Reuse type nodes from optional parameters even when not written as a union with undefined

src/compiler/checker.ts

@@ -5915,9 +5915,6 @@ namespace ts {
                 if (parameterDeclaration && isRequiredInitializedParameter(parameterDeclaration)) {
                     parameterType = getOptionalType(parameterType);
                 }
-                if ((context.flags & NodeBuilderFlags.NoUndefinedOptionalParameterType) && parameterDeclaration && !isJSDocParameterTag(parameterDeclaration) && isOptionalUninitializedParameter(parameterDeclaration)) {
-                    parameterType = getTypeWithFacts(parameterType, TypeFacts.NEUndefined);
-                }
                 const parameterTypeNode = serializeTypeForDeclaration(context, parameterType, parameterSymbol, context.enclosingDeclaration, privateSymbolVisitor, bundledImports);
 
                 const modifiers = !(context.flags & NodeBuilderFlags.OmitParameterModifiers) && preserveModifierFlags && parameterDeclaration && parameterDeclaration.modifiers ? parameterDeclaration.modifiers.map(factory.cloneNode) : undefined;
@@ -6544,7 +6541,7 @@ namespace ts {
                     if (declWithExistingAnnotation && !isFunctionLikeDeclaration(declWithExistingAnnotation) && !isGetAccessorDeclaration(declWithExistingAnnotation)) {
                         // try to reuse the existing annotation
                         const existing = getEffectiveTypeAnnotationNode(declWithExistingAnnotation)!;
-                        if (getTypeFromTypeNode(existing) === type && existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing, type)) {
+                        if (typeNodeIsEquivalentToType(existing, declWithExistingAnnotation, type) && existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing, type)) {
                             const result = serializeExistingTypeNode(context, existing, includePrivateSymbol, bundled);
                             if (result) {
                                 return result;
@@ -6562,6 +6559,17 @@ namespace ts {
                 return result;
             }
 
+            function typeNodeIsEquivalentToType(typeNode: TypeNode, annotatedDeclaration: Declaration, type: Type) {
+                const typeFromTypeNode = getTypeFromTypeNode(typeNode);
+                if (typeFromTypeNode === type) {
+                    return true;
+                }
+                if (isParameter(annotatedDeclaration) && annotatedDeclaration.questionToken) {
+                    return getTypeWithFacts(type, TypeFacts.NEUndefined) === typeFromTypeNode;
+                }
+                return false;
+            }
+
             function serializeReturnTypeForSignature(context: NodeBuilderContext, type: Type, signature: Signature, includePrivateSymbol?: (s: Symbol) => void, bundled?: boolean) {
                 if (!isErrorType(type) && context.enclosingDeclaration) {
                     const annotation = signature.declaration && getEffectiveReturnTypeNode(signature.declaration);
@@ -42579,12 +42587,6 @@ namespace ts {
                 hasSyntacticModifier(parameter, ModifierFlags.ParameterPropertyModifier);
         }
 
-        function isOptionalUninitializedParameter(parameter: ParameterDeclaration) {
-            return !!strictNullChecks &&
-                isOptionalParameter(parameter) &&
-                !parameter.initializer;
-        }
-
         function isExpandoFunctionDeclaration(node: Declaration): boolean {
             const declaration = getParseTreeNode(node, isFunctionDeclaration);
             if (!declaration) {

src/compiler/types.ts

@@ -4490,7 +4490,6 @@ namespace ts {
         UseAliasDefinedOutsideCurrentScope      = 1 << 14,  // Allow non-visible aliases
         UseSingleQuotesForStringLiteralType     = 1 << 28,  // Use single quotes for string literal type
         NoTypeReduction                         = 1 << 29,  // Don't call getReducedType
-        NoUndefinedOptionalParameterType        = 1 << 30,  // Do not add undefined to optional parameter type
 
         // Error handling
         AllowThisInObjectLiteral                = 1 << 15,

src/compiler/utilities.ts

@@ -7659,4 +7659,8 @@ namespace ts {
 
         return state > States.NodeModules ? { topLevelNodeModulesIndex, topLevelPackageNameIndex, packageRootIndex, fileNameIndex } : undefined;
     }
+
+    export function getParameterTypeNode(parameter: ParameterDeclaration | JSDocParameterTag) {
+        return parameter.kind === SyntaxKind.JSDocParameterTag ? parameter.typeExpression?.type : parameter.type;
+    }
 }

src/services/codefixes/helpers.ts

@@ -194,7 +194,6 @@ namespace ts.codefix {
         const scriptTarget = getEmitScriptTarget(program.getCompilerOptions());
         const flags =
             NodeBuilderFlags.NoTruncation
-            | NodeBuilderFlags.NoUndefinedOptionalParameterType
             | NodeBuilderFlags.SuppressAnyReturnType
             | NodeBuilderFlags.AllowEmptyTuple
             | (quotePreference === QuotePreference.Single ? NodeBuilderFlags.UseSingleQuotesForStringLiteralType : NodeBuilderFlags.None);

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

@@ -2394,7 +2394,6 @@ declare namespace ts {
         UseAliasDefinedOutsideCurrentScope = 16384,
         UseSingleQuotesForStringLiteralType = 268435456,
         NoTypeReduction = 536870912,
-        NoUndefinedOptionalParameterType = 1073741824,
         AllowThisInObjectLiteral = 32768,
         AllowQualifiedNameInPlaceOfIdentifier = 65536,
         /** @deprecated AllowQualifedNameInPlaceOfIdentifier. Use AllowQualifiedNameInPlaceOfIdentifier instead. */

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

@@ -2394,7 +2394,6 @@ declare namespace ts {
         UseAliasDefinedOutsideCurrentScope = 16384,
         UseSingleQuotesForStringLiteralType = 268435456,
         NoTypeReduction = 536870912,
-        NoUndefinedOptionalParameterType = 1073741824,
         AllowThisInObjectLiteral = 32768,
         AllowQualifiedNameInPlaceOfIdentifier = 65536,
         /** @deprecated AllowQualifedNameInPlaceOfIdentifier. Use AllowQualifiedNameInPlaceOfIdentifier instead. */

tests/baselines/reference/arrayFakeFlatNoCrashInferenceDeclarations.types

@@ -19,7 +19,7 @@ type BadFlatArray<Arr, Depth extends number> = {obj: {
 >1 : 1
 
 declare function flat<A, D extends number = 1>(
->flat : <A, D extends number = 1>(arr: A, depth?: D | undefined) => BadFlatArray<A, D>[]
+>flat : <A, D extends number = 1>(arr: A, depth?: D) => BadFlatArray<A, D>[]
 
     arr: A,
 >arr : A

tests/baselines/reference/assertionTypePredicates1.types

@@ -270,7 +270,7 @@ namespace Debug {
 >Debug : typeof Debug
 
     export declare function assert(value: unknown, message?: string): asserts value;
->assert : (value: unknown, message?: string | undefined) => asserts value
+>assert : (value: unknown, message?: string) => asserts value
 >value : unknown
 >message : string | undefined
 

tests/baselines/reference/asyncFunctionsAndStrictNullChecks.types

@@ -75,7 +75,7 @@ declare function resolve2<T>(value: T): Windows.Foundation.IPromise<T>;
 >Foundation : any
 
 async function sample2(x?: number) {
->sample2 : (x?: number | undefined) => Promise<void>
+>sample2 : (x?: number) => Promise<void>
 >x : number | undefined
 
     let x1 = await resolve1(x);

tests/baselines/reference/callsOnComplexSignatures.types

@@ -110,7 +110,7 @@ function test3(items: string[] | number[]) {
 }
 
 function test4(
->test4 : (arg1: ((...objs: {    x: number;}[]) => number) | ((...objs: {    y: number;}[]) => number), arg2: ((a: {    x: number;}, b: object) => number) | ((a: object, b: {    x: number;}) => number), arg3: ((a: {    x: number;}, ...objs: {    y: number;}[]) => number) | ((...objs: {    x: number;}[]) => number), arg4: ((a?: { x: number; } | undefined, b?: { x: number; } | undefined) => number) | ((a?: { y: number; } | undefined) => number), arg5: ((a?: { x: number; } | undefined, ...b: {    x: number;}[]) => number) | ((a?: { y: number; } | undefined) => number), arg6: ((a?: { x: number; } | undefined, b?: { x: number; } | undefined) => number) | ((...a: {    y: number;}[]) => number)) => void
+>test4 : (arg1: ((...objs: {    x: number;}[]) => number) | ((...objs: {    y: number;}[]) => number), arg2: ((a: {    x: number;}, b: object) => number) | ((a: object, b: {    x: number;}) => number), arg3: ((a: {    x: number;}, ...objs: {    y: number;}[]) => number) | ((...objs: {    x: number;}[]) => number), arg4: ((a?: {    x: number;}, b?: {    x: number;}) => number) | ((a?: {    y: number;}) => number), arg5: ((a?: {    x: number;}, ...b: {    x: number;}[]) => number) | ((a?: {    y: number;}) => number), arg6: ((a?: {    x: number;}, b?: {    x: number;}) => number) | ((...a: {    y: number;}[]) => number)) => void
 
     arg1: ((...objs: {x: number}[]) => number) | ((...objs: {y: number}[]) => number),
 >arg1 : ((...objs: {    x: number;}[]) => number) | ((...objs: {    y: number;}[]) => number)
@@ -138,7 +138,7 @@ function test4(
 >x : number
 
     arg4: ((a?: {x: number}, b?: {x: number}) => number) | ((a?: {y: number}) => number),
->arg4 : ((a?: { x: number; } | undefined, b?: { x: number; } | undefined) => number) | ((a?: { y: number; } | undefined) => number)
+>arg4 : ((a?: {    x: number;}, b?: {    x: number;}) => number) | ((a?: {    y: number;}) => number)
 >a : { x: number; } | undefined
 >x : number
 >b : { x: number; } | undefined
@@ -147,7 +147,7 @@ function test4(
 >y : number
 
     arg5: ((a?: {x: number}, ...b: {x: number}[]) => number) | ((a?: {y: number}) => number),
->arg5 : ((a?: { x: number; } | undefined, ...b: {    x: number;}[]) => number) | ((a?: { y: number; } | undefined) => number)
+>arg5 : ((a?: {    x: number;}, ...b: {    x: number;}[]) => number) | ((a?: {    y: number;}) => number)
 >a : { x: number; } | undefined
 >x : number
 >b : { x: number; }[]
@@ -156,7 +156,7 @@ function test4(
 >y : number
 
     arg6: ((a?: {x: number}, b?: {x: number}) => number) | ((...a: {y: number}[]) => number),
->arg6 : ((a?: { x: number; } | undefined, b?: { x: number; } | undefined) => number) | ((...a: {    y: number;}[]) => number)
+>arg6 : ((a?: {    x: number;}, b?: {    x: number;}) => number) | ((...a: {    y: number;}[]) => number)
 >a : { x: number; } | undefined
 >x : number
 >b : { x: number; } | undefined
@@ -339,7 +339,7 @@ function test5() {
 
     // Pair of non-like intrinsics
     function render(url?: string): React.ReactNode {
->render : (url?: string | undefined) => React.ReactNode
+>render : (url?: string) => React.ReactNode
 >url : string | undefined
 >React : any
 

tests/baselines/reference/circularOptionalityRemoval.types

@@ -12,7 +12,7 @@ function fn1(x: number | undefined = x > 0 ? x : 0) { }
 
 // Report from user
 function fn2(x?: string = someCondition ? 'value1' : x) { }
->fn2 : (x?: string | undefined) => void
+>fn2 : (x?: string) => void
 >x : string | undefined
 >someCondition ? 'value1' : x : string | undefined
 >someCondition : any

tests/baselines/reference/contextuallyTypedParametersWithInitializers.types

@@ -21,7 +21,7 @@ declare function id4<T extends (x: { foo?: number }) => any>(input: T): T;
 >input : T
 
 declare function id5<T extends (x?: number) => any>(input: T): T;
->id5 : <T extends (x?: number | undefined) => any>(input: T) => T
+>id5 : <T extends (x?: number) => any>(input: T) => T
 >x : number | undefined
 >input : T
 

tests/baselines/reference/controlFlowAliasing.types

@@ -532,7 +532,7 @@ function f27(outer: { obj: { kind: 'foo', foo: string } | { kind: 'bar', bar: nu
 }
 
 function f28(obj?: { kind: 'foo', foo: string } | { kind: 'bar', bar: number }) {
->f28 : (obj?: { kind: 'foo'; foo: string; } | { kind: 'bar'; bar: number; } | undefined) => void
+>f28 : (obj?: {    kind: 'foo';    foo: string;} | {    kind: 'bar';    bar: number;}) => void
 >obj : { kind: 'foo'; foo: string; } | { kind: 'bar'; bar: number; } | undefined
 >kind : "foo"
 >foo : string

tests/baselines/reference/controlFlowForIndexSignatures.types

@@ -10,7 +10,7 @@ const boo: Foo = { bar: 'bar' };
 >'bar' : "bar"
 
 function a(aboo1?: Foo) {
->a : (aboo1?: Foo | undefined) => void
+>a : (aboo1?: Foo) => void
 >aboo1 : Foo | undefined
 
     if (!aboo1) return;

tests/baselines/reference/controlFlowOptionalChain.types

@@ -1882,7 +1882,7 @@ type Shape =
 >radius : number
 
 function getArea(shape?: Shape) {
->getArea : (shape?: Shape | undefined) => number
+>getArea : (shape?: Shape) => number
 >shape : Shape | undefined
 
     switch (shape?.type) {

tests/baselines/reference/defaultParameterAddsUndefinedWithStrictNullChecks.types

@@ -1,6 +1,6 @@
 === tests/cases/compiler/defaultParameterAddsUndefinedWithStrictNullChecks.ts ===
 function f(addUndefined1 = "J", addUndefined2?: number) {
->f : (addUndefined1?: string, addUndefined2?: number | undefined) => number
+>f : (addUndefined1?: string, addUndefined2?: number) => number
 >addUndefined1 : string
 >"J" : "J"
 >addUndefined2 : number | undefined

tests/baselines/reference/destructureOptionalParameter.types

@@ -1,6 +1,6 @@
 === tests/cases/compiler/destructureOptionalParameter.ts ===
 declare function f1({ a, b }?: { a: number, b: string }): void;
->f1 : ({ a, b }?: { a: number; b: string; } | undefined) => void
+>f1 : ({ a, b }?: {    a: number;    b: string;}) => void
 >a : number
 >b : string
 >a : number

tests/baselines/reference/destructuringAssignmentWithDefault.types

@@ -61,7 +61,7 @@ function f1(options?: { color?: string, width?: number }) {
 }
 
 function f2(options?: [string?, number?]) {
->f2 : (options?: [(string | undefined)?, (number | undefined)?] | undefined) => void
+>f2 : (options?: [string?, number?]) => void
 >options : [(string | undefined)?, (number | undefined)?] | undefined
 
     let [str, num] = options || [];
@@ -133,7 +133,7 @@ function f3(options?: { color: string, width: number }) {
 }
 
 function f4(options?: [string, number]) {
->f4 : (options?: [string, number] | undefined) => void
+>f4 : (options?: [string, number]) => void
 >options : [string, number] | undefined
 
     let [str, num] = options || [];

tests/baselines/reference/genericFunctionInference1.types

@@ -801,7 +801,7 @@ const fn20 = pipe((_a?: {}) => 1);
 >fn20 : (_a?: {} | undefined) => number
 >pipe((_a?: {}) => 1) : (_a?: {} | undefined) => number
 >pipe : { <A extends any[], B>(ab: (...args: A) => B): (...args: A) => B; <A extends any[], B, C>(ab: (...args: A) => B, bc: (b: B) => C): (...args: A) => C; <A extends any[], B, C, D>(ab: (...args: A) => B, bc: (b: B) => C, cd: (c: C) => D): (...args: A) => D; }
->(_a?: {}) => 1 : (_a?: {} | undefined) => number
+>(_a?: {}) => 1 : (_a?: {}) => number
 >_a : {} | undefined
 >1 : 1
 
@@ -968,7 +968,7 @@ const fn62 = pipe(
 // Repro from #30297
 
 declare function foo2<T, U = T>(fn: T, a?: U, b?: U): [T, U];
->foo2 : <T, U = T>(fn: T, a?: U | undefined, b?: U | undefined) => [T, U]
+>foo2 : <T, U = T>(fn: T, a?: U, b?: U) => [T, U]
 >fn : T
 >a : U | undefined
 >b : U | undefined

tests/baselines/reference/genericRestParameters1.types

@@ -570,7 +570,7 @@ f23();
 >f23 : () => string[]
 
 declare const g20: (x: number, y?: string, z?: boolean) => string[];
->g20 : (x: number, y?: string | undefined, z?: boolean | undefined) => string[]
+>g20 : (x: number, y?: string, z?: boolean) => string[]
 >x : number
 >y : string | undefined
 >z : boolean | undefined

tests/baselines/reference/indexedAccessNormalization.types

@@ -11,7 +11,7 @@ type MyMap<M extends object> = {
 }
 
 declare function g<T>(value?: T): void;
->g : <T>(value?: T | undefined) => void
+>g : <T>(value?: T) => void
 >value : T | undefined
 
 function f1<M extends object>(mymap: MyMap<M>, k: keyof M) {

tests/baselines/reference/inferFromBindingPattern.types

@@ -60,7 +60,7 @@ interface Person {
 }
 
 declare function selectJohn<K = Person>(props?: SelectProps<Person, K>): SelectResult<Person, K>;
->selectJohn : <K = Person>(props?: SelectProps<Person, K> | undefined) => SelectResult<Person, K>
+>selectJohn : <K = Person>(props?: SelectProps<Person, K>) => SelectResult<Person, K>
 >props : SelectProps<Person, K> | undefined
 
 const [person] = selectJohn();
@@ -91,7 +91,7 @@ declare function makeTuple<T1>(arg: T1): [T1];
 >arg : T1
 
 declare function stringy<T = string>(arg?: T): T;
->stringy : <T = string>(arg?: T | undefined) => T
+>stringy : <T = string>(arg?: T) => T
 >arg : T | undefined
 
 const isStringTuple = makeTuple(stringy());  // [string]

tests/baselines/reference/inferenceErasedSignatures.types

@@ -15,7 +15,7 @@ abstract class SomeAbstractClass<C, M, R> extends SomeBaseClass {
 >SomeBaseClass : SomeBaseClass
 
     foo!: (r?: R) => void;
->foo : (r?: R | undefined) => void
+>foo : (r?: R) => void
 >r : R | undefined
 
     bar!: (r?: any) => void;
@@ -72,7 +72,7 @@ interface BaseType<T1, T2>  {
 >c : T1
 
     useT2(r?: T2): void;
->useT2 : (r?: T2 | undefined) => void
+>useT2 : (r?: T2) => void
 >r : T2 | undefined
 
     unrelatedButSomehowRelevant(r?: any): void;
@@ -99,7 +99,7 @@ interface StructuralVersion  {
 >c : number
 
     useT2(r?: boolean): void;
->useT2 : (r?: boolean | undefined) => void
+>useT2 : (r?: boolean) => void
 >r : boolean | undefined
 
     unrelatedButSomehowRelevant(r?: any): void;

tests/baselines/reference/initializedParameterBeforeNonoptionalNotOptional.types

@@ -1,6 +1,6 @@
 === tests/cases/compiler/index.d.ts ===
 export declare function foo({a}?: {
->foo : ({ a }?: { a?: string | undefined; } | undefined) => void
+>foo : ({ a }?: {    a?: string;}) => void
 >a : string | undefined
 
     a?: string;

tests/baselines/reference/intersectionWithConflictingPrivates.types

@@ -138,7 +138,7 @@ class Foo {
 	}
 
   private async bar(node: CommitFileNode | ResultsFileNode | StashFileNode | StatusFileNode, options?: {}) {
->bar : (node: CommitFileNode | ResultsFileNode | StashFileNode | StatusFileNode, options?: {} | undefined) => Promise<undefined>
+>bar : (node: CommitFileNode | ResultsFileNode | StashFileNode | StatusFileNode, options?: {}) => Promise<undefined>
 >node : CommitFileNode | ResultsFileNode | StashFileNode | StatusFileNode
 >options : {} | undefined
 

tests/baselines/reference/jsDeclarationsReactComponents.js

@@ -216,7 +216,7 @@ declare const TabbedShowLayout: {
     };
 } & ((props?: {
     elem: string;
-} | undefined) => JSX.Element);
+}) => JSX.Element);
 //// [jsDeclarationsReactComponents4.d.ts]
 export default TabbedShowLayout;
 declare function TabbedShowLayout(prop: {