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Fix noUncheckedIndexedAccess with tuple rest types and generic index types (microsoft#40681)
* Fix noUncheckedIndexedAccess for tuple rest elements * Defer inclusion of undefined for generic indexed access types * Create separate IndexedAccessTypes depending on whether --noUncheckedIndexedAccess applies * Undo accidental export * Parenthesize for clearer precedence
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7 files changed

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-31
lines changed

7 files changed

+243
-31
lines changed

‎src/compiler/checker.ts

Lines changed: 32 additions & 30 deletions
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‎src/compiler/types.ts

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -5323,6 +5323,12 @@ namespace ts {
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export interface IndexedAccessType extends InstantiableType {
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objectType: Type;
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indexType: Type;
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/**
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* @internal
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* Indicates that --noUncheckedIndexedAccess may introduce 'undefined' into
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* the resulting type, depending on how type variable constraints are resolved.
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*/
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noUncheckedIndexedAccessCandidate: boolean;
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constraint?: Type;
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simplifiedForReading?: Type;
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simplifiedForWriting?: Type;

‎tests/baselines/reference/noUncheckedIndexedAccess.errors.txt

Lines changed: 34 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -49,9 +49,16 @@ tests/cases/conformance/pedantic/noUncheckedIndexedAccess.ts(63,5): error TS2322
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tests/cases/conformance/pedantic/noUncheckedIndexedAccess.ts(79,7): error TS2322: Type 'number | boolean | undefined' is not assignable to type 'number | boolean'.
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Type 'undefined' is not assignable to type 'number | boolean'.
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tests/cases/conformance/pedantic/noUncheckedIndexedAccess.ts(85,1): error TS2322: Type 'undefined' is not assignable to type 'string'.
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tests/cases/conformance/pedantic/noUncheckedIndexedAccess.ts(90,7): error TS2322: Type 'string | undefined' is not assignable to type 'string'.
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Type 'undefined' is not assignable to type 'string'.
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tests/cases/conformance/pedantic/noUncheckedIndexedAccess.ts(98,5): error TS2322: Type 'undefined' is not assignable to type '{ [key: string]: string; a: string; b: string; }[Key]'.
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Type 'undefined' is not assignable to type 'string'.
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tests/cases/conformance/pedantic/noUncheckedIndexedAccess.ts(99,11): error TS2322: Type '{ [key: string]: string; a: string; b: string; }[Key]' is not assignable to type 'string'.
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Type 'string | undefined' is not assignable to type 'string'.
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Type 'undefined' is not assignable to type 'string'.
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==== tests/cases/conformance/pedantic/noUncheckedIndexedAccess.ts (28 errors) ====
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==== tests/cases/conformance/pedantic/noUncheckedIndexedAccess.ts (31 errors) ====
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type CheckBooleanOnly<T extends boolean> = any;
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// Validate CheckBooleanOnly works - should error
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type T_ERR1 = CheckBooleanOnly<boolean | undefined>;
@@ -216,4 +223,30 @@ tests/cases/conformance/pedantic/noUncheckedIndexedAccess.ts(85,1): error TS2322
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symbolMap[s] = undefined; // Should error
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~~~~~~~~~~~~
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!!! error TS2322: Type 'undefined' is not assignable to type 'string'.
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// Variadic tuples
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declare const nonEmptyStringArray: [string, ...string[]];
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const variadicOk1: string = nonEmptyStringArray[0]; // Should OK
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const variadicError1: string = nonEmptyStringArray[1]; // Should error
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~~~~~~~~~~~~~~
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!!! error TS2322: Type 'string | undefined' is not assignable to type 'string'.
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!!! error TS2322: Type 'undefined' is not assignable to type 'string'.
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// Generic index type
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declare const myRecord1: { a: string; b: string };
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declare const myRecord2: { a: string; b: string, [key: string]: string };
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const fn1 = <Key extends keyof typeof myRecord1>(key: Key): string => myRecord1[key]; // Should OK
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const fn2 = <Key extends keyof typeof myRecord1>(key: Key): string => myRecord2[key]; // Should OK
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const fn3 = <Key extends keyof typeof myRecord2>(key: Key) => {
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myRecord2[key] = undefined; // Should error
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~~~~~~~~~~~~~~
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!!! error TS2322: Type 'undefined' is not assignable to type '{ [key: string]: string; a: string; b: string; }[Key]'.
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!!! error TS2322: Type 'undefined' is not assignable to type 'string'.
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const v: string = myRecord2[key]; // Should error
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~
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!!! error TS2322: Type '{ [key: string]: string; a: string; b: string; }[Key]' is not assignable to type 'string'.
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!!! error TS2322: Type 'string | undefined' is not assignable to type 'string'.
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!!! error TS2322: Type 'undefined' is not assignable to type 'string'.
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};
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‎tests/baselines/reference/noUncheckedIndexedAccess.js

Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -84,6 +84,22 @@ declare const s: unique symbol;
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declare const symbolMap: { [s]: string };
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const e15: string = symbolMap[s]; // Should OK
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symbolMap[s] = undefined; // Should error
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// Variadic tuples
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declare const nonEmptyStringArray: [string, ...string[]];
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const variadicOk1: string = nonEmptyStringArray[0]; // Should OK
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const variadicError1: string = nonEmptyStringArray[1]; // Should error
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// Generic index type
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declare const myRecord1: { a: string; b: string };
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declare const myRecord2: { a: string; b: string, [key: string]: string };
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const fn1 = <Key extends keyof typeof myRecord1>(key: Key): string => myRecord1[key]; // Should OK
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const fn2 = <Key extends keyof typeof myRecord1>(key: Key): string => myRecord2[key]; // Should OK
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const fn3 = <Key extends keyof typeof myRecord2>(key: Key) => {
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myRecord2[key] = undefined; // Should error
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const v: string = myRecord2[key]; // Should error
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};
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87103

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//// [noUncheckedIndexedAccess.js]
@@ -158,3 +174,11 @@ obj1[z];
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var f1 = strMapUnion["foo"];
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var e15 = symbolMap[s]; // Should OK
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symbolMap[s] = undefined; // Should error
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var variadicOk1 = nonEmptyStringArray[0]; // Should OK
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var variadicError1 = nonEmptyStringArray[1]; // Should error
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var fn1 = function (key) { return myRecord1[key]; }; // Should OK
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var fn2 = function (key) { return myRecord2[key]; }; // Should OK
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var fn3 = function (key) {
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myRecord2[key] = undefined; // Should error
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var v = myRecord2[key]; // Should error
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};

‎tests/baselines/reference/noUncheckedIndexedAccess.symbols

Lines changed: 63 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -287,3 +287,66 @@ symbolMap[s] = undefined; // Should error
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>s : Symbol(s, Decl(noUncheckedIndexedAccess.ts, 81, 13))
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>undefined : Symbol(undefined)
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// Variadic tuples
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declare const nonEmptyStringArray: [string, ...string[]];
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>nonEmptyStringArray : Symbol(nonEmptyStringArray, Decl(noUncheckedIndexedAccess.ts, 87, 13))
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const variadicOk1: string = nonEmptyStringArray[0]; // Should OK
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>variadicOk1 : Symbol(variadicOk1, Decl(noUncheckedIndexedAccess.ts, 88, 5))
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>nonEmptyStringArray : Symbol(nonEmptyStringArray, Decl(noUncheckedIndexedAccess.ts, 87, 13))
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>0 : Symbol(0)
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const variadicError1: string = nonEmptyStringArray[1]; // Should error
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>variadicError1 : Symbol(variadicError1, Decl(noUncheckedIndexedAccess.ts, 89, 5))
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>nonEmptyStringArray : Symbol(nonEmptyStringArray, Decl(noUncheckedIndexedAccess.ts, 87, 13))
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// Generic index type
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declare const myRecord1: { a: string; b: string };
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>myRecord1 : Symbol(myRecord1, Decl(noUncheckedIndexedAccess.ts, 92, 13))
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>a : Symbol(a, Decl(noUncheckedIndexedAccess.ts, 92, 26))
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>b : Symbol(b, Decl(noUncheckedIndexedAccess.ts, 92, 37))
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declare const myRecord2: { a: string; b: string, [key: string]: string };
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>myRecord2 : Symbol(myRecord2, Decl(noUncheckedIndexedAccess.ts, 93, 13))
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>a : Symbol(a, Decl(noUncheckedIndexedAccess.ts, 93, 26))
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>b : Symbol(b, Decl(noUncheckedIndexedAccess.ts, 93, 37))
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>key : Symbol(key, Decl(noUncheckedIndexedAccess.ts, 93, 50))
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const fn1 = <Key extends keyof typeof myRecord1>(key: Key): string => myRecord1[key]; // Should OK
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>fn1 : Symbol(fn1, Decl(noUncheckedIndexedAccess.ts, 94, 5))
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>Key : Symbol(Key, Decl(noUncheckedIndexedAccess.ts, 94, 13))
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>myRecord1 : Symbol(myRecord1, Decl(noUncheckedIndexedAccess.ts, 92, 13))
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>key : Symbol(key, Decl(noUncheckedIndexedAccess.ts, 94, 49))
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>Key : Symbol(Key, Decl(noUncheckedIndexedAccess.ts, 94, 13))
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>myRecord1 : Symbol(myRecord1, Decl(noUncheckedIndexedAccess.ts, 92, 13))
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>key : Symbol(key, Decl(noUncheckedIndexedAccess.ts, 94, 49))
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const fn2 = <Key extends keyof typeof myRecord1>(key: Key): string => myRecord2[key]; // Should OK
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>fn2 : Symbol(fn2, Decl(noUncheckedIndexedAccess.ts, 95, 5))
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>Key : Symbol(Key, Decl(noUncheckedIndexedAccess.ts, 95, 13))
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>myRecord1 : Symbol(myRecord1, Decl(noUncheckedIndexedAccess.ts, 92, 13))
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>key : Symbol(key, Decl(noUncheckedIndexedAccess.ts, 95, 49))
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>Key : Symbol(Key, Decl(noUncheckedIndexedAccess.ts, 95, 13))
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>myRecord2 : Symbol(myRecord2, Decl(noUncheckedIndexedAccess.ts, 93, 13))
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>key : Symbol(key, Decl(noUncheckedIndexedAccess.ts, 95, 49))
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const fn3 = <Key extends keyof typeof myRecord2>(key: Key) => {
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>fn3 : Symbol(fn3, Decl(noUncheckedIndexedAccess.ts, 96, 5))
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>Key : Symbol(Key, Decl(noUncheckedIndexedAccess.ts, 96, 13))
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>myRecord2 : Symbol(myRecord2, Decl(noUncheckedIndexedAccess.ts, 93, 13))
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>key : Symbol(key, Decl(noUncheckedIndexedAccess.ts, 96, 49))
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>Key : Symbol(Key, Decl(noUncheckedIndexedAccess.ts, 96, 13))
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myRecord2[key] = undefined; // Should error
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>myRecord2 : Symbol(myRecord2, Decl(noUncheckedIndexedAccess.ts, 93, 13))
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>key : Symbol(key, Decl(noUncheckedIndexedAccess.ts, 96, 49))
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>undefined : Symbol(undefined)
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const v: string = myRecord2[key]; // Should error
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>v : Symbol(v, Decl(noUncheckedIndexedAccess.ts, 98, 9))
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>myRecord2 : Symbol(myRecord2, Decl(noUncheckedIndexedAccess.ts, 93, 13))
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>key : Symbol(key, Decl(noUncheckedIndexedAccess.ts, 96, 49))
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};
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‎tests/baselines/reference/noUncheckedIndexedAccess.types

Lines changed: 68 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -351,3 +351,71 @@ symbolMap[s] = undefined; // Should error
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>s : unique symbol
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>undefined : undefined
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// Variadic tuples
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declare const nonEmptyStringArray: [string, ...string[]];
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>nonEmptyStringArray : [string, ...string[]]
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const variadicOk1: string = nonEmptyStringArray[0]; // Should OK
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>variadicOk1 : string
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>nonEmptyStringArray[0] : string
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>nonEmptyStringArray : [string, ...string[]]
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>0 : 0
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const variadicError1: string = nonEmptyStringArray[1]; // Should error
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>variadicError1 : string
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>nonEmptyStringArray[1] : string | undefined
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>nonEmptyStringArray : [string, ...string[]]
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>1 : 1
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// Generic index type
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declare const myRecord1: { a: string; b: string };
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>myRecord1 : { a: string; b: string; }
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>a : string
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>b : string
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declare const myRecord2: { a: string; b: string, [key: string]: string };
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>myRecord2 : { [key: string]: string; a: string; b: string; }
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>a : string
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>b : string
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>key : string
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const fn1 = <Key extends keyof typeof myRecord1>(key: Key): string => myRecord1[key]; // Should OK
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>fn1 : <Key extends "a" | "b">(key: Key) => string
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><Key extends keyof typeof myRecord1>(key: Key): string => myRecord1[key] : <Key extends "a" | "b">(key: Key) => string
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>myRecord1 : { a: string; b: string; }
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>key : Key
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>myRecord1[key] : { a: string; b: string; }[Key]
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>myRecord1 : { a: string; b: string; }
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>key : Key
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const fn2 = <Key extends keyof typeof myRecord1>(key: Key): string => myRecord2[key]; // Should OK
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>fn2 : <Key extends "a" | "b">(key: Key) => string
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><Key extends keyof typeof myRecord1>(key: Key): string => myRecord2[key] : <Key extends "a" | "b">(key: Key) => string
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>myRecord1 : { a: string; b: string; }
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>key : Key
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>myRecord2[key] : { [key: string]: string; a: string; b: string; }[Key]
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>myRecord2 : { [key: string]: string; a: string; b: string; }
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>key : Key
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const fn3 = <Key extends keyof typeof myRecord2>(key: Key) => {
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>fn3 : <Key extends string | number>(key: Key) => void
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><Key extends keyof typeof myRecord2>(key: Key) => { myRecord2[key] = undefined; // Should error const v: string = myRecord2[key]; // Should error} : <Key extends string | number>(key: Key) => void
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>myRecord2 : { [key: string]: string; a: string; b: string; }
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>key : Key
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myRecord2[key] = undefined; // Should error
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>myRecord2[key] = undefined : undefined
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>myRecord2[key] : { [key: string]: string; a: string; b: string; }[Key]
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>myRecord2 : { [key: string]: string; a: string; b: string; }
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>key : Key
411+
>undefined : undefined
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const v: string = myRecord2[key]; // Should error
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>v : string
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>myRecord2[key] : { [key: string]: string; a: string; b: string; }[Key]
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>myRecord2 : { [key: string]: string; a: string; b: string; }
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>key : Key
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};
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‎tests/cases/conformance/pedantic/noUncheckedIndexedAccess.ts

Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -86,3 +86,19 @@ declare const s: unique symbol;
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declare const symbolMap: { [s]: string };
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const e15: string = symbolMap[s]; // Should OK
8888
symbolMap[s] = undefined; // Should error
89+
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// Variadic tuples
91+
declare const nonEmptyStringArray: [string, ...string[]];
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const variadicOk1: string = nonEmptyStringArray[0]; // Should OK
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const variadicError1: string = nonEmptyStringArray[1]; // Should error
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// Generic index type
96+
declare const myRecord1: { a: string; b: string };
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declare const myRecord2: { a: string; b: string, [key: string]: string };
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const fn1 = <Key extends keyof typeof myRecord1>(key: Key): string => myRecord1[key]; // Should OK
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const fn2 = <Key extends keyof typeof myRecord1>(key: Key): string => myRecord2[key]; // Should OK
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const fn3 = <Key extends keyof typeof myRecord2>(key: Key) => {
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myRecord2[key] = undefined; // Should error
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const v: string = myRecord2[key]; // Should error
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};
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