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Destructing assignment fail to implicit cast type #26804

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@joshuaavalon

Description

@joshuaavalon

TypeScript Version: 3.1.0

Search Terms: destruct implicit type

Code

enum Kind {
    Square = "square",
    Rectangle = "rectangle"
  }
  
  type Shape =
    | {
        kind: Kind.Square;
        size: number;
      }
    | {
        kind: Kind.Rectangle;
        width: number;
        height: number;
      };
  
  function area(s: Shape) {
    switch (s.kind) {
      case Kind.Square: {
        let b = s.size * s.size;
        break;
      }
      default: {
        let b = s.width * s.height;
        break;
      }
    }
  }
  
  function area2(s: Shape) {
    const { kind } = s;
    switch (kind) {
      case Kind.Square: {
        // [ts]
        // Property 'width' does not exist on type 'Shape'.
        // Property 'width' does not exist on type '{ kind: Kind.Square; size: number; }'.
        let b = s.size * s.size;
        break;
      }
      default: {
        // [ts]
        // Property 'width' does not exist on type 'Shape'.
        // Property 'width' does not exist on type '{ kind: Kind.Square; size: number; }'.
        let b = s.width * s.height;
        break;
      }
    }
  }

Expected behavior:
No error

Actual behavior:

test.ts(34,19): error TS2339: Property 'size' does not exist on type 'Shape'.
  Property 'size' does not exist on type '{ kind: Kind.Rectangle; width: number; height: number; }'.
test.ts(34,28): error TS2339: Property 'size' does not exist on type 'Shape'.
  Property 'size' does not exist on type '{ kind: Kind.Rectangle; width: number; height: number; }'.
test.ts(38,19): error TS2339: Property 'width' does not exist on type 'Shape'.
  Property 'width' does not exist on type '{ kind: Kind.Square; size: number; }'.
test.ts(38,29): error TS2339: Property 'height' does not exist on type 'Shape'.
  Property 'height' does not exist on type '{ kind: Kind.Square; size: number; }'.

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