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Consistent narrowing by discriminant #38311

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Merged
merged 2 commits into from
May 6, 2020
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Merged

Consistent narrowing by discriminant #38311

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e8f1c58
Consistent requirements for narrowing by discriminant
ahejlsberg May 3, 2020
88025e6
Add tests
ahejlsberg May 3, 2020
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15 changes: 8 additions & 7 deletions src/compiler/checker.ts
View file
Original file line number Diff line number Diff line change
@@ -20587,14 +20587,15 @@ namespace ts {
}

function isMatchingReferenceDiscriminant(expr: Expression, computedType: Type) {
if (!(computedType.flags & TypeFlags.Union) || !isAccessExpression(expr)) {
const type = declaredType.flags & TypeFlags.Union ? declaredType : computedType;
if (!(type.flags & TypeFlags.Union) || !isAccessExpression(expr)) {
return false;
}
const name = getAccessedPropertyName(expr);
if (name === undefined) {
return false;
}
return isMatchingReference(reference, expr.expression) && isDiscriminantProperty(computedType, name);
return isMatchingReference(reference, expr.expression) && isDiscriminantProperty(type, name);
}

function narrowTypeByDiscriminant(type: Type, access: AccessExpression, narrowType: (t: Type) => Type): Type {
@@ -20620,7 +20621,7 @@ namespace ts {
if (strictNullChecks && assumeTrue && optionalChainContainsReference(expr, reference)) {
type = getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull);
}
if (isMatchingReferenceDiscriminant(expr, declaredType)) {
if (isMatchingReferenceDiscriminant(expr, type)) {
return narrowTypeByDiscriminant(type, <AccessExpression>expr, t => getTypeWithFacts(t, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy));
}
return type;
@@ -20676,10 +20677,10 @@ namespace ts {
type = narrowTypeByOptionalChainContainment(type, operator, left, assumeTrue);
}
}
if (isMatchingReferenceDiscriminant(left, declaredType)) {
if (isMatchingReferenceDiscriminant(left, type)) {
return narrowTypeByDiscriminant(type, <AccessExpression>left, t => narrowTypeByEquality(t, operator, right, assumeTrue));
}
if (isMatchingReferenceDiscriminant(right, declaredType)) {
if (isMatchingReferenceDiscriminant(right, type)) {
return narrowTypeByDiscriminant(type, <AccessExpression>right, t => narrowTypeByEquality(t, operator, left, assumeTrue));
}
if (isMatchingConstructorReference(left)) {
@@ -21101,7 +21102,7 @@ namespace ts {
!(getTypeFacts(predicate.type) & TypeFacts.EQUndefined)) {
type = getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull);
}
if (isMatchingReferenceDiscriminant(predicateArgument, declaredType)) {
if (isMatchingReferenceDiscriminant(predicateArgument, type)) {
return narrowTypeByDiscriminant(type, predicateArgument as AccessExpression, t => getNarrowedType(t, predicate.type!, assumeTrue, isTypeSubtypeOf));
}
}
@@ -21143,7 +21144,7 @@ namespace ts {
if (isMatchingReference(reference, expr)) {
return getTypeWithFacts(type, assumePresent ? TypeFacts.NEUndefinedOrNull : TypeFacts.EQUndefinedOrNull);
}
if (isMatchingReferenceDiscriminant(expr, declaredType)) {
if (isMatchingReferenceDiscriminant(expr, type)) {
return narrowTypeByDiscriminant(type, <AccessExpression>expr, t => getTypeWithFacts(t, assumePresent ? TypeFacts.NEUndefinedOrNull : TypeFacts.EQUndefinedOrNull));
}
return type;
87 changes: 87 additions & 0 deletions tests/baselines/reference/discriminantPropertyCheck.js
View file
Original file line number Diff line number Diff line change
@@ -174,6 +174,67 @@ function func3(value: Partial<UnionOfBar>) {
}
}
}

// Repro from #30557

interface TypeA {
Name: "TypeA";
Value1: "Cool stuff!";
}

interface TypeB {
Name: "TypeB";
Value2: 0;
}

type Type = TypeA | TypeB;

declare function isType(x: unknown): x is Type;

function WorksProperly(data: Type) {
if (data.Name === "TypeA") {
const value1 = data.Value1;
}
}

function DoesNotWork(data: unknown) {
if (isType(data)) {
if (data.Name === "TypeA") {
const value1 = data.Value1;
}
}
}

// Repro from #36777

type TestA = {
type: 'testA';
bananas: 3;
}

type TestB = {
type: 'testB';
apples: 5;
}

type AllTests = TestA | TestB;

type MapOfAllTests = Record<string, AllTests>;

const doTestingStuff = (mapOfTests: MapOfAllTests, ids: string[]) => {
ids.forEach(id => {
let test;
test = mapOfTests[id];
if (test.type === 'testA') {
console.log(test.bananas);
}
switch (test.type) {
case 'testA': {
console.log(test.bananas);
}
}
});
};


//// [discriminantPropertyCheck.js]
@@ -269,3 +330,29 @@ function func3(value) {
}
}
}
function WorksProperly(data) {
if (data.Name === "TypeA") {
var value1 = data.Value1;
}
}
function DoesNotWork(data) {
if (isType(data)) {
if (data.Name === "TypeA") {
var value1 = data.Value1;
}
}
}
var doTestingStuff = function (mapOfTests, ids) {
ids.forEach(function (id) {
var test;
test = mapOfTests[id];
if (test.type === 'testA') {
console.log(test.bananas);
}
switch (test.type) {
case 'testA': {
console.log(test.bananas);
}
}
});
};
156 changes: 156 additions & 0 deletions tests/baselines/reference/discriminantPropertyCheck.symbols
View file
Original file line number Diff line number Diff line change
@@ -508,3 +508,159 @@ function func3(value: Partial<UnionOfBar>) {
}
}

// Repro from #30557

interface TypeA {
>TypeA : Symbol(TypeA, Decl(discriminantPropertyCheck.ts, 174, 1))

Name: "TypeA";
>Name : Symbol(TypeA.Name, Decl(discriminantPropertyCheck.ts, 178, 17))

Value1: "Cool stuff!";
>Value1 : Symbol(TypeA.Value1, Decl(discriminantPropertyCheck.ts, 179, 18))
}

interface TypeB {
>TypeB : Symbol(TypeB, Decl(discriminantPropertyCheck.ts, 181, 1))

Name: "TypeB";
>Name : Symbol(TypeB.Name, Decl(discriminantPropertyCheck.ts, 183, 17))

Value2: 0;
>Value2 : Symbol(TypeB.Value2, Decl(discriminantPropertyCheck.ts, 184, 18))
}

type Type = TypeA | TypeB;
>Type : Symbol(Type, Decl(discriminantPropertyCheck.ts, 186, 1))
>TypeA : Symbol(TypeA, Decl(discriminantPropertyCheck.ts, 174, 1))
>TypeB : Symbol(TypeB, Decl(discriminantPropertyCheck.ts, 181, 1))

declare function isType(x: unknown): x is Type;
>isType : Symbol(isType, Decl(discriminantPropertyCheck.ts, 188, 26))
>x : Symbol(x, Decl(discriminantPropertyCheck.ts, 190, 24))
>x : Symbol(x, Decl(discriminantPropertyCheck.ts, 190, 24))
>Type : Symbol(Type, Decl(discriminantPropertyCheck.ts, 186, 1))

function WorksProperly(data: Type) {
>WorksProperly : Symbol(WorksProperly, Decl(discriminantPropertyCheck.ts, 190, 47))
>data : Symbol(data, Decl(discriminantPropertyCheck.ts, 192, 23))
>Type : Symbol(Type, Decl(discriminantPropertyCheck.ts, 186, 1))

if (data.Name === "TypeA") {
>data.Name : Symbol(Name, Decl(discriminantPropertyCheck.ts, 178, 17), Decl(discriminantPropertyCheck.ts, 183, 17))
>data : Symbol(data, Decl(discriminantPropertyCheck.ts, 192, 23))
>Name : Symbol(Name, Decl(discriminantPropertyCheck.ts, 178, 17), Decl(discriminantPropertyCheck.ts, 183, 17))

const value1 = data.Value1;
>value1 : Symbol(value1, Decl(discriminantPropertyCheck.ts, 194, 13))
>data.Value1 : Symbol(TypeA.Value1, Decl(discriminantPropertyCheck.ts, 179, 18))
>data : Symbol(data, Decl(discriminantPropertyCheck.ts, 192, 23))
>Value1 : Symbol(TypeA.Value1, Decl(discriminantPropertyCheck.ts, 179, 18))
}
}

function DoesNotWork(data: unknown) {
>DoesNotWork : Symbol(DoesNotWork, Decl(discriminantPropertyCheck.ts, 196, 1))
>data : Symbol(data, Decl(discriminantPropertyCheck.ts, 198, 21))

if (isType(data)) {
>isType : Symbol(isType, Decl(discriminantPropertyCheck.ts, 188, 26))
>data : Symbol(data, Decl(discriminantPropertyCheck.ts, 198, 21))

if (data.Name === "TypeA") {
>data.Name : Symbol(Name, Decl(discriminantPropertyCheck.ts, 178, 17), Decl(discriminantPropertyCheck.ts, 183, 17))
>data : Symbol(data, Decl(discriminantPropertyCheck.ts, 198, 21))
>Name : Symbol(Name, Decl(discriminantPropertyCheck.ts, 178, 17), Decl(discriminantPropertyCheck.ts, 183, 17))

const value1 = data.Value1;
>value1 : Symbol(value1, Decl(discriminantPropertyCheck.ts, 201, 17))
>data.Value1 : Symbol(TypeA.Value1, Decl(discriminantPropertyCheck.ts, 179, 18))
>data : Symbol(data, Decl(discriminantPropertyCheck.ts, 198, 21))
>Value1 : Symbol(TypeA.Value1, Decl(discriminantPropertyCheck.ts, 179, 18))
}
}
}

// Repro from #36777

type TestA = {
>TestA : Symbol(TestA, Decl(discriminantPropertyCheck.ts, 204, 1))

type: 'testA';
>type : Symbol(type, Decl(discriminantPropertyCheck.ts, 208, 14))

bananas: 3;
>bananas : Symbol(bananas, Decl(discriminantPropertyCheck.ts, 209, 18))
}

type TestB = {
>TestB : Symbol(TestB, Decl(discriminantPropertyCheck.ts, 211, 1))

type: 'testB';
>type : Symbol(type, Decl(discriminantPropertyCheck.ts, 213, 14))

apples: 5;
>apples : Symbol(apples, Decl(discriminantPropertyCheck.ts, 214, 18))
}

type AllTests = TestA | TestB;
>AllTests : Symbol(AllTests, Decl(discriminantPropertyCheck.ts, 216, 1))
>TestA : Symbol(TestA, Decl(discriminantPropertyCheck.ts, 204, 1))
>TestB : Symbol(TestB, Decl(discriminantPropertyCheck.ts, 211, 1))

type MapOfAllTests = Record<string, AllTests>;
>MapOfAllTests : Symbol(MapOfAllTests, Decl(discriminantPropertyCheck.ts, 218, 30))
>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
>AllTests : Symbol(AllTests, Decl(discriminantPropertyCheck.ts, 216, 1))

const doTestingStuff = (mapOfTests: MapOfAllTests, ids: string[]) => {
>doTestingStuff : Symbol(doTestingStuff, Decl(discriminantPropertyCheck.ts, 222, 5))
>mapOfTests : Symbol(mapOfTests, Decl(discriminantPropertyCheck.ts, 222, 24))
>MapOfAllTests : Symbol(MapOfAllTests, Decl(discriminantPropertyCheck.ts, 218, 30))
>ids : Symbol(ids, Decl(discriminantPropertyCheck.ts, 222, 50))

ids.forEach(id => {
>ids.forEach : Symbol(Array.forEach, Decl(lib.es5.d.ts, --, --))
>ids : Symbol(ids, Decl(discriminantPropertyCheck.ts, 222, 50))
>forEach : Symbol(Array.forEach, Decl(lib.es5.d.ts, --, --))
>id : Symbol(id, Decl(discriminantPropertyCheck.ts, 223, 16))

let test;
>test : Symbol(test, Decl(discriminantPropertyCheck.ts, 224, 11))

test = mapOfTests[id];
>test : Symbol(test, Decl(discriminantPropertyCheck.ts, 224, 11))
>mapOfTests : Symbol(mapOfTests, Decl(discriminantPropertyCheck.ts, 222, 24))
>id : Symbol(id, Decl(discriminantPropertyCheck.ts, 223, 16))

if (test.type === 'testA') {
>test.type : Symbol(type, Decl(discriminantPropertyCheck.ts, 208, 14), Decl(discriminantPropertyCheck.ts, 213, 14))
>test : Symbol(test, Decl(discriminantPropertyCheck.ts, 224, 11))
>type : Symbol(type, Decl(discriminantPropertyCheck.ts, 208, 14), Decl(discriminantPropertyCheck.ts, 213, 14))

console.log(test.bananas);
>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
>test.bananas : Symbol(bananas, Decl(discriminantPropertyCheck.ts, 209, 18))
>test : Symbol(test, Decl(discriminantPropertyCheck.ts, 224, 11))
>bananas : Symbol(bananas, Decl(discriminantPropertyCheck.ts, 209, 18))
}
switch (test.type) {
>test.type : Symbol(type, Decl(discriminantPropertyCheck.ts, 208, 14), Decl(discriminantPropertyCheck.ts, 213, 14))
>test : Symbol(test, Decl(discriminantPropertyCheck.ts, 224, 11))
>type : Symbol(type, Decl(discriminantPropertyCheck.ts, 208, 14), Decl(discriminantPropertyCheck.ts, 213, 14))

case 'testA': {
console.log(test.bananas);
>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
>test.bananas : Symbol(bananas, Decl(discriminantPropertyCheck.ts, 209, 18))
>test : Symbol(test, Decl(discriminantPropertyCheck.ts, 224, 11))
>bananas : Symbol(bananas, Decl(discriminantPropertyCheck.ts, 209, 18))
}
}
});
};

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