType(type: Type, isOptional: boolean) {
-            return strictOptionalProperties && isOptional ? removeType(type, missingType) : type;
+            return exactOptionalPropertyTypes && isOptional ? removeType(type, missingType) : type;
         }
 
         function containsMissingType(type: Type) {
-            return strictOptionalProperties && (type === missingType || type.flags & TypeFlags.Union && containsType((type as UnionType).types, missingType));
+            return exactOptionalPropertyTypes && (type === missingType || type.flags & TypeFlags.Union && containsType((type as UnionType).types, missingType));
         }
 
         function removeMissingOrUndefinedType(type: Type): Type {
-            return strictOptionalProperties ? removeType(type, missingType) : getTypeWithFacts(type, TypeFacts.NEUndefined);
+            return exactOptionalPropertyTypes ? removeType(type, missingType) : getTypeWithFacts(type, TypeFacts.NEUndefined);
         }
 
         /**
@@ -21750,7 +21750,7 @@ namespace ts {
         }
 
         function isTypeOrBaseIdenticalTo(s: Type, t: Type) {
-            return strictOptionalProperties && t === missingType ? s === t :
+            return exactOptionalPropertyTypes && t === missingType ? s === t :
                 (isTypeIdenticalTo(s, t) || !!(t.flags & TypeFlags.String && s.flags & TypeFlags.StringLiteral || t.flags & TypeFlags.Number && s.flags & TypeFlags.NumberLiteral));
         }
 
@@ -26079,7 +26079,7 @@ namespace ts {
                         elementFlags.push(ElementFlags.Rest);
                     }
                 }
-                else if (strictOptionalProperties && e.kind === SyntaxKind.OmittedExpression) {
+                else if (exactOptionalPropertyTypes && e.kind === SyntaxKind.OmittedExpression) {
                     hasOmittedExpression = true;
                     elementTypes.push(missingType);
                     elementFlags.push(ElementFlags.Optional);

src/compiler/commandLineParser.ts

@@ -648,14 +648,6 @@ namespace ts {
             description: Diagnostics.Check_for_class_properties_that_are_declared_but_not_set_in_the_constructor,
             defaultValueDescription: Diagnostics.false_unless_strict_is_set
         },
-        {
-            name: "strictOptionalProperties",
-            type: "boolean",
-            affectsSemanticDiagnostics: true,
-            strictFlag: true,
-            category: Diagnostics.Type_Checking,
-            description: Diagnostics.Enable_strict_checking_of_optional_properties
-        },
         {
             name: "noImplicitThis",
             type: "boolean",
@@ -700,6 +692,13 @@ namespace ts {
             description: Diagnostics.Raise_an_error_when_a_function_parameter_isn_t_read,
             defaultValueDescription: "false"
         },
+        {
+            name: "exactOptionalPropertyTypes",
+            type: "boolean",
+            affectsSemanticDiagnostics: true,
+            category: Diagnostics.Type_Checking,
+            description: Diagnostics.Interpret_optional_property_types_as_written_rather_than_adding_undefined
+        },
         {
             name: "noImplicitReturns",
             type: "boolean",

src/compiler/diagnosticMessages.json

@@ -4853,7 +4853,7 @@
         "category": "Message",
         "code": 6242
     },
-    "Enable strict checking of optional properties.": {
+    "Interpret optional property types as written, rather than adding 'undefined'.": {
         "category": "Message",
         "code": 6243
     },

src/compiler/program.ts

@@ -3043,8 +3043,8 @@ namespace ts {
             if (options.strictPropertyInitialization && !getStrictOptionValue(options, "strictNullChecks")) {
                 createDiagnosticForOptionName(Diagnostics.Option_0_cannot_be_specified_without_specifying_option_1, "strictPropertyInitialization", "strictNullChecks");
             }
-            if (options.strictOptionalProperties && !getStrictOptionValue(options, "strictNullChecks")) {
-                createDiagnosticForOptionName(Diagnostics.Option_0_cannot_be_specified_without_specifying_option_1, "strictOptionalProperties", "strictNullChecks");
+            if (options.exactOptionalPropertyTypes && !getStrictOptionValue(options, "strictNullChecks")) {
+                createDiagnosticForOptionName(Diagnostics.Option_0_cannot_be_specified_without_specifying_option_1, "exactOptionalPropertyTypes", "strictNullChecks");
             }
 
             if (options.isolatedModules) {

src/compiler/types.ts

@@ -5971,6 +5971,7 @@ namespace ts {
         downlevelIteration?: boolean;
         emitBOM?: boolean;
         emitDecoratorMetadata?: boolean;
+        exactOptionalPropertyTypes?: boolean;
         experimentalDecorators?: boolean;
         forceConsistentCasingInFileNames?: boolean;
         /*@internal*/generateCpuProfile?: string;
@@ -6045,7 +6046,6 @@ namespace ts {
         strictBindCallApply?: boolean;  // Always combine with strict property
         strictNullChecks?: boolean;  // Always combine with strict property
         strictPropertyInitialization?: boolean;  // Always combine with strict property
-        strictOptionalProperties?: boolean;  // Always combine with strict property
         stripInternal?: boolean;
         suppressExcessPropertyErrors?: boolean;
         suppressImplicitAnyIndexErrors?: boolean;

src/compiler/utilities.ts

@@ -6086,7 +6086,6 @@ namespace ts {
         | "strictFunctionTypes"
         | "strictBindCallApply"
         | "strictPropertyInitialization"
-        | "strictOptionalProperties"
         | "alwaysStrict"
         | "useUnknownInCatchVariables"
         ;

tests/baselines/reference/api/tsserverlibrary.d.ts

@@ -2853,6 +2853,7 @@ declare namespace ts {
         downlevelIteration?: boolean;
         emitBOM?: boolean;
         emitDecoratorMetadata?: boolean;
+        exactOptionalPropertyTypes?: boolean;
         experimentalDecorators?: boolean;
         forceConsistentCasingInFileNames?: boolean;
         importHelpers?: boolean;
@@ -2913,7 +2914,6 @@ declare namespace ts {
         strictBindCallApply?: boolean;
         strictNullChecks?: boolean;
         strictPropertyInitialization?: boolean;
-        strictOptionalProperties?: boolean;
         stripInternal?: boolean;
         suppressExcessPropertyErrors?: boolean;
         suppressImplicitAnyIndexErrors?: boolean;

tests/baselines/reference/api/typescript.d.ts

@@ -2853,6 +2853,7 @@ declare namespace ts {
         downlevelIteration?: boolean;
         emitBOM?: boolean;
         emitDecoratorMetadata?: boolean;
+        exactOptionalPropertyTypes?: boolean;
         experimentalDecorators?: boolean;
         forceConsistentCasingInFileNames?: boolean;
         importHelpers?: boolean;
@@ -2913,7 +2914,6 @@ declare namespace ts {
         strictBindCallApply?: boolean;
         strictNullChecks?: boolean;
         strictPropertyInitialization?: boolean;
-        strictOptionalProperties?: boolean;
         stripInternal?: boolean;
         suppressExcessPropertyErrors?: boolean;
         suppressImplicitAnyIndexErrors?: boolean;

tests/baselines/reference/checkJsxIntersectionElementPropsType.types

@@ -16,7 +16,7 @@ declare class Component<P> {
 
 class C<T> extends Component<{ x?: boolean; } & T> {}
 >C : C<T>
->Component : Component<{ x?: boolean; } & T>
+>Component : Component<{ x?: boolean | undefined; } & T>
 >x : boolean | undefined
 
 const y = new C({foobar: "example"});

tests/baselines/reference/circularlyConstrainedMappedTypeContainingConditionalNoInfiniteInstantiationDepth.types

@@ -10,7 +10,7 @@ declare class Component<P> {
 >context : any
 
     readonly props: Readonly<P> & Readonly<{ children?: {} }>;
->props : Readonly<P> & Readonly<{ children?: {}; }>
+>props : Readonly<P> & Readonly<{ children?: {} | undefined; }>
 >children : {} | undefined
 }
 interface ComponentClass<P = {}> {
@@ -29,7 +29,7 @@ interface ComponentClass<P = {}> {
 }
 interface FunctionComponent<P = {}> {
     (props: P & { children?: {} }, context?: any): {} | null;
->props : P & { children?: {}; }
+>props : P & { children?: {} | undefined; }
 >children : {} | undefined
 >context : any
 >null : null

tests/baselines/reference/contextuallyTypedParametersWithInitializers.types

@@ -16,7 +16,7 @@ declare function id3<T extends (x: { foo: any }) => any>(input: T): T;
 
 declare function id4<T extends (x: { foo?: number }) => any>(input: T): T;
 >id4 : <T extends (x: {    foo?: number;}) => any>(input: T) => T
->x : { foo?: number; }
+>x : { foo?: number | undefined; }
 >foo : number | undefined
 >input : T
 
@@ -60,10 +60,10 @@ const f13 = id3(function ({ foo = 42 }) { return foo });
 >foo : any
 
 const f14 = id4(function ({ foo = 42 }) { return foo });
->f14 : ({ foo }: { foo?: number; }) => number
->id4(function ({ foo = 42 }) { return foo }) : ({ foo }: { foo?: number; }) => number
->id4 : <T extends (x: { foo?: number; }) => any>(input: T) => T
->function ({ foo = 42 }) { return foo } : ({ foo }: { foo?: number; }) => number
+>f14 : ({ foo }: { foo?: number | undefined; }) => number
+>id4(function ({ foo = 42 }) { return foo }) : ({ foo }: { foo?: number | undefined; }) => number
+>id4 : <T extends (x: { foo?: number | undefined; }) => any>(input: T) => T
+>function ({ foo = 42 }) { return foo } : ({ foo }: { foo?: number | undefined; }) => number
 >foo : number
 >42 : 42
 >foo : number