New Linting Rule - No Accumulating Spread

[Vivalldi]

Suggested Rule - performance.noAccumulatingSpread

Disallow the use of spread (...) syntax on accumulators.

Spread syntax allows an iterable to be expanded into its individual elements.

Spread syntax should be avoided on accumulators (like those in .reduce) because it causes a time complexity of O(n^2).

Examples

Invalid

something.reduce((acc, item) => ({ ...acc, [item.key]: item.value }), {});

Valid

something.reduce((acc, item) => {
	acc[item.key] = item.value;
	return acc;
}, {});

Object.fromEntries(something.map((item) => [item.key, item.value]));

something.reduce((acc, item) => Object.assign(acc, { [item.key]: item.value }), {});

[Vivalldi]

Initial implementation done in #4426