Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Remove assignability cases in getNarrowedType + an isArray improvement for readonly arrays #39258

Merged
merged 4 commits into from Sep 8, 2020
Merged

Remove assignability cases in getNarrowedType + an isArray improvement for readonly arrays #39258

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
636bc9d
Explore using a different isArray declaration
orta Jun 24, 2020
e81d845
Add tests and the new isArray definition
orta Jun 25, 2020
ed01085
Baseline updates
orta Jun 25, 2020
c69b255
Upda the isArray type
orta Jul 8, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
14 changes: 5 additions & 9 deletions src/compiler/checker.ts
View file
Open in desktop
Expand Up @@ -21761,15 +21761,11 @@ namespace ts {
return assignableType;
}
}
// If the candidate type is a subtype of the target type, narrow to the candidate type.
// Otherwise, if the target type is assignable to the candidate type, keep the target type.
// Otherwise, if the candidate type is assignable to the target type, narrow to the candidate
// type. Otherwise, the types are completely unrelated, so narrow to an intersection of the
// two types.
return isTypeSubtypeOf(candidate, type) ? candidate :
isTypeAssignableTo(type, candidate) ? type :
isTypeAssignableTo(candidate, type) ? candidate :
getIntersectionType([type, candidate]);

// If the candidate type is a subtype of the target type, narrow to the candidate type,
// if the target type is a subtype of the candidate type, narrow to the target type,
// otherwise, narrow to an intersection of the two types.
return isTypeSubtypeOf(candidate, type) ? candidate : isTypeSubtypeOf(type, candidate) ? type : getIntersectionType([type, candidate]);
}

function narrowTypeByCallExpression(type: Type, callExpression: CallExpression, assumeTrue: boolean): Type {
Expand Down
2 changes: 1 addition & 1 deletion src/lib/es5.d.ts
View file
Open in desktop
Expand Up @@ -1376,7 +1376,7 @@ interface ArrayConstructor {
(arrayLength?: number): any[];
<T>(arrayLength: number): T[];
<T>(...items: T[]): T[];
isArray(arg: any): arg is any[];
isArray<T>(arg: T | {}): arg is T extends readonly any[] ? (unknown extends T ? never : readonly any[]) : any[];
readonly prototype: any[];
}

Expand Down
100 changes: 100 additions & 0 deletions tests/baselines/reference/consistentUnionSubtypeReduction.js
View file
Open in desktop
@@ -0,0 +1,100 @@
//// [consistentUnionSubtypeReduction.ts]
// https://github.com/microsoft/TypeScript/issues/31155

declare const MyArray: {
isArray<T>(arg: T | {}): arg is T extends readonly any[] ? (unknown extends T ? never : readonly any[]) : any[];
};

declare const a: readonly string[] | string;
declare const b: string[] | string;
declare const c: unknown;

if (MyArray.isArray(a)) {
a; // readonly string[]
}
else {
a; // string
}
a; // readonly string[] | string;

if (MyArray.isArray(b)) {
b; // string[] | string;
}
else {
b; // string
}
b; // string[] | string;

if (MyArray.isArray(c)) {
c; // any[]
}


function f<T>(x: T) {
const a: readonly T[] | string = null!;
const b: T[] | string = null!;
const c: T = null!;

if (MyArray.isArray(a)) {
a; // readonly T[]
}
else {
a; // string
}
a; // readonly T[] | string;

if (MyArray.isArray(b)) {
b; // T[]
}
else {
b; // string
}
b;

if (MyArray.isArray(c)) {
c; // T & (T extends readonly any[] ? readonly any[] : any[])
}
}


//// [consistentUnionSubtypeReduction.js]
// https://github.com/microsoft/TypeScript/issues/31155
if (MyArray.isArray(a)) {
a; // readonly string[]
}
else {
a; // string
}
a; // readonly string[] | string;
if (MyArray.isArray(b)) {
b; // string[] | string;
}
else {
b; // string
}
b; // string[] | string;
if (MyArray.isArray(c)) {
c; // any[]
}
function f(x) {
var a = null;
var b = null;
var c = null;
if (MyArray.isArray(a)) {
a; // readonly T[]
}
else {
a; // string
}
a; // readonly T[] | string;
if (MyArray.isArray(b)) {
b; // T[]
}
else {
b; // string
}
b;
if (MyArray.isArray(c)) {
c; // T & (T extends readonly any[] ? readonly any[] : any[])
}
}
130 changes: 130 additions & 0 deletions tests/baselines/reference/consistentUnionSubtypeReduction.symbols
View file
Open in desktop
@@ -0,0 +1,130 @@
=== tests/cases/compiler/consistentUnionSubtypeReduction.ts ===
// https://github.com/microsoft/TypeScript/issues/31155

declare const MyArray: {
>MyArray : Symbol(MyArray, Decl(consistentUnionSubtypeReduction.ts, 2, 13))

isArray<T>(arg: T | {}): arg is T extends readonly any[] ? (unknown extends T ? never : readonly any[]) : any[];
>isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>T : Symbol(T, Decl(consistentUnionSubtypeReduction.ts, 3, 12))
>arg : Symbol(arg, Decl(consistentUnionSubtypeReduction.ts, 3, 15))
>T : Symbol(T, Decl(consistentUnionSubtypeReduction.ts, 3, 12))
>arg : Symbol(arg, Decl(consistentUnionSubtypeReduction.ts, 3, 15))
>T : Symbol(T, Decl(consistentUnionSubtypeReduction.ts, 3, 12))
>T : Symbol(T, Decl(consistentUnionSubtypeReduction.ts, 3, 12))

};

declare const a: readonly string[] | string;
>a : Symbol(a, Decl(consistentUnionSubtypeReduction.ts, 6, 13))

declare const b: string[] | string;
>b : Symbol(b, Decl(consistentUnionSubtypeReduction.ts, 7, 13))

declare const c: unknown;
>c : Symbol(c, Decl(consistentUnionSubtypeReduction.ts, 8, 13))

if (MyArray.isArray(a)) {
>MyArray.isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>MyArray : Symbol(MyArray, Decl(consistentUnionSubtypeReduction.ts, 2, 13))
>isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>a : Symbol(a, Decl(consistentUnionSubtypeReduction.ts, 6, 13))

a; // readonly string[]
>a : Symbol(a, Decl(consistentUnionSubtypeReduction.ts, 6, 13))
}
else {
a; // string
>a : Symbol(a, Decl(consistentUnionSubtypeReduction.ts, 6, 13))
}
a; // readonly string[] | string;
>a : Symbol(a, Decl(consistentUnionSubtypeReduction.ts, 6, 13))

if (MyArray.isArray(b)) {
>MyArray.isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>MyArray : Symbol(MyArray, Decl(consistentUnionSubtypeReduction.ts, 2, 13))
>isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>b : Symbol(b, Decl(consistentUnionSubtypeReduction.ts, 7, 13))

b; // string[] | string;
>b : Symbol(b, Decl(consistentUnionSubtypeReduction.ts, 7, 13))
}
else {
b; // string
>b : Symbol(b, Decl(consistentUnionSubtypeReduction.ts, 7, 13))
}
b; // string[] | string;
>b : Symbol(b, Decl(consistentUnionSubtypeReduction.ts, 7, 13))

if (MyArray.isArray(c)) {
>MyArray.isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>MyArray : Symbol(MyArray, Decl(consistentUnionSubtypeReduction.ts, 2, 13))
>isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>c : Symbol(c, Decl(consistentUnionSubtypeReduction.ts, 8, 13))

c; // any[]
>c : Symbol(c, Decl(consistentUnionSubtypeReduction.ts, 8, 13))
}


function f<T>(x: T) {
>f : Symbol(f, Decl(consistentUnionSubtypeReduction.ts, 28, 1))
>T : Symbol(T, Decl(consistentUnionSubtypeReduction.ts, 31, 11))
>x : Symbol(x, Decl(consistentUnionSubtypeReduction.ts, 31, 14))
>T : Symbol(T, Decl(consistentUnionSubtypeReduction.ts, 31, 11))

const a: readonly T[] | string = null!;
>a : Symbol(a, Decl(consistentUnionSubtypeReduction.ts, 32, 9))
>T : Symbol(T, Decl(consistentUnionSubtypeReduction.ts, 31, 11))

const b: T[] | string = null!;
>b : Symbol(b, Decl(consistentUnionSubtypeReduction.ts, 33, 9))
>T : Symbol(T, Decl(consistentUnionSubtypeReduction.ts, 31, 11))

const c: T = null!;
>c : Symbol(c, Decl(consistentUnionSubtypeReduction.ts, 34, 9))
>T : Symbol(T, Decl(consistentUnionSubtypeReduction.ts, 31, 11))

if (MyArray.isArray(a)) {
>MyArray.isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>MyArray : Symbol(MyArray, Decl(consistentUnionSubtypeReduction.ts, 2, 13))
>isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>a : Symbol(a, Decl(consistentUnionSubtypeReduction.ts, 32, 9))

a; // readonly T[]
>a : Symbol(a, Decl(consistentUnionSubtypeReduction.ts, 32, 9))
}
else {
a; // string
>a : Symbol(a, Decl(consistentUnionSubtypeReduction.ts, 32, 9))
}
a; // readonly T[] | string;
>a : Symbol(a, Decl(consistentUnionSubtypeReduction.ts, 32, 9))

if (MyArray.isArray(b)) {
>MyArray.isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>MyArray : Symbol(MyArray, Decl(consistentUnionSubtypeReduction.ts, 2, 13))
>isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>b : Symbol(b, Decl(consistentUnionSubtypeReduction.ts, 33, 9))

b; // T[]
>b : Symbol(b, Decl(consistentUnionSubtypeReduction.ts, 33, 9))
}
else {
b; // string
>b : Symbol(b, Decl(consistentUnionSubtypeReduction.ts, 33, 9))
}
b;
>b : Symbol(b, Decl(consistentUnionSubtypeReduction.ts, 33, 9))

if (MyArray.isArray(c)) {
>MyArray.isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>MyArray : Symbol(MyArray, Decl(consistentUnionSubtypeReduction.ts, 2, 13))
>isArray : Symbol(isArray, Decl(consistentUnionSubtypeReduction.ts, 2, 24))
>c : Symbol(c, Decl(consistentUnionSubtypeReduction.ts, 34, 9))

c; // T & (T extends readonly any[] ? readonly any[] : any[])
>c : Symbol(c, Decl(consistentUnionSubtypeReduction.ts, 34, 9))
}
}

132 changes: 132 additions & 0 deletions tests/baselines/reference/consistentUnionSubtypeReduction.types
View file
Open in desktop
@@ -0,0 +1,132 @@
=== tests/cases/compiler/consistentUnionSubtypeReduction.ts ===
// https://github.com/microsoft/TypeScript/issues/31155

declare const MyArray: {
>MyArray : { isArray<T>(arg: {} | T): arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]; }

isArray<T>(arg: T | {}): arg is T extends readonly any[] ? (unknown extends T ? never : readonly any[]) : any[];
>isArray : <T>(arg: T | {}) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>arg : {} | T

};

declare const a: readonly string[] | string;
>a : string | readonly string[]

declare const b: string[] | string;
>b : string | string[]

declare const c: unknown;
>c : unknown

if (MyArray.isArray(a)) {
>MyArray.isArray(a) : boolean
>MyArray.isArray : <T>(arg: {} | T) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>MyArray : { isArray<T>(arg: {} | T): arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]; }
>isArray : <T>(arg: {} | T) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>a : string | readonly string[]

a; // readonly string[]
>a : readonly string[]
}
else {
a; // string
>a : string
}
a; // readonly string[] | string;
>a : string | readonly string[]

if (MyArray.isArray(b)) {
>MyArray.isArray(b) : boolean
>MyArray.isArray : <T>(arg: {} | T) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>MyArray : { isArray<T>(arg: {} | T): arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]; }
>isArray : <T>(arg: {} | T) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>b : string | string[]

b; // string[] | string;
>b : string[]
}
else {
b; // string
>b : string
}
b; // string[] | string;
>b : string | string[]

if (MyArray.isArray(c)) {
>MyArray.isArray(c) : boolean
>MyArray.isArray : <T>(arg: {} | T) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>MyArray : { isArray<T>(arg: {} | T): arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]; }
>isArray : <T>(arg: {} | T) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>c : unknown

c; // any[]
>c : any[]
}


function f<T>(x: T) {
>f : <T>(x: T) => void
>x : T

const a: readonly T[] | string = null!;
>a : string | readonly T[]
>null! : null
>null : null

const b: T[] | string = null!;
>b : string | T[]
>null! : null
>null : null

const c: T = null!;
>c : T
>null! : null
>null : null

if (MyArray.isArray(a)) {
>MyArray.isArray(a) : boolean
>MyArray.isArray : <T>(arg: {} | T) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>MyArray : { isArray<T>(arg: {} | T): arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]; }
>isArray : <T>(arg: {} | T) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>a : string | readonly T[]

a; // readonly T[]
>a : readonly T[]
}
else {
a; // string
>a : string
}
a; // readonly T[] | string;
>a : string | readonly T[]

if (MyArray.isArray(b)) {
>MyArray.isArray(b) : boolean
>MyArray.isArray : <T>(arg: {} | T) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>MyArray : { isArray<T>(arg: {} | T): arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]; }
>isArray : <T>(arg: {} | T) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>b : string | T[]

b; // T[]
>b : T[]
}
else {
b; // string
>b : string
}
b;
>b : string | T[]

if (MyArray.isArray(c)) {
>MyArray.isArray(c) : boolean
>MyArray.isArray : <T>(arg: {} | T) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>MyArray : { isArray<T>(arg: {} | T): arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]; }
>isArray : <T>(arg: {} | T) => arg is T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[]
>c : T

c; // T & (T extends readonly any[] ? readonly any[] : any[])
>c : T & (T extends readonly any[] ? unknown extends T ? never : readonly any[] : any[])
}
}