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Fixed string completions from generic conditional types that match typed argument against template literal type #52997

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Fixed string completions from generic conditional types that match typed argument against template literal type #52997

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178acd9
Fixed string completions from generic conditional types that match ty…
Andarist Feb 27, 2023
e267157
Merge remote-tracking branch 'origin/main' into fix/string-completion…
Andarist Jun 13, 2023
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8 changes: 4 additions & 4 deletions src/services/stringCompletions.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -495,7 +495,7 @@ function getStringLiteralCompletionsFromSignature(call: CallLikeExpression, arg:
}
}
isNewIdentifier = isNewIdentifier || !!(type.flags & TypeFlags.String);
return getStringLiteralTypes(type, uniques);
return getStringLiteralTypes(type, uniques, arg.text);
});
return length(types) ? { kind: StringLiteralCompletionKind.Types, types, isNewIdentifier } : undefined;
}
Expand Down Expand Up @@ -527,11 +527,11 @@ function stringLiteralCompletionsForObjectLiteral(checker: TypeChecker, objectLi
};
}

function getStringLiteralTypes(type: Type | undefined, uniques = new Map<string, true>()): readonly StringLiteralType[] {
function getStringLiteralTypes(type: Type | undefined, uniques = new Map<string, true>(), alreadyTyped = ""): readonly StringLiteralType[] {
if (!type) return emptyArray;
type = skipConstraint(type);
return type.isUnion() ? flatMap(type.types, t => getStringLiteralTypes(t, uniques)) :
type.isStringLiteral() && !(type.flags & TypeFlags.EnumLiteral) && addToSeen(uniques, type.value) ? [type] : emptyArray;
return type.isUnion() ? flatMap(type.types, t => getStringLiteralTypes(t, uniques, alreadyTyped)) :
type.isStringLiteral() && !(type.flags & TypeFlags.EnumLiteral) && type.value.startsWith(alreadyTyped) && addToSeen(uniques, type.value) ? [type] : emptyArray;
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Based on those few test failures it seems that I can't just simply discard the already matched strings at this stage. Those are still useful for creating replacement spans here:

TypeScript/src/services/stringCompletions.ts

Line 266 in 178acd9

replacementSpan: getReplacementSpanForContextToken(contextToken)

However, I'm not exactly sure what is the relation between what is being returned by TS and what is displayed by VS Code. VS code tends to skip some completions... like even if we take a look at the added test case: before this change TS returns "a" | "b" but VS Code doesn't display anything.

The goal behind this change here was for the logic to fallback to the fromContextualType() here:

TypeScript/src/services/stringCompletions.ts

Line 419 in 178acd9

return argumentInfo && getStringLiteralCompletionsFromSignature(argumentInfo.invocation, node, argumentInfo, typeChecker) || fromContextualType();

I tried to avoid doing both requests unconditionally and concatenating their results but perhaps that is the way to go here? Or perhaps this filtering should happen on a different level (like before doing the second request) but it doesn't affect the returned types? Maybe it should just test out if anything "interesting" was returned from the first request?

}

interface NameAndKind {
Expand Down
13 changes: 13 additions & 0 deletions .../cases/fourslash/stringCompletionsFromGenericConditionalTypesUsingTemplateLiteralTypes.ts
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@@ -0,0 +1,13 @@
/// <reference path="fourslash.ts" />

// @Filename: /a.tsx
//// type PathOf<T, K extends string, P extends string = ""> =
//// K extends `${infer U}.${infer V}`
//// ? U extends keyof T ? PathOf<T[U], V, `${P}${U}.`> : `${P}${keyof T & (string | number)}`
//// : K extends keyof T ? `${P}${K}` : `${P}${keyof T & (string | number)}`;
////
//// declare function consumer<K extends string>(path: PathOf<{a: string, b: {c: string}}, K>) : number;
////
//// consumer('b./*ts*/')

verify.completions({ marker: ["ts"], exact: ["b.c"] });