Component Not Defined not working for buildin javascript objects

[bwbroersma]

Describe the bug

<String />

Compiles and results in a runtime error of string.$$ is undefined: REPL.

Math, Map, Set, RexExp, etc. (resulting in other errors)

Instead of <Random /> which would result in 'Random' is not defined. Consider adding a <script> block with 'export let Random' to declare a prop (1:0)

Expected behavior
Check if String is a defined Svelte Component instead of defined in javascript.

[Conduitry]

String is one of the known globals that we don't warn about not being declared, so I guess this is a proposal to not consider those when encountering names used for components. I'm not sure how much trouble that'd be. We currently don't really distinguish between different ways that variables are used.

[bwbroersma]

@Conduitry I guess it's just adding a node.type check in Component.ts:

if (globals.has(name) && node.type != 'InlineComponent') return;

[anlexN]

@bwbroersma do you review svelte source code?

[bwbroersma]

@anlexN If you wonder how we found this bug: @neoel and I sat down on a project he started making slate-svelte (a svelte rich text editor). During the debugging of a rewrite step from React to Svelte we noticed something strange (I think I noticed the WTF is going on and he immediately said "haha, it's a bug", we forgot to import String from './String.svelte'). After the reply from Conduitry I searched for the error message and poked around: first making a failing test case, then first tried:

if (globals.has(name) && !template_scope) return;

which fixed my test case, but ❌ failed many others 😉, then wondered if it could be solved with the node parameter, so added a console.log(node), rerun the tests, looked at some output, made the final code change, and all test ✔️ succeeded. This is about my way of problem solving in a large unknown codebase, it only works if there are lot's of tests. Also, please consider my patch with this in mind, I have little knowledge about the Svelte internals.

[Conduitry]

In 3.16.1 this now produces a warning - https://svelte.dev/repl/1ad764d626f54d60b4b03cef168d6b85?version=3.16.1