Fix line returns segments being one character too long on Windows

.changeset/eleven-planets-camp.md

@@ -0,0 +1,5 @@
+---
+"@astrojs/compiler": patch
+---
+
+Fixes sourcemapping for CRLF line endings wrongfully including the last character

internal/printer/printer.go

@@ -107,14 +107,22 @@ func (p *printer) addTSXStyle(start int, end int, content string, styleType stri
 
 func (p *printer) printTextWithSourcemap(text string, l loc.Loc) {
 	start := l.Start
+	skipNext := false
 	for pos, c := range text {
-		// Handle Windows-specific "\r\n" newlines
+		if skipNext {
+			skipNext = false
+			continue
+		}
+
+		// If we encounter a CRLF, map both characters to the same location
 		if c == '\r' && len(text[pos:]) > 1 && text[pos+1] == '\n' {
-			// tiny optimization: avoid calling `utf8.DecodeRuneInString`
-			// if we know the next char is `\n`
-			start++
+			p.addSourceMapping(loc.Loc{Start: start})
+			p.print("\r\n")
+			start += 2
+			skipNext = true
 			continue
 		}
+
 		_, nextCharByteSize := utf8.DecodeRuneInString(text[pos:])
 		p.addSourceMapping(loc.Loc{Start: start})
 		p.print(string(c))
@@ -124,12 +132,19 @@ func (p *printer) printTextWithSourcemap(text string, l loc.Loc) {
 
 func (p *printer) printEscapedJSXTextWithSourcemap(text string, l loc.Loc) {
 	start := l.Start
+	skipNext := false
 	for pos, c := range text {
-		// Handle Windows-specific "\r\n" newlines
+		if skipNext {
+			skipNext = false
+			continue
+		}
+
+		// If we encounter a CRLF, map both characters to the same location
 		if c == '\r' && len(text[pos:]) > 1 && text[pos+1] == '\n' {
-			// tiny optimization: avoid calling `utf8.DecodeRuneInString`
-			// if we know the next char is `\n`
-			start++
+			p.addSourceMapping(loc.Loc{Start: start})
+			p.print("\r\n")
+			start += 2
+			skipNext = true
 			continue
 		}
 

packages/compiler/test/tsx-sourcemaps/template-windows.ts

@@ -3,6 +3,17 @@ import { test } from 'uvu';
 import * as assert from 'uvu/assert';
 import { testTSXSourcemap } from '../utils.js';
 
+test('last character does not end up in middle of CRLF', async () => {
+	const input = "---\r\nimport { Meta } from '$lib/components/Meta.astro';\r\n---\r\n";
+	const output = await testTSXSourcemap(input, ';');
+	assert.equal(output, {
+		source: 'index.astro',
+		line: 2,
+		column: 50,
+		name: null,
+	});
+});
+
 test('template expression basic', async () => {
 	const input = '<div>{\r\nnonexistent\r\n}</div>';