microsoft / microsoft/TypeScript
Mapped types created from reverse mapped types with union/intersection constraints don't have declaration linked
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Description
🔎 Search Terms
reverse mapped type go to definition union intersection constraint declarations
🕗 Version & Regression Information
- This is the behavior in every version I tried
⏯ Playground Link
💻 Code
type StrictOptionName = "noImplicitAny" | "strictNullChecks";
interface CompilerOptions {
isolatedModules?: boolean;
noImplicitAny?: boolean;
strict?: boolean;
strictNullChecks?: boolean;
verbatimModuleSyntax?: boolean;
}
type CompilerOptionKeys = keyof {
[K in keyof CompilerOptions as string extends K ? never : K]: any;
};
declare function getStrictOptionValue(compilerOptions: CompilerOptions, flag: StrictOptionName): boolean;
declare function createComputedCompilerOptions<T extends Record<string, CompilerOptionKeys[]>>(options: {
[K in (keyof T & CompilerOptionKeys) | StrictOptionName]: {
dependencies: T[K];
computeValue: (compilerOptions: Pick<CompilerOptions, K | T[K][number]>) => Exclude<CompilerOptions[K], undefined>;
};
}): typeof options;
const computed = createComputedCompilerOptions({
isolatedModules: {
dependencies: ["verbatimModuleSyntax"],
computeValue: (compilerOptions) => {
return !!(
compilerOptions.isolatedModules || compilerOptions.verbatimModuleSyntax
);
},
},
noImplicitAny: {
dependencies: ["strict"],
computeValue: (compilerOptions) => {
return getStrictOptionValue(compilerOptions, "noImplicitAny");
},
},
strictNullChecks: {
dependencies: ["strict"],
computeValue: (compilerOptions) => {
return getStrictOptionValue(compilerOptions, "strictNullChecks");
},
},
});
const getIsIsolatedModules = computed.isolatedModules/*1*/.computeValue
🙁 Actual behavior
Go to definition doesn't go anywhere at marker 1
🙂 Expected behavior
Go to definition should go to the property at the line 21
Additional information about the issue
modifiersType for this mapped type is unknown. I think that potentially the modifiers type when iterating over any reverse mapped type (when reversed.mappedType === (mappedType.target || mappedType) could use that reversed.source as the modifiers type. If not that then at least declarations could be outsourced to that type for linking properties.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the linked TypeScript Playground reproduction and inspect the go-to-definition request at marker 1, focusing on the reverse mapped type and its modifiersType. Compare the result with the expected property on line 21. Done means go-to-definition from computed.isolatedModules.computeValue resolves to that property declaration.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- typescript
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 38/100