Add support for dynamic `<slot>` names about lwc HOT 4 OPEN

I tried implementing this and to my surprise it seems to work by simply removing the check:

if (ast.isExpression(nameAttribute.value)) {
    ctx.throwOnNode(ParserDiagnostics.NAME_ON_SLOT_CANNOT_BE_EXPRESSION, nameAttribute);
}

Am I missing something as I suspect? Should I submit a PR?

from lwc.

Does it work if you run yarn && yarn test && yarn test:karma && DISABLE_SYNTHETIC=1 yarn test:karma? Curious whether it actually works across both synthetic and native shadow.

from lwc.

@nolanlawson yes, it only fails the test for the NAME_ON_SLOT_CANNOT_BE_EXPRESSION error, which I believe would be updated / removed.

packages/@lwc/template-compiler/src/tests/fixtures/slots/error-definition-dynamic-name/expected.js

- Expected
+ Received

+ import { registerTemplate } from "lwc";
+ const stc0 = [];
+ function tmpl($api, $cmp, $slotset, $ctx) {
+   const { s: api_slot } = $api;
+   return [
+     api_slot(
+       "",
+       {
+         attrs: {
+           name: $cmp.slotName,
+         },
+         key: 0,
+       },
+       stc0,
+       $slotset
+     ),
+   ];
+   /*LWC compiler vX.X.X*/
+ }
+ export default registerTemplate(tmpl);
+ tmpl.slots = [""];
+ tmpl.stylesheets = [];

I'm guessing we would need a test for the actual feature and perhaps that would fail for non-native dom.

from lwc.

I looked into this a bit further. What makes this complex is that we have a compile-time check to ensure you don't have duplicate slots in the same template:

<slot name="foo"></slot>
<slot name="foo"></slot> <!-- Duplicate -->

One reason to get rid of this check is that native shadow will happily render duplicate slots. It just ignores the second one.

We'd need to check first how this works with light/synthetic shadow though. And possibly mimic the native shadow behavior (or perhaps throw an error at runtime). This may or may not be backwards compatible, though (due to the lwc:spread workaround).

from lwc.