Whitespace inside elements is not being preserved inside loops

[TehShrike]

Very related to bug #608.

Reproduction: https://svelte.technology/repl?version=1.25.0&gist=10dd087fc24ff3dbf326c06b04e0611a

[Rich-Harris]

thanks, fixed in 1.26

[TehShrike]

So, weird thing - it doesn't look like this was actually fixed: https://svelte.technology/repl?version=1.34.0&gist=10dd087fc24ff3dbf326c06b04e0611a

I'm not sure how this is possible, since that test case in #718 seems to match it pretty exactly, but that repl still shows the issue even in 1.26.0.

[Conduitry]

In that gist, if you take out the second paragraph about "^ Those letters should all have a space between them", then spaces do appear between the letters, which is kind of hilarious.

edit: Also, perhaps more helpful for debugging, if you make sure there's no whitespace between the paragraph the each block (so you have {{/each}}<p> or {{/each}}foo<p>), the spaces appear. This seems in line with what's intended, given the comment

 	// We want to remove trailing whitespace inside an element/component/block,
 	// *unless* there is no whitespace between this node and its next sibling

but I don't know what the goal of this rule is.

[Conduitry]

Been taking another look at this, and I'm still confused. I'm not sure what exactly the nextSibling is meant to be in relation to the current Node. In @TehShrike's REPL example above, it's the '\n\n' after the EachBlock. Since the nextSibling exists and is a Text node beginning with whitespace, we strip the whitespace at the end of the <span>. It seems like in this case for the shouldTrim to be correct, nextSibling would have to be null.

[Conduitry]

v3 repro from #2905:

{#each ['dog', 'hen', 'fox', 'cat', 'pig', 'ant', 'cow', 'koi'] as value}
	<span>{value} </span>
{/each}
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