[ID-Prep] Parameter types are not preserved for optional parameters /fields with undefined in type and for required params with default value

[dragomirtitian]

The [ID-prep] set of issues aligns Declaration Emit with the forthcoming Isolated Declarations feature.

🔎 Search Terms

optional parameter types not preserved

🕗 Version & Regression Information

• This is the behavior in every version I tried

⏯ Playground Link

Playground Link

💻 Code

type Map = {} & { [P in string]: any }
type MapOrUndefined = Map | undefined | "dummy"
export class Foo {
  constructor(
    // Type node is accurate, preserve
    public reuseTypeNode?: Map | undefined,
    public reuseTypeNode2?: Exclude<MapOrUndefined, "dummy">,
    // Resolve type node, requires adding | undefined
    public resolveType?: Map,
  ) { }
}

export function foo1(
    // Type node is accurate, preserve
    reuseTypeNode: Map | undefined = {},
    reuseTypeNode2: Exclude<MapOrUndefined, "dummy">  = {},
    // Resolve type node, requires adding | undefined
    resolveType: Map = {}, 
    requiredParam: number) {

}

🙁 Actual behavior

Parameters and fields named reuseTypeNode* have their types re-printed (and mangled) by the declaration transform even though the re-printed type is semantically equivalent to the source type.

🙂 Expected behavior

Parameters and fields named reuseTypeNode* should have their types preserved as they are written in source code

Additional information about the issue

No response