allow unterminated strings in css

CHANGELOG.md

@@ -6,6 +6,45 @@
 
     Go's WebAssembly implementation returns `EINVAL` instead of `ENOTDIR` when using the `readdir` syscall on a file. This messes up esbuild's implementation of node's module resolution algorithm since encountering `ENOTDIR` causes esbuild to continue its search (since it's a normal condition) while other encountering other errors causes esbuild to fail with an I/O error (since it's an unexpected condition). You can encounter this issue in practice if you use node's legacy `NODE_PATH` feature to tell esbuild to resolve node modules in a custom directory that was not installed by npm. This release works around this problem by converting `EINVAL` into `ENOTDIR` for the `readdir` syscall.
 
+* Unterminated strings in CSS are no longer an error
+
+    The CSS specification provides [rules for handling parsing errors](https://www.w3.org/TR/CSS22/syndata.html#parsing-errors). One of those rules is that user agents must close strings upon reaching the end of a line (i.e., before an unescaped line feed, carriage return or form feed character), but then drop the construct (declaration or rule) in which the string was found. For example:
+
+    ```css
+    p {
+      color: green;
+      font-family: 'Courier New Times
+      color: red;
+      color: green;
+    }
+    ```
+
+    ...would be treated the same as:
+
+    ```css
+    p { color: green; color: green; }
+    ```
+
+    ...because the second declaration (from `font-family` to the semicolon after `color: red`) is invalid and is dropped.
+
+    Previously using this CSS with esbuild failed to build due to a syntax error, even though the code can be interpreted by a browser. With this release, the code now produces a warning instead of an error, and esbuild prints the invalid CSS such that it stays invalid in the output:
+
+    ```css
+    /* esbuild's new non-minified output: */
+    p {
+      color: green;
+      font-family: 'Courier New Times
+      color: red;
+      color: green;
+    }
+    ```
+
+    ```css
+    /* esbuild's new minified output: */
+    p{font-family:'Courier New Times
+    color: red;color:green}
+    ```
+
 ## 0.17.12
 
 * Fix a crash when parsing inline TypeScript decorators ([#2991](https://github.com/evanw/esbuild/issues/2991))

internal/css_lexer/css_lexer.go

@@ -19,7 +19,7 @@ const (
 	TEndOfFile T = iota
 
 	TAtKeyword
-	TBadString
+	TUnterminatedString
 	TBadURL
 	TCDC // "-->"
 	TCDO // "<!--"
@@ -785,17 +785,11 @@ func (lexer *lexer) consumeString() T {
 
 			// Otherwise, fall through to ignore the character after the backslash
 
-		case eof:
-			lexer.log.AddError(&lexer.tracker,
-				logger.Range{Loc: logger.Loc{Start: lexer.Token.Range.End()}},
-				"Unterminated string token")
-			return TBadString
-
-		case '\n', '\r', '\f':
-			lexer.log.AddError(&lexer.tracker,
+		case eof, '\n', '\r', '\f':
+			lexer.log.AddID(logger.MsgID_CSS_CSSSyntaxError, logger.Warning, &lexer.tracker,
 				logger.Range{Loc: logger.Loc{Start: lexer.Token.Range.End()}},
 				"Unterminated string token")
-			return TBadString
+			return TUnterminatedString
 
 		case quote:
 			lexer.step()

internal/css_lexer/css_lexer_test.go

@@ -129,10 +129,10 @@ func TestComment(t *testing.T) {
 }
 
 func TestString(t *testing.T) {
-	test.AssertEqualWithDiff(t, lexerError("'"), "<stdin>: ERROR: Unterminated string token\n")
-	test.AssertEqualWithDiff(t, lexerError("\""), "<stdin>: ERROR: Unterminated string token\n")
-	test.AssertEqualWithDiff(t, lexerError("'\\'"), "<stdin>: ERROR: Unterminated string token\n")
-	test.AssertEqualWithDiff(t, lexerError("\"\\\""), "<stdin>: ERROR: Unterminated string token\n")
+	test.AssertEqualWithDiff(t, lexerError("'"), "<stdin>: WARNING: Unterminated string token\n")
+	test.AssertEqualWithDiff(t, lexerError("\""), "<stdin>: WARNING: Unterminated string token\n")
+	test.AssertEqualWithDiff(t, lexerError("'\\'"), "<stdin>: WARNING: Unterminated string token\n")
+	test.AssertEqualWithDiff(t, lexerError("\"\\\""), "<stdin>: WARNING: Unterminated string token\n")
 	test.AssertEqualWithDiff(t, lexerError("''"), "")
 	test.AssertEqualWithDiff(t, lexerError("\"\""), "")
 }

internal/css_parser/css_parser.go

@@ -149,7 +149,7 @@ func (p *parser) expectWithMatchingLoc(kind css_lexer.T, matchingLoc logger.Loc)
 		case css_lexer.TEndOfFile, css_lexer.TWhitespace:
 			text = fmt.Sprintf("Expected %s but found %s", expected, t.Kind.String())
 			t.Range.Len = 0
-		case css_lexer.TBadURL, css_lexer.TBadString:
+		case css_lexer.TBadURL, css_lexer.TUnterminatedString:
 			text = fmt.Sprintf("Expected %s but found %s", expected, t.Kind.String())
 		default:
 			text = fmt.Sprintf("Expected %s but found %q", expected, p.raw())
@@ -172,7 +172,7 @@ func (p *parser) unexpected() {
 		case css_lexer.TEndOfFile, css_lexer.TWhitespace:
 			text = fmt.Sprintf("Unexpected %s", t.Kind.String())
 			t.Range.Len = 0
-		case css_lexer.TBadURL, css_lexer.TBadString:
+		case css_lexer.TBadURL, css_lexer.TUnterminatedString:
 			text = fmt.Sprintf("Unexpected %s", t.Kind.String())
 		default:
 			text = fmt.Sprintf("Unexpected %q", p.raw())

internal/css_parser/css_parser_test.go

@@ -48,6 +48,13 @@ func expectParseError(t *testing.T, contents string, expected string, expectedLo
 	expectPrintedCommon(t, contents, contents, expected, &expectedLog, config.Options{})
 }
 
+func expectParseErrorMinify(t *testing.T, contents string, expected string, expectedLog string) {
+	t.Helper()
+	expectPrintedCommon(t, contents, contents, expected, &expectedLog, config.Options{
+		MinifyWhitespace: true,
+	})
+}
+
 func expectPrinted(t *testing.T, contents string, expected string) {
 	t.Helper()
 	expectPrintedCommon(t, contents, contents, expected, nil, config.Options{})
@@ -278,29 +285,29 @@ func TestString(t *testing.T) {
 	expectPrinted(t, "a:after { content: 'a\\\r\nb' }", "a:after {\n  content: \"ab\";\n}\n")
 	expectPrinted(t, "a:after { content: 'a\\62 c' }", "a:after {\n  content: \"abc\";\n}\n")
 
-	expectParseError(t, "a:after { content: '\r' }", "a:after {\n  content: ' ' };\n}\n",
-		`<stdin>: ERROR: Unterminated string token
-<stdin>: ERROR: Unterminated string token
+	expectParseError(t, "a:after { content: '\r' }", "a:after {\n  content: '\n  ' }\n  ;\n}\n",
+		`<stdin>: WARNING: Unterminated string token
 <stdin>: WARNING: Expected "}" to go with "{"
 <stdin>: NOTE: The unbalanced "{" is here:
+<stdin>: WARNING: Unterminated string token
 `)
-	expectParseError(t, "a:after { content: '\n' }", "a:after {\n  content: ' ' };\n}\n",
-		`<stdin>: ERROR: Unterminated string token
-<stdin>: ERROR: Unterminated string token
+	expectParseError(t, "a:after { content: '\n' }", "a:after {\n  content: '\n  ' }\n  ;\n}\n",
+		`<stdin>: WARNING: Unterminated string token
 <stdin>: WARNING: Expected "}" to go with "{"
 <stdin>: NOTE: The unbalanced "{" is here:
+<stdin>: WARNING: Unterminated string token
 `)
-	expectParseError(t, "a:after { content: '\f' }", "a:after {\n  content: ' ' };\n}\n",
-		`<stdin>: ERROR: Unterminated string token
-<stdin>: ERROR: Unterminated string token
+	expectParseError(t, "a:after { content: '\f' }", "a:after {\n  content: '\n  ' }\n  ;\n}\n",
+		`<stdin>: WARNING: Unterminated string token
 <stdin>: WARNING: Expected "}" to go with "{"
 <stdin>: NOTE: The unbalanced "{" is here:
+<stdin>: WARNING: Unterminated string token
 `)
-	expectParseError(t, "a:after { content: '\r\n' }", "a:after {\n  content: ' ' };\n}\n",
-		`<stdin>: ERROR: Unterminated string token
-<stdin>: ERROR: Unterminated string token
+	expectParseError(t, "a:after { content: '\r\n' }", "a:after {\n  content: '\n  ' }\n  ;\n}\n",
+		`<stdin>: WARNING: Unterminated string token
 <stdin>: WARNING: Expected "}" to go with "{"
 <stdin>: NOTE: The unbalanced "{" is here:
+<stdin>: WARNING: Unterminated string token
 `)
 
 	expectPrinted(t, "a:after { content: '\\1010101' }", "a:after {\n  content: \"\U001010101\";\n}\n")
@@ -1890,4 +1897,6 @@ func TestParseErrorRecovery(t *testing.T) {
 		"<stdin>: ERROR: Expected \")\" to end URL token\n<stdin>: WARNING: Expected \"}\" to go with \"{\"\n<stdin>: NOTE: The unbalanced \"{\" is here:\n")
 	expectParseError(t, "/* @license */ x {} /* @preserve", "/* @license */\nx {\n}\n",
 		"<stdin>: ERROR: Expected \"*/\" to terminate multi-line comment\n<stdin>: NOTE: The multi-line comment starts here:\n")
+	expectParseError(t, "a { b: c; d: 'e\n f: g; h: i }", "a {\n  b: c;\n  d: 'e\n  f: g;\n  h: i;\n}\n", "<stdin>: WARNING: Unterminated string token\n")
+	expectParseErrorMinify(t, "a { b: c; d: 'e\n f: g; h: i }", "a{b:c;d:'e\nf: g;h:i}", "<stdin>: WARNING: Unterminated string token\n")
 }

internal/css_printer/css_printer.go

@@ -805,6 +805,15 @@ func (p *printer) printTokens(tokens []css_ast.Token, opts printTokensOpts) bool
 			p.print(")")
 			p.recordImportPathForMetafile(t.ImportRecordIndex)
 
+		case css_lexer.TUnterminatedString:
+			// We must end this with a newline so that this string stays unterminated
+			p.print(t.Text)
+			p.print("\n")
+			if !p.options.MinifyWhitespace {
+				p.printIndent(opts.indent)
+			}
+			hasWhitespaceAfter = false
+
 		default:
 			p.print(t.Text)
 		}