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Allow weak type detection for intersection sources (#26668)

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Previously, intersections were only allowed as targets, but this was
just an artifact of the original implementation, which operated inside
the structural part of isRelatedTo. Removing this restriction catches
subtle bugs in React user code, where a function named `create` returns
a mapped type whose types are all branded numbers. The display of these
properties, for some original type `T`, is not `number & { __ }` but
the much-less-obvious `RegisteredStyle<T>`.
This commit is contained in:
Nathan Shively-Sanders 2018-08-24 10:30:39 -07:00 committed by GitHub
parent bdb7c351a2
commit 0043ba16b1
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6 changed files with 207 additions and 1 deletions
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2
src/compiler/checker.ts
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@ -11178,7 +11178,7 @@ namespace ts {
}
if (relation !== comparableRelation &&
!(source.flags & TypeFlags.UnionOrIntersection) &&
!(source.flags & TypeFlags.Union) &&
!(target.flags & TypeFlags.Union) &&
!isIntersectionConstituent &&
source !== globalObjectType &&

30
tests/baselines/reference/intersectionAsWeakTypeSource.errors.txt Normal file
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@ -0,0 +1,30 @@
tests/cases/conformance/types/intersection/intersectionAsWeakTypeSource.ts(8,7): error TS2559: Type 'XY' has no properties in common with type 'Z'.
tests/cases/conformance/types/intersection/intersectionAsWeakTypeSource.ts(18,7): error TS2322: Type 'Brand<{ view: number; styleMedia: string; }>' is not assignable to type 'ViewStyle'.
Property 'view' is missing in type 'Number & { __brand: { view: number; styleMedia: string; }; }'.
==== tests/cases/conformance/types/intersection/intersectionAsWeakTypeSource.ts (2 errors) ====
interface X { x: string }
interface Y { y: number }
interface Z { z?: boolean }
type XY = X & Y;
const xy: XY = {x: 'x', y: 10};
const z1: Z = xy; // error, {xy} doesn't overlap with {z}
~~
!!! error TS2559: Type 'XY' has no properties in common with type 'Z'.
interface ViewStyle {
view: number
styleMedia: string
}
type Brand<T> = number & { __brand: T }
declare function create<T extends { [s: string]: ViewStyle }>(styles: T): { [P in keyof T]: Brand<T[P]> };
const wrapped = create({ first: { view: 0, styleMedia: "???" } });
const vs: ViewStyle = wrapped.first // error, first is a branded number
~~
!!! error TS2322: Type 'Brand<{ view: number; styleMedia: string; }>' is not assignable to type 'ViewStyle'.
!!! error TS2322: Property 'view' is missing in type 'Number & { __brand: { view: number; styleMedia: string; }; }'.

26
tests/baselines/reference/intersectionAsWeakTypeSource.js Normal file
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@ -0,0 +1,26 @@
//// [intersectionAsWeakTypeSource.ts]
interface X { x: string }
interface Y { y: number }
interface Z { z?: boolean }
type XY = X & Y;
const xy: XY = {x: 'x', y: 10};
const z1: Z = xy; // error, {xy} doesn't overlap with {z}
interface ViewStyle {
view: number
styleMedia: string
}
type Brand<T> = number & { __brand: T }
declare function create<T extends { [s: string]: ViewStyle }>(styles: T): { [P in keyof T]: Brand<T[P]> };
const wrapped = create({ first: { view: 0, styleMedia: "???" } });
const vs: ViewStyle = wrapped.first // error, first is a branded number
//// [intersectionAsWeakTypeSource.js]
var xy = { x: 'x', y: 10 };
var z1 = xy; // error, {xy} doesn't overlap with {z}
var wrapped = create({ first: { view: 0, styleMedia: "???" } });
var vs = wrapped.first; // error, first is a branded number

72
tests/baselines/reference/intersectionAsWeakTypeSource.symbols Normal file
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@ -0,0 +1,72 @@
=== tests/cases/conformance/types/intersection/intersectionAsWeakTypeSource.ts ===
interface X { x: string }
>X : Symbol(X, Decl(intersectionAsWeakTypeSource.ts, 0, 0))
>x : Symbol(X.x, Decl(intersectionAsWeakTypeSource.ts, 0, 13))
interface Y { y: number }
>Y : Symbol(Y, Decl(intersectionAsWeakTypeSource.ts, 0, 25))
>y : Symbol(Y.y, Decl(intersectionAsWeakTypeSource.ts, 1, 13))
interface Z { z?: boolean }
>Z : Symbol(Z, Decl(intersectionAsWeakTypeSource.ts, 1, 25))
>z : Symbol(Z.z, Decl(intersectionAsWeakTypeSource.ts, 2, 13))
type XY = X & Y;
>XY : Symbol(XY, Decl(intersectionAsWeakTypeSource.ts, 2, 27))
>X : Symbol(X, Decl(intersectionAsWeakTypeSource.ts, 0, 0))
>Y : Symbol(Y, Decl(intersectionAsWeakTypeSource.ts, 0, 25))
const xy: XY = {x: 'x', y: 10};
>xy : Symbol(xy, Decl(intersectionAsWeakTypeSource.ts, 5, 5))
>XY : Symbol(XY, Decl(intersectionAsWeakTypeSource.ts, 2, 27))
>x : Symbol(x, Decl(intersectionAsWeakTypeSource.ts, 5, 16))
>y : Symbol(y, Decl(intersectionAsWeakTypeSource.ts, 5, 23))
const z1: Z = xy; // error, {xy} doesn't overlap with {z}
>z1 : Symbol(z1, Decl(intersectionAsWeakTypeSource.ts, 7, 5))
>Z : Symbol(Z, Decl(intersectionAsWeakTypeSource.ts, 1, 25))
>xy : Symbol(xy, Decl(intersectionAsWeakTypeSource.ts, 5, 5))
interface ViewStyle {
>ViewStyle : Symbol(ViewStyle, Decl(intersectionAsWeakTypeSource.ts, 7, 17))
view: number
>view : Symbol(ViewStyle.view, Decl(intersectionAsWeakTypeSource.ts, 10, 21))
styleMedia: string
>styleMedia : Symbol(ViewStyle.styleMedia, Decl(intersectionAsWeakTypeSource.ts, 11, 16))
}
type Brand<T> = number & { __brand: T }
>Brand : Symbol(Brand, Decl(intersectionAsWeakTypeSource.ts, 13, 1))
>T : Symbol(T, Decl(intersectionAsWeakTypeSource.ts, 14, 11))
>__brand : Symbol(__brand, Decl(intersectionAsWeakTypeSource.ts, 14, 26))
>T : Symbol(T, Decl(intersectionAsWeakTypeSource.ts, 14, 11))
declare function create<T extends { [s: string]: ViewStyle }>(styles: T): { [P in keyof T]: Brand<T[P]> };
>create : Symbol(create, Decl(intersectionAsWeakTypeSource.ts, 14, 39))
>T : Symbol(T, Decl(intersectionAsWeakTypeSource.ts, 15, 24))
>s : Symbol(s, Decl(intersectionAsWeakTypeSource.ts, 15, 37))
>ViewStyle : Symbol(ViewStyle, Decl(intersectionAsWeakTypeSource.ts, 7, 17))
>styles : Symbol(styles, Decl(intersectionAsWeakTypeSource.ts, 15, 62))
>T : Symbol(T, Decl(intersectionAsWeakTypeSource.ts, 15, 24))
>P : Symbol(P, Decl(intersectionAsWeakTypeSource.ts, 15, 77))
>T : Symbol(T, Decl(intersectionAsWeakTypeSource.ts, 15, 24))
>Brand : Symbol(Brand, Decl(intersectionAsWeakTypeSource.ts, 13, 1))
>T : Symbol(T, Decl(intersectionAsWeakTypeSource.ts, 15, 24))
>P : Symbol(P, Decl(intersectionAsWeakTypeSource.ts, 15, 77))
const wrapped = create({ first: { view: 0, styleMedia: "???" } });
>wrapped : Symbol(wrapped, Decl(intersectionAsWeakTypeSource.ts, 16, 5))
>create : Symbol(create, Decl(intersectionAsWeakTypeSource.ts, 14, 39))
>first : Symbol(first, Decl(intersectionAsWeakTypeSource.ts, 16, 24))
>view : Symbol(view, Decl(intersectionAsWeakTypeSource.ts, 16, 33))
>styleMedia : Symbol(styleMedia, Decl(intersectionAsWeakTypeSource.ts, 16, 42))
const vs: ViewStyle = wrapped.first // error, first is a branded number
>vs : Symbol(vs, Decl(intersectionAsWeakTypeSource.ts, 17, 5))
>ViewStyle : Symbol(ViewStyle, Decl(intersectionAsWeakTypeSource.ts, 7, 17))
>wrapped.first : Symbol(first, Decl(intersectionAsWeakTypeSource.ts, 16, 24))
>wrapped : Symbol(wrapped, Decl(intersectionAsWeakTypeSource.ts, 16, 5))
>first : Symbol(first, Decl(intersectionAsWeakTypeSource.ts, 16, 24))

60
tests/baselines/reference/intersectionAsWeakTypeSource.types Normal file
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@ -0,0 +1,60 @@
=== tests/cases/conformance/types/intersection/intersectionAsWeakTypeSource.ts ===
interface X { x: string }
>x : string
interface Y { y: number }
>y : number
interface Z { z?: boolean }
>z : boolean
type XY = X & Y;
>XY : XY
const xy: XY = {x: 'x', y: 10};
>xy : XY
>{x: 'x', y: 10} : { x: string; y: number; }
>x : string
>'x' : "x"
>y : number
>10 : 10
const z1: Z = xy; // error, {xy} doesn't overlap with {z}
>z1 : Z
>xy : XY
interface ViewStyle {
view: number
>view : number
styleMedia: string
>styleMedia : string
}
type Brand<T> = number & { __brand: T }
>Brand : Brand<T>
>__brand : T
declare function create<T extends { [s: string]: ViewStyle }>(styles: T): { [P in keyof T]: Brand<T[P]> };
>create : <T extends { [s: string]: ViewStyle; }>(styles: T) => { [P in keyof T]: Brand<T[P]>; }
>s : string
>styles : T
const wrapped = create({ first: { view: 0, styleMedia: "???" } });
>wrapped : { first: Brand<{ view: number; styleMedia: string; }>; }
>create({ first: { view: 0, styleMedia: "???" } }) : { first: Brand<{ view: number; styleMedia: string; }>; }
>create : <T extends { [s: string]: ViewStyle; }>(styles: T) => { [P in keyof T]: Brand<T[P]>; }
>{ first: { view: 0, styleMedia: "???" } } : { first: { view: number; styleMedia: string; }; }
>first : { view: number; styleMedia: string; }
>{ view: 0, styleMedia: "???" } : { view: number; styleMedia: string; }
>view : number
>0 : 0
>styleMedia : string
>"???" : "???"
const vs: ViewStyle = wrapped.first // error, first is a branded number
>vs : ViewStyle
>wrapped.first : Brand<{ view: number; styleMedia: string; }>
>wrapped : { first: Brand<{ view: number; styleMedia: string; }>; }
>first : Brand<{ view: number; styleMedia: string; }>

18
tests/cases/conformance/types/intersection/intersectionAsWeakTypeSource.ts Normal file
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@ -0,0 +1,18 @@
interface X { x: string }
interface Y { y: number }
interface Z { z?: boolean }
type XY = X & Y;
const xy: XY = {x: 'x', y: 10};
const z1: Z = xy; // error, {xy} doesn't overlap with {z}
interface ViewStyle {
view: number
styleMedia: string
}
type Brand<T> = number & { __brand: T }
declare function create<T extends { [s: string]: ViewStyle }>(styles: T): { [P in keyof T]: Brand<T[P]> };
const wrapped = create({ first: { view: 0, styleMedia: "???" } });
const vs: ViewStyle = wrapped.first // error, first is a branded number