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Fix inferences between alias type arguments and defaulted alias type arguments #51771

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merged 5 commits into from
Jan 11, 2023
Merged

Fix inferences between alias type arguments and defaulted alias type arguments #51771

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eb8ed4f
Fix inferences between alias type arguments and defaulted alias type …
weswigham Dec 5, 2022
978b474
Extract value
weswigham Dec 5, 2022
9f806ef
Ensure type parameter lists are filled at each callsite, rather than …
weswigham Dec 8, 2022
c27fc75
Revert "Ensure type parameter lists are filled at each callsite, rath…
weswigham Dec 8, 2022
9e8c50d
Ensure incomplete alias type argument lists are handled across the ch…
weswigham Dec 8, 2022
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14 changes: 11 additions & 3 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -20763,7 +20763,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
if (variances === emptyArray) {
return Ternary.Unknown;
}
const varianceResult = relateVariances(source.aliasTypeArguments, target.aliasTypeArguments, variances, intersectionState);
const params = getSymbolLinks(source.aliasSymbol).typeParameters!;
const minParams = getMinTypeArgumentCount(params);
const sourceTypes = fillMissingTypeArguments(source.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration));
const targetTypes = fillMissingTypeArguments(target.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration));
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const varianceResult = relateVariances(sourceTypes, targetTypes, variances, intersectionState);
if (varianceResult !== undefined) {
return varianceResult;
}
Expand Down Expand Up @@ -23698,8 +23702,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
if (source.aliasSymbol && source.aliasSymbol === target.aliasSymbol) {
if (source.aliasTypeArguments) {
// Source and target are types originating in the same generic type alias declaration.
// Simply infer from source type arguments to target type arguments.
inferFromTypeArguments(source.aliasTypeArguments, target.aliasTypeArguments!, getAliasVariances(source.aliasSymbol));
// Simply infer from source type arguments to target type arguments, with defaults applied.
const params = getSymbolLinks(source.aliasSymbol).typeParameters!;
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Hmm, I wasn't even aware that the type argument list could be incomplete at this point, and I'm not sure that was ever intended. It's fine for type arguments to be missing at the lexical level, but once we're dealing with types we pretty much assume that the length of a type argument list matches the length of the corresponding type parameter list. That assumption is pretty pervasive throughout the compiler (modulo the this type argument that sometimes isn't present). I think it would make more sense to find the origin of the incomplete list and put the call to fillMissingTypeArguments there.

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@weswigham weswigham Dec 8, 2022 •
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Right, so, our old logic for giving an alias symbol instantiation an alias symbol didn't fill missing type arguments, which is why the new condition I added also didn't - it didn't seem required, since our existing usage didn't fill them. Obviously, broader usage of these unfilled lists reveals the flaw, namely inference (and probably comparison checking) not going well, since, as you said, they currently expect filled lists. Thing is, I think trafficking the unfilled lists has an advantage - it may be worth handling incomplete lists in inference/comparison checking. If we start filling them eagerly, rather than getting the user-supplied list, when we printback, we don't printback the user supplied list anymore. Meaning, even though you wrote Component, we print back and serialize Component<{}, any, any>. For complex defaults, this means we can muddy the printback unnecessarily quite a bit. So while I could fix this by passing in filled lists at the now 2 locations we supply an alias for an alias symbol instantiation, the UX is much nicer if instead we update inference and comparison checking to handle incomplete type alias argument lists, imo.

const minParams = getMinTypeArgumentCount(params);
const sourceTypes = fillMissingTypeArguments(source.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration));
const targetTypes = fillMissingTypeArguments(target.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration));
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inferFromTypeArguments(sourceTypes, targetTypes!, getAliasVariances(source.aliasSymbol));
}
// And if there weren't any type arguments, there's no reason to run inference as the types must be the same.
return;
Expand Down
50 changes: 50 additions & 0 deletions tests/baselines/reference/importedAliasedConditionalTypeInstantiation.js
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@@ -0,0 +1,50 @@
//// [tests/cases/compiler/importedAliasedConditionalTypeInstantiation.ts] ////

//// [index.d.ts]
export type Handler<TEvent = any, TResult = any> = (
event: TEvent,
context: {},
callback: Callback<TResult>,
) => void | Promise<TResult>;

export type Callback<TResult = any> = (error?: Error | string | null, result?: TResult) => void;

//// [index.d.ts]
import { Handler, Callback } from 'aws-lambda';
declare namespace lambdaTester {
type HandlerEvent<T extends Handler> = T extends Handler<infer TEvent> ? TEvent : never;
type HandlerResult<T extends Handler> = T extends Handler<any, infer TResult> ? TResult : never;
type HandlerError<T extends Handler> = T extends Handler<any, infer TResult>
? NonNullable<Parameters<Callback<TResult>>['0']>
: never;

interface VerifierFn<S> {
(result: S, additional?: any): void | Promise<void>;
(result: S, additional?: any, done?: () => {}): void;
}
type Verifier<S> = S extends HandlerError<Handler>
? S extends string
? VerifierFn<string>
: S extends Error
? VerifierFn<Error>
: never
: VerifierFn<S>;

class LambdaTester<T extends Handler> {
event(event: HandlerEvent<T>): this;
}
}

declare function lambdaTester<T extends Handler>(handler: T): lambdaTester.LambdaTester<T>;

export = lambdaTester;
//// [index.ts]
import * as lambdaTester from 'lambda-tester';
import { Handler } from 'aws-lambda';

type Actual = lambdaTester.Verifier<lambdaTester.HandlerResult<Handler>>;
type Expected = lambdaTester.Verifier<lambdaTester.HandlerResult<Handler<any, any>>>;

//// [index.js]
"use strict";
exports.__esModule = true;
163 changes: 163 additions & 0 deletions tests/baselines/reference/importedAliasedConditionalTypeInstantiation.symbols
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=== tests/cases/compiler/node_modules/aws-lambda/index.d.ts ===
export type Handler<TEvent = any, TResult = any> = (
>Handler : Symbol(Handler, Decl(index.d.ts, 0, 0))
>TEvent : Symbol(TEvent, Decl(index.d.ts, 0, 20))
>TResult : Symbol(TResult, Decl(index.d.ts, 0, 33))

event: TEvent,
>event : Symbol(event, Decl(index.d.ts, 0, 52))
>TEvent : Symbol(TEvent, Decl(index.d.ts, 0, 20))

context: {},
>context : Symbol(context, Decl(index.d.ts, 1, 18))

callback: Callback<TResult>,
>callback : Symbol(callback, Decl(index.d.ts, 2, 16))
>Callback : Symbol(Callback, Decl(index.d.ts, 4, 29))
>TResult : Symbol(TResult, Decl(index.d.ts, 0, 33))

) => void | Promise<TResult>;
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --))
>TResult : Symbol(TResult, Decl(index.d.ts, 0, 33))

export type Callback<TResult = any> = (error?: Error | string | null, result?: TResult) => void;
>Callback : Symbol(Callback, Decl(index.d.ts, 4, 29))
>TResult : Symbol(TResult, Decl(index.d.ts, 6, 21))
>error : Symbol(error, Decl(index.d.ts, 6, 39))
>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
>result : Symbol(result, Decl(index.d.ts, 6, 69))
>TResult : Symbol(TResult, Decl(index.d.ts, 6, 21))

=== tests/cases/compiler/node_modules/lambda-tester/index.d.ts ===
import { Handler, Callback } from 'aws-lambda';
>Handler : Symbol(Handler, Decl(index.d.ts, 0, 8))
>Callback : Symbol(Callback, Decl(index.d.ts, 0, 17))

declare namespace lambdaTester {
>lambdaTester : Symbol(lambdaTester, Decl(index.d.ts, 23, 1), Decl(index.d.ts, 0, 47))

type HandlerEvent<T extends Handler> = T extends Handler<infer TEvent> ? TEvent : never;
>HandlerEvent : Symbol(HandlerEvent, Decl(index.d.ts, 1, 32))
>T : Symbol(T, Decl(index.d.ts, 2, 22))
>Handler : Symbol(Handler, Decl(index.d.ts, 0, 8))
>T : Symbol(T, Decl(index.d.ts, 2, 22))
>Handler : Symbol(Handler, Decl(index.d.ts, 0, 8))
>TEvent : Symbol(TEvent, Decl(index.d.ts, 2, 66))
>TEvent : Symbol(TEvent, Decl(index.d.ts, 2, 66))

type HandlerResult<T extends Handler> = T extends Handler<any, infer TResult> ? TResult : never;
>HandlerResult : Symbol(HandlerResult, Decl(index.d.ts, 2, 92))
>T : Symbol(T, Decl(index.d.ts, 3, 23))
>Handler : Symbol(Handler, Decl(index.d.ts, 0, 8))
>T : Symbol(T, Decl(index.d.ts, 3, 23))
>Handler : Symbol(Handler, Decl(index.d.ts, 0, 8))
>TResult : Symbol(TResult, Decl(index.d.ts, 3, 72))
>TResult : Symbol(TResult, Decl(index.d.ts, 3, 72))

type HandlerError<T extends Handler> = T extends Handler<any, infer TResult>
>HandlerError : Symbol(HandlerError, Decl(index.d.ts, 3, 100))
>T : Symbol(T, Decl(index.d.ts, 4, 22))
>Handler : Symbol(Handler, Decl(index.d.ts, 0, 8))
>T : Symbol(T, Decl(index.d.ts, 4, 22))
>Handler : Symbol(Handler, Decl(index.d.ts, 0, 8))
>TResult : Symbol(TResult, Decl(index.d.ts, 4, 71))

? NonNullable<Parameters<Callback<TResult>>['0']>
>NonNullable : Symbol(NonNullable, Decl(lib.es5.d.ts, --, --))
>Parameters : Symbol(Parameters, Decl(lib.es5.d.ts, --, --))
>Callback : Symbol(Callback, Decl(index.d.ts, 0, 17))
>TResult : Symbol(TResult, Decl(index.d.ts, 4, 71))

: never;

interface VerifierFn<S> {
>VerifierFn : Symbol(VerifierFn, Decl(index.d.ts, 6, 16))
>S : Symbol(S, Decl(index.d.ts, 8, 25))

(result: S, additional?: any): void | Promise<void>;
>result : Symbol(result, Decl(index.d.ts, 9, 9))
>S : Symbol(S, Decl(index.d.ts, 8, 25))
>additional : Symbol(additional, Decl(index.d.ts, 9, 19))
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --))

(result: S, additional?: any, done?: () => {}): void;
>result : Symbol(result, Decl(index.d.ts, 10, 9))
>S : Symbol(S, Decl(index.d.ts, 8, 25))
>additional : Symbol(additional, Decl(index.d.ts, 10, 19))
>done : Symbol(done, Decl(index.d.ts, 10, 37))
}
type Verifier<S> = S extends HandlerError<Handler>
>Verifier : Symbol(Verifier, Decl(index.d.ts, 11, 5))
>S : Symbol(S, Decl(index.d.ts, 12, 18))
>S : Symbol(S, Decl(index.d.ts, 12, 18))
>HandlerError : Symbol(HandlerError, Decl(index.d.ts, 3, 100))
>Handler : Symbol(Handler, Decl(index.d.ts, 0, 8))

? S extends string
>S : Symbol(S, Decl(index.d.ts, 12, 18))

? VerifierFn<string>
>VerifierFn : Symbol(VerifierFn, Decl(index.d.ts, 6, 16))

: S extends Error
>S : Symbol(S, Decl(index.d.ts, 12, 18))
>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))

? VerifierFn<Error>
>VerifierFn : Symbol(VerifierFn, Decl(index.d.ts, 6, 16))
>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))

: never
: VerifierFn<S>;
>VerifierFn : Symbol(VerifierFn, Decl(index.d.ts, 6, 16))
>S : Symbol(S, Decl(index.d.ts, 12, 18))

class LambdaTester<T extends Handler> {
>LambdaTester : Symbol(LambdaTester, Decl(index.d.ts, 18, 24))
>T : Symbol(T, Decl(index.d.ts, 20, 23))
>Handler : Symbol(Handler, Decl(index.d.ts, 0, 8))

event(event: HandlerEvent<T>): this;
>event : Symbol(LambdaTester.event, Decl(index.d.ts, 20, 43))
>event : Symbol(event, Decl(index.d.ts, 21, 14))
>HandlerEvent : Symbol(HandlerEvent, Decl(index.d.ts, 1, 32))
>T : Symbol(T, Decl(index.d.ts, 20, 23))
}
}

declare function lambdaTester<T extends Handler>(handler: T): lambdaTester.LambdaTester<T>;
>lambdaTester : Symbol(lambdaTester, Decl(index.d.ts, 23, 1), Decl(index.d.ts, 0, 47))
>T : Symbol(T, Decl(index.d.ts, 25, 30))
>Handler : Symbol(Handler, Decl(index.d.ts, 0, 8))
>handler : Symbol(handler, Decl(index.d.ts, 25, 49))
>T : Symbol(T, Decl(index.d.ts, 25, 30))
>lambdaTester : Symbol(lambdaTester, Decl(index.d.ts, 23, 1), Decl(index.d.ts, 0, 47))
>LambdaTester : Symbol(lambdaTester.LambdaTester, Decl(index.d.ts, 18, 24))
>T : Symbol(T, Decl(index.d.ts, 25, 30))

export = lambdaTester;
>lambdaTester : Symbol(lambdaTester, Decl(index.d.ts, 23, 1), Decl(index.d.ts, 0, 47))

=== tests/cases/compiler/index.ts ===
import * as lambdaTester from 'lambda-tester';
>lambdaTester : Symbol(lambdaTester, Decl(index.ts, 0, 6))

import { Handler } from 'aws-lambda';
>Handler : Symbol(Handler, Decl(index.ts, 1, 8))

type Actual = lambdaTester.Verifier<lambdaTester.HandlerResult<Handler>>;
>Actual : Symbol(Actual, Decl(index.ts, 1, 37))
>lambdaTester : Symbol(lambdaTester, Decl(index.ts, 0, 6))
>Verifier : Symbol(lambdaTester.Verifier, Decl(index.d.ts, 11, 5))
>lambdaTester : Symbol(lambdaTester, Decl(index.ts, 0, 6))
>HandlerResult : Symbol(lambdaTester.HandlerResult, Decl(index.d.ts, 2, 92))
>Handler : Symbol(Handler, Decl(index.ts, 1, 8))

type Expected = lambdaTester.Verifier<lambdaTester.HandlerResult<Handler<any, any>>>;
>Expected : Symbol(Expected, Decl(index.ts, 3, 73))
>lambdaTester : Symbol(lambdaTester, Decl(index.ts, 0, 6))
>Verifier : Symbol(lambdaTester.Verifier, Decl(index.d.ts, 11, 5))
>lambdaTester : Symbol(lambdaTester, Decl(index.ts, 0, 6))
>HandlerResult : Symbol(lambdaTester.HandlerResult, Decl(index.d.ts, 2, 92))
>Handler : Symbol(Handler, Decl(index.ts, 1, 8))

95 changes: 95 additions & 0 deletions tests/baselines/reference/importedAliasedConditionalTypeInstantiation.types
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=== tests/cases/compiler/node_modules/aws-lambda/index.d.ts ===
export type Handler<TEvent = any, TResult = any> = (
>Handler : Handler<TEvent, TResult>

event: TEvent,
>event : TEvent

context: {},
>context : {}

callback: Callback<TResult>,
>callback : Callback<TResult>

) => void | Promise<TResult>;

export type Callback<TResult = any> = (error?: Error | string | null, result?: TResult) => void;
>Callback : Callback<TResult>
>error : string | Error
>null : null
>result : TResult

=== tests/cases/compiler/node_modules/lambda-tester/index.d.ts ===
import { Handler, Callback } from 'aws-lambda';
>Handler : any
>Callback : any

declare namespace lambdaTester {
>lambdaTester : typeof lambdaTester

type HandlerEvent<T extends Handler> = T extends Handler<infer TEvent> ? TEvent : never;
>HandlerEvent : HandlerEvent<T>

type HandlerResult<T extends Handler> = T extends Handler<any, infer TResult> ? TResult : never;
>HandlerResult : HandlerResult<T>

type HandlerError<T extends Handler> = T extends Handler<any, infer TResult>
>HandlerError : HandlerError<T>

? NonNullable<Parameters<Callback<TResult>>['0']>
: never;

interface VerifierFn<S> {
(result: S, additional?: any): void | Promise<void>;
>result : S
>additional : any

(result: S, additional?: any, done?: () => {}): void;
>result : S
>additional : any
>done : () => {}
}
type Verifier<S> = S extends HandlerError<Handler>
>Verifier : Verifier<S>

? S extends string
? VerifierFn<string>
: S extends Error
? VerifierFn<Error>
: never
: VerifierFn<S>;

class LambdaTester<T extends Handler> {
>LambdaTester : LambdaTester<T>

event(event: HandlerEvent<T>): this;
>event : (event: HandlerEvent<T>) => this
>event : HandlerEvent<T>
}
}

declare function lambdaTester<T extends Handler>(handler: T): lambdaTester.LambdaTester<T>;
>lambdaTester : typeof lambdaTester
>handler : T
>lambdaTester : any

export = lambdaTester;
>lambdaTester : typeof lambdaTester

=== tests/cases/compiler/index.ts ===
import * as lambdaTester from 'lambda-tester';
>lambdaTester : typeof lambdaTester

import { Handler } from 'aws-lambda';
>Handler : any

type Actual = lambdaTester.Verifier<lambdaTester.HandlerResult<Handler>>;
>Actual : lambdaTester.VerifierFn<string> | lambdaTester.VerifierFn<Error> | lambdaTester.VerifierFn<any>
>lambdaTester : any
>lambdaTester : any

type Expected = lambdaTester.Verifier<lambdaTester.HandlerResult<Handler<any, any>>>;
>Expected : lambdaTester.VerifierFn<string> | lambdaTester.VerifierFn<Error> | lambdaTester.VerifierFn<any>
>lambdaTester : any
>lambdaTester : any

45 changes: 45 additions & 0 deletions tests/cases/compiler/importedAliasedConditionalTypeInstantiation.ts
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// @filename: node_modules/aws-lambda/index.d.ts
export type Handler<TEvent = any, TResult = any> = (
event: TEvent,
context: {},
callback: Callback<TResult>,
) => void | Promise<TResult>;

export type Callback<TResult = any> = (error?: Error | string | null, result?: TResult) => void;

// @filename: node_modules/lambda-tester/index.d.ts
import { Handler, Callback } from 'aws-lambda';
declare namespace lambdaTester {
type HandlerEvent<T extends Handler> = T extends Handler<infer TEvent> ? TEvent : never;
type HandlerResult<T extends Handler> = T extends Handler<any, infer TResult> ? TResult : never;
type HandlerError<T extends Handler> = T extends Handler<any, infer TResult>
? NonNullable<Parameters<Callback<TResult>>['0']>
: never;

interface VerifierFn<S> {
(result: S, additional?: any): void | Promise<void>;
(result: S, additional?: any, done?: () => {}): void;
}
type Verifier<S> = S extends HandlerError<Handler>
? S extends string
? VerifierFn<string>
: S extends Error
? VerifierFn<Error>
: never
: VerifierFn<S>;

class LambdaTester<T extends Handler> {
event(event: HandlerEvent<T>): this;
}
}

declare function lambdaTester<T extends Handler>(handler: T): lambdaTester.LambdaTester<T>;

export = lambdaTester;
// @filename: index.ts

import * as lambdaTester from 'lambda-tester';
import { Handler } from 'aws-lambda';

type Actual = lambdaTester.Verifier<lambdaTester.HandlerResult<Handler>>;
type Expected = lambdaTester.Verifier<lambdaTester.HandlerResult<Handler<any, any>>>;