tidy up

packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js

@@ -1682,16 +1682,18 @@ export const template_visitors = {
 
 				process_children(trimmed, expression, false, { ...context, state });
 
-				let flags = TEMPLATE_FRAGMENT;
-
-				if (state.metadata.context.template_needs_import_node) {
-					flags |= TEMPLATE_USE_IMPORT_NODE;
-				}
-
+				/**
+				 * If the first item in an effect is a static slot or render tag, it will clone
+				 * a template but without creating a child effect. In these cases, we need to keep
+				 * the current `effect.nodes.start` undefined, so that it can be populated by
+				 * the item in question
+				 * TODO come up with a better name than `unset`
+				 */
+				var unset = false;
 				var first = trimmed[0];
 
 				if (first.type === 'SlotElement') {
-					flags |= TEMPLATE_UNSET_START;
+					unset = true;
 				}
 
 				if (first.type === 'Component') {
@@ -1700,7 +1702,7 @@ export const template_visitors = {
 						first.name.includes('.') ? first.name.slice(0, first.name.indexOf('.')) : first.name
 					);
 					if (binding === null || binding.kind === 'normal') {
-						flags |= TEMPLATE_UNSET_START;
+						unset = true;
 					}
 				}
 
@@ -1710,7 +1712,7 @@ export const template_visitors = {
 						callee.type !== 'Identifier' || context.state.scope.get(callee.name)?.kind !== 'normal';
 
 					if (!is_reactive) {
-						flags |= TEMPLATE_UNSET_START;
+						unset = true;
 					}
 				}
 
@@ -1718,8 +1720,18 @@ export const template_visitors = {
 
 				if (use_comment_template) {
 					// special case — we can use `$.comment` instead of creating a unique template
-					body.push(b.var(id, b.call('$.comment', flags !== 0 && b.literal(flags))));
+					body.push(b.var(id, b.call('$.comment', unset && b.literal(unset))));
 				} else {
+					let flags = TEMPLATE_FRAGMENT;
+
+					if (unset) {
+						flags |= TEMPLATE_UNSET_START;
+					}
+
+					if (state.metadata.context.template_needs_import_node) {
+						flags |= TEMPLATE_USE_IMPORT_NODE;
+					}
+
 					add_template(template_name, [
 						b.template([b.quasi(state.template.join(''), true)], []),
 						b.literal(flags)

packages/svelte/src/internal/client/dom/template.js

@@ -238,9 +238,9 @@ export function text(anchor) {
 }
 
 /**
- * @param {number} [flags]
+ * @param {boolean} unset
  */
-export function comment(flags = 0) {
+export function comment(unset = false) {
 	// we're not delegating to `template` here for performance reasons
 	if (hydrating) {
 		assign_nodes(get_start(), hydrate_nodes[hydrate_nodes.length - 1]);
@@ -252,7 +252,7 @@ export function comment(flags = 0) {
 	var anchor = empty();
 	frag.append(anchor);
 
-	assign_nodes((flags & TEMPLATE_UNSET_START) !== 0 ? undefined : null, anchor, anchor);
+	assign_nodes(unset ? undefined : null, anchor, anchor);
 
 	return frag;
 }

packages/svelte/tests/snapshot/samples/bind-this/_expected/client/index.svelte.js

@@ -2,7 +2,7 @@ import "svelte/internal/disclose-version";
 import * as $ from "svelte/internal/client";
 
 export default function Bind_this($$anchor) {
-	var fragment = $.comment(5);
+	var fragment = $.comment(true);
 	var node = $.first_child(fragment);
 
 	$.bind_this(Foo(node, { $$legacy: true }), ($$value) => foo = $$value, () => foo);

packages/svelte/tests/snapshot/samples/each-string-template/_expected/client/index.svelte.js

@@ -2,7 +2,7 @@ import "svelte/internal/disclose-version";
 import * as $ from "svelte/internal/client";
 
 export default function Each_string_template($$anchor) {
-	var fragment = $.comment(1);
+	var fragment = $.comment();
 	var node = $.first_child(fragment);
 
 	$.each(node, 1, () => ['foo', 'bar', 'baz'], $.index, ($$anchor, thing, $$index) => {

packages/svelte/tests/snapshot/samples/function-prop-no-getter/_expected/client/index.svelte.js

@@ -9,7 +9,7 @@ export default function Function_prop_no_getter($$anchor) {
 	}
 
 	const plusOne = (num) => num + 1;
-	var fragment = $.comment(5);
+	var fragment = $.comment(true);
 	var node = $.first_child(fragment);
 
 	Button(node, {

packages/svelte/tests/snapshot/samples/svelte-element/_expected/client/index.svelte.js

@@ -3,7 +3,7 @@ import * as $ from "svelte/internal/client";
 
 export default function Svelte_element($$anchor, $$props) {
 	let tag = $.prop($$props, "tag", 3, 'hr');
-	var fragment = $.comment(1);
+	var fragment = $.comment();
 	var node = $.first_child(fragment);
 
 	$.element(node, tag, false);