WIP

packages/svelte/src/compiler/phases/1-parse/state/tag.js

@@ -315,7 +315,10 @@ function open(parser) {
 				name
 			},
 			parameters: function_expression.params,
-			body: create_fragment()
+			body: create_fragment(),
+			metadata: {
+				sites: new Set()
+			}
 		});
 		parser.stack.push(block);
 		parser.fragments.push(block.body);
@@ -609,7 +612,8 @@ function special(parser) {
 			expression: expression,
 			metadata: {
 				dynamic: false,
-				args_with_call_expression: new Set()
+				args_with_call_expression: new Set(),
+				snippets: []
 			}
 		});
 	}

packages/svelte/src/compiler/phases/2-analyze/visitors/RenderTag.js

@@ -20,6 +20,9 @@ export function RenderTag(node, context) {
 	node.metadata.dynamic =
 		callee.type !== 'Identifier' || context.state.scope.get(callee.name)?.kind !== 'normal';
 
+	// TODO populate node.metadata.snippets with all the locally-defined snippets that this
+	// could refer to, and create bidirectional links
+
 	context.state.analysis.uses_render_tags = true;
 
 	const raw_args = unwrap_optional(node.expression).arguments;

packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js

@@ -15,6 +15,11 @@ import { mark_subtree_dynamic } from './fragment.js';
  * @param {Context} context
  */
 export function visit_component(node, context) {
+	node.metadata.snippets = [];
+
+	// TODO populate node.metadata.snippets with all the locally-defined snippets that this
+	// could refer to, and create bidirectional links
+
 	mark_subtree_dynamic(context.path);
 
 	for (const attribute of node.attributes) {

packages/svelte/src/compiler/types/template.d.ts

@@ -168,6 +168,9 @@ export namespace AST {
 			dynamic: boolean;
 			args_with_call_expression: Set<number>;
 			path: SvelteNode[];
+			/** The set of locally-defined snippets that this render tag could correspond to,
+			 * used for CSS pruning purposes */
+			snippets: SnippetBlock[];
 		};
 	}
 
@@ -280,6 +283,9 @@ export namespace AST {
 		metadata: {
 			scopes: Record<string, Scope>;
 			dynamic: boolean;
+			/** The set of locally-defined snippets that this component tag could render,
+			 * used for CSS pruning purposes */
+			snippets: SnippetBlock[];
 		};
 	}
 
@@ -320,6 +326,9 @@ export namespace AST {
 		/** @internal */
 		metadata: {
 			scopes: Record<string, Scope>;
+			/** The set of locally-defined snippets that this component tag could render,
+			 * used for CSS pruning purposes */
+			snippets: SnippetBlock[];
 		};
 	}
 
@@ -371,6 +380,9 @@ export namespace AST {
 		/** @internal */
 		metadata: {
 			scopes: Record<string, Scope>;
+			/** The set of locally-defined snippets that this component tag could render,
+			 * used for CSS pruning purposes */
+			snippets: SnippetBlock[];
 		};
 	}
 
@@ -440,6 +452,12 @@ export namespace AST {
 		expression: Identifier;
 		parameters: Pattern[];
 		body: Fragment;
+		/** @internal */
+		metadata: {
+			/** The set of components/render tags that could render this snippet,
+			 * used for CSS pruning */
+			sites: Set<Component | SvelteComponent | RenderTag>;
+		};
 	}
 
 	export interface Attribute extends BaseNode {