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jack-williamsjack-williams
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Enforce strictNullChecks for RHS of empty destructuring assignment
When strictNullChecks is on, check the RHS of the following destructuring assignments for possible null or undefined: const {} = ... const [] = ... let {} = ... let [] = ... ({} = ...)
1 parent 8bce69e commit 4acdca5

6 files changed

Lines changed: 268 additions & 1 deletion

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‎src/compiler/checker.ts‎

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -18908,6 +18908,9 @@ namespace ts {
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target = (<BinaryExpression>target).left;
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}
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if (target.kind === SyntaxKind.ObjectLiteralExpression) {
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if (strictNullChecks && (<ObjectLiteralExpression>target).properties.length === 0) {
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return checkNonNullType(sourceType, target);
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}
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return checkObjectLiteralAssignment(<ObjectLiteralExpression>target, sourceType);
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}
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if (target.kind === SyntaxKind.ArrayLiteralExpression) {
@@ -21833,7 +21836,11 @@ namespace ts {
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if (isBindingPattern(node.name)) {
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// Don't validate for-in initializer as it is already an error
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if (node.initializer && node.parent.parent.kind !== SyntaxKind.ForInStatement) {
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checkTypeAssignableTo(checkExpressionCached(node.initializer), getWidenedTypeForVariableLikeDeclaration(node), node, /*headMessage*/ undefined);
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const initializerType = checkExpressionCached(node.initializer);
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if (strictNullChecks && node.name.elements.length === 0) {
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checkNonNullType(initializerType, node);
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}
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checkTypeAssignableTo(initializerType, getWidenedTypeForVariableLikeDeclaration(node), node, /*headMessage*/ undefined);
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checkParameterInitializer(node);
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}
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return;

‎tests/baselines/reference/strictNullEmptyDestructuring.errors.txt‎

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tests/cases/compiler/strictNullEmptyDestructuring.ts(3,5): error TS2531: Object is possibly 'null'.
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tests/cases/compiler/strictNullEmptyDestructuring.ts(5,5): error TS2531: Object is possibly 'null'.
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tests/cases/compiler/strictNullEmptyDestructuring.ts(7,2): error TS2531: Object is possibly 'null'.
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tests/cases/compiler/strictNullEmptyDestructuring.ts(9,5): error TS2532: Object is possibly 'undefined'.
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tests/cases/compiler/strictNullEmptyDestructuring.ts(11,2): error TS2532: Object is possibly 'undefined'.
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tests/cases/compiler/strictNullEmptyDestructuring.ts(13,5): error TS2531: Object is possibly 'null'.
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tests/cases/compiler/strictNullEmptyDestructuring.ts(15,2): error TS2531: Object is possibly 'null'.
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tests/cases/compiler/strictNullEmptyDestructuring.ts(17,5): error TS2532: Object is possibly 'undefined'.
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tests/cases/compiler/strictNullEmptyDestructuring.ts(19,2): error TS2532: Object is possibly 'undefined'.
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tests/cases/compiler/strictNullEmptyDestructuring.ts(21,5): error TS2533: Object is possibly 'null' or 'undefined'.
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tests/cases/compiler/strictNullEmptyDestructuring.ts(23,2): error TS2533: Object is possibly 'null' or 'undefined'.
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==== tests/cases/compiler/strictNullEmptyDestructuring.ts (11 errors) ====
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// Repro from #20873
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let [] = null;
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~~
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!!! error TS2531: Object is possibly 'null'.
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let { } = null;
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~~~
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!!! error TS2531: Object is possibly 'null'.
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({} = null);
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~~
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!!! error TS2531: Object is possibly 'null'.
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let { } = undefined;
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~~~
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!!! error TS2532: Object is possibly 'undefined'.
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({} = undefined);
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~~
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!!! error TS2532: Object is possibly 'undefined'.
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let { } = Math.random() ? {} : null;
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~~~
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!!! error TS2531: Object is possibly 'null'.
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({} = Math.random() ? {} : null);
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~~
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!!! error TS2531: Object is possibly 'null'.
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let { } = Math.random() ? {} : undefined;
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~~~
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!!! error TS2532: Object is possibly 'undefined'.
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({} = Math.random() ? {} : undefined);
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~~
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!!! error TS2532: Object is possibly 'undefined'.
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let { } = Math.random() ? null : undefined;
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~~~
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!!! error TS2533: Object is possibly 'null' or 'undefined'.
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({} = Math.random() ? null : undefined);
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~~
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!!! error TS2533: Object is possibly 'null' or 'undefined'.
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‎tests/baselines/reference/strictNullEmptyDestructuring.js‎

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//// [strictNullEmptyDestructuring.ts]
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// Repro from #20873
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let [] = null;
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let { } = null;
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({} = null);
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let { } = undefined;
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({} = undefined);
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let { } = Math.random() ? {} : null;
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({} = Math.random() ? {} : null);
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let { } = Math.random() ? {} : undefined;
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({} = Math.random() ? {} : undefined);
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let { } = Math.random() ? null : undefined;
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({} = Math.random() ? null : undefined);
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//// [strictNullEmptyDestructuring.js]
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// Repro from #20873
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var _a = null;
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var _b = null;
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(null);
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var _c = undefined;
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(undefined);
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var _d = Math.random() ? {} : null;
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(Math.random() ? {} : null);
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var _e = Math.random() ? {} : undefined;
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(Math.random() ? {} : undefined);
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var _f = Math.random() ? null : undefined;
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(Math.random() ? null : undefined);

‎tests/baselines/reference/strictNullEmptyDestructuring.symbols‎

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=== tests/cases/compiler/strictNullEmptyDestructuring.ts ===
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// Repro from #20873
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let [] = null;
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let { } = null;
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({} = null);
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let { } = undefined;
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>undefined : Symbol(undefined)
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({} = undefined);
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>undefined : Symbol(undefined)
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let { } = Math.random() ? {} : null;
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>Math.random : Symbol(Math.random, Decl(lib.d.ts, --, --))
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>Math : Symbol(Math, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
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>random : Symbol(Math.random, Decl(lib.d.ts, --, --))
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({} = Math.random() ? {} : null);
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>Math.random : Symbol(Math.random, Decl(lib.d.ts, --, --))
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>Math : Symbol(Math, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
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>random : Symbol(Math.random, Decl(lib.d.ts, --, --))
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let { } = Math.random() ? {} : undefined;
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>Math.random : Symbol(Math.random, Decl(lib.d.ts, --, --))
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>Math : Symbol(Math, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
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>random : Symbol(Math.random, Decl(lib.d.ts, --, --))
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>undefined : Symbol(undefined)
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({} = Math.random() ? {} : undefined);
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>Math.random : Symbol(Math.random, Decl(lib.d.ts, --, --))
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>Math : Symbol(Math, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
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>random : Symbol(Math.random, Decl(lib.d.ts, --, --))
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>undefined : Symbol(undefined)
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let { } = Math.random() ? null : undefined;
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>Math.random : Symbol(Math.random, Decl(lib.d.ts, --, --))
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>Math : Symbol(Math, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
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>random : Symbol(Math.random, Decl(lib.d.ts, --, --))
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>undefined : Symbol(undefined)
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({} = Math.random() ? null : undefined);
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>Math.random : Symbol(Math.random, Decl(lib.d.ts, --, --))
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>Math : Symbol(Math, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
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>random : Symbol(Math.random, Decl(lib.d.ts, --, --))
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>undefined : Symbol(undefined)
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‎tests/baselines/reference/strictNullEmptyDestructuring.types‎

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=== tests/cases/compiler/strictNullEmptyDestructuring.ts ===
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// Repro from #20873
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let [] = null;
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>null : null
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let { } = null;
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>null : null
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({} = null);
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>({} = null) : any
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>{} = null : any
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>{} : {}
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>null : null
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let { } = undefined;
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>undefined : undefined
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({} = undefined);
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>({} = undefined) : any
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>{} = undefined : any
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>{} : {}
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>undefined : undefined
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let { } = Math.random() ? {} : null;
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>Math.random() ? {} : null : {} | null
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>Math.random() : number
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>Math.random : () => number
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>Math : Math
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>random : () => number
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>{} : {}
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>null : null
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({} = Math.random() ? {} : null);
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>({} = Math.random() ? {} : null) : {}
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>{} = Math.random() ? {} : null : {}
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>{} : {}
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>Math.random() ? {} : null : {} | null
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>Math.random() : number
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>Math.random : () => number
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>Math : Math
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>random : () => number
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>{} : {}
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>null : null
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let { } = Math.random() ? {} : undefined;
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>Math.random() ? {} : undefined : {} | undefined
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>Math.random() : number
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>Math.random : () => number
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>Math : Math
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>random : () => number
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>{} : {}
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>undefined : undefined
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({} = Math.random() ? {} : undefined);
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>({} = Math.random() ? {} : undefined) : {}
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>{} = Math.random() ? {} : undefined : {}
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>{} : {}
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>Math.random() ? {} : undefined : {} | undefined
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>Math.random() : number
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>Math.random : () => number
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>Math : Math
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>random : () => number
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>{} : {}
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>undefined : undefined
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let { } = Math.random() ? null : undefined;
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>Math.random() ? null : undefined : null | undefined
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>Math.random() : number
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>Math.random : () => number
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>Math : Math
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>random : () => number
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>null : null
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>undefined : undefined
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({} = Math.random() ? null : undefined);
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>({} = Math.random() ? null : undefined) : any
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>{} = Math.random() ? null : undefined : any
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>{} : {}
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>Math.random() ? null : undefined : null | undefined
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>Math.random() : number
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>Math.random : () => number
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>Math : Math
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>random : () => number
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>null : null
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>undefined : undefined
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‎tests/cases/compiler/strictNullEmptyDestructuring.ts‎

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// @strictNullChecks: true
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// Repro from #20873
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let [] = null;
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let { } = null;
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({} = null);
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let { } = undefined;
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({} = undefined);
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let { } = Math.random() ? {} : null;
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({} = Math.random() ? {} : null);
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let { } = Math.random() ? {} : undefined;
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({} = Math.random() ? {} : undefined);
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let { } = Math.random() ? null : undefined;
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({} = Math.random() ? null : undefined);

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