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navya9singhnavya9singh
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noUncheckedIndexedAccess with enums Type narrowed
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‎src/compiler/checker.ts

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@@ -15589,6 +15589,11 @@ m2: ${(this.mapper2 as unknown as DebugTypeMapper).__debugToString().split("\n")
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return accessFlags & AccessFlags.IncludeUndefined ? getUnionType([indexInfo.type, undefinedType]) : indexInfo.type;
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}
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errorIfWritingToReadonlyIndex(indexInfo);
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if (accessFlags & AccessFlags.IncludeUndefined && objectType.symbol.flags & (SymbolFlags.RegularEnum | SymbolFlags.ConstEnum)) {
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if(indexType.flags & TypeFlags.EnumLiteral){
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return indexInfo.type;
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}
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}
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return accessFlags & AccessFlags.IncludeUndefined ? getUnionType([indexInfo.type, undefinedType]) : indexInfo.type;
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}
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if (indexType.flags & TypeFlags.Never) {

‎tests/baselines/reference/noUncheckedIndexAccess.js

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//// [noUncheckedIndexAccess.ts]
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enum Meat {
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Sausage,
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Bacon
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}
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const sausage = Meat.Sausage
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const valueSausage = Meat[sausage]
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const bacon = Meat.Bacon
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const valueBacon = Meat[bacon]
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const union: Meat.Bacon | Meat.Sausage = Meat.Bacon
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const valueUnion = Meat[union]
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//Avoiding a false positive
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const value = Meat[0]
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const t = "testing"
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const value2 = Meat[t]
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//// [noUncheckedIndexAccess.js]
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var Meat;
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(function (Meat) {
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Meat[Meat["Sausage"] = 0] = "Sausage";
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Meat[Meat["Bacon"] = 1] = "Bacon";
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})(Meat || (Meat = {}));
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var sausage = Meat.Sausage;
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var valueSausage = Meat[sausage];
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var bacon = Meat.Bacon;
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var valueBacon = Meat[bacon];
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var union = Meat.Bacon;
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var valueUnion = Meat[union];
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//Avoiding a false positive
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var value = Meat[0];
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var t = "testing";
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var value2 = Meat[t];

‎tests/baselines/reference/noUncheckedIndexAccess.symbols

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=== tests/cases/compiler/noUncheckedIndexAccess.ts ===
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enum Meat {
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>Meat : Symbol(Meat, Decl(noUncheckedIndexAccess.ts, 0, 0))
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Sausage,
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>Sausage : Symbol(Meat.Sausage, Decl(noUncheckedIndexAccess.ts, 0, 11))
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Bacon
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>Bacon : Symbol(Meat.Bacon, Decl(noUncheckedIndexAccess.ts, 1, 12))
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}
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const sausage = Meat.Sausage
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>sausage : Symbol(sausage, Decl(noUncheckedIndexAccess.ts, 4, 7))
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>Meat.Sausage : Symbol(Meat.Sausage, Decl(noUncheckedIndexAccess.ts, 0, 11))
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>Meat : Symbol(Meat, Decl(noUncheckedIndexAccess.ts, 0, 0))
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>Sausage : Symbol(Meat.Sausage, Decl(noUncheckedIndexAccess.ts, 0, 11))
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const valueSausage = Meat[sausage]
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>valueSausage : Symbol(valueSausage, Decl(noUncheckedIndexAccess.ts, 5, 7))
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>Meat : Symbol(Meat, Decl(noUncheckedIndexAccess.ts, 0, 0))
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>sausage : Symbol(sausage, Decl(noUncheckedIndexAccess.ts, 4, 7))
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const bacon = Meat.Bacon
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>bacon : Symbol(bacon, Decl(noUncheckedIndexAccess.ts, 7, 7))
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>Meat.Bacon : Symbol(Meat.Bacon, Decl(noUncheckedIndexAccess.ts, 1, 12))
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>Meat : Symbol(Meat, Decl(noUncheckedIndexAccess.ts, 0, 0))
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>Bacon : Symbol(Meat.Bacon, Decl(noUncheckedIndexAccess.ts, 1, 12))
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const valueBacon = Meat[bacon]
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>valueBacon : Symbol(valueBacon, Decl(noUncheckedIndexAccess.ts, 8, 7))
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>Meat : Symbol(Meat, Decl(noUncheckedIndexAccess.ts, 0, 0))
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>bacon : Symbol(bacon, Decl(noUncheckedIndexAccess.ts, 7, 7))
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const union: Meat.Bacon | Meat.Sausage = Meat.Bacon
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>union : Symbol(union, Decl(noUncheckedIndexAccess.ts, 10, 7))
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>Meat : Symbol(Meat, Decl(noUncheckedIndexAccess.ts, 0, 0))
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>Bacon : Symbol(Meat.Bacon, Decl(noUncheckedIndexAccess.ts, 1, 12))
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>Meat : Symbol(Meat, Decl(noUncheckedIndexAccess.ts, 0, 0))
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>Sausage : Symbol(Meat.Sausage, Decl(noUncheckedIndexAccess.ts, 0, 11))
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>Meat.Bacon : Symbol(Meat.Bacon, Decl(noUncheckedIndexAccess.ts, 1, 12))
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>Meat : Symbol(Meat, Decl(noUncheckedIndexAccess.ts, 0, 0))
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>Bacon : Symbol(Meat.Bacon, Decl(noUncheckedIndexAccess.ts, 1, 12))
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const valueUnion = Meat[union]
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>valueUnion : Symbol(valueUnion, Decl(noUncheckedIndexAccess.ts, 11, 7))
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>Meat : Symbol(Meat, Decl(noUncheckedIndexAccess.ts, 0, 0))
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>union : Symbol(union, Decl(noUncheckedIndexAccess.ts, 10, 7))
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//Avoiding a false positive
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const value = Meat[0]
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>value : Symbol(value, Decl(noUncheckedIndexAccess.ts, 14, 7))
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>Meat : Symbol(Meat, Decl(noUncheckedIndexAccess.ts, 0, 0))
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const t = "testing"
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>t : Symbol(t, Decl(noUncheckedIndexAccess.ts, 16, 7))
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const value2 = Meat[t]
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>value2 : Symbol(value2, Decl(noUncheckedIndexAccess.ts, 17, 7))
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>Meat : Symbol(Meat, Decl(noUncheckedIndexAccess.ts, 0, 0))
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>t : Symbol(t, Decl(noUncheckedIndexAccess.ts, 16, 7))
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‎tests/baselines/reference/noUncheckedIndexAccess.types

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=== tests/cases/compiler/noUncheckedIndexAccess.ts ===
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enum Meat {
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>Meat : Meat
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Sausage,
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>Sausage : Meat.Sausage
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Bacon
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>Bacon : Meat.Bacon
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}
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const sausage = Meat.Sausage
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>sausage : Meat.Sausage
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>Meat.Sausage : Meat.Sausage
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>Meat : typeof Meat
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>Sausage : Meat.Sausage
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const valueSausage = Meat[sausage]
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>valueSausage : string
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>Meat[sausage] : string
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>Meat : typeof Meat
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>sausage : Meat.Sausage
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const bacon = Meat.Bacon
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>bacon : Meat.Bacon
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>Meat.Bacon : Meat.Bacon
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>Meat : typeof Meat
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>Bacon : Meat.Bacon
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const valueBacon = Meat[bacon]
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>valueBacon : string
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>Meat[bacon] : string
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>Meat : typeof Meat
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>bacon : Meat.Bacon
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const union: Meat.Bacon | Meat.Sausage = Meat.Bacon
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>union : Meat
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>Meat : any
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>Meat : any
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>Meat.Bacon : Meat.Bacon
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>Meat : typeof Meat
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>Bacon : Meat.Bacon
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const valueUnion = Meat[union]
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>valueUnion : string
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>Meat[union] : string
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>Meat : typeof Meat
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>union : Meat.Bacon
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//Avoiding a false positive
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const value = Meat[0]
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>value : string | undefined
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>Meat[0] : string | undefined
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>Meat : typeof Meat
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>0 : 0
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const t = "testing"
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>t : "testing"
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>"testing" : "testing"
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const value2 = Meat[t]
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>value2 : error
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>Meat[t] : error
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>Meat : typeof Meat
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>t : "testing"
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‎tests/cases/compiler/noUncheckedIndexAccess.ts

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//@noUncheckedIndexedAccess: true
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//@strictNullChecks: true
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enum Meat {
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Sausage,
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Bacon
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}
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const sausage = Meat.Sausage
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const valueSausage = Meat[sausage]
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const bacon = Meat.Bacon
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const valueBacon = Meat[bacon]
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const union: Meat.Bacon | Meat.Sausage = Meat.Bacon
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const valueUnion = Meat[union]
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//Avoiding a false positive
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const value = Meat[0]
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const t = "testing"
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const value2 = Meat[t]

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