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Merged
ahejlsberg merged 5 commits into from
Dec 12, 2019
Merged

Fix33448 #35513

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0929a2f
Filter out discriminants of type 'never'.
ahejlsberg Dec 5, 2019
220034d
Add tests
ahejlsberg Dec 5, 2019
6bc8b12
Accept new baselines
ahejlsberg Dec 5, 2019
c14b160
Remove unnecessary '!' assertion
ahejlsberg Dec 5, 2019
ec7e2c4
Merge branch 'master' into fix33448
ahejlsberg Dec 6, 2019
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17 changes: 9 additions & 8 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -18310,19 +18310,14 @@ namespace ts {
return undefined;
}

function isDiscriminantType(type: Type): boolean {
return !!(type.flags & TypeFlags.Union &&
(type.flags & (TypeFlags.Boolean | TypeFlags.EnumLiteral) || !isGenericIndexType(type)));
}

function isDiscriminantProperty(type: Type | undefined, name: __String) {
if (type && type.flags & TypeFlags.Union) {
const prop = getUnionOrIntersectionProperty(<UnionType>type, name);
if (prop && getCheckFlags(prop) & CheckFlags.SyntheticProperty) {
if ((<TransientSymbol>prop).isDiscriminantProperty === undefined) {
(<TransientSymbol>prop).isDiscriminantProperty =
((<TransientSymbol>prop).checkFlags & CheckFlags.Discriminant) === CheckFlags.Discriminant &&
isDiscriminantType(getTypeOfSymbol(prop));
!maybeTypeOfKind(getTypeOfSymbol(prop), TypeFlags.Instantiable);
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@weswigham weswigham Dec 9, 2019

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What's the justification for not maybe instantiables here? Previously it was "not generic indexes", so this is quite a bit broader an exclusion, if I'm not mistaken.

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@ahejlsberg ahejlsberg Dec 9, 2019

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If you look at isGenericIndexType you'll see that it's more than just generic index types. The code change just clarifies what's actually going on, there's no change in behavior.

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@weswigham weswigham Dec 9, 2019

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Huh, alright, so it's equivalent. Neat.

}
return !!(<TransientSymbol>prop).isDiscriminantProperty;
}
Expand Down Expand Up @@ -19511,8 +19506,14 @@ namespace ts {
return type;
}
const propType = getTypeOfPropertyOfType(type, propName);
const narrowedPropType = propType && narrowType(propType);
return propType === narrowedPropType ? type : filterType(type, t => isTypeComparableTo(getTypeOfPropertyOrIndexSignature(t, propName), narrowedPropType!));
if (!propType) {
return type;
}
const narrowedPropType = narrowType(propType);
return filterType(type, t => {
const discriminantType = getTypeOfPropertyOrIndexSignature(t, propName);
return !(discriminantType.flags & TypeFlags.Never) && isTypeComparableTo(discriminantType, narrowedPropType);
});
}

function narrowTypeByTruthiness(type: Type, expr: Expression, assumeTrue: boolean): Type {
Expand Down
54 changes: 53 additions & 1 deletion tests/baselines/reference/discriminatedUnionTypes2.errors.txt
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Expand Up @@ -2,9 +2,10 @@ tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(27,30): error TS
Object literal may only specify known properties, and 'c' does not exist in type '{ a: null; b: string; }'.
tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(32,11): error TS2339: Property 'b' does not exist on type '{ a: 0; b: string; } | { a: T; c: number; }'.
Property 'b' does not exist on type '{ a: T; c: number; }'.
tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(132,11): error TS2339: Property 'value' does not exist on type 'never'.


==== tests/cases/conformance/types/union/discriminatedUnionTypes2.ts (2 errors) ====
==== tests/cases/conformance/types/union/discriminatedUnionTypes2.ts (3 errors) ====
function f10(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
if (x.kind === false) {
x.a;
Expand Down Expand Up @@ -105,4 +106,55 @@ tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(32,11): error TS
foo;
}
}

// Repro from #33448

type a = {
type: 'a',
data: string
}
type b = {
type: 'b',
name: string
}
type c = {
type: 'c',
other: string
}

type abc = a | b | c;

function f(problem: abc & (b | c)) {
if (problem.type === 'b') {
problem.name;
}
else {
problem.other;
}
}

type RuntimeValue =
| { type: 'number', value: number }
| { type: 'string', value: string }
| { type: 'boolean', value: boolean };

function foo1(x: RuntimeValue & { type: 'number' }) {
if (x.type === 'number') {
x.value; // number
}
else {
x.value; // Error, x is never
~~~~~
!!! error TS2339: Property 'value' does not exist on type 'never'.
}
}

function foo2(x: RuntimeValue & ({ type: 'number' } | { type: 'string' })) {
if (x.type === 'number') {
x.value; // number
}
else {
x.value; // string
}
}

73 changes: 73 additions & 0 deletions tests/baselines/reference/discriminatedUnionTypes2.js
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Original file line number Diff line number Diff line change
Expand Up @@ -93,6 +93,55 @@ function f31(foo: Foo) {
foo;
}
}

// Repro from #33448

type a = {
type: 'a',
data: string
}
type b = {
type: 'b',
name: string
}
type c = {
type: 'c',
other: string
}

type abc = a | b | c;

function f(problem: abc & (b | c)) {
if (problem.type === 'b') {
problem.name;
}
else {
problem.other;
}
}

type RuntimeValue =
| { type: 'number', value: number }
| { type: 'string', value: string }
| { type: 'boolean', value: boolean };

function foo1(x: RuntimeValue & { type: 'number' }) {
if (x.type === 'number') {
x.value; // number
}
else {
x.value; // Error, x is never
}
}

function foo2(x: RuntimeValue & ({ type: 'number' } | { type: 'string' })) {
if (x.type === 'number') {
x.value; // number
}
else {
x.value; // string
}
}


//// [discriminatedUnionTypes2.js]
Expand Down Expand Up @@ -164,3 +213,27 @@ function f31(foo) {
foo;
}
}
function f(problem) {
if (problem.type === 'b') {
problem.name;
}
else {
problem.other;
}
}
function foo1(x) {
if (x.type === 'number') {
x.value; // number
}
else {
x.value; // Error, x is never
}
}
function foo2(x) {
if (x.type === 'number') {
x.value; // number
}
else {
x.value; // string
}
}
123 changes: 123 additions & 0 deletions tests/baselines/reference/discriminatedUnionTypes2.symbols
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Original file line number Diff line number Diff line change
Expand Up @@ -273,3 +273,126 @@ function f31(foo: Foo) {
}
}

// Repro from #33448

type a = {
>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 93, 1))

type: 'a',
>type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 97, 10))

data: string
>data : Symbol(data, Decl(discriminatedUnionTypes2.ts, 98, 14))
}
type b = {
>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 100, 1))

type: 'b',
>type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 101, 10))

name: string
>name : Symbol(name, Decl(discriminatedUnionTypes2.ts, 102, 14))
}
type c = {
>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 104, 1))

type: 'c',
>type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 105, 10))

other: string
>other : Symbol(other, Decl(discriminatedUnionTypes2.ts, 106, 14))
}

type abc = a | b | c;
>abc : Symbol(abc, Decl(discriminatedUnionTypes2.ts, 108, 1))
>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 93, 1))
>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 100, 1))
>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 104, 1))

function f(problem: abc & (b | c)) {
>f : Symbol(f, Decl(discriminatedUnionTypes2.ts, 110, 21))
>problem : Symbol(problem, Decl(discriminatedUnionTypes2.ts, 112, 11))
>abc : Symbol(abc, Decl(discriminatedUnionTypes2.ts, 108, 1))
>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 100, 1))
>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 104, 1))

if (problem.type === 'b') {
>problem.type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 101, 10), Decl(discriminatedUnionTypes2.ts, 105, 10), Decl(discriminatedUnionTypes2.ts, 97, 10), Decl(discriminatedUnionTypes2.ts, 101, 10), Decl(discriminatedUnionTypes2.ts, 97, 10) ... and 5 more)
>problem : Symbol(problem, Decl(discriminatedUnionTypes2.ts, 112, 11))
>type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 101, 10), Decl(discriminatedUnionTypes2.ts, 105, 10), Decl(discriminatedUnionTypes2.ts, 97, 10), Decl(discriminatedUnionTypes2.ts, 101, 10), Decl(discriminatedUnionTypes2.ts, 97, 10) ... and 5 more)

problem.name;
>problem.name : Symbol(name, Decl(discriminatedUnionTypes2.ts, 102, 14))
>problem : Symbol(problem, Decl(discriminatedUnionTypes2.ts, 112, 11))
>name : Symbol(name, Decl(discriminatedUnionTypes2.ts, 102, 14))
}
else {
problem.other;
>problem.other : Symbol(other, Decl(discriminatedUnionTypes2.ts, 106, 14))
>problem : Symbol(problem, Decl(discriminatedUnionTypes2.ts, 112, 11))
>other : Symbol(other, Decl(discriminatedUnionTypes2.ts, 106, 14))
}
}

type RuntimeValue =
>RuntimeValue : Symbol(RuntimeValue, Decl(discriminatedUnionTypes2.ts, 119, 1))

| { type: 'number', value: number }
>type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 122, 7))
>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 122, 23))

| { type: 'string', value: string }
>type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 123, 7))
>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 123, 23))

| { type: 'boolean', value: boolean };
>type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 124, 7))
>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 124, 24))

function foo1(x: RuntimeValue & { type: 'number' }) {
>foo1 : Symbol(foo1, Decl(discriminatedUnionTypes2.ts, 124, 42))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 126, 14))
>RuntimeValue : Symbol(RuntimeValue, Decl(discriminatedUnionTypes2.ts, 119, 1))
>type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 126, 33))

if (x.type === 'number') {
>x.type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 122, 7), Decl(discriminatedUnionTypes2.ts, 126, 33), Decl(discriminatedUnionTypes2.ts, 123, 7), Decl(discriminatedUnionTypes2.ts, 126, 33), Decl(discriminatedUnionTypes2.ts, 124, 7) ... and 1 more)
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 126, 14))
>type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 122, 7), Decl(discriminatedUnionTypes2.ts, 126, 33), Decl(discriminatedUnionTypes2.ts, 123, 7), Decl(discriminatedUnionTypes2.ts, 126, 33), Decl(discriminatedUnionTypes2.ts, 124, 7) ... and 1 more)

x.value; // number
>x.value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 122, 23))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 126, 14))
>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 122, 23))
}
else {
x.value; // Error, x is never
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 126, 14))
}
}

function foo2(x: RuntimeValue & ({ type: 'number' } | { type: 'string' })) {
>foo2 : Symbol(foo2, Decl(discriminatedUnionTypes2.ts, 133, 1))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 135, 14))
>RuntimeValue : Symbol(RuntimeValue, Decl(discriminatedUnionTypes2.ts, 119, 1))
>type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 135, 34))
>type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 135, 55))

if (x.type === 'number') {
>x.type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 122, 7), Decl(discriminatedUnionTypes2.ts, 135, 34), Decl(discriminatedUnionTypes2.ts, 122, 7), Decl(discriminatedUnionTypes2.ts, 135, 55), Decl(discriminatedUnionTypes2.ts, 123, 7) ... and 7 more)
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 135, 14))
>type : Symbol(type, Decl(discriminatedUnionTypes2.ts, 122, 7), Decl(discriminatedUnionTypes2.ts, 135, 34), Decl(discriminatedUnionTypes2.ts, 122, 7), Decl(discriminatedUnionTypes2.ts, 135, 55), Decl(discriminatedUnionTypes2.ts, 123, 7) ... and 7 more)

x.value; // number
>x.value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 122, 23))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 135, 14))
>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 122, 23))
}
else {
x.value; // string
>x.value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 123, 23))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 135, 14))
>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 123, 23))
}
}

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