Discrepancy when typeToString when enclosingDeclaration is undefined vs defined.

Bug Report

I'm using typeToString functionality from the typescript compiler (via ts-morph) to build auto-generated API documentation. I've run into an issue with certain types that use default generic types. My goals:

• I don't want the default parameters to show up
• I want the module/sourcefile import included

If I pass enclosingDeclaration, the default parameters don't show up, but the import is gone. If I don't pass enclosingDeclaration the opposite happens - import is there, but the default parameters show up.

🔎 Search Terms

Typescript typeToString generic optional default parameter ignore enclosingDeclaration

🕗 Version & Regression Information

I'm not sure this is bug but there is nothing I could find about it anywhere else.

⏯ Playground Link

link

Code sandbox which shows the issue.

💻 Code

Types:

export interface WithDefaultGenerics<A = string, B = number> {
  irrelevant: string;
}

export type Test = () => WithDefaultGenerics;

    const text = compiler.typeToString(
      compilerType, // This is the type of `Test`
      undefined,
      TypeFormatFlags.UseFullyQualifiedType | TypeFormatFlags.InTypeAlias
    );
    console.log('text is ', text);

    const text2 = compiler.typeToString(
      compilerType, // This is the type of `Test`
      node.compilerNode, // This is the node container of `Test`
      TypeFormatFlags.UseFullyQualifiedType | TypeFormatFlags.InTypeAlias
    );
    console.log('text2 is ', text2);

🙁 Actual behavior

text is  () => import("/Users/path/to/file").WithDefaultGenerics<string, number>

text2 is  () => WithDefaultGenerics

🙂 Expected behavior

I'm trying to get () => import("/Users/path/to/file").WithDefaultGenerics

The reason this is important to me is because in conjunction with, I suspect, this issue, getting a type for (props: AllCasesProps) => ReactElement<AllCasesProps> ends up looking like this:

Inizia con il link Playground e le chiamate compiler typeToString nel report, confrontando l’output quando enclosingDeclaration non è definito con quello quando è node.compilerNode. Analizza in che modo TypeFormatFlags.UseFullyQualifiedType e InTypeAlias influenzano gli argomenti generici predefiniti e i nomi qualificati dal modulo. Il lavoro è completo quando viene prodotto il tipo qualificato richiesto senza mostrare i parametri predefiniti, con una copertura di regressione per entrambi i casi.