fix: set Root start/end to null when fragment contains only whitespace (#17125)

* fix: set Root start/end to null when fragment contains only whitespace

* format

* always set root.start to 0 and root.end to template.length

* Update .changeset/fruity-knives-ring.md

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
Co-authored-by: Rich Harris <hello@rich-harris.dev>

.changeset/fruity-knives-ring.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: set AST `root.start` to `0` and `root.end` to `template.length`

packages/svelte/src/compiler/phases/1-parse/index.js

@@ -117,21 +117,8 @@ export class Parser {
 			e.unexpected_eof(this.index);
 		}
 
-		if (this.root.fragment.nodes.length) {
+		this.root.start = 0;
-			let start = /** @type {number} */ (this.root.fragment.nodes[0].start);
+		this.root.end = template.length;
-			while (regex_whitespace.test(template[start])) start += 1;
-
-			let end = /** @type {number} */ (
-				this.root.fragment.nodes[this.root.fragment.nodes.length - 1].end
-			);
-			while (regex_whitespace.test(template[end - 1])) end -= 1;
-
-			this.root.start = start;
-			this.root.end = end;
-		} else {
-			// @ts-ignore
-			this.root.start = this.root.end = null;
-		}
 
 		const options_index = this.root.fragment.nodes.findIndex(
 			/** @param {any} thing */

packages/svelte/tests/parser-modern/samples/comment-before-function-binding/output.json

@@ -1,7 +1,7 @@
 {
 	"css": null,
 	"js": [],
-	"start": 37,
+	"start": 0,
 	"end": 117,
 	"type": "Root",
 	"fragment": {

packages/svelte/tests/parser-modern/samples/comment-before-script/output.json

@@ -2,7 +2,7 @@
 	"css": null,
 	"js": [],
 	"start": 0,
-	"end": 27,
+	"end": 76,
 	"type": "Root",
 	"fragment": {
 		"type": "Fragment",

packages/svelte/tests/parser-modern/samples/css-nth-syntax/output.json

@@ -1079,7 +1079,7 @@
 		}
 	},
 	"js": [],
-	"start": 808,
+	"start": 0,
 	"end": 820,
 	"type": "Root",
 	"fragment": {

packages/svelte/tests/parser-modern/samples/css-pseudo-classes/output.json

@@ -398,8 +398,8 @@
 		}
 	},
 	"js": [],
-	"start": null,
+	"start": 0,
-	"end": null,
+	"end": 386,
 	"type": "Root",
 	"fragment": {
 		"type": "Fragment",

packages/svelte/tests/parser-modern/samples/generic-snippets/output.json

@@ -1,7 +1,7 @@
 {
 	"css": null,
 	"js": [],
-	"start": 30,
+	"start": 0,
 	"end": 192,
 	"type": "Root",
 	"fragment": {

packages/svelte/tests/parser-modern/samples/loose-valid-each-as/output.json

@@ -1,7 +1,7 @@
 {
 	"css": null,
 	"js": [],
-	"start": 45,
+	"start": 0,
 	"end": 119,
 	"type": "Root",
 	"fragment": {

packages/svelte/tests/parser-modern/samples/options/output.json

@@ -2,7 +2,7 @@
 	"css": null,
 	"js": [],
 	"start": 0,
-	"end": 102,
+	"end": 169,
 	"type": "Root",
 	"fragment": {
 		"type": "Fragment",

packages/svelte/tests/parser-modern/samples/script-style-no-markup/input.svelte

@@ -0,0 +1,6 @@
+<script>
+	// script and style but no markup
+</script>
+<style>
+	div { color: red; }
+</style>

packages/svelte/tests/parser-modern/samples/script-style-no-markup/output.json

@@ -0,0 +1,112 @@
+{
+	"css": {
+		"type": "StyleSheet",
+		"start": 54,
+		"end": 91,
+		"attributes": [],
+		"children": [
+			{
+				"type": "Rule",
+				"prelude": {
+					"type": "SelectorList",
+					"start": 63,
+					"end": 66,
+					"children": [
+						{
+							"type": "ComplexSelector",
+							"start": 63,
+							"end": 66,
+							"children": [
+								{
+									"type": "RelativeSelector",
+									"combinator": null,
+									"selectors": [
+										{
+											"type": "TypeSelector",
+											"name": "div",
+											"start": 63,
+											"end": 66
+										}
+									],
+									"start": 63,
+									"end": 66
+								}
+							]
+						}
+					]
+				},
+				"block": {
+					"type": "Block",
+					"start": 67,
+					"end": 82,
+					"children": [
+						{
+							"type": "Declaration",
+							"start": 69,
+							"end": 79,
+							"property": "color",
+							"value": "red"
+						}
+					]
+				},
+				"start": 63,
+				"end": 82
+			}
+		],
+		"content": {
+			"start": 61,
+			"end": 83,
+			"styles": "\n\tdiv { color: red; }\n",
+			"comment": null
+		}
+	},
+	"js": [],
+	"start": 0,
+	"end": 91,
+	"type": "Root",
+	"fragment": {
+		"type": "Fragment",
+		"nodes": [
+			{
+				"type": "Text",
+				"start": 53,
+				"end": 54,
+				"raw": "\n",
+				"data": "\n"
+			}
+		]
+	},
+	"options": null,
+	"instance": {
+		"type": "Script",
+		"start": 0,
+		"end": 53,
+		"context": "default",
+		"content": {
+			"type": "Program",
+			"start": 8,
+			"end": 44,
+			"loc": {
+				"start": {
+					"line": 1,
+					"column": 0
+				},
+				"end": {
+					"line": 3,
+					"column": 0
+				}
+			},
+			"body": [],
+			"sourceType": "module",
+			"trailingComments": [
+				{
+					"type": "Line",
+					"value": " script and style but no markup",
+					"start": 10,
+					"end": 43
+				}
+			]
+		},
+		"attributes": []
+	}
+}

packages/svelte/tests/parser-modern/samples/semicolon-inside-quotes/output.json

@@ -77,7 +77,7 @@
 	},
 	"js": [],
 	"start": 0,
-	"end": 35,
+	"end": 205,
 	"type": "Root",
 	"fragment": {
 		"type": "Fragment",

packages/svelte/tests/parser-modern/samples/snippets/output.json

@@ -1,7 +1,7 @@
 {
 	"css": null,
 	"js": [],
-	"start": 29,
+	"start": 0,
 	"end": 101,
 	"type": "Root",
 	"fragment": {

packages/svelte/tests/parser-modern/samples/typescript-in-event-handler/output.json

@@ -1,7 +1,7 @@
 {
 	"css": null,
 	"js": [],
-	"start": 54,
+	"start": 0,
 	"end": 173,
 	"type": "Root",
 	"fragment": {