fixes after landing #2038

Author: evanw

CHANGELOG.md

@@ -2,6 +2,17 @@
 
 ## Unreleased
 
+* Add support for parsing "instantiation expressions" from TypeScript 4.7 ([#2038](https://github.com/evanw/esbuild/pull/2038))
+
+    The upcoming version of TypeScript now lets you specify `<...>` type parameters on a JavaScript identifier without using a call expression:
+
+    ```ts
+    const ErrorMap = Map<string, Error>;  // new () => Map<string, Error>
+    const errorMap = new ErrorMap();  // Map<string, Error>
+    ```
+
+    With this release, esbuild can now parse these new type annotations. This feature was contributed by [@g-plane](https://github.com/g-plane).
+
 * Avoid `new Function` in esbuild's library code ([#2081](https://github.com/evanw/esbuild/issues/2081))
 
     Some JavaScript environments such as Cloudflare Workers or Deno Deploy don't allow `new Function` because they disallow dynamic JavaScript evaluation. Previously esbuild's WebAssembly-based library used this to construct the WebAssembly worker function. With this release, the code is now inlined without using `new Function` so it will be able to run even when this restriction is in place.

internal/js_lexer/js_lexer.go

@@ -2191,12 +2191,10 @@ func (lexer *Lexer) ScanRegExp() {
 		}
 
 		switch lexer.codePoint {
-		case '\r', '\n', 0x2028, 0x2029:
-			// Newlines aren't allowed in regular expressions
-			lexer.SyntaxError()
-
-		case -1: // This indicates the end of the file
-			lexer.SyntaxError()
+		case -1, // This indicates the end of the file
+			'\r', '\n', 0x2028, 0x2029: // Newlines aren't allowed in regular expressions
+			lexer.addRangeError(logger.Range{Loc: logger.Loc{Start: int32(lexer.end)}}, "Unterminated regular expression")
+			panic(LexerPanic{})
 
 		default:
 			lexer.step()

internal/js_parser/ts_parser.go

@@ -790,17 +790,16 @@ func (p *parser) isTSArrowFnJSX() (isTSArrowFn bool) {
 func (p *parser) canFollowTypeArgumentsInExpression() bool {
 	switch p.lexer.Token {
 	case
-		// These are the only tokens can legally follow a type argument list. So we
-		// definitely want to treat them as type arg lists.
+		// These tokens can follow a type argument list in a call expression.
 		js_lexer.TOpenParen,                     // foo<x>(
 		js_lexer.TNoSubstitutionTemplateLiteral, // foo<T> `...`
 		js_lexer.TTemplateHead:                  // foo<T> `...${100}...`
 		return true
 
 	case
-		// These tokens can't follow in a call expression,
-		// nor can they start an expression.
-		// So, consider the type argument list part of an instantiation expression.
+		// These tokens can't follow in a call expression, nor can they start an
+		// expression. So, consider the type argument list part of an instantiation
+		// expression.
 		js_lexer.TComma,                   // foo<x>,
 		js_lexer.TDot,                     // foo<x>.
 		js_lexer.TQuestionDot,             // foo<x>?.

internal/js_parser/ts_parser_test.go

@@ -1620,6 +1620,14 @@ func TestTSInstantiationExpression(t *testing.T) {
 
 	expectParseErrorTS(t, "const a8 = f<number><number>;", "<stdin>: ERROR: Unexpected \";\"\n")
 	expectParseErrorTS(t, "const b1 = f?.<number>;", "<stdin>: ERROR: Expected \"(\" but found \";\"\n")
+
+	// The TypeScript compiler doesn't do semicolon insertion before "<" when
+	// inside "typeof" but does in other situations. Was this an oversight? Not sure,
+	// but we replicate this behavior because it matters when JSX syntax is enabled.
+	expectPrintedTSX(t, "type x = typeof y\n<number>\n1", "1;\n")
+	expectParseErrorTS(t, "type x = typeof y\n<number>\n1\n</number>", "<stdin>: ERROR: Unterminated regular expression\n")
+	expectParseErrorTSX(t, "type x = y\n<number>\n1", "<stdin>: ERROR: Unexpected end of file\n")
+	expectPrintedTSX(t, "type x = y\n<number>\n1\n</number>", "/* @__PURE__ */ React.createElement(\"number\", null, \"1\");\n")
 }
 
 func TestTSExponentiation(t *testing.T) {
@@ -1952,7 +1960,7 @@ func TestTSNoAmbiguousLessThan(t *testing.T) {
 		"<stdin>: ERROR: This syntax is not allowed in files with the \".mts\" or \".cts\" extension\n")
 	expectParseErrorTSNoAmbiguousLessThan(t, "<x>y</x>",
 		"<stdin>: ERROR: This syntax is not allowed in files with the \".mts\" or \".cts\" extension\n"+
-			"<stdin>: ERROR: Unexpected end of file\n")
+			"<stdin>: ERROR: Unterminated regular expression\n")
 	expectParseErrorTSNoAmbiguousLessThan(t, "<x extends></x>",
 		"<stdin>: ERROR: This syntax is not allowed in files with the \".mts\" or \".cts\" extension\n"+
 			"<stdin>: ERROR: Unexpected \">\"\n")