Why can I initialize a Map with an iterable literal but not a variable of an iterable?

I can initialize a new Map() with a literal iterable (array of tuples) without a problem:

const tmp = new Map([
  [1, true],
  [2, false]
])

But if I try to initialize the Map with an iterable array:

const d = [
  [1, true],
  [2, false]
]
const tmp = new Map(d)

I receive error: (I'm not understanding the error)

TS2769: No overload matches this call. Overload 1 of 4 , (iterable?: Iterable<readonly [unknown, unknown]>): Map<unknown, unknown> , gave the following error. Argument of type (number | boolean)[][] is not assignable to parameter of type Iterable<readonly [unknown, unknown]> The types returned by Symbol.iterator.next(...) are incompatible between these types. Type IteratorResult<(number | boolean)[], any> is not assignable to type IteratorResult<readonly [unknown, unknown], any> Type IteratorYieldResult<(number | boolean)[]> is not assignable to type IteratorResult<readonly [unknown, unknown], any> Type IteratorYieldResult<(number | boolean)[]> is not assignable to type IteratorYieldResult<readonly [unknown, unknown]> Type (number | boolean)[] is not assignable to type readonly [unknown, unknown] Target requires 2 element(s) but source may have fewer.

Solution

MapConstructor requires readonly array of readonly tuples of size 2.

interface MapConstructor {
    new(): Map<any, any>;
    new<K, V>(entries?: readonly (readonly [K, V])[] | null): Map<K, V>;
    readonly prototype: Map<any, any>;
}

If you assign an array to a temporary variable, it is inferred to be mutable array of arrays:

size of each inner array is not constrained to 2
Types at each position are not constrained

const d = [
  [1, true],
  [2, false]
];
// const d: (number | boolean)[][]

You can use as const assertion to force it to be readonly tuple of readonly tuples:

const d = [
  [1, true],
  [2, false]
] as const;
// const d: readonly [readonly [1, true], readonly [2, false]]
const tmp = new Map(d);