sibling stuff

Author: Rich-Harris

packages/svelte/src/compiler/phases/2-analyze/css/css-prune.js

@@ -844,17 +844,17 @@ function get_element_parent(node) {
 }
 
 /**
- * @param {Compiler.AST.RegularElement | Compiler.AST.SvelteElement} element
+ * @param {Compiler.AST.RegularElement | Compiler.AST.SvelteElement | Compiler.AST.RenderTag | Compiler.AST.Component | Compiler.AST.SvelteComponent | Compiler.AST.SvelteSelf} node
  * @param {boolean} adjacent_only
  * @returns {Map<Compiler.AST.RegularElement | Compiler.AST.SvelteElement | Compiler.AST.SlotElement | Compiler.AST.RenderTag, NodeExistsValue>}
  */
-function get_possible_element_siblings(element, adjacent_only) {
+function get_possible_element_siblings(node, adjacent_only) {
 	/** @type {Map<Compiler.AST.RegularElement | Compiler.AST.SvelteElement | Compiler.AST.SlotElement | Compiler.AST.RenderTag, NodeExistsValue>} */
 	const result = new Map();
-	const path = element.metadata.path;
+	const path = node.metadata.path;
 
 	/** @type {Compiler.SvelteNode} */
-	let current = element;
+	let current = node;
 
 	let i = path.length;
 
@@ -896,7 +896,20 @@ function get_possible_element_siblings(element, adjacent_only) {
 
 		current = path[i];
 
-		if (!current || !is_block(current)) break;
+		if (!current) break;
+
+		if (current.type === 'SnippetBlock') {
+			for (const site of current.metadata.sites) {
+				const siblings = get_possible_element_siblings(site, adjacent_only);
+				add_to_map(siblings, result);
+
+				if (adjacent_only && current.metadata.sites.size === 1 && has_definite_elements(siblings)) {
+					return result;
+				}
+			}
+		}
+
+		if (!is_block(current)) break;
 
 		if (current.type === 'EachBlock' && fragment === current.body) {
 			// `{#each ...}<a /><b />{/each}` — `<b>` can be previous sibling of `<a />`

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

@@ -16,6 +16,8 @@ import { mark_subtree_dynamic } from './fragment.js';
  * @param {Context} context
  */
 export function visit_component(node, context) {
+	node.metadata.path = [...context.path];
+
 	// link this node to all the snippets that it could render, so that we can prune CSS correctly
 	node.metadata.snippets = new Set();
 

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

@@ -284,6 +284,7 @@ export namespace AST {
 			/** The set of locally-defined snippets that this component tag could render,
 			 * used for CSS pruning purposes */
 			snippets: Set<SnippetBlock>;
+			path: SvelteNode[];
 		};
 	}
 
@@ -327,6 +328,7 @@ export namespace AST {
 			/** The set of locally-defined snippets that this component tag could render,
 			 * used for CSS pruning purposes */
 			snippets: Set<SnippetBlock>;
+			path: SvelteNode[];
 		};
 	}
 
@@ -381,6 +383,7 @@ export namespace AST {
 			/** The set of locally-defined snippets that this component tag could render,
 			 * used for CSS pruning purposes */
 			snippets: Set<SnippetBlock>;
+			path: SvelteNode[];
 		};
 	}
 

packages/svelte/tests/css/samples/siblings-combinator-render-tag/expected.css

@@ -1,3 +1,4 @@
-  h1.svelte-xyz + p:where(.svelte-xyz) {
-    color: green;
-  }
+
+	h1.svelte-xyz + p:where(.svelte-xyz) {
+		color: green;
+	}