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Merged
merged 5 commits into from
Oct 15, 2018
+775 −7
Merged

Allow non-unit types in union discriminants #27695

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d069875
Allow discriminant property to contain some non-unit types
ahejlsberg Oct 10, 2018
c110f57
Discriminant must include at least one unit type and no instantiable …
ahejlsberg Oct 10, 2018
7737cd5
Accept new baselines
ahejlsberg Oct 10, 2018
22907bf
Add tests
ahejlsberg Oct 10, 2018
6cdba6d
Accept new baselines
ahejlsberg Oct 10, 2018
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16 changes: 15 additions & 1 deletion src/compiler/checker.ts
View file
Original file line number Diff line number Diff line change
@@ -14212,12 +14212,26 @@ namespace ts {
return undefined;
}

function isDiscriminantType(type: Type): boolean {
if (type.flags & TypeFlags.Union) {
if (type.flags & (TypeFlags.Boolean | TypeFlags.EnumLiteral)) {
return true;
}
let combined = 0;
for (const t of (<UnionType>type).types) combined |= t.flags;
if (combined & TypeFlags.Unit && !(combined & TypeFlags.Instantiable)) {
return true;
}
}
return false;
}

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.HasNonUniformType) && isLiteralType(getTypeOfSymbol(prop));
(<TransientSymbol>prop).isDiscriminantProperty = !!((<TransientSymbol>prop).checkFlags & CheckFlags.HasNonUniformType) && isDiscriminantType(getTypeOfSymbol(prop));
}
return !!(<TransientSymbol>prop).isDiscriminantProperty;
}
86 changes: 86 additions & 0 deletions tests/baselines/reference/discriminatedUnionTypes2.errors.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,86 @@
tests/cases/conformance/types/union/discriminatedUnionTypes2.ts(27,30): error TS2322: Type '{ a: null; b: string; c: number; }' is not assignable to type '{ a: null; b: string; } | { a: string; c: number; }'.
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 (2 errors) ====
function f10(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
if (x.kind === false) {
x.a;
}
else if (x.kind === true) {
x.b;
}
else {
x.c;
}
}

function f11(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
switch (x.kind) {
case false:
x.a;
break;
case true:
x.b;
break;
default:
x.c;
}
}

function f13(x: { a: null; b: string } | { a: string, c: number }) {
x = { a: null, b: "foo", c: 4}; // Error
~~~~
!!! error TS2322: Type '{ a: null; b: string; c: number; }' is not assignable to type '{ a: null; b: string; } | { a: string; c: number; }'.
!!! error TS2322: Object literal may only specify known properties, and 'c' does not exist in type '{ a: null; b: string; }'.
}

function f14<T>(x: { a: 0; b: string } | { a: T, c: number }) {
if (x.a === 0) {
x.b; // Error
~
!!! error TS2339: Property 'b' does not exist on type '{ a: 0; b: string; } | { a: T; c: number; }'.
!!! error TS2339: Property 'b' does not exist on type '{ a: T; c: number; }'.
}
}

type Result<T> = { error?: undefined, value: T } | { error: Error };

function f15(x: Result<number>) {
if (!x.error) {
x.value;
}
else {
x.error.message;
}
}

f15({ value: 10 });
f15({ error: new Error("boom") });

// Repro from #24193

interface WithError {
error: Error
data: null
}

interface WithoutError<Data> {
error: null
data: Data
}

type DataCarrier<Data> = WithError | WithoutError<Data>

function f20<Data>(carrier: DataCarrier<Data>) {
if (carrier.error === null) {
const error: null = carrier.error
const data: Data = carrier.data
} else {
const error: Error = carrier.error
const data: null = carrier.data
}
}

128 changes: 128 additions & 0 deletions tests/baselines/reference/discriminatedUnionTypes2.js
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,128 @@
//// [discriminatedUnionTypes2.ts]
function f10(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
if (x.kind === false) {
x.a;
}
else if (x.kind === true) {
x.b;
}
else {
x.c;
}
}

function f11(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
switch (x.kind) {
case false:
x.a;
break;
case true:
x.b;
break;
default:
x.c;
}
}

function f13(x: { a: null; b: string } | { a: string, c: number }) {
x = { a: null, b: "foo", c: 4}; // Error
}

function f14<T>(x: { a: 0; b: string } | { a: T, c: number }) {
if (x.a === 0) {
x.b; // Error
}
}

type Result<T> = { error?: undefined, value: T } | { error: Error };

function f15(x: Result<number>) {
if (!x.error) {
x.value;
}
else {
x.error.message;
}
}

f15({ value: 10 });
f15({ error: new Error("boom") });

// Repro from #24193

interface WithError {
error: Error
data: null
}

interface WithoutError<Data> {
error: null
data: Data
}

type DataCarrier<Data> = WithError | WithoutError<Data>

function f20<Data>(carrier: DataCarrier<Data>) {
if (carrier.error === null) {
const error: null = carrier.error
const data: Data = carrier.data
} else {
const error: Error = carrier.error
const data: null = carrier.data
}
}


//// [discriminatedUnionTypes2.js]
"use strict";
function f10(x) {
if (x.kind === false) {
x.a;
}
else if (x.kind === true) {
x.b;
}
else {
x.c;
}
}
function f11(x) {
switch (x.kind) {
case false:
x.a;
break;
case true:
x.b;
break;
default:
x.c;
}
}
function f13(x) {
x = { a: null, b: "foo", c: 4 }; // Error
}
function f14(x) {
if (x.a === 0) {
x.b; // Error
}
}
function f15(x) {
if (!x.error) {
x.value;
}
else {
x.error.message;
}
}
f15({ value: 10 });
f15({ error: new Error("boom") });
function f20(carrier) {
if (carrier.error === null) {
var error = carrier.error;
var data = carrier.data;
}
else {
var error = carrier.error;
var data = carrier.data;
}
}
227 changes: 227 additions & 0 deletions tests/baselines/reference/discriminatedUnionTypes2.symbols
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Original file line number Diff line number Diff line change
@@ -0,0 +1,227 @@
=== tests/cases/conformance/types/union/discriminatedUnionTypes2.ts ===
function f10(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
>f10 : Symbol(f10, Decl(discriminatedUnionTypes2.ts, 0, 0))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 0, 13))
>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 18))
>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 0, 31))
>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 47))
>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 0, 59))
>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 75))
>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 0, 89))

if (x.kind === false) {
>x.kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 18), Decl(discriminatedUnionTypes2.ts, 0, 47), Decl(discriminatedUnionTypes2.ts, 0, 75))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 0, 13))
>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 18), Decl(discriminatedUnionTypes2.ts, 0, 47), Decl(discriminatedUnionTypes2.ts, 0, 75))

x.a;
>x.a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 0, 31))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 0, 13))
>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 0, 31))
}
else if (x.kind === true) {
>x.kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 47), Decl(discriminatedUnionTypes2.ts, 0, 75))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 0, 13))
>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 0, 47), Decl(discriminatedUnionTypes2.ts, 0, 75))

x.b;
>x.b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 0, 59))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 0, 13))
>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 0, 59))
}
else {
x.c;
>x.c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 0, 89))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 0, 13))
>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 0, 89))
}
}

function f11(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
>f11 : Symbol(f11, Decl(discriminatedUnionTypes2.ts, 10, 1))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 12, 13))
>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 12, 18))
>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 12, 31))
>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 12, 47))
>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 12, 59))
>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 12, 75))
>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 12, 89))

switch (x.kind) {
>x.kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 12, 18), Decl(discriminatedUnionTypes2.ts, 12, 47), Decl(discriminatedUnionTypes2.ts, 12, 75))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 12, 13))
>kind : Symbol(kind, Decl(discriminatedUnionTypes2.ts, 12, 18), Decl(discriminatedUnionTypes2.ts, 12, 47), Decl(discriminatedUnionTypes2.ts, 12, 75))

case false:
x.a;
>x.a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 12, 31))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 12, 13))
>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 12, 31))

break;
case true:
x.b;
>x.b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 12, 59))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 12, 13))
>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 12, 59))

break;
default:
x.c;
>x.c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 12, 89))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 12, 13))
>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 12, 89))
}
}

function f13(x: { a: null; b: string } | { a: string, c: number }) {
>f13 : Symbol(f13, Decl(discriminatedUnionTypes2.ts, 23, 1))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 25, 13))
>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 25, 17))
>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 25, 26))
>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 25, 42))
>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 25, 53))

x = { a: null, b: "foo", c: 4}; // Error
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 25, 13))
>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 26, 9))
>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 26, 18))
>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 26, 28))
}

function f14<T>(x: { a: 0; b: string } | { a: T, c: number }) {
>f14 : Symbol(f14, Decl(discriminatedUnionTypes2.ts, 27, 1))
>T : Symbol(T, Decl(discriminatedUnionTypes2.ts, 29, 13))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 29, 16))
>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 29, 20))
>b : Symbol(b, Decl(discriminatedUnionTypes2.ts, 29, 26))
>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 29, 42))
>T : Symbol(T, Decl(discriminatedUnionTypes2.ts, 29, 13))
>c : Symbol(c, Decl(discriminatedUnionTypes2.ts, 29, 48))

if (x.a === 0) {
>x.a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 29, 20), Decl(discriminatedUnionTypes2.ts, 29, 42))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 29, 16))
>a : Symbol(a, Decl(discriminatedUnionTypes2.ts, 29, 20), Decl(discriminatedUnionTypes2.ts, 29, 42))

x.b; // Error
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 29, 16))
}
}

type Result<T> = { error?: undefined, value: T } | { error: Error };
>Result : Symbol(Result, Decl(discriminatedUnionTypes2.ts, 33, 1))
>T : Symbol(T, Decl(discriminatedUnionTypes2.ts, 35, 12))
>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 35, 18))
>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 35, 37))
>T : Symbol(T, Decl(discriminatedUnionTypes2.ts, 35, 12))
>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 35, 52))
>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))

function f15(x: Result<number>) {
>f15 : Symbol(f15, Decl(discriminatedUnionTypes2.ts, 35, 68))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 37, 13))
>Result : Symbol(Result, Decl(discriminatedUnionTypes2.ts, 33, 1))

if (!x.error) {
>x.error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 35, 52), Decl(discriminatedUnionTypes2.ts, 35, 18))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 37, 13))
>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 35, 52), Decl(discriminatedUnionTypes2.ts, 35, 18))

x.value;
>x.value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 35, 37))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 37, 13))
>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 35, 37))
}
else {
x.error.message;
>x.error.message : Symbol(Error.message, Decl(lib.es5.d.ts, --, --))
>x.error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 35, 52))
>x : Symbol(x, Decl(discriminatedUnionTypes2.ts, 37, 13))
>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 35, 52))
>message : Symbol(Error.message, Decl(lib.es5.d.ts, --, --))
}
}

f15({ value: 10 });
>f15 : Symbol(f15, Decl(discriminatedUnionTypes2.ts, 35, 68))
>value : Symbol(value, Decl(discriminatedUnionTypes2.ts, 46, 5))

f15({ error: new Error("boom") });
>f15 : Symbol(f15, Decl(discriminatedUnionTypes2.ts, 35, 68))
>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 47, 5))
>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))

// Repro from #24193

interface WithError {
>WithError : Symbol(WithError, Decl(discriminatedUnionTypes2.ts, 47, 34))

error: Error
>error : Symbol(WithError.error, Decl(discriminatedUnionTypes2.ts, 51, 21))
>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))

data: null
>data : Symbol(WithError.data, Decl(discriminatedUnionTypes2.ts, 52, 16))
}

interface WithoutError<Data> {
>WithoutError : Symbol(WithoutError, Decl(discriminatedUnionTypes2.ts, 54, 1))
>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 56, 23))

error: null
>error : Symbol(WithoutError.error, Decl(discriminatedUnionTypes2.ts, 56, 30))

data: Data
>data : Symbol(WithoutError.data, Decl(discriminatedUnionTypes2.ts, 57, 15))
>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 56, 23))
}

type DataCarrier<Data> = WithError | WithoutError<Data>
>DataCarrier : Symbol(DataCarrier, Decl(discriminatedUnionTypes2.ts, 59, 1))
>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 61, 17))
>WithError : Symbol(WithError, Decl(discriminatedUnionTypes2.ts, 47, 34))
>WithoutError : Symbol(WithoutError, Decl(discriminatedUnionTypes2.ts, 54, 1))
>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 61, 17))

function f20<Data>(carrier: DataCarrier<Data>) {
>f20 : Symbol(f20, Decl(discriminatedUnionTypes2.ts, 61, 55))
>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 63, 13))
>carrier : Symbol(carrier, Decl(discriminatedUnionTypes2.ts, 63, 19))
>DataCarrier : Symbol(DataCarrier, Decl(discriminatedUnionTypes2.ts, 59, 1))
>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 63, 13))

if (carrier.error === null) {
>carrier.error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 51, 21), Decl(discriminatedUnionTypes2.ts, 56, 30))
>carrier : Symbol(carrier, Decl(discriminatedUnionTypes2.ts, 63, 19))
>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 51, 21), Decl(discriminatedUnionTypes2.ts, 56, 30))

const error: null = carrier.error
>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 65, 13))
>carrier.error : Symbol(WithoutError.error, Decl(discriminatedUnionTypes2.ts, 56, 30))
>carrier : Symbol(carrier, Decl(discriminatedUnionTypes2.ts, 63, 19))
>error : Symbol(WithoutError.error, Decl(discriminatedUnionTypes2.ts, 56, 30))

const data: Data = carrier.data
>data : Symbol(data, Decl(discriminatedUnionTypes2.ts, 66, 13))
>Data : Symbol(Data, Decl(discriminatedUnionTypes2.ts, 63, 13))
>carrier.data : Symbol(WithoutError.data, Decl(discriminatedUnionTypes2.ts, 57, 15))
>carrier : Symbol(carrier, Decl(discriminatedUnionTypes2.ts, 63, 19))
>data : Symbol(WithoutError.data, Decl(discriminatedUnionTypes2.ts, 57, 15))

} else {
const error: Error = carrier.error
>error : Symbol(error, Decl(discriminatedUnionTypes2.ts, 68, 13))
>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
>carrier.error : Symbol(WithError.error, Decl(discriminatedUnionTypes2.ts, 51, 21))
>carrier : Symbol(carrier, Decl(discriminatedUnionTypes2.ts, 63, 19))
>error : Symbol(WithError.error, Decl(discriminatedUnionTypes2.ts, 51, 21))

const data: null = carrier.data
>data : Symbol(data, Decl(discriminatedUnionTypes2.ts, 69, 13))
>carrier.data : Symbol(WithError.data, Decl(discriminatedUnionTypes2.ts, 52, 16))
>carrier : Symbol(carrier, Decl(discriminatedUnionTypes2.ts, 63, 19))
>data : Symbol(WithError.data, Decl(discriminatedUnionTypes2.ts, 52, 16))
}
}

241 changes: 241 additions & 0 deletions tests/baselines/reference/discriminatedUnionTypes2.types
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,241 @@
=== tests/cases/conformance/types/union/discriminatedUnionTypes2.ts ===
function f10(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
>f10 : (x: { kind: false; a: string; } | { kind: true; b: string; } | { kind: string; c: string; }) => void
>x : { kind: false; a: string; } | { kind: true; b: string; } | { kind: string; c: string; }
>kind : false
>false : false
>a : string
>kind : true
>true : true
>b : string
>kind : string
>c : string

if (x.kind === false) {
>x.kind === false : boolean
>x.kind : string | boolean
>x : { kind: false; a: string; } | { kind: true; b: string; } | { kind: string; c: string; }
>kind : string | boolean
>false : false

x.a;
>x.a : string
>x : { kind: false; a: string; }
>a : string
}
else if (x.kind === true) {
>x.kind === true : boolean
>x.kind : string | true
>x : { kind: true; b: string; } | { kind: string; c: string; }
>kind : string | true
>true : true

x.b;
>x.b : string
>x : { kind: true; b: string; }
>b : string
}
else {
x.c;
>x.c : string
>x : { kind: string; c: string; }
>c : string
}
}

function f11(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
>f11 : (x: { kind: false; a: string; } | { kind: true; b: string; } | { kind: string; c: string; }) => void
>x : { kind: false; a: string; } | { kind: true; b: string; } | { kind: string; c: string; }
>kind : false
>false : false
>a : string
>kind : true
>true : true
>b : string
>kind : string
>c : string

switch (x.kind) {
>x.kind : string | boolean
>x : { kind: false; a: string; } | { kind: true; b: string; } | { kind: string; c: string; }
>kind : string | boolean

case false:
>false : false

x.a;
>x.a : string
>x : { kind: false; a: string; }
>a : string

break;
case true:
>true : true

x.b;
>x.b : string
>x : { kind: true; b: string; }
>b : string

break;
default:
x.c;
>x.c : string
>x : { kind: string; c: string; }
>c : string
}
}

function f13(x: { a: null; b: string } | { a: string, c: number }) {
>f13 : (x: { a: null; b: string; } | { a: string; c: number; }) => void
>x : { a: null; b: string; } | { a: string; c: number; }
>a : null
>null : null
>b : string
>a : string
>c : number

x = { a: null, b: "foo", c: 4}; // Error
>x = { a: null, b: "foo", c: 4} : { a: null; b: string; c: number; }
>x : { a: null; b: string; } | { a: string; c: number; }
>{ a: null, b: "foo", c: 4} : { a: null; b: string; c: number; }
>a : null
>null : null
>b : string
>"foo" : "foo"
>c : number
>4 : 4
}

function f14<T>(x: { a: 0; b: string } | { a: T, c: number }) {
>f14 : <T>(x: { a: 0; b: string; } | { a: T; c: number; }) => void
>x : { a: 0; b: string; } | { a: T; c: number; }
>a : 0
>b : string
>a : T
>c : number

if (x.a === 0) {
>x.a === 0 : boolean
>x.a : 0 | T
>x : { a: 0; b: string; } | { a: T; c: number; }
>a : 0 | T
>0 : 0

x.b; // Error
>x.b : any
>x : { a: 0; b: string; } | { a: T; c: number; }
>b : any
}
}

type Result<T> = { error?: undefined, value: T } | { error: Error };
>Result : Result<T>
>error : undefined
>value : T
>error : Error

function f15(x: Result<number>) {
>f15 : (x: Result<number>) => void
>x : Result<number>

if (!x.error) {
>!x.error : boolean
>x.error : Error | undefined
>x : Result<number>
>error : Error | undefined

x.value;
>x.value : number
>x : { error?: undefined; value: number; }
>value : number
}
else {
x.error.message;
>x.error.message : string
>x.error : Error
>x : { error: Error; }
>error : Error
>message : string
}
}

f15({ value: 10 });
>f15({ value: 10 }) : void
>f15 : (x: Result<number>) => void
>{ value: 10 } : { value: number; }
>value : number
>10 : 10

f15({ error: new Error("boom") });
>f15({ error: new Error("boom") }) : void
>f15 : (x: Result<number>) => void
>{ error: new Error("boom") } : { error: Error; }
>error : Error
>new Error("boom") : Error
>Error : ErrorConstructor
>"boom" : "boom"

// Repro from #24193

interface WithError {
error: Error
>error : Error

data: null
>data : null
>null : null
}

interface WithoutError<Data> {
error: null
>error : null
>null : null

data: Data
>data : Data
}

type DataCarrier<Data> = WithError | WithoutError<Data>
>DataCarrier : DataCarrier<Data>

function f20<Data>(carrier: DataCarrier<Data>) {
>f20 : <Data>(carrier: DataCarrier<Data>) => void
>carrier : DataCarrier<Data>

if (carrier.error === null) {
>carrier.error === null : boolean
>carrier.error : Error | null
>carrier : DataCarrier<Data>
>error : Error | null
>null : null

const error: null = carrier.error
>error : null
>null : null
>carrier.error : null
>carrier : WithoutError<Data>
>error : null

const data: Data = carrier.data
>data : Data
>carrier.data : Data
>carrier : WithoutError<Data>
>data : Data

} else {
const error: Error = carrier.error
>error : Error
>carrier.error : Error
>carrier : WithError
>error : Error

const data: null = carrier.data
>data : null
>null : null
>carrier.data : null
>carrier : WithError
>data : null
}
}

10 changes: 4 additions & 6 deletions tests/baselines/reference/objectLiteralNormalization.errors.txt
View file
Original file line number Diff line number Diff line change
@@ -10,9 +10,8 @@ tests/cases/conformance/expressions/objectLiterals/objectLiteralNormalization.ts
Types of property 'a' are incompatible.
Type 'string' is not assignable to type 'undefined'.
tests/cases/conformance/expressions/objectLiterals/objectLiteralNormalization.ts(18,1): error TS2322: Type '{ a: number; }' is not assignable to type '{ a: number; b: number; } | { a: string; b?: undefined; } | { a?: undefined; b?: undefined; }'.
Type '{ a: number; }' is not assignable to type '{ a?: undefined; b?: undefined; }'.
Types of property 'a' are incompatible.
Type 'number' is not assignable to type 'undefined'.
Type '{ a: number; }' is not assignable to type '{ a: number; b: number; }'.
Property 'b' is missing in type '{ a: number; }'.


==== tests/cases/conformance/expressions/objectLiterals/objectLiteralNormalization.ts (5 errors) ====
@@ -52,9 +51,8 @@ tests/cases/conformance/expressions/objectLiterals/objectLiteralNormalization.ts
a2 = { a: 1 }; // Error
~~
!!! error TS2322: Type '{ a: number; }' is not assignable to type '{ a: number; b: number; } | { a: string; b?: undefined; } | { a?: undefined; b?: undefined; }'.
!!! error TS2322: Type '{ a: number; }' is not assignable to type '{ a?: undefined; b?: undefined; }'.
!!! error TS2322: Types of property 'a' are incompatible.
!!! error TS2322: Type 'number' is not assignable to type 'undefined'.
!!! error TS2322: Type '{ a: number; }' is not assignable to type '{ a: number; b: number; }'.
!!! error TS2322: Property 'b' is missing in type '{ a: number; }'.

// Object literals containing spreads are not normalized
declare let b1: { a: string, b: string } | { b: string, c: string };
74 changes: 74 additions & 0 deletions tests/cases/conformance/types/union/discriminatedUnionTypes2.ts
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,74 @@
// @strict: true

function f10(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
if (x.kind === false) {
x.a;
}
else if (x.kind === true) {
x.b;
}
else {
x.c;
}
}

function f11(x : { kind: false, a: string } | { kind: true, b: string } | { kind: string, c: string }) {
switch (x.kind) {
case false:
x.a;
break;
case true:
x.b;
break;
default:
x.c;
}
}

function f13(x: { a: null; b: string } | { a: string, c: number }) {
x = { a: null, b: "foo", c: 4}; // Error
}

function f14<T>(x: { a: 0; b: string } | { a: T, c: number }) {
if (x.a === 0) {
x.b; // Error
}
}

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Could it be worth adding a test that includes constrained generics? My reasoning being that in the future it might be worth considering discriminants that have constrained parameters because they are comparable to literals in some form. Having a test that would flag any changes might be helpful. Something like:

function f21<T extends number>(x: { a: undefined; b: { x: number } } | { a: T, b: { y: number } }) {
    if (x.a === undefined) {
        x.b = { y: 42 };
    }
}

type Result<T> = { error?: undefined, value: T } | { error: Error };

function f15(x: Result<number>) {
if (!x.error) {
x.value;
}
else {
x.error.message;
}
}

f15({ value: 10 });
f15({ error: new Error("boom") });

// Repro from #24193

interface WithError {
error: Error
data: null
}

interface WithoutError<Data> {
error: null
data: Data
}

type DataCarrier<Data> = WithError | WithoutError<Data>

function f20<Data>(carrier: DataCarrier<Data>) {
if (carrier.error === null) {
const error: null = carrier.error
const data: Data = carrier.data
} else {
const error: Error = carrier.error
const data: null = carrier.data
}
}