fix: Don’t require getCollection() filter to be a type guard (#5998)

Commit dabce6b (#5970) broke the use
of a plain boolean filter.  Add an overload similar to TypeScript’s
Array#filter overload:

https://github.com/microsoft/TypeScript/blob/v4.9.4/lib/lib.es5.d.ts#L1442-L1453

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

.changeset/rotten-dogs-hide.md

@@ -0,0 +1,5 @@
+---
+"astro": patch
+---
+
+Update `getCollection()` filter to support type guards _or_ unknown values

packages/astro/src/content/internal.ts

@@ -40,7 +40,7 @@ export function createGetCollection({
 	collectionToEntryMap: CollectionToEntryMap;
 	collectionToRenderEntryMap: CollectionToEntryMap;
 }) {
-	return async function getCollection(collection: string, filter?: () => boolean) {
+	return async function getCollection(collection: string, filter?: (entry: any) => unknown) {
 		const lazyImports = Object.values(collectionToEntryMap[collection] ?? {});
 		const entries = Promise.all(
 			lazyImports.map(async (lazyImport) => {

packages/astro/src/content/template/types.d.ts

@@ -48,6 +48,10 @@ declare module 'astro:content' {
 		collection: C,
 		filter?: (entry: CollectionEntry<C>) => entry is E
 	): Promise<E[]>;
+	export function getCollection<C extends keyof typeof entryMap>(
+		collection: C,
+		filter?: (entry: CollectionEntry<C>) => unknown
+	): Promise<CollectionEntry<C>[]>;
 
 	type InferEntrySchema<C extends keyof typeof entryMap> = import('astro/zod').infer<
 		Required<ContentConfig['collections'][C]>['schema']