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Smarter algorithm to distribute intersections of unions. #25728

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38 changes: 35 additions & 3 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8874,10 +8874,42 @@ namespace ts {
}
// We are attempting to construct a type of the form X & (A | B) & Y. Transform this into a type of
// the form X & A & Y | X & B & Y and recursively reduce until no union type constituents remain.
const unionIndex = findIndex(typeSet, t => (t.flags & TypeFlags.Union) !== 0);
const lastNonfinalUnionIndex = findLastIndex(typeSet, t => (t.flags & TypeFlags.Union) !== 0, typeSet.length - 2);
let partialIntersectionStartIndex: number, unionIndex: number;
if (lastNonfinalUnionIndex === -1) {
// typeSet[typeSet.length - 1] must be the only union. Distribute it and we're done.
partialIntersectionStartIndex = 0;
unionIndex = typeSet.length - 1;
}
else {
// `keyof` a large union of types results in an intersection of unions containing many unit types (GH#24223).
// To help avoid an exponential blowup, distribute the last union over the later constituents of the
// intersection and simplify the resulting union before distributing earlier unions. (Exception: don't
// distribute a union that is the last constituent of the intersection over the zero remaining constituents
// because that would have no effect.)
partialIntersectionStartIndex = lastNonfinalUnionIndex;
unionIndex = lastNonfinalUnionIndex;
}
const unionType = <UnionType>typeSet[unionIndex];
return getUnionType(map(unionType.types, t => getIntersectionType(replaceElement(typeSet, unionIndex, t))),
UnionReduction.Literal, aliasSymbol, aliasTypeArguments);
let relevantUnionMembers = unionType.types;
// As of 2018-07-19, discarding mismatching unit types here rather than letting it
// happen when we create the distributed union gives a 5x speedup on the test case
// for #23977.
if (includes & TypeFlags.Unit) {
const unitTypeInIntersection = find(typeSet, t => (t.flags & TypeFlags.Unit) !== 0)!;
relevantUnionMembers = filter(unionType.types, t => t === unitTypeInIntersection || (t.flags & TypeFlags.Unit) === 0);
}
const partialIntersectionMembers = typeSet.slice(partialIntersectionStartIndex);
const distributedMembers = map(relevantUnionMembers, t => getIntersectionType(replaceElement(partialIntersectionMembers, unionIndex - partialIntersectionStartIndex, t)));
if (partialIntersectionStartIndex === 0) {
return getUnionType(distributedMembers, UnionReduction.Literal, aliasSymbol, aliasTypeArguments);
}
else {
const distributedUnion = getUnionType(distributedMembers, UnionReduction.Literal);
const newIntersectionMembers = typeSet.slice(0, partialIntersectionStartIndex + 1);
newIntersectionMembers[partialIntersectionStartIndex] = distributedUnion;
return getIntersectionType(newIntersectionMembers, aliasSymbol, aliasTypeArguments);
}
}
const id = getTypeListId(typeSet);
let type = intersectionTypes.get(id);
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45 changes: 45 additions & 0 deletions tests/baselines/reference/intersectionsOfLargeUnions2.errors.txt
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@@ -0,0 +1,45 @@
tests/cases/compiler/intersectionsOfLargeUnions2.ts(31,15): error TS2536: Type 'T' cannot be used to index type 'HTMLElementTagNameMap'.
tests/cases/compiler/intersectionsOfLargeUnions2.ts(31,15): error TS2536: Type 'P' cannot be used to index type 'HTMLElementTagNameMap[T]'.


==== tests/cases/compiler/intersectionsOfLargeUnions2.ts (2 errors) ====
// Repro from #24223

declare global {
interface ElementTagNameMap {
[index: number]: HTMLElement
}

interface HTMLElement {
[index: number]: HTMLElement;
}
}

export function assertIsElement(node: Node | null): node is Element {
let nodeType = node === null ? null : node.nodeType;
return nodeType === 1;
}

export function assertNodeTagName<
T extends keyof ElementTagNameMap,
U extends ElementTagNameMap[T]>(node: Node | null, tagName: T): node is U {
if (assertIsElement(node)) {
const nodeTagName = node.tagName.toLowerCase();
return nodeTagName === tagName;
}
return false;
}

export function assertNodeProperty<
T extends keyof ElementTagNameMap,
P extends keyof ElementTagNameMap[T],
V extends HTMLElementTagNameMap[T][P]>(node: Node | null, tagName: T, prop: P, value: V) {
~~~~~~~~~~~~~~~~~~~~~~~~
!!! error TS2536: Type 'T' cannot be used to index type 'HTMLElementTagNameMap'.
~~~~~~~~~~~~~~~~~~~~~~~~~~~
!!! error TS2536: Type 'P' cannot be used to index type 'HTMLElementTagNameMap[T]'.
if (assertNodeTagName(node, tagName)) {
node[prop];
}
}

61 changes: 61 additions & 0 deletions tests/baselines/reference/intersectionsOfLargeUnions2.js
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@@ -0,0 +1,61 @@
//// [intersectionsOfLargeUnions2.ts]
// Repro from #24223

declare global {
interface ElementTagNameMap {
[index: number]: HTMLElement
}

interface HTMLElement {
[index: number]: HTMLElement;
}
}

export function assertIsElement(node: Node | null): node is Element {
let nodeType = node === null ? null : node.nodeType;
return nodeType === 1;
}

export function assertNodeTagName<
T extends keyof ElementTagNameMap,
U extends ElementTagNameMap[T]>(node: Node | null, tagName: T): node is U {
if (assertIsElement(node)) {
const nodeTagName = node.tagName.toLowerCase();
return nodeTagName === tagName;
}
return false;
}

export function assertNodeProperty<
T extends keyof ElementTagNameMap,
P extends keyof ElementTagNameMap[T],
V extends HTMLElementTagNameMap[T][P]>(node: Node | null, tagName: T, prop: P, value: V) {
if (assertNodeTagName(node, tagName)) {
node[prop];
}
}


//// [intersectionsOfLargeUnions2.js]
"use strict";
// Repro from #24223
exports.__esModule = true;
function assertIsElement(node) {
var nodeType = node === null ? null : node.nodeType;
return nodeType === 1;
}
exports.assertIsElement = assertIsElement;
function assertNodeTagName(node, tagName) {
if (assertIsElement(node)) {
var nodeTagName = node.tagName.toLowerCase();
return nodeTagName === tagName;
}
return false;
}
exports.assertNodeTagName = assertNodeTagName;
function assertNodeProperty(node, tagName, prop, value) {
if (assertNodeTagName(node, tagName)) {
node[prop];
}
}
exports.assertNodeProperty = assertNodeProperty;
115 changes: 115 additions & 0 deletions tests/baselines/reference/intersectionsOfLargeUnions2.symbols
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@@ -0,0 +1,115 @@
=== tests/cases/compiler/intersectionsOfLargeUnions2.ts ===
// Repro from #24223

declare global {
>global : Symbol(global, Decl(intersectionsOfLargeUnions2.ts, 0, 0))

interface ElementTagNameMap {
>ElementTagNameMap : Symbol(ElementTagNameMap, Decl(lib.dom.d.ts, --, --), Decl(intersectionsOfLargeUnions2.ts, 2, 16))

[index: number]: HTMLElement
>index : Symbol(index, Decl(intersectionsOfLargeUnions2.ts, 4, 9))
>HTMLElement : Symbol(HTMLElement, Decl(intersectionsOfLargeUnions2.ts, 5, 5))
}

interface HTMLElement {
>HTMLElement : Symbol(HTMLElement, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --), Decl(intersectionsOfLargeUnions2.ts, 5, 5))

[index: number]: HTMLElement;
>index : Symbol(index, Decl(intersectionsOfLargeUnions2.ts, 8, 9))
>HTMLElement : Symbol(HTMLElement, Decl(intersectionsOfLargeUnions2.ts, 5, 5))
}
}

export function assertIsElement(node: Node | null): node is Element {
>assertIsElement : Symbol(assertIsElement, Decl(intersectionsOfLargeUnions2.ts, 10, 1))
>node : Symbol(node, Decl(intersectionsOfLargeUnions2.ts, 12, 32))
>Node : Symbol(Node, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --))
>node : Symbol(node, Decl(intersectionsOfLargeUnions2.ts, 12, 32))
>Element : Symbol(Element, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --))

let nodeType = node === null ? null : node.nodeType;
>nodeType : Symbol(nodeType, Decl(intersectionsOfLargeUnions2.ts, 13, 7))
>node : Symbol(node, Decl(intersectionsOfLargeUnions2.ts, 12, 32))
>node.nodeType : Symbol(Node.nodeType, Decl(lib.dom.d.ts, --, --))
>node : Symbol(node, Decl(intersectionsOfLargeUnions2.ts, 12, 32))
>nodeType : Symbol(Node.nodeType, Decl(lib.dom.d.ts, --, --))

return nodeType === 1;
>nodeType : Symbol(nodeType, Decl(intersectionsOfLargeUnions2.ts, 13, 7))
}

export function assertNodeTagName<
>assertNodeTagName : Symbol(assertNodeTagName, Decl(intersectionsOfLargeUnions2.ts, 15, 1))

T extends keyof ElementTagNameMap,
>T : Symbol(T, Decl(intersectionsOfLargeUnions2.ts, 17, 34))
>ElementTagNameMap : Symbol(ElementTagNameMap, Decl(lib.dom.d.ts, --, --), Decl(intersectionsOfLargeUnions2.ts, 2, 16))

U extends ElementTagNameMap[T]>(node: Node | null, tagName: T): node is U {
>U : Symbol(U, Decl(intersectionsOfLargeUnions2.ts, 18, 38))
>ElementTagNameMap : Symbol(ElementTagNameMap, Decl(lib.dom.d.ts, --, --), Decl(intersectionsOfLargeUnions2.ts, 2, 16))
>T : Symbol(T, Decl(intersectionsOfLargeUnions2.ts, 17, 34))
>node : Symbol(node, Decl(intersectionsOfLargeUnions2.ts, 19, 36))
>Node : Symbol(Node, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --))
>tagName : Symbol(tagName, Decl(intersectionsOfLargeUnions2.ts, 19, 54))
>T : Symbol(T, Decl(intersectionsOfLargeUnions2.ts, 17, 34))
>node : Symbol(node, Decl(intersectionsOfLargeUnions2.ts, 19, 36))
>U : Symbol(U, Decl(intersectionsOfLargeUnions2.ts, 18, 38))

if (assertIsElement(node)) {
>assertIsElement : Symbol(assertIsElement, Decl(intersectionsOfLargeUnions2.ts, 10, 1))
>node : Symbol(node, Decl(intersectionsOfLargeUnions2.ts, 19, 36))

const nodeTagName = node.tagName.toLowerCase();
>nodeTagName : Symbol(nodeTagName, Decl(intersectionsOfLargeUnions2.ts, 21, 13))
>node.tagName.toLowerCase : Symbol(String.toLowerCase, Decl(lib.es5.d.ts, --, --))
>node.tagName : Symbol(Element.tagName, Decl(lib.dom.d.ts, --, --))
>node : Symbol(node, Decl(intersectionsOfLargeUnions2.ts, 19, 36))
>tagName : Symbol(Element.tagName, Decl(lib.dom.d.ts, --, --))
>toLowerCase : Symbol(String.toLowerCase, Decl(lib.es5.d.ts, --, --))

return nodeTagName === tagName;
>nodeTagName : Symbol(nodeTagName, Decl(intersectionsOfLargeUnions2.ts, 21, 13))
>tagName : Symbol(tagName, Decl(intersectionsOfLargeUnions2.ts, 19, 54))
}
return false;
}

export function assertNodeProperty<
>assertNodeProperty : Symbol(assertNodeProperty, Decl(intersectionsOfLargeUnions2.ts, 25, 1))

T extends keyof ElementTagNameMap,
>T : Symbol(T, Decl(intersectionsOfLargeUnions2.ts, 27, 35))
>ElementTagNameMap : Symbol(ElementTagNameMap, Decl(lib.dom.d.ts, --, --), Decl(intersectionsOfLargeUnions2.ts, 2, 16))

P extends keyof ElementTagNameMap[T],
>P : Symbol(P, Decl(intersectionsOfLargeUnions2.ts, 28, 38))
>ElementTagNameMap : Symbol(ElementTagNameMap, Decl(lib.dom.d.ts, --, --), Decl(intersectionsOfLargeUnions2.ts, 2, 16))
>T : Symbol(T, Decl(intersectionsOfLargeUnions2.ts, 27, 35))

V extends HTMLElementTagNameMap[T][P]>(node: Node | null, tagName: T, prop: P, value: V) {
>V : Symbol(V, Decl(intersectionsOfLargeUnions2.ts, 29, 41))
>HTMLElementTagNameMap : Symbol(HTMLElementTagNameMap, Decl(lib.dom.d.ts, --, --))
>T : Symbol(T, Decl(intersectionsOfLargeUnions2.ts, 27, 35))
>P : Symbol(P, Decl(intersectionsOfLargeUnions2.ts, 28, 38))
>node : Symbol(node, Decl(intersectionsOfLargeUnions2.ts, 30, 43))
>Node : Symbol(Node, Decl(lib.dom.d.ts, --, --), Decl(lib.dom.d.ts, --, --))
>tagName : Symbol(tagName, Decl(intersectionsOfLargeUnions2.ts, 30, 61))
>T : Symbol(T, Decl(intersectionsOfLargeUnions2.ts, 27, 35))
>prop : Symbol(prop, Decl(intersectionsOfLargeUnions2.ts, 30, 73))
>P : Symbol(P, Decl(intersectionsOfLargeUnions2.ts, 28, 38))
>value : Symbol(value, Decl(intersectionsOfLargeUnions2.ts, 30, 82))
>V : Symbol(V, Decl(intersectionsOfLargeUnions2.ts, 29, 41))

if (assertNodeTagName(node, tagName)) {
>assertNodeTagName : Symbol(assertNodeTagName, Decl(intersectionsOfLargeUnions2.ts, 15, 1))
>node : Symbol(node, Decl(intersectionsOfLargeUnions2.ts, 30, 43))
>tagName : Symbol(tagName, Decl(intersectionsOfLargeUnions2.ts, 30, 61))

node[prop];
>node : Symbol(node, Decl(intersectionsOfLargeUnions2.ts, 30, 43))
>prop : Symbol(prop, Decl(intersectionsOfLargeUnions2.ts, 30, 73))
}
}

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