DecorationSet.create unexpectedly modifies input argument array to empty it

[Nantris]

I have some code like this:

const decorations = findDecorations(
  tr.doc,
  mappedPrevDecorations
);
// `decorations` array has 2 items which appear valid to me
const newDecorationSet = DecorationSet.create(
  tr.doc,
  decorations
);
// `decorations` array is empty

Whether my input decorations are valid or not (they may not be as they overlap) - I would never expect for decorations to be emptied out by this code, but it is.

It appears to occur because of these lines: https://github.com/ProseMirror/prosemirror-view/blob/db2223a88b540a8f381fc2720198342e29a60566/src/decoration.ts#L677-L682

[Nantris]

My suggestion is that the array be cloned before being used in this function: https://github.com/ProseMirror/prosemirror-view/blob/db2223a88b540a8f381fc2720198342e29a60566/src/decoration.ts#L689 @marijnh

[marijnh]

I've added a note warning about this to the docs in attached patch. But since it is not typical for code calling this function to use the array passed to it for anything else, enforcing a copy seems needlessly wasteful.

[Nantris]

Seems fair. Thanks for the speed response @marijnh!