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Don’t error for missing await when promise is referenced in condition body #43593

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Apr 13, 2021
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Don’t error for missing await when promise is referenced in condition body #43593

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64bb782
Don’t error for missing await when promise is referenced in condition…
andrewbranch Apr 8, 2021
e7a449e
Reword error messages
andrewbranch Apr 13, 2021
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39 changes: 20 additions & 19 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -35371,15 +35371,6 @@ namespace ts {
if (!strictNullChecks) return;
if (getFalsyFlags(type)) return;

if (getAwaitedTypeOfPromise(type)) {
errorAndMaybeSuggestAwait(
condExpr,
/*maybeMissingAwait*/ true,
Diagnostics.This_condition_will_always_return_true_since_this_0_appears_to_always_be_defined,
getTypeNameForErrorDisplay(type));
return;
}

const location = isBinaryExpression(condExpr) ? condExpr.right : condExpr;
const testedNode = isIdentifier(location) ? location
: isPropertyAccessExpression(location) ? location.name
Expand All @@ -35392,12 +35383,13 @@ namespace ts {
}

// While it technically should be invalid for any known-truthy value
// to be tested, we de-scope to functions unrefenced in the block as a
// heuristic to identify the most common bugs. There are too many
// false positives for values sourced from type definitions without
// strictNullChecks otherwise.
// to be tested, we de-scope to functions and Promises unrefenced in
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// the block as a heuristic to identify the most common bugs. There
// are too many false positives for values sourced from type
// definitions without strictNullChecks otherwise.
const callSignatures = getSignaturesOfType(type, SignatureKind.Call);
if (callSignatures.length === 0) {
const isPromise = !!getAwaitedTypeOfPromise(type);
if (callSignatures.length === 0 && !isPromise) {
return;
}

Expand All @@ -35406,14 +35398,23 @@ namespace ts {
return;
}

const isUsed = isBinaryExpression(condExpr.parent) && isFunctionUsedInBinaryExpressionChain(condExpr.parent, testedSymbol)
|| body && isFunctionUsedInConditionBody(condExpr, body, testedNode, testedSymbol);
const isUsed = isBinaryExpression(condExpr.parent) && isSymbolUsedInBinaryExpressionChain(condExpr.parent, testedSymbol)
|| body && isSymbolUsedInConditionBody(condExpr, body, testedNode, testedSymbol);
if (!isUsed) {
error(location, Diagnostics.This_condition_will_always_return_true_since_this_function_appears_to_always_be_defined_Did_you_mean_to_call_it_instead);
if (isPromise) {
errorAndMaybeSuggestAwait(
location,
/*maybeMissingAwait*/ true,
Diagnostics.This_condition_will_always_return_true_since_this_0_appears_to_always_be_defined,
getTypeNameForErrorDisplay(type));
}
else {
error(location, Diagnostics.This_condition_will_always_return_true_since_this_function_appears_to_always_be_defined_Did_you_mean_to_call_it_instead);
}
}
}

function isFunctionUsedInConditionBody(expr: Expression, body: Statement | Expression, testedNode: Node, testedSymbol: Symbol): boolean {
function isSymbolUsedInConditionBody(expr: Expression, body: Statement | Expression, testedNode: Node, testedSymbol: Symbol): boolean {
return !!forEachChild(body, function check(childNode): boolean | undefined {
if (isIdentifier(childNode)) {
const childSymbol = getSymbolAtLocation(childNode);
Expand Down Expand Up @@ -35451,7 +35452,7 @@ namespace ts {
});
}

function isFunctionUsedInBinaryExpressionChain(node: Node, testedSymbol: Symbol): boolean {
function isSymbolUsedInBinaryExpressionChain(node: Node, testedSymbol: Symbol): boolean {
while (isBinaryExpression(node) && node.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken) {
const isUsed = forEachChild(node.right, function visit(child): boolean | undefined {
if (isIdentifier(child)) {
Expand Down
38 changes: 33 additions & 5 deletions tests/baselines/reference/truthinessPromiseCoercion.errors.txt
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Original file line number Diff line number Diff line change
@@ -1,24 +1,52 @@
tests/cases/compiler/truthinessPromiseCoercion.ts(5,9): error TS2801: This condition will always return true since this 'Promise<number>' appears to always be defined.
tests/cases/compiler/truthinessPromiseCoercion.ts(9,5): error TS2801: This condition will always return true since this 'Promise<number>' appears to always be defined.
tests/cases/compiler/truthinessPromiseCoercion.ts(6,9): error TS2801: This condition will always return true since this 'Promise<number>' appears to always be defined.
tests/cases/compiler/truthinessPromiseCoercion.ts(10,5): error TS2801: This condition will always return true since this 'Promise<number>' appears to always be defined.
tests/cases/compiler/truthinessPromiseCoercion.ts(31,9): error TS2801: This condition will always return true since this 'Promise<unknown>' appears to always be defined.


==== tests/cases/compiler/truthinessPromiseCoercion.ts (2 errors) ====
==== tests/cases/compiler/truthinessPromiseCoercion.ts (3 errors) ====
declare const p: Promise<number>
declare const p2: null | Promise<number>
declare const obj: { p: Promise<unknown> }

async function f() {
if (p) {} // err
~
!!! error TS2801: This condition will always return true since this 'Promise<number>' appears to always be defined.
!!! related TS2773 tests/cases/compiler/truthinessPromiseCoercion.ts:5:9: Did you forget to use 'await'?
!!! related TS2773 tests/cases/compiler/truthinessPromiseCoercion.ts:6:9: Did you forget to use 'await'?
if (!!p) {} // no err
if (p2) {} // no err

p ? f.arguments : f.arguments;
~
!!! error TS2801: This condition will always return true since this 'Promise<number>' appears to always be defined.
!!! related TS2773 tests/cases/compiler/truthinessPromiseCoercion.ts:9:5: Did you forget to use 'await'?
!!! related TS2773 tests/cases/compiler/truthinessPromiseCoercion.ts:10:5: Did you forget to use 'await'?
!!p ? f.arguments : f.arguments;
p2 ? f.arguments : f.arguments;
}

// all ok
async function g() {
if (p) {
p;
}
if (p && p.then.length) {}
if (p) {
if (p) {
if (p) {
!!await (((((((p)))))));
}
}
}
}

async function h() {
if (obj.p) {} // error
~~~~~
!!! error TS2801: This condition will always return true since this 'Promise<unknown>' appears to always be defined.
!!! related TS2773 tests/cases/compiler/truthinessPromiseCoercion.ts:31:9: Did you forget to use 'await'?
if (obj.p) { // ok
await obj.p;
}
if (obj.p && await obj.p) {} // ok
}

45 changes: 45 additions & 0 deletions tests/baselines/reference/truthinessPromiseCoercion.js
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
//// [truthinessPromiseCoercion.ts]
declare const p: Promise<number>
declare const p2: null | Promise<number>
declare const obj: { p: Promise<unknown> }

async function f() {
if (p) {} // err
Expand All @@ -11,6 +12,29 @@ async function f() {
!!p ? f.arguments : f.arguments;
p2 ? f.arguments : f.arguments;
}

// all ok
async function g() {
if (p) {
p;
}
if (p && p.then.length) {}
if (p) {
if (p) {
if (p) {
!!await (((((((p)))))));
}
}
}
}

async function h() {
if (obj.p) {} // error
if (obj.p) { // ok
await obj.p;
}
if (obj.p && await obj.p) {} // ok
}


//// [truthinessPromiseCoercion.js]
Expand All @@ -22,3 +46,24 @@ async function f() {
!!p ? f.arguments : f.arguments;
p2 ? f.arguments : f.arguments;
}
// all ok
async function g() {
if (p) {
p;
}
if (p && p.then.length) { }
if (p) {
if (p) {
if (p) {
!!await (((((((p)))))));
}
}
}
}
async function h() {
if (obj.p) { } // error
if (obj.p) { // ok
await obj.p;
}
if (obj.p && await obj.p) { } // ok
}
80 changes: 73 additions & 7 deletions tests/baselines/reference/truthinessPromiseCoercion.symbols
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Original file line number Diff line number Diff line change
Expand Up @@ -7,8 +7,13 @@ declare const p2: null | Promise<number>
>p2 : Symbol(p2, Decl(truthinessPromiseCoercion.ts, 1, 13))
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2018.promise.d.ts, --, --))

declare const obj: { p: Promise<unknown> }
>obj : Symbol(obj, Decl(truthinessPromiseCoercion.ts, 2, 13))
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 2, 20))
>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2018.promise.d.ts, --, --))

async function f() {
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 1, 40))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 2, 42))

if (p) {} // err
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 0, 13))
Expand All @@ -22,28 +27,89 @@ async function f() {
p ? f.arguments : f.arguments;
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 0, 13))
>f.arguments : Symbol(Function.arguments, Decl(lib.es5.d.ts, --, --))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 1, 40))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 2, 42))
>arguments : Symbol(Function.arguments, Decl(lib.es5.d.ts, --, --))
>f.arguments : Symbol(Function.arguments, Decl(lib.es5.d.ts, --, --))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 1, 40))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 2, 42))
>arguments : Symbol(Function.arguments, Decl(lib.es5.d.ts, --, --))

!!p ? f.arguments : f.arguments;
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 0, 13))
>f.arguments : Symbol(Function.arguments, Decl(lib.es5.d.ts, --, --))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 1, 40))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 2, 42))
>arguments : Symbol(Function.arguments, Decl(lib.es5.d.ts, --, --))
>f.arguments : Symbol(Function.arguments, Decl(lib.es5.d.ts, --, --))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 1, 40))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 2, 42))
>arguments : Symbol(Function.arguments, Decl(lib.es5.d.ts, --, --))

p2 ? f.arguments : f.arguments;
>p2 : Symbol(p2, Decl(truthinessPromiseCoercion.ts, 1, 13))
>f.arguments : Symbol(Function.arguments, Decl(lib.es5.d.ts, --, --))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 1, 40))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 2, 42))
>arguments : Symbol(Function.arguments, Decl(lib.es5.d.ts, --, --))
>f.arguments : Symbol(Function.arguments, Decl(lib.es5.d.ts, --, --))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 1, 40))
>f : Symbol(f, Decl(truthinessPromiseCoercion.ts, 2, 42))
>arguments : Symbol(Function.arguments, Decl(lib.es5.d.ts, --, --))
}

// all ok
async function g() {
>g : Symbol(g, Decl(truthinessPromiseCoercion.ts, 12, 1))

if (p) {
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 0, 13))

p;
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 0, 13))
}
if (p && p.then.length) {}
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 0, 13))
>p.then.length : Symbol(Function.length, Decl(lib.es5.d.ts, --, --))
>p.then : Symbol(Promise.then, Decl(lib.es5.d.ts, --, --))
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 0, 13))
>then : Symbol(Promise.then, Decl(lib.es5.d.ts, --, --))
>length : Symbol(Function.length, Decl(lib.es5.d.ts, --, --))

if (p) {
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 0, 13))

if (p) {
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 0, 13))

if (p) {
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 0, 13))

!!await (((((((p)))))));
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 0, 13))
}
}
}
}

async function h() {
>h : Symbol(h, Decl(truthinessPromiseCoercion.ts, 27, 1))

if (obj.p) {} // error
>obj.p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 2, 20))
>obj : Symbol(obj, Decl(truthinessPromiseCoercion.ts, 2, 13))
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 2, 20))

if (obj.p) { // ok
>obj.p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 2, 20))
>obj : Symbol(obj, Decl(truthinessPromiseCoercion.ts, 2, 13))
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 2, 20))

await obj.p;
>obj.p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 2, 20))
>obj : Symbol(obj, Decl(truthinessPromiseCoercion.ts, 2, 13))
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 2, 20))
}
if (obj.p && await obj.p) {} // ok
>obj.p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 2, 20))
>obj : Symbol(obj, Decl(truthinessPromiseCoercion.ts, 2, 13))
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 2, 20))
>obj.p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 2, 20))
>obj : Symbol(obj, Decl(truthinessPromiseCoercion.ts, 2, 13))
>p : Symbol(p, Decl(truthinessPromiseCoercion.ts, 2, 20))
}

79 changes: 79 additions & 0 deletions tests/baselines/reference/truthinessPromiseCoercion.types
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,10 @@ declare const p2: null | Promise<number>
>p2 : Promise<number> | null
>null : null

declare const obj: { p: Promise<unknown> }
>obj : { p: Promise<unknown>; }
>p : Promise<unknown>

async function f() {
>f : () => Promise<void>

Expand Down Expand Up @@ -53,3 +57,78 @@ async function f() {
>arguments : any
}

// all ok
async function g() {
>g : () => Promise<void>

if (p) {
>p : Promise<number>

p;
>p : Promise<number>
}
if (p && p.then.length) {}
>p && p.then.length : number
>p : Promise<number>
>p.then.length : number
>p.then : <TResult1 = number, TResult2 = never>(onfulfilled?: ((value: number) => TResult1 | PromiseLike<TResult1>) | null | undefined, onrejected?: ((reason: any) => TResult2 | PromiseLike<TResult2>) | null | undefined) => Promise<TResult1 | TResult2>
>p : Promise<number>
>then : <TResult1 = number, TResult2 = never>(onfulfilled?: ((value: number) => TResult1 | PromiseLike<TResult1>) | null | undefined, onrejected?: ((reason: any) => TResult2 | PromiseLike<TResult2>) | null | undefined) => Promise<TResult1 | TResult2>
>length : number

if (p) {
>p : Promise<number>

if (p) {
>p : Promise<number>

if (p) {
>p : Promise<number>

!!await (((((((p)))))));
>!!await (((((((p))))))) : boolean
>!await (((((((p))))))) : boolean
>await (((((((p))))))) : number
>(((((((p))))))) : Promise<number>
>((((((p)))))) : Promise<number>
>(((((p))))) : Promise<number>
>((((p)))) : Promise<number>
>(((p))) : Promise<number>
>((p)) : Promise<number>
>(p) : Promise<number>
>p : Promise<number>
}
}
}
}

async function h() {
>h : () => Promise<void>

if (obj.p) {} // error
>obj.p : Promise<unknown>
>obj : { p: Promise<unknown>; }
>p : Promise<unknown>

if (obj.p) { // ok
>obj.p : Promise<unknown>
>obj : { p: Promise<unknown>; }
>p : Promise<unknown>

await obj.p;
>await obj.p : unknown
>obj.p : Promise<unknown>
>obj : { p: Promise<unknown>; }
>p : Promise<unknown>
}
if (obj.p && await obj.p) {} // ok
>obj.p && await obj.p : unknown
>obj.p : Promise<unknown>
>obj : { p: Promise<unknown>; }
>p : Promise<unknown>
>await obj.p : unknown
>obj.p : Promise<unknown>
>obj : { p: Promise<unknown>; }
>p : Promise<unknown>
}

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