Uncalled function checks don't work with negation #43097
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,69 @@ | ||
| tests/cases/compiler/three.ts(28,14): error TS2803: This condition will always return false since the function is always defined. Did you mean to call it instead? | ||
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| ==== tests/cases/compiler/one.ts (0 errors) ==== | ||
| declare const y: never[] | string[]; | ||
| export const yThen = y.map(item => item.length); | ||
| ==== tests/cases/compiler/two.ts (0 errors) ==== | ||
| declare const y: number[][] | string[]; | ||
| export const yThen = y.map(item => item.length); | ||
| ==== tests/cases/compiler/three.ts (1 errors) ==== | ||
| // #42504 | ||
| interface ResizeObserverCallback { | ||
| (entries: ResizeObserverEntry[], observer: ResizeObserver): void; | ||
| } | ||
| interface ResizeObserverCallback { // duplicate for effect | ||
| (entries: ResizeObserverEntry[], observer: ResizeObserver): void; | ||
| } | ||
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| const resizeObserver = new ResizeObserver(([entry]) => { | ||
| entry | ||
| }); | ||
| // comment in #35501 | ||
| interface Callback<T> { | ||
| (error: null, result: T): unknown | ||
| (error: Error, result: null): unknown | ||
| } | ||
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| interface Task<T> { | ||
| (callback: Callback<T>): unknown | ||
| } | ||
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| export function series<T>(tasks: Task<T>[], callback: Callback<T[]>): void { | ||
| let index = 0 | ||
| let results: T[] = [] | ||
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| function next() { | ||
| let task = tasks[index] | ||
| if (!task) { | ||
| ~~~~ | ||
| !!! error TS2803: This condition will always return false since the function is always defined. Did you mean to call it instead? | ||
| callback(null, results) | ||
| } else { | ||
| task((error, result) => { | ||
| if (error) { | ||
| callback(error, null) | ||
| } else { | ||
| // must use postfix-!, since `error` and `result` don't have a | ||
| // causal relationship when the overloads are combined | ||
| results.push(result!) | ||
| next() | ||
| } | ||
| }) | ||
| } | ||
| } | ||
| next() | ||
| } | ||
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| series([ | ||
| cb => setTimeout(() => cb(null, 1), 300), | ||
| cb => setTimeout(() => cb(null, 2), 200), | ||
| cb => setTimeout(() => cb(null, 3), 100), | ||
| ], (error, results) => { | ||
| if (error) { | ||
| console.error(error) | ||
| } else { | ||
| console.log(results) | ||
| } | ||
| }) | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,24 @@ | ||
| tests/cases/compiler/uncalledFunctionChecksDontWorkWithNegation.ts(4,5): error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead? | ||
| tests/cases/compiler/uncalledFunctionChecksDontWorkWithNegation.ts(8,6): error TS2803: This condition will always return false since the function is always defined. Did you mean to call it instead? | ||
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| ==== tests/cases/compiler/uncalledFunctionChecksDontWorkWithNegation.ts (2 errors) ==== | ||
| declare function isFoo(): boolean; | ||
| declare const isUndefinedFoo: (() => boolean) | undefined; | ||
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| if (isFoo) { | ||
| ~~~~~ | ||
| !!! error TS2774: This condition will always return true since the function is always defined. Did you mean to call it instead? | ||
| // error | ||
| } | ||
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| if (!isFoo) { | ||
| ~~~~~ | ||
| !!! error TS2803: This condition will always return false since the function is always defined. Did you mean to call it instead? | ||
| // error | ||
| } | ||
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| if (!isUndefinedFoo) { | ||
| // no error | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,27 @@ | ||
| //// [uncalledFunctionChecksDontWorkWithNegation.ts] | ||
| declare function isFoo(): boolean; | ||
| declare const isUndefinedFoo: (() => boolean) | undefined; | ||
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| if (isFoo) { | ||
| // error | ||
| } | ||
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| if (!isFoo) { | ||
| // error | ||
| } | ||
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| if (!isUndefinedFoo) { | ||
| // no error | ||
| } | ||
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| //// [uncalledFunctionChecksDontWorkWithNegation.js] | ||
| if (isFoo) { | ||
| // error | ||
| } | ||
| if (!isFoo) { | ||
| // error | ||
| } | ||
| if (!isUndefinedFoo) { | ||
| // no error | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,25 @@ | ||
| === tests/cases/compiler/uncalledFunctionChecksDontWorkWithNegation.ts === | ||
| declare function isFoo(): boolean; | ||
| >isFoo : Symbol(isFoo, Decl(uncalledFunctionChecksDontWorkWithNegation.ts, 0, 0)) | ||
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| declare const isUndefinedFoo: (() => boolean) | undefined; | ||
| >isUndefinedFoo : Symbol(isUndefinedFoo, Decl(uncalledFunctionChecksDontWorkWithNegation.ts, 1, 13)) | ||
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| if (isFoo) { | ||
| >isFoo : Symbol(isFoo, Decl(uncalledFunctionChecksDontWorkWithNegation.ts, 0, 0)) | ||
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| // error | ||
| } | ||
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| if (!isFoo) { | ||
| >isFoo : Symbol(isFoo, Decl(uncalledFunctionChecksDontWorkWithNegation.ts, 0, 0)) | ||
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| // error | ||
| } | ||
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| if (!isUndefinedFoo) { | ||
| >isUndefinedFoo : Symbol(isUndefinedFoo, Decl(uncalledFunctionChecksDontWorkWithNegation.ts, 1, 13)) | ||
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| // no error | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,27 @@ | ||
| === tests/cases/compiler/uncalledFunctionChecksDontWorkWithNegation.ts === | ||
| declare function isFoo(): boolean; | ||
| >isFoo : () => boolean | ||
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| declare const isUndefinedFoo: (() => boolean) | undefined; | ||
| >isUndefinedFoo : (() => boolean) | undefined | ||
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| if (isFoo) { | ||
| >isFoo : () => boolean | ||
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| // error | ||
| } | ||
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| if (!isFoo) { | ||
| >!isFoo : false | ||
| >isFoo : () => boolean | ||
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| // error | ||
| } | ||
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| if (!isUndefinedFoo) { | ||
| >!isUndefinedFoo : boolean | ||
| >isUndefinedFoo : (() => boolean) | undefined | ||
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| // no error | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,16 @@ | ||
| // @strictNullChecks: true | ||
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| declare function isFoo(): boolean; | ||
| declare const isUndefinedFoo: (() => boolean) | undefined; | ||
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| if (isFoo) { | ||
| // error | ||
| } | ||
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| if (!isFoo) { | ||
| // error | ||
| } | ||
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| if (!isUndefinedFoo) { | ||
| // no error | ||
| } | ||
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There was a problem hiding this comment. would also like to see what happens when we issue this error for unawaited promises, like so: declare function foo(): Promise<string | undefined>;
const awaitedValue = foo();
if (awaitedValue) { // Emits ts2801
// ...
}
if (!awaitedValue) { // What happens here?
// ...
} |
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would be nice to have tests for when those negated expressions are part of larger logical expressions (e.g.
!isFoo || x, etc)