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Fix: Make discriminant property selection order-independent in unions (#62512) (#62516)

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Prathmesh Ravindra Salunkhe 2025-10-13 23:08:34 +05:30 committed by GitHub
parent 10b2cf52c3
commit 0b6a241886
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61
tests/baselines/reference/discriminantOrderIndependence.js Normal file
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//// [tests/cases/compiler/discriminantOrderIndependence.ts] ////
//// [discriminantOrderIndependence.ts]
interface A {
subType: "b";
type: "a";
}
declare let order1:
| { type: "1" }
| A
| { type: "2" }
| { type: "3" }
| undefined;
// Should NOT error: 'order1' is possibly 'undefined' after the guard
if (order1 && order1.type === "a") {
order1.type; // Should be OK
}
interface B {
subType: "b";
type: "a";
}
declare let order2:
| { type: "1" }
| { type: "2" }
| { type: "3" }
| B
| undefined;
// Should NOT error: 'order2' is possibly 'undefined' after the guard
if (order2 && order2.type === "a") {
order2.type; // Should be OK
}
// Also test with !. type assertion
if (order1 && order1.type === "a") {
order1.type; // Should be OK
}
if (order2 && order2.type === "a") {
order2.type; // Should be OK
}
//// [discriminantOrderIndependence.js]
// Should NOT error: 'order1' is possibly 'undefined' after the guard
if (order1 && order1.type === "a") {
order1.type; // Should be OK
}
// Should NOT error: 'order2' is possibly 'undefined' after the guard
if (order2 && order2.type === "a") {
order2.type; // Should be OK
}
// Also test with !. type assertion
if (order1 && order1.type === "a") {
order1.type; // Should be OK
}
if (order2 && order2.type === "a") {
order2.type; // Should be OK
}

106
tests/baselines/reference/discriminantOrderIndependence.symbols Normal file
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//// [tests/cases/compiler/discriminantOrderIndependence.ts] ////
=== discriminantOrderIndependence.ts ===
interface A {
>A : Symbol(A, Decl(discriminantOrderIndependence.ts, 0, 0))
subType: "b";
>subType : Symbol(A.subType, Decl(discriminantOrderIndependence.ts, 0, 13))
type: "a";
>type : Symbol(A.type, Decl(discriminantOrderIndependence.ts, 1, 17))
}
declare let order1:
>order1 : Symbol(order1, Decl(discriminantOrderIndependence.ts, 5, 11))
| { type: "1" }
>type : Symbol(type, Decl(discriminantOrderIndependence.ts, 6, 7))
| A
>A : Symbol(A, Decl(discriminantOrderIndependence.ts, 0, 0))
| { type: "2" }
>type : Symbol(type, Decl(discriminantOrderIndependence.ts, 8, 7))
| { type: "3" }
>type : Symbol(type, Decl(discriminantOrderIndependence.ts, 9, 7))
| undefined;
// Should NOT error: 'order1' is possibly 'undefined' after the guard
if (order1 && order1.type === "a") {
>order1 : Symbol(order1, Decl(discriminantOrderIndependence.ts, 5, 11))
>order1.type : Symbol(type, Decl(discriminantOrderIndependence.ts, 1, 17), Decl(discriminantOrderIndependence.ts, 6, 7), Decl(discriminantOrderIndependence.ts, 8, 7), Decl(discriminantOrderIndependence.ts, 9, 7))
>order1 : Symbol(order1, Decl(discriminantOrderIndependence.ts, 5, 11))
>type : Symbol(type, Decl(discriminantOrderIndependence.ts, 1, 17), Decl(discriminantOrderIndependence.ts, 6, 7), Decl(discriminantOrderIndependence.ts, 8, 7), Decl(discriminantOrderIndependence.ts, 9, 7))
order1.type; // Should be OK
>order1.type : Symbol(A.type, Decl(discriminantOrderIndependence.ts, 1, 17))
>order1 : Symbol(order1, Decl(discriminantOrderIndependence.ts, 5, 11))
>type : Symbol(A.type, Decl(discriminantOrderIndependence.ts, 1, 17))
}
interface B {
>B : Symbol(B, Decl(discriminantOrderIndependence.ts, 15, 1))
subType: "b";
>subType : Symbol(B.subType, Decl(discriminantOrderIndependence.ts, 17, 13))
type: "a";
>type : Symbol(B.type, Decl(discriminantOrderIndependence.ts, 18, 17))
}
declare let order2:
>order2 : Symbol(order2, Decl(discriminantOrderIndependence.ts, 22, 11))
| { type: "1" }
>type : Symbol(type, Decl(discriminantOrderIndependence.ts, 23, 7))
| { type: "2" }
>type : Symbol(type, Decl(discriminantOrderIndependence.ts, 24, 7))
| { type: "3" }
>type : Symbol(type, Decl(discriminantOrderIndependence.ts, 25, 7))
| B
>B : Symbol(B, Decl(discriminantOrderIndependence.ts, 15, 1))
| undefined;
// Should NOT error: 'order2' is possibly 'undefined' after the guard
if (order2 && order2.type === "a") {
>order2 : Symbol(order2, Decl(discriminantOrderIndependence.ts, 22, 11))
>order2.type : Symbol(type, Decl(discriminantOrderIndependence.ts, 18, 17), Decl(discriminantOrderIndependence.ts, 23, 7), Decl(discriminantOrderIndependence.ts, 24, 7), Decl(discriminantOrderIndependence.ts, 25, 7))
>order2 : Symbol(order2, Decl(discriminantOrderIndependence.ts, 22, 11))
>type : Symbol(type, Decl(discriminantOrderIndependence.ts, 18, 17), Decl(discriminantOrderIndependence.ts, 23, 7), Decl(discriminantOrderIndependence.ts, 24, 7), Decl(discriminantOrderIndependence.ts, 25, 7))
order2.type; // Should be OK
>order2.type : Symbol(B.type, Decl(discriminantOrderIndependence.ts, 18, 17))
>order2 : Symbol(order2, Decl(discriminantOrderIndependence.ts, 22, 11))
>type : Symbol(B.type, Decl(discriminantOrderIndependence.ts, 18, 17))
}
// Also test with !. type assertion
if (order1 && order1.type === "a") {
>order1 : Symbol(order1, Decl(discriminantOrderIndependence.ts, 5, 11))
>order1.type : Symbol(type, Decl(discriminantOrderIndependence.ts, 1, 17), Decl(discriminantOrderIndependence.ts, 6, 7), Decl(discriminantOrderIndependence.ts, 8, 7), Decl(discriminantOrderIndependence.ts, 9, 7))
>order1 : Symbol(order1, Decl(discriminantOrderIndependence.ts, 5, 11))
>type : Symbol(type, Decl(discriminantOrderIndependence.ts, 1, 17), Decl(discriminantOrderIndependence.ts, 6, 7), Decl(discriminantOrderIndependence.ts, 8, 7), Decl(discriminantOrderIndependence.ts, 9, 7))
order1.type; // Should be OK
>order1.type : Symbol(A.type, Decl(discriminantOrderIndependence.ts, 1, 17))
>order1 : Symbol(order1, Decl(discriminantOrderIndependence.ts, 5, 11))
>type : Symbol(A.type, Decl(discriminantOrderIndependence.ts, 1, 17))
}
if (order2 && order2.type === "a") {
>order2 : Symbol(order2, Decl(discriminantOrderIndependence.ts, 22, 11))
>order2.type : Symbol(type, Decl(discriminantOrderIndependence.ts, 18, 17), Decl(discriminantOrderIndependence.ts, 23, 7), Decl(discriminantOrderIndependence.ts, 24, 7), Decl(discriminantOrderIndependence.ts, 25, 7))
>order2 : Symbol(order2, Decl(discriminantOrderIndependence.ts, 22, 11))
>type : Symbol(type, Decl(discriminantOrderIndependence.ts, 18, 17), Decl(discriminantOrderIndependence.ts, 23, 7), Decl(discriminantOrderIndependence.ts, 24, 7), Decl(discriminantOrderIndependence.ts, 25, 7))
order2.type; // Should be OK
>order2.type : Symbol(B.type, Decl(discriminantOrderIndependence.ts, 18, 17))
>order2 : Symbol(order2, Decl(discriminantOrderIndependence.ts, 22, 11))
>type : Symbol(B.type, Decl(discriminantOrderIndependence.ts, 18, 17))
}

162
tests/baselines/reference/discriminantOrderIndependence.types Normal file
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//// [tests/cases/compiler/discriminantOrderIndependence.ts] ////
=== discriminantOrderIndependence.ts ===
interface A {
subType: "b";
>subType : "b"
> : ^^^
type: "a";
>type : "a"
> : ^^^
}
declare let order1:
>order1 : A | { type: "1"; } | { type: "2"; } | { type: "3"; }
> : ^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
| { type: "1" }
>type : "1"
> : ^^^
| A
| { type: "2" }
>type : "2"
> : ^^^
| { type: "3" }
>type : "3"
> : ^^^
| undefined;
// Should NOT error: 'order1' is possibly 'undefined' after the guard
if (order1 && order1.type === "a") {
>order1 && order1.type === "a" : boolean
> : ^^^^^^^
>order1 : A | { type: "1"; } | { type: "2"; } | { type: "3"; }
> : ^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
>order1.type === "a" : boolean
> : ^^^^^^^
>order1.type : "a" | "1" | "2" | "3"
> : ^^^^^^^^^^^^^^^^^^^^^
>order1 : A | { type: "1"; } | { type: "2"; } | { type: "3"; }
> : ^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
>type : "a" | "1" | "2" | "3"
> : ^^^^^^^^^^^^^^^^^^^^^
>"a" : "a"
> : ^^^
order1.type; // Should be OK
>order1.type : "a"
> : ^^^
>order1 : A
> : ^
>type : "a"
> : ^^^
}
interface B {
subType: "b";
>subType : "b"
> : ^^^
type: "a";
>type : "a"
> : ^^^
}
declare let order2:
>order2 : B | { type: "1"; } | { type: "2"; } | { type: "3"; }
> : ^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
| { type: "1" }
>type : "1"
> : ^^^
| { type: "2" }
>type : "2"
> : ^^^
| { type: "3" }
>type : "3"
> : ^^^
| B
| undefined;
// Should NOT error: 'order2' is possibly 'undefined' after the guard
if (order2 && order2.type === "a") {
>order2 && order2.type === "a" : boolean
> : ^^^^^^^
>order2 : B | { type: "1"; } | { type: "2"; } | { type: "3"; }
> : ^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
>order2.type === "a" : boolean
> : ^^^^^^^
>order2.type : "a" | "1" | "2" | "3"
> : ^^^^^^^^^^^^^^^^^^^^^
>order2 : B | { type: "1"; } | { type: "2"; } | { type: "3"; }
> : ^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
>type : "a" | "1" | "2" | "3"
> : ^^^^^^^^^^^^^^^^^^^^^
>"a" : "a"
> : ^^^
order2.type; // Should be OK
>order2.type : "a"
> : ^^^
>order2 : B
> : ^
>type : "a"
> : ^^^
}
// Also test with !. type assertion
if (order1 && order1.type === "a") {
>order1 && order1.type === "a" : boolean
> : ^^^^^^^
>order1 : A | { type: "1"; } | { type: "2"; } | { type: "3"; }
> : ^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
>order1.type === "a" : boolean
> : ^^^^^^^
>order1.type : "a" | "1" | "2" | "3"
> : ^^^^^^^^^^^^^^^^^^^^^
>order1 : A | { type: "1"; } | { type: "2"; } | { type: "3"; }
> : ^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
>type : "a" | "1" | "2" | "3"
> : ^^^^^^^^^^^^^^^^^^^^^
>"a" : "a"
> : ^^^
order1.type; // Should be OK
>order1.type : "a"
> : ^^^
>order1 : A
> : ^
>type : "a"
> : ^^^
}
if (order2 && order2.type === "a") {
>order2 && order2.type === "a" : boolean
> : ^^^^^^^
>order2 : B | { type: "1"; } | { type: "2"; } | { type: "3"; }
> : ^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
>order2.type === "a" : boolean
> : ^^^^^^^
>order2.type : "a" | "1" | "2" | "3"
> : ^^^^^^^^^^^^^^^^^^^^^
>order2 : B | { type: "1"; } | { type: "2"; } | { type: "3"; }
> : ^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^ ^^^
>type : "a" | "1" | "2" | "3"
> : ^^^^^^^^^^^^^^^^^^^^^
>"a" : "a"
> : ^^^
order2.type; // Should be OK
>order2.type : "a"
> : ^^^
>order2 : B
> : ^
>type : "a"
> : ^^^
}

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tests/cases/compiler/discriminantOrderIndependence.ts Normal file
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interface A {
subType: "b";
type: "a";
}
declare let order1:
| { type: "1" }
| A
| { type: "2" }
| { type: "3" }
| undefined;
// Should NOT error: 'order1' is possibly 'undefined' after the guard
if (order1 && order1.type === "a") {
order1.type; // Should be OK
}
interface B {
subType: "b";
type: "a";
}
declare let order2:
| { type: "1" }
| { type: "2" }
| { type: "3" }
| B
| undefined;
// Should NOT error: 'order2' is possibly 'undefined' after the guard
if (order2 && order2.type === "a") {
order2.type; // Should be OK
}
// Also test with !. type assertion
if (order1 && order1.type === "a") {
order1.type; // Should be OK
}
if (order2 && order2.type === "a") {
order2.type; // Should be OK
}