Optimize checking involving large discriminated union types

src/compiler/types.ts

@@ -5303,6 +5303,10 @@ namespace ts {
  regularType?: UnionType;
  /* @internal */
  origin?: Type; // Denormalized union, intersection, or index type in which union originates
+ /* @internal */
+ keyPropertyName?: __String; // Property with unique unit type that exists in every object/intersection in union type
+ /* @internal */
+ constituentMap?: ESMap<TypeId, Type>; // Constituents keyed by unit type discriminants
  }
 
  export interface IntersectionType extends UnionOrIntersectionType {

tests/baselines/reference/arrayBestCommonTypes.types

@@ -231,7 +231,7 @@ module EmptyTypes {
 >t1 : { x: number; y: base; }[]
 >x : number
 >y : base
->[{ x: 7, y: new derived() }, { x: 5, y: new base() }] : { x: number; y: derived; }[]
+>[{ x: 7, y: new derived() }, { x: 5, y: new base() }] : ({ x: number; y: derived; } | { x: number; y: base; })[]
 >{ x: 7, y: new derived() } : { x: number; y: derived; }
 >x : number
 >7 : 7
@@ -267,7 +267,7 @@ module EmptyTypes {
 >t3 : { x: string; y: base; }[]
 >x : string
 >y : base
->[{ x: undefined, y: new base() }, { x: '', y: new derived() }] : { x: string; y: derived; }[]
+>[{ x: undefined, y: new base() }, { x: '', y: new derived() }] : ({ x: undefined; y: base; } | { x: string; y: derived; })[]
 >{ x: undefined, y: new base() } : { x: undefined; y: base; }
 >x : undefined
 >undefined : undefined
@@ -627,7 +627,7 @@ module NonEmptyTypes {
 >t1 : { x: number; y: base; }[]
 >x : number
 >y : base
->[{ x: 7, y: new derived() }, { x: 5, y: new base() }] : { x: number; y: base; }[]
+>[{ x: 7, y: new derived() }, { x: 5, y: new base() }] : ({ x: number; y: derived; } | { x: number; y: base; })[]
 >{ x: 7, y: new derived() } : { x: number; y: derived; }
 >x : number
 >7 : 7

tests/baselines/reference/arrayLiteralTypeInference.types

@@ -58,7 +58,7 @@ var x2: Action[] = [
 
 var x3: Action[] = [
 >x3 : Action[]
->[ new Action(), new ActionA(), new ActionB()] : Action[]
+>[ new Action(), new ActionA(), new ActionB()] : (Action | ActionA | ActionB)[]
 
  new Action(),
 >new Action() : Action
@@ -119,7 +119,7 @@ var z3: { id: number }[] =
 >id : number
 
  [
->[ new Action(), new ActionA(), new ActionB() ] : Action[]
+>[ new Action(), new ActionA(), new ActionB() ] : (Action | ActionA | ActionB)[]
 
  new Action(),
 >new Action() : Action

tests/baselines/reference/contextualTypeWithUnionTypeMembers.types

@@ -162,7 +162,7 @@ var i1Ori2: I1<number> | I2<number> = { // Like i1 and i2 both
 
 var arrayI1OrI2: Array<I1<number> | I2<number>> = [i1, i2, { // Like i1
 >arrayI1OrI2 : (I1<number> | I2<number>)[]
->[i1, i2, { // Like i1 commonPropertyType: "hello", commonMethodType: a=> a, commonMethodWithTypeParameter: a => a, methodOnlyInI1: a => a, propertyOnlyInI1: "Hello", }, { // Like i2 commonPropertyType: "hello", commonMethodType: a=> a, commonMethodWithTypeParameter: a => a, methodOnlyInI2: a => a, propertyOnlyInI2: "Hello", }, { // Like i1 and i2 both commonPropertyType: "hello", commonMethodType: a=> a, commonMethodWithTypeParameter: a => a, methodOnlyInI1: a => a, propertyOnlyInI1: "Hello", methodOnlyInI2: a => a, propertyOnlyInI2: "Hello", }] : (I1<number> | I2<number> | { commonPropertyType: string; commonMethodType: (a: string) => string; commonMethodWithTypeParameter: (a: number) => number; methodOnlyInI1: (a: string) => string; propertyOnlyInI1: string; methodOnlyInI2: (a: string) => string; propertyOnlyInI2: string; })[]
+>[i1, i2, { // Like i1 commonPropertyType: "hello", commonMethodType: a=> a, commonMethodWithTypeParameter: a => a, methodOnlyInI1: a => a, propertyOnlyInI1: "Hello", }, { // Like i2 commonPropertyType: "hello", commonMethodType: a=> a, commonMethodWithTypeParameter: a => a, methodOnlyInI2: a => a, propertyOnlyInI2: "Hello", }, { // Like i1 and i2 both commonPropertyType: "hello", commonMethodType: a=> a, commonMethodWithTypeParameter: a => a, methodOnlyInI1: a => a, propertyOnlyInI1: "Hello", methodOnlyInI2: a => a, propertyOnlyInI2: "Hello", }] : (I1<number> | I2<number> | { commonPropertyType: string; commonMethodType: (a: string) => string; commonMethodWithTypeParameter: (a: number) => number; methodOnlyInI1: (a: string) => string; propertyOnlyInI1: string; } | { commonPropertyType: string; commonMethodType: (a: string) => string; commonMethodWithTypeParameter: (a: number) => number; methodOnlyInI2: (a: string) => string; propertyOnlyInI2: string; } | { commonPropertyType: string; commonMethodType: (a: string) => string; commonMethodWithTypeParameter: (a: number) => number; methodOnlyInI1: (a: string) => string; propertyOnlyInI1: string; methodOnlyInI2: (a: string) => string; propertyOnlyInI2: string; })[]
 >i1 : I1<number>
 >i2 : I2<number>
 >{ // Like i1 commonPropertyType: "hello", commonMethodType: a=> a, commonMethodWithTypeParameter: a => a, methodOnlyInI1: a => a, propertyOnlyInI1: "Hello", } : { commonPropertyType: string; commonMethodType: (a: string) => string; commonMethodWithTypeParameter: (a: number) => number; methodOnlyInI1: (a: string) => string; propertyOnlyInI1: string; }
@@ -354,7 +354,7 @@ var i11Ori21: I11 | I21 = {
 };
 var arrayOrI11OrI21: Array<I11 | I21> = [i11, i21, i11 || i21, { 
 >arrayOrI11OrI21 : (I11 | I21)[]
->[i11, i21, i11 || i21, { // Like i1 commonMethodDifferentReturnType: (a, b) => { var z = a.charAt(b); return z; }, commonPropertyDifferentType: "hello", }, { // Like i2 commonMethodDifferentReturnType: (a, b) => { var z = a.charCodeAt(b); return z; }, commonPropertyDifferentType: 10, }] : (I11 | I21)[]
+>[i11, i21, i11 || i21, { // Like i1 commonMethodDifferentReturnType: (a, b) => { var z = a.charAt(b); return z; }, commonPropertyDifferentType: "hello", }, { // Like i2 commonMethodDifferentReturnType: (a, b) => { var z = a.charCodeAt(b); return z; }, commonPropertyDifferentType: 10, }] : (I11 | I21 | { commonMethodDifferentReturnType: (a: string, b: number) => string; commonPropertyDifferentType: string; } | { commonMethodDifferentReturnType: (a: string, b: number) => number; commonPropertyDifferentType: number; })[]
 >i11 : I11
 >i21 : I21
 >i11 || i21 : I11 | I21

tests/baselines/reference/contextualTyping10.types

@@ -3,7 +3,7 @@ class foo { public bar:{id:number;}[] = [{id:1}, {id:2}]; }
 >foo : foo
 >bar : { id: number; }[]
 >id : number
->[{id:1}, {id:2}] : { id: number; }[]
+>[{id:1}, {id:2}] : ({ id: number; } | { id: number; })[]
 >{id:1} : { id: number; }
 >id : number
 >1 : 1

tests/baselines/reference/contextualTyping19.types

@@ -6,9 +6,9 @@ var foo:{id:number;}[] = [{id:1}]; foo = [{id:1}, {id:2}];
 >{id:1} : { id: number; }
 >id : number
 >1 : 1
->foo = [{id:1}, {id:2}] : { id: number; }[]
+>foo = [{id:1}, {id:2}] : ({ id: number; } | { id: number; })[]
 >foo : { id: number; }[]
->[{id:1}, {id:2}] : { id: number; }[]
+>[{id:1}, {id:2}] : ({ id: number; } | { id: number; })[]
 >{id:1} : { id: number; }
 >id : number
 >1 : 1

tests/baselines/reference/contextualTyping32.types

@@ -5,7 +5,7 @@ function foo(param: {():number; (i:number):number; }[]) { }; foo([function(){ret
 >i : number
 >foo([function(){return 1;}, function(){return 4}]) : void
 >foo : (param: { (): number; (i: number): number; }[]) => void
->[function(){return 1;}, function(){return 4}] : (() => number)[]
+>[function(){return 1;}, function(){return 4}] : ((() => number) | (() => number))[]
 >function(){return 1;} : () => number
 >1 : 1
 >function(){return 4} : () => number

tests/baselines/reference/contextualTyping36.types

@@ -3,7 +3,7 @@ var foo = <{ id: number; }[]>[{ id: 4 }, <{ id: number; }>({ })];
 >foo : { id: number; }[]
 ><{ id: number; }[]>[{ id: 4 }, <{ id: number; }>({ })] : { id: number; }[]
 >id : number
->[{ id: 4 }, <{ id: number; }>({ })] : { id: number; }[]
+>[{ id: 4 }, <{ id: number; }>({ })] : ({ id: number; } | { id: number; })[]
 >{ id: 4 } : { id: number; }
 >id : number
 >4 : 4

tests/baselines/reference/contextualTyping6.types

@@ -2,7 +2,7 @@
 var foo:{id:number;}[] = [{id:1}, {id:2}];
 >foo : { id: number; }[]
 >id : number
->[{id:1}, {id:2}] : { id: number; }[]
+>[{id:1}, {id:2}] : ({ id: number; } | { id: number; })[]
 >{id:1} : { id: number; }
 >id : number
 >1 : 1

tests/baselines/reference/lambdaParamTypes.types

@@ -19,7 +19,7 @@ var thing = create([{ name: "bob", id: 24 }, { name: "doug", id: 32 }]);
 >thing : MyArrayWrapper<{ name: string; id: number; }>
 >create([{ name: "bob", id: 24 }, { name: "doug", id: 32 }]) : MyArrayWrapper<{ name: string; id: number; }>
 >create : <T>(initialValues?: T[]) => MyArrayWrapper<T>
->[{ name: "bob", id: 24 }, { name: "doug", id: 32 }] : { name: string; id: number; }[]
+>[{ name: "bob", id: 24 }, { name: "doug", id: 32 }] : ({ name: string; id: number; } | { name: string; id: number; })[]
 >{ name: "bob", id: 24 } : { name: string; id: number; }
 >name : string
 >"bob" : "bob"

tests/baselines/reference/objectLiteralArraySpecialization.types

@@ -18,7 +18,7 @@ var thing = create([ { name: "bob", id: 24 }, { name: "doug", id: 32 } ]); // sh
 >thing : MyArrayWrapper<{ name: string; id: number; }>
 >create([ { name: "bob", id: 24 }, { name: "doug", id: 32 } ]) : MyArrayWrapper<{ name: string; id: number; }>
 >create : <T>(initialValues?: T[]) => MyArrayWrapper<T>
->[ { name: "bob", id: 24 }, { name: "doug", id: 32 } ] : { name: string; id: number; }[]
+>[ { name: "bob", id: 24 }, { name: "doug", id: 32 } ] : ({ name: string; id: number; } | { name: string; id: number; })[]
 >{ name: "bob", id: 24 } : { name: string; id: number; }
 >name : string
 >"bob" : "bob"

tests/baselines/reference/recursiveTypeReferences1.types

@@ -8,7 +8,7 @@ const a0: ValueOrArray<number> = 1;
 
 const a1: ValueOrArray<number> = [1, [2, 3], [4, [5, [6, 7]]]];
 >a1 : ValueOrArray<number>
->[1, [2, 3], [4, [5, [6, 7]]]] : (number | (number | (number | number[])[])[])[]
+>[1, [2, 3], [4, [5, [6, 7]]]] : (number | number[] | (number | (number | number[])[])[])[]
 >1 : 1
 >[2, 3] : number[]
 >2 : 2
@@ -538,7 +538,7 @@ function cons(hs: HTMLHeadingElement[]): Tree {
 >concat(hss, [hs, [h]]) : any
 >concat : any
 >hss : HTMLHeadingElement[][]
->[hs, [h]] : HTMLHeadingElement[][]
+>[hs, [h]] : (HTMLHeadingElement[] | HTMLHeadingElement[])[]
 >hs : HTMLHeadingElement[]
 >[h] : HTMLHeadingElement[]
 >h : HTMLHeadingElement

tests/baselines/reference/sourceMapValidationDestructuringForOfObjectBindingPattern.types

@@ -32,7 +32,7 @@ interface MultiRobot {
 
 let robots: Robot[] = [{ name: "mower", skill: "mowing" }, { name: "trimmer", skill: "trimming" }];
 >robots : Robot[]
->[{ name: "mower", skill: "mowing" }, { name: "trimmer", skill: "trimming" }] : { name: string; skill: string; }[]
+>[{ name: "mower", skill: "mowing" }, { name: "trimmer", skill: "trimming" }] : ({ name: string; skill: string; } | { name: string; skill: string; })[]
 >{ name: "mower", skill: "mowing" } : { name: string; skill: string; }
 >name : string
 >"mower" : "mower"
@@ -46,7 +46,7 @@ let robots: Robot[] = [{ name: "mower", skill: "mowing" }, { name: "trimmer", sk
 
 let multiRobots: MultiRobot[] = [{ name: "mower", skills: { primary: "mowing", secondary: "none" } },
 >multiRobots : MultiRobot[]
->[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : { name: string; skills: { primary: string; secondary: string; }; }[]
+>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : ({ name: string; skills: { primary: string; secondary: string; }; } | { name: string; skills: { primary: string; secondary: string; }; })[]
 >{ name: "mower", skills: { primary: "mowing", secondary: "none" } } : { name: string; skills: { primary: string; secondary: string; }; }
 >name : string
 >"mower" : "mower"

tests/baselines/reference/sourceMapValidationDestructuringForOfObjectBindingPattern2.types

@@ -32,7 +32,7 @@ interface MultiRobot {
 
 let robots: Robot[] = [{ name: "mower", skill: "mowing" }, { name: "trimmer", skill: "trimming" }];
 >robots : Robot[]
->[{ name: "mower", skill: "mowing" }, { name: "trimmer", skill: "trimming" }] : { name: string; skill: string; }[]
+>[{ name: "mower", skill: "mowing" }, { name: "trimmer", skill: "trimming" }] : ({ name: string; skill: string; } | { name: string; skill: string; })[]
 >{ name: "mower", skill: "mowing" } : { name: string; skill: string; }
 >name : string
 >"mower" : "mower"
@@ -46,7 +46,7 @@ let robots: Robot[] = [{ name: "mower", skill: "mowing" }, { name: "trimmer", sk
 
 let multiRobots: MultiRobot[] = [{ name: "mower", skills: { primary: "mowing", secondary: "none" } },
 >multiRobots : MultiRobot[]
->[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : { name: string; skills: { primary: string; secondary: string; }; }[]
+>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : ({ name: string; skills: { primary: string; secondary: string; }; } | { name: string; skills: { primary: string; secondary: string; }; })[]
 >{ name: "mower", skills: { primary: "mowing", secondary: "none" } } : { name: string; skills: { primary: string; secondary: string; }; }
 >name : string
 >"mower" : "mower"

tests/baselines/reference/sourceMapValidationDestructuringForOfObjectBindingPatternDefaultValues.types

@@ -32,7 +32,7 @@ interface MultiRobot {
 
 let robots: Robot[] = [{ name: "mower", skill: "mowing" }, { name: "trimmer", skill: "trimming" }];
 >robots : Robot[]
->[{ name: "mower", skill: "mowing" }, { name: "trimmer", skill: "trimming" }] : { name: string; skill: string; }[]
+>[{ name: "mower", skill: "mowing" }, { name: "trimmer", skill: "trimming" }] : ({ name: string; skill: string; } | { name: string; skill: string; })[]
 >{ name: "mower", skill: "mowing" } : { name: string; skill: string; }
 >name : string
 >"mower" : "mower"
@@ -46,7 +46,7 @@ let robots: Robot[] = [{ name: "mower", skill: "mowing" }, { name: "trimmer", sk
 
 let multiRobots: MultiRobot[] = [{ name: "mower", skills: { primary: "mowing", secondary: "none" } },
 >multiRobots : MultiRobot[]
->[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : { name: string; skills: { primary: string; secondary: string; }; }[]
+>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : ({ name: string; skills: { primary: string; secondary: string; }; } | { name: string; skills: { primary: string; secondary: string; }; })[]
 >{ name: "mower", skills: { primary: "mowing", secondary: "none" } } : { name: string; skills: { primary: string; secondary: string; }; }
 >name : string
 >"mower" : "mower"
@@ -199,7 +199,7 @@ for (let { skills: { primary: primaryA = "primary", secondary: secondaryA = "sec
 
  <MultiRobot[]>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } },
 ><MultiRobot[]>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : MultiRobot[]
->[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : { name: string; skills: { primary: string; secondary: string; }; }[]
+>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : ({ name: string; skills: { primary: string; secondary: string; }; } | { name: string; skills: { primary: string; secondary: string; }; })[]
 >{ name: "mower", skills: { primary: "mowing", secondary: "none" } } : { name: string; skills: { primary: string; secondary: string; }; }
 >name : string
 >"mower" : "mower"
@@ -389,7 +389,7 @@ for (let {
 
 } of <MultiRobot[]>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } },
 ><MultiRobot[]>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : MultiRobot[]
->[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : { name: string; skills: { primary: string; secondary: string; }; }[]
+>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : ({ name: string; skills: { primary: string; secondary: string; }; } | { name: string; skills: { primary: string; secondary: string; }; })[]
 >{ name: "mower", skills: { primary: "mowing", secondary: "none" } } : { name: string; skills: { primary: string; secondary: string; }; }
 >name : string
 >"mower" : "mower"

tests/baselines/reference/sourceMapValidationDestructuringForOfObjectBindingPatternDefaultValues2.types

@@ -32,7 +32,7 @@ interface MultiRobot {
 
 let robots: Robot[] = [{ name: "mower", skill: "mowing" }, { name: "trimmer", skill: "trimming" }];
 >robots : Robot[]
->[{ name: "mower", skill: "mowing" }, { name: "trimmer", skill: "trimming" }] : { name: string; skill: string; }[]
+>[{ name: "mower", skill: "mowing" }, { name: "trimmer", skill: "trimming" }] : ({ name: string; skill: string; } | { name: string; skill: string; })[]
 >{ name: "mower", skill: "mowing" } : { name: string; skill: string; }
 >name : string
 >"mower" : "mower"
@@ -46,7 +46,7 @@ let robots: Robot[] = [{ name: "mower", skill: "mowing" }, { name: "trimmer", sk
 
 let multiRobots: MultiRobot[] = [{ name: "mower", skills: { primary: "mowing", secondary: "none" } },
 >multiRobots : MultiRobot[]
->[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : { name: string; skills: { primary: string; secondary: string; }; }[]
+>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : ({ name: string; skills: { primary: string; secondary: string; }; } | { name: string; skills: { primary: string; secondary: string; }; })[]
 >{ name: "mower", skills: { primary: "mowing", secondary: "none" } } : { name: string; skills: { primary: string; secondary: string; }; }
 >name : string
 >"mower" : "mower"
@@ -233,7 +233,7 @@ for ({ skills: { primary: primaryA = "primary", secondary: secondaryA = "seconda
 
  <MultiRobot[]>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } },
 ><MultiRobot[]>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : MultiRobot[]
->[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : { name: string; skills: { primary: string; secondary: string; }; }[]
+>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : ({ name: string; skills: { primary: string; secondary: string; }; } | { name: string; skills: { primary: string; secondary: string; }; })[]
 >{ name: "mower", skills: { primary: "mowing", secondary: "none" } } : { name: string; skills: { primary: string; secondary: string; }; }
 >name : string
 >"mower" : "mower"
@@ -625,7 +625,7 @@ for ({
 
 } of <MultiRobot[]>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } },
 ><MultiRobot[]>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : MultiRobot[]
->[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : { name: string; skills: { primary: string; secondary: string; }; }[]
+>[{ name: "mower", skills: { primary: "mowing", secondary: "none" } }, { name: "trimmer", skills: { primary: "trimming", secondary: "edging" } }] : ({ name: string; skills: { primary: string; secondary: string; }; } | { name: string; skills: { primary: string; secondary: string; }; })[]
 >{ name: "mower", skills: { primary: "mowing", secondary: "none" } } : { name: string; skills: { primary: string; secondary: string; }; }
 >name : string
 >"mower" : "mower"