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CopilotRyanCavanaugh
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RyanCavanaugh
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Port PR #61376: Fix spurious "used before being assigned" errors in for of/in loops (#2462)
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: RyanCavanaugh <6685088+RyanCavanaugh@users.noreply.github.com>
1 parent 01cac67 commit 4ec6989

5 files changed

Lines changed: 416 additions & 3 deletions

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‎internal/checker/checker.go‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -10831,9 +10831,9 @@ func (c *Checker) checkIdentifier(node *ast.Node, checkMode CheckMode) *Type {
1083110831
// We only look for uninitialized variables in strict null checking mode, and only when we can analyze
1083210832
// the entire control flow graph from the variable's declaration (i.e. when the flow container and
1083310833
// declaration container are the same).
10834-
isNeverInitialized := immediateDeclaration != nil && ast.IsVariableDeclaration(immediateDeclaration) && immediateDeclaration.Initializer() == nil &&
10835-
immediateDeclaration.AsVariableDeclaration().ExclamationToken == nil && c.isMutableLocalVariableDeclaration(immediateDeclaration) &&
10836-
!c.isSymbolAssignedDefinitely(symbol)
10834+
isNeverInitialized := immediateDeclaration != nil && ast.IsVariableDeclaration(immediateDeclaration) && !ast.IsForInOrOfStatement(immediateDeclaration.Parent.Parent) &&
10835+
immediateDeclaration.Initializer() == nil && immediateDeclaration.AsVariableDeclaration().ExclamationToken == nil &&
10836+
c.isMutableLocalVariableDeclaration(immediateDeclaration) && !c.isSymbolAssignedDefinitely(symbol)
1083710837
assumeInitialized := isParameter ||
1083810838
isAlias ||
1083910839
(isOuterVariable && !isNeverInitialized) ||

‎testdata/baselines/reference/compiler/unusedLocalsInForInOrOf1.errors.txt‎

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unusedLocalsInForInOrOf1.ts(2,12): error TS6133: 'f' is declared but its value is never read.
2+
unusedLocalsInForInOrOf1.ts(8,7): error TS6133: 'f' is declared but its value is never read.
3+
unusedLocalsInForInOrOf1.ts(14,12): error TS6133: 'g' is declared but its value is never read.
4+
unusedLocalsInForInOrOf1.ts(20,12): error TS6133: 'f2' is declared but its value is never read.
5+
unusedLocalsInForInOrOf1.ts(26,7): error TS6133: 'f2' is declared but its value is never read.
6+
unusedLocalsInForInOrOf1.ts(32,12): error TS6133: 'g2' is declared but its value is never read.
7+
unusedLocalsInForInOrOf1.ts(38,12): error TS6133: 'f3' is declared but its value is never read.
8+
unusedLocalsInForInOrOf1.ts(44,7): error TS6133: 'f3' is declared but its value is never read.
9+
unusedLocalsInForInOrOf1.ts(50,12): error TS6133: 'g3' is declared but its value is never read.
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==== unusedLocalsInForInOrOf1.ts (9 errors) ====
13+
for (let x of [1, 2]) {
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function f() {
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~
16+
!!! error TS6133: 'f' is declared but its value is never read.
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x;
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}
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}
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for (let x of [1, 2]) {
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let f = () => {
23+
~
24+
!!! error TS6133: 'f' is declared but its value is never read.
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x;
26+
};
27+
}
28+
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for (const x of [1, 2]) {
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function g() {
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~
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!!! error TS6133: 'g' is declared but its value is never read.
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x;
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}
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}
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for (let x in { a: 1, b: 2 }) {
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function f2() {
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~~
40+
!!! error TS6133: 'f2' is declared but its value is never read.
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x;
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}
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}
44+
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for (let x in { a: 1, b: 2 }) {
46+
let f2 = () => {
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~~
48+
!!! error TS6133: 'f2' is declared but its value is never read.
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x;
50+
};
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}
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for (const x in { a: 1, b: 2 }) {
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function g2() {
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~~
56+
!!! error TS6133: 'g2' is declared but its value is never read.
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x;
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}
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}
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for (let { x } of [{ x: 1 }, { x: 2 }]) {
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function f3() {
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~~
64+
!!! error TS6133: 'f3' is declared but its value is never read.
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x;
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}
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}
68+
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for (let { x } of [{ x: 1 }, { x: 2 }]) {
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let f3 = () => {
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~~
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!!! error TS6133: 'f3' is declared but its value is never read.
73+
x;
74+
};
75+
}
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for (const { x } of [{ x: 1 }, { x: 2 }]) {
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function g3() {
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~~
80+
!!! error TS6133: 'g3' is declared but its value is never read.
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x;
82+
}
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}
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‎testdata/baselines/reference/compiler/unusedLocalsInForInOrOf1.symbols‎

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//// [tests/cases/compiler/unusedLocalsInForInOrOf1.ts] ////
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=== unusedLocalsInForInOrOf1.ts ===
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for (let x of [1, 2]) {
5+
>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 0, 8))
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function f() {
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>f : Symbol(f, Decl(unusedLocalsInForInOrOf1.ts, 0, 23))
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x;
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 0, 8))
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}
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}
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for (let x of [1, 2]) {
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 6, 8))
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let f = () => {
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>f : Symbol(f, Decl(unusedLocalsInForInOrOf1.ts, 7, 5))
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x;
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 6, 8))
23+
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};
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}
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for (const x of [1, 2]) {
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 12, 10))
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function g() {
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>g : Symbol(g, Decl(unusedLocalsInForInOrOf1.ts, 12, 25))
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x;
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 12, 10))
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}
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}
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for (let x in { a: 1, b: 2 }) {
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 18, 8))
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>a : Symbol(a, Decl(unusedLocalsInForInOrOf1.ts, 18, 15))
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>b : Symbol(b, Decl(unusedLocalsInForInOrOf1.ts, 18, 21))
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function f2() {
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>f2 : Symbol(f2, Decl(unusedLocalsInForInOrOf1.ts, 18, 31))
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x;
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 18, 8))
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}
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}
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for (let x in { a: 1, b: 2 }) {
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 24, 8))
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>a : Symbol(a, Decl(unusedLocalsInForInOrOf1.ts, 24, 15))
54+
>b : Symbol(b, Decl(unusedLocalsInForInOrOf1.ts, 24, 21))
55+
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let f2 = () => {
57+
>f2 : Symbol(f2, Decl(unusedLocalsInForInOrOf1.ts, 25, 5))
58+
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x;
60+
>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 24, 8))
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};
63+
}
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for (const x in { a: 1, b: 2 }) {
66+
>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 30, 10))
67+
>a : Symbol(a, Decl(unusedLocalsInForInOrOf1.ts, 30, 17))
68+
>b : Symbol(b, Decl(unusedLocalsInForInOrOf1.ts, 30, 23))
69+
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function g2() {
71+
>g2 : Symbol(g2, Decl(unusedLocalsInForInOrOf1.ts, 30, 33))
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x;
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 30, 10))
75+
}
76+
}
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for (let { x } of [{ x: 1 }, { x: 2 }]) {
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 36, 10))
80+
>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 36, 20))
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 36, 30))
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function f3() {
84+
>f3 : Symbol(f3, Decl(unusedLocalsInForInOrOf1.ts, 36, 41))
85+
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x;
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 36, 10))
88+
}
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}
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for (let { x } of [{ x: 1 }, { x: 2 }]) {
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 42, 10))
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 42, 20))
94+
>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 42, 30))
95+
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let f3 = () => {
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>f3 : Symbol(f3, Decl(unusedLocalsInForInOrOf1.ts, 43, 5))
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x;
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 42, 10))
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};
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}
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for (const { x } of [{ x: 1 }, { x: 2 }]) {
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 48, 12))
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 48, 22))
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 48, 32))
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function g3() {
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>g3 : Symbol(g3, Decl(unusedLocalsInForInOrOf1.ts, 48, 43))
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x;
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>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 48, 12))
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}
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}
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‎testdata/baselines/reference/compiler/unusedLocalsInForInOrOf1.types‎

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//// [tests/cases/compiler/unusedLocalsInForInOrOf1.ts] ////
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=== unusedLocalsInForInOrOf1.ts ===
4+
for (let x of [1, 2]) {
5+
>x : number
6+
>[1, 2] : number[]
7+
>1 : 1
8+
>2 : 2
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function f() {
11+
>f : () => void
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x;
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>x : number
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}
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}
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for (let x of [1, 2]) {
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>x : number
20+
>[1, 2] : number[]
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>1 : 1
22+
>2 : 2
23+
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let f = () => {
25+
>f : () => void
26+
>() => { x; } : () => void
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x;
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>x : number
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};
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}
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for (const x of [1, 2]) {
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>x : number
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>[1, 2] : number[]
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>1 : 1
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>2 : 2
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function g() {
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>g : () => void
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x;
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>x : number
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}
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}
47+
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for (let x in { a: 1, b: 2 }) {
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>x : string
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>{ a: 1, b: 2 } : { a: number; b: number; }
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>a : number
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>1 : 1
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>b : number
54+
>2 : 2
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function f2() {
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>f2 : () => void
58+
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x;
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>x : string
61+
}
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}
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for (let x in { a: 1, b: 2 }) {
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>x : string
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>{ a: 1, b: 2 } : { a: number; b: number; }
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>a : number
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>1 : 1
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>b : number
70+
>2 : 2
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let f2 = () => {
73+
>f2 : () => void
74+
>() => { x; } : () => void
75+
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x;
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>x : string
78+
79+
};
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}
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for (const x in { a: 1, b: 2 }) {
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>x : string
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>{ a: 1, b: 2 } : { a: number; b: number; }
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>a : number
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>1 : 1
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>b : number
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>2 : 2
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function g2() {
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>g2 : () => void
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x;
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>x : string
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}
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}
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for (let { x } of [{ x: 1 }, { x: 2 }]) {
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>x : number
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>[{ x: 1 }, { x: 2 }] : { x: number; }[]
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>{ x: 1 } : { x: number; }
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>x : number
103+
>1 : 1
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>{ x: 2 } : { x: number; }
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>x : number
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>2 : 2
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function f3() {
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>f3 : () => void
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x;
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>x : number
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}
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}
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for (let { x } of [{ x: 1 }, { x: 2 }]) {
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>x : number
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>[{ x: 1 }, { x: 2 }] : { x: number; }[]
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>{ x: 1 } : { x: number; }
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>x : number
121+
>1 : 1
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>{ x: 2 } : { x: number; }
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>x : number
124+
>2 : 2
125+
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let f3 = () => {
127+
>f3 : () => void
128+
>() => { x; } : () => void
129+
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x;
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>x : number
132+
133+
};
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}
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for (const { x } of [{ x: 1 }, { x: 2 }]) {
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>x : number
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>[{ x: 1 }, { x: 2 }] : { x: number; }[]
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>{ x: 1 } : { x: number; }
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>x : number
141+
>1 : 1
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>{ x: 2 } : { x: number; }
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>x : number
144+
>2 : 2
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function g3() {
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>g3 : () => void
148+
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x;
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>x : number
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}
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}
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