<svelte:component> evaluates props twice

[cleiner]

Describe the bug

In a <svelte:component> like the following, where a prop value is the result of a function call and both the function as well as the component constructor are contained in a common parent object, the function call is executed twice each time the constructor changes:

<svelte:component this={view.component} value={view.fn()}/>

Looking at the generated code, it appears that the component's p() method computes the values for switch_instance_changes without checking if it's actually required -- if the constructor (switch_value) changes, switch_instance_changes will never be used, but fn() will be called again in switch_props() instead:

function switch_props(ctx) {
	return { props: { value: /*view*/ ctx[0].fn() } };
}

p(ctx, [dirty]) {
	const switch_instance_changes = {};
	if (dirty & /*view*/ 1) switch_instance_changes.value = /*view*/ ctx[0].fn();

	if (switch_value !== (switch_value = /*view*/ ctx[0].comp)) {
		...
		switch_instance = new switch_value(switch_props(ctx));
	} else if (switch_value) {
		switch_instance.$set(switch_instance_changes);
	}
},
...

Reproduction

https://svelte.dev/repl/b00cabd142d64ab9b872ec69dbe9b0bb?version=3.42.1

Logs

No response

System Info

n/a

Severity

annoyance

[dummdidumm]

Possibly the same underlying reason as for #5689