Distribute property type union members to create union of object types

TypeScript Version: v3.9.0-dev.20200222

Search Terms: union type object property

Code

type Test =
  | { b: [false, "a"] }
  | { b: [true, "b"] }
  
declare const b2: boolean;
const a: Test = { b: b2 ? [b2, "b"] : [b2, "a"] }

Expected behavior:
No error. I'm not exactly sure if this is a bug or feature request but, essentially, it'd be nice if TS could recognize that: { b: [true, "b"] | [false, "a"]; } is identical to { b: [true, "b"] } | { b: [false, "a"]; }

Actual behavior:

Type '{ b: [true, "b"] | [false, "a"]; }' is not assignable to type 'Test'.
  Type '{ b: [true, "b"] | [false, "a"]; }' is not assignable to type '{ b: [true, "b"]; }'.
    Types of property 'b' are incompatible.
      Type '[true, "b"] | [false, "a"]' is not assignable to type '[true, "b"]'.
        Type '[false, "a"]' is not assignable to type '[true, "b"]'.
          Type 'false' is not assignable to type 'true'.

Playground Link: Playground Link

首先，在链接的 Playground 中重现 issue 的 TypeScript 代码示例中的赋值，并将报告的诊断与预期行为进行比较。完成的标准是示例被接受，同时保留对不兼容的元组和对象联合类型的正确检查；issue 中未指定源文件或测试路径。