---
source: crates/oxc_isolated_declarations/tests/mod.rs
input_file: crates/oxc_isolated_declarations/tests/fixtures/function-parameters.ts
---
```
==================== .D.TS ====================

export declare function fnDeclGood(p?: T, rParam?: string): void;
export declare function fnDeclGood2(p?: T, rParam?: number): void;
export declare function fooGood([a, b]?: any[]): number;
export declare const fooGood2: ({ a, b }?: object) => number;
export declare function fooGood3({ a, b: [{ c }] }: object): void;
export declare function fnDeclBad<T>(p: T, rParam: T, r2: T): void;
export declare function fnDeclBad2<T>(p: T, r2: T): void;
export declare function fnDeclBad3<T>(p: T, rParam?: T, r2: T): void;
export declare function fooBad(): number;
export declare const fooBad2: () => number;
export declare function withAny(a: any, b: string): void;
export declare function withUnknown(a: unknown, b: string): void;
export declare function withTypeAssertion(a?: any): void;


==================== Errors ====================

  x TS9025: Declaration emit for this parameter requires implicitly adding
  | undefined to it's type. This is not supported with --isolatedDeclarations.
    ,-[18:30]
 17 | // Incorrect
 18 | export function fnDeclBad<T>(p: T = [], rParam: T = "", r2: T): void { }
    :                              ^^^^^^^^^
 19 | export function fnDeclBad2<T>(p: T = [], r2: T): void { }
    `----

  x TS9025: Declaration emit for this parameter requires implicitly adding
  | undefined to it's type. This is not supported with --isolatedDeclarations.
    ,-[18:41]
 17 | // Incorrect
 18 | export function fnDeclBad<T>(p: T = [], rParam: T = "", r2: T): void { }
    :                                         ^^^^^^^^^^^^^^
 19 | export function fnDeclBad2<T>(p: T = [], r2: T): void { }
    `----

  x TS9025: Declaration emit for this parameter requires implicitly adding
  | undefined to it's type. This is not supported with --isolatedDeclarations.
    ,-[19:31]
 18 | export function fnDeclBad<T>(p: T = [], rParam: T = "", r2: T): void { }
 19 | export function fnDeclBad2<T>(p: T = [], r2: T): void { }
    :                               ^^^^^^^^^
 20 | export function fnDeclBad3<T>(p: T = [], rParam?: T, r2: T): void { }
    `----

  x TS9025: Declaration emit for this parameter requires implicitly adding
  | undefined to it's type. This is not supported with --isolatedDeclarations.
    ,-[20:31]
 19 | export function fnDeclBad2<T>(p: T = [], r2: T): void { }
 20 | export function fnDeclBad3<T>(p: T = [], rParam?: T, r2: T): void { }
    :                               ^^^^^^^^^
 21 | 
    `----

  x TS9011: Parameter must have an explicit type annotation with
  | --isolatedDeclarations.
    ,-[22:24]
 21 | 
 22 | export function fooBad([a, b] = [1, 2]): number {
    :                        ^^^^^^^^^^^^^^^
 23 |   return 2;
    `----

  x TS9011: Parameter must have an explicit type annotation with
  | --isolatedDeclarations.
    ,-[26:25]
 25 | 
 26 | export const fooBad2 = ({a, b} = { a: 1, b: 2 }): number => {
    :                         ^^^^^^^^^^^^^^^^^^^^^^^
 27 |   return 2;
    `----


```