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Fix check in getDiscriminantPropertyAccess (#55464)
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5 files changed

+166
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‎src/compiler/checker.ts

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -27460,7 +27460,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
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}
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function getDiscriminantPropertyAccess(expr: Expression, computedType: Type) {
27463-
const type = declaredType.flags & TypeFlags.Union ? declaredType : computedType;
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const type = !(computedType.flags & TypeFlags.Union) && declaredType.flags & TypeFlags.Union ? declaredType : computedType;
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if (type.flags & TypeFlags.Union) {
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const access = getCandidateDiscriminantPropertyAccess(expr);
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if (access) {

‎tests/baselines/reference/narrowingUnionToUnion.js

Lines changed: 28 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -212,6 +212,20 @@ function f1x(obj: (string | number)[] | null) {
212212
assertRelationIsNullOrStringArray(obj);
213213
obj; // string[] | null
214214
}
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// Repro from #55425
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type MyDiscriminatedUnion = { type: 'A', aProp: number } | { type: 'B', bProp: string };
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declare function isMyDiscriminatedUnion(item: unknown): item is MyDiscriminatedUnion;
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declare const working: unknown;
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declare const broken: Record<string, any> | undefined;
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declare const workingAgain: Record<string, any> | undefined | unknown;
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isMyDiscriminatedUnion(working) && working.type === 'A' && working.aProp;
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isMyDiscriminatedUnion(broken) && broken.type === 'A' && broken.aProp;
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isMyDiscriminatedUnion(workingAgain) && workingAgain.type === 'A' && workingAgain.aProp;
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216230

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//// [narrowingUnionToUnion.js]
@@ -370,6 +384,9 @@ function f1x(obj) {
370384
assertRelationIsNullOrStringArray(obj);
371385
obj; // string[] | null
372386
}
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isMyDiscriminatedUnion(working) && working.type === 'A' && working.aProp;
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isMyDiscriminatedUnion(broken) && broken.type === 'A' && broken.aProp;
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isMyDiscriminatedUnion(workingAgain) && workingAgain.type === 'A' && workingAgain.aProp;
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374391

375392
//// [narrowingUnionToUnion.d.ts]
@@ -423,3 +440,14 @@ declare function check2(x: unknown): x is ("hello" | 0);
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declare function test3(x: unknown): void;
424441
declare function assertRelationIsNullOrStringArray(v: (string | number)[] | null): asserts v is string[] | null;
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declare function f1x(obj: (string | number)[] | null): void;
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type MyDiscriminatedUnion = {
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type: 'A';
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aProp: number;
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} | {
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type: 'B';
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bProp: string;
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};
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declare function isMyDiscriminatedUnion(item: unknown): item is MyDiscriminatedUnion;
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declare const working: unknown;
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declare const broken: Record<string, any> | undefined;
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declare const workingAgain: Record<string, any> | undefined | unknown;

‎tests/baselines/reference/narrowingUnionToUnion.symbols

Lines changed: 56 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -482,3 +482,59 @@ function f1x(obj: (string | number)[] | null) {
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>obj : Symbol(obj, Decl(narrowingUnionToUnion.ts, 207, 13))
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}
484484

485+
// Repro from #55425
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type MyDiscriminatedUnion = { type: 'A', aProp: number } | { type: 'B', bProp: string };
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>MyDiscriminatedUnion : Symbol(MyDiscriminatedUnion, Decl(narrowingUnionToUnion.ts, 210, 1))
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>type : Symbol(type, Decl(narrowingUnionToUnion.ts, 214, 29))
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>aProp : Symbol(aProp, Decl(narrowingUnionToUnion.ts, 214, 40))
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>type : Symbol(type, Decl(narrowingUnionToUnion.ts, 214, 60))
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>bProp : Symbol(bProp, Decl(narrowingUnionToUnion.ts, 214, 71))
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declare function isMyDiscriminatedUnion(item: unknown): item is MyDiscriminatedUnion;
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>isMyDiscriminatedUnion : Symbol(isMyDiscriminatedUnion, Decl(narrowingUnionToUnion.ts, 214, 88))
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>item : Symbol(item, Decl(narrowingUnionToUnion.ts, 216, 40))
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>item : Symbol(item, Decl(narrowingUnionToUnion.ts, 216, 40))
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>MyDiscriminatedUnion : Symbol(MyDiscriminatedUnion, Decl(narrowingUnionToUnion.ts, 210, 1))
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declare const working: unknown;
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>working : Symbol(working, Decl(narrowingUnionToUnion.ts, 218, 13))
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declare const broken: Record<string, any> | undefined;
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>broken : Symbol(broken, Decl(narrowingUnionToUnion.ts, 219, 13))
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>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
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declare const workingAgain: Record<string, any> | undefined | unknown;
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>workingAgain : Symbol(workingAgain, Decl(narrowingUnionToUnion.ts, 220, 13))
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>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
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isMyDiscriminatedUnion(working) && working.type === 'A' && working.aProp;
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>isMyDiscriminatedUnion : Symbol(isMyDiscriminatedUnion, Decl(narrowingUnionToUnion.ts, 214, 88))
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>working : Symbol(working, Decl(narrowingUnionToUnion.ts, 218, 13))
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>working.type : Symbol(type, Decl(narrowingUnionToUnion.ts, 214, 29), Decl(narrowingUnionToUnion.ts, 214, 60))
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>working : Symbol(working, Decl(narrowingUnionToUnion.ts, 218, 13))
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>type : Symbol(type, Decl(narrowingUnionToUnion.ts, 214, 29), Decl(narrowingUnionToUnion.ts, 214, 60))
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>working.aProp : Symbol(aProp, Decl(narrowingUnionToUnion.ts, 214, 40))
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>working : Symbol(working, Decl(narrowingUnionToUnion.ts, 218, 13))
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>aProp : Symbol(aProp, Decl(narrowingUnionToUnion.ts, 214, 40))
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isMyDiscriminatedUnion(broken) && broken.type === 'A' && broken.aProp;
522+
>isMyDiscriminatedUnion : Symbol(isMyDiscriminatedUnion, Decl(narrowingUnionToUnion.ts, 214, 88))
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>broken : Symbol(broken, Decl(narrowingUnionToUnion.ts, 219, 13))
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>broken.type : Symbol(type, Decl(narrowingUnionToUnion.ts, 214, 29), Decl(narrowingUnionToUnion.ts, 214, 60))
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>broken : Symbol(broken, Decl(narrowingUnionToUnion.ts, 219, 13))
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>type : Symbol(type, Decl(narrowingUnionToUnion.ts, 214, 29), Decl(narrowingUnionToUnion.ts, 214, 60))
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>broken.aProp : Symbol(aProp, Decl(narrowingUnionToUnion.ts, 214, 40))
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>broken : Symbol(broken, Decl(narrowingUnionToUnion.ts, 219, 13))
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>aProp : Symbol(aProp, Decl(narrowingUnionToUnion.ts, 214, 40))
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531+
isMyDiscriminatedUnion(workingAgain) && workingAgain.type === 'A' && workingAgain.aProp;
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>isMyDiscriminatedUnion : Symbol(isMyDiscriminatedUnion, Decl(narrowingUnionToUnion.ts, 214, 88))
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>workingAgain : Symbol(workingAgain, Decl(narrowingUnionToUnion.ts, 220, 13))
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>workingAgain.type : Symbol(type, Decl(narrowingUnionToUnion.ts, 214, 29), Decl(narrowingUnionToUnion.ts, 214, 60))
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>workingAgain : Symbol(workingAgain, Decl(narrowingUnionToUnion.ts, 220, 13))
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>type : Symbol(type, Decl(narrowingUnionToUnion.ts, 214, 29), Decl(narrowingUnionToUnion.ts, 214, 60))
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>workingAgain.aProp : Symbol(aProp, Decl(narrowingUnionToUnion.ts, 214, 40))
538+
>workingAgain : Symbol(workingAgain, Decl(narrowingUnionToUnion.ts, 220, 13))
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>aProp : Symbol(aProp, Decl(narrowingUnionToUnion.ts, 214, 40))
540+

‎tests/baselines/reference/narrowingUnionToUnion.types

Lines changed: 67 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -507,3 +507,70 @@ function f1x(obj: (string | number)[] | null) {
507507
>obj : string[] | null
508508
}
509509

510+
// Repro from #55425
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type MyDiscriminatedUnion = { type: 'A', aProp: number } | { type: 'B', bProp: string };
513+
>MyDiscriminatedUnion : { type: 'A'; aProp: number; } | { type: 'B'; bProp: string; }
514+
>type : "A"
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>aProp : number
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>type : "B"
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>bProp : string
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519+
declare function isMyDiscriminatedUnion(item: unknown): item is MyDiscriminatedUnion;
520+
>isMyDiscriminatedUnion : (item: unknown) => item is MyDiscriminatedUnion
521+
>item : unknown
522+
523+
declare const working: unknown;
524+
>working : unknown
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declare const broken: Record<string, any> | undefined;
527+
>broken : Record<string, any> | undefined
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declare const workingAgain: Record<string, any> | undefined | unknown;
530+
>workingAgain : unknown
531+
532+
isMyDiscriminatedUnion(working) && working.type === 'A' && working.aProp;
533+
>isMyDiscriminatedUnion(working) && working.type === 'A' && working.aProp : number | false
534+
>isMyDiscriminatedUnion(working) && working.type === 'A' : boolean
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>isMyDiscriminatedUnion(working) : boolean
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>isMyDiscriminatedUnion : (item: unknown) => item is MyDiscriminatedUnion
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>working : unknown
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>working.type === 'A' : boolean
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>working.type : "A" | "B"
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>working : MyDiscriminatedUnion
541+
>type : "A" | "B"
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>'A' : "A"
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>working.aProp : number
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>working : { type: "A"; aProp: number; }
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>aProp : number
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547+
isMyDiscriminatedUnion(broken) && broken.type === 'A' && broken.aProp;
548+
>isMyDiscriminatedUnion(broken) && broken.type === 'A' && broken.aProp : number | false
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>isMyDiscriminatedUnion(broken) && broken.type === 'A' : boolean
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>isMyDiscriminatedUnion(broken) : boolean
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>isMyDiscriminatedUnion : (item: unknown) => item is MyDiscriminatedUnion
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>broken : Record<string, any> | undefined
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>broken.type === 'A' : boolean
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>broken.type : "A" | "B"
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>broken : MyDiscriminatedUnion
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>type : "A" | "B"
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>'A' : "A"
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>broken.aProp : number
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>broken : { type: "A"; aProp: number; }
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>aProp : number
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isMyDiscriminatedUnion(workingAgain) && workingAgain.type === 'A' && workingAgain.aProp;
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>isMyDiscriminatedUnion(workingAgain) && workingAgain.type === 'A' && workingAgain.aProp : number | false
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>isMyDiscriminatedUnion(workingAgain) && workingAgain.type === 'A' : boolean
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>isMyDiscriminatedUnion(workingAgain) : boolean
566+
>isMyDiscriminatedUnion : (item: unknown) => item is MyDiscriminatedUnion
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>workingAgain : unknown
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>workingAgain.type === 'A' : boolean
569+
>workingAgain.type : "A" | "B"
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>workingAgain : MyDiscriminatedUnion
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>type : "A" | "B"
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>'A' : "A"
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>workingAgain.aProp : number
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>workingAgain : { type: "A"; aProp: number; }
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>aProp : number
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‎tests/cases/compiler/narrowingUnionToUnion.ts

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -212,3 +212,17 @@ function f1x(obj: (string | number)[] | null) {
212212
assertRelationIsNullOrStringArray(obj);
213213
obj; // string[] | null
214214
}
215+
216+
// Repro from #55425
217+
218+
type MyDiscriminatedUnion = { type: 'A', aProp: number } | { type: 'B', bProp: string };
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220+
declare function isMyDiscriminatedUnion(item: unknown): item is MyDiscriminatedUnion;
221+
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declare const working: unknown;
223+
declare const broken: Record<string, any> | undefined;
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declare const workingAgain: Record<string, any> | undefined | unknown;
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isMyDiscriminatedUnion(working) && working.type === 'A' && working.aProp;
227+
isMyDiscriminatedUnion(broken) && broken.type === 'A' && broken.aProp;
228+
isMyDiscriminatedUnion(workingAgain) && workingAgain.type === 'A' && workingAgain.aProp;

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