allow for (await using of of of) ;

evanw · Nov 18, 2023 · 7a697c0 · 7a697c0
1 parent 08b4607
commit 7a697c0
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Showing 3 changed files with 15 additions and 9 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -35,17 +35,18 @@
     document.onkeydown=o=>o.keyCode===65&&console.log("🧀");
     ```
 
-* Parse an upcoming change to TypeScript type syntax ([#3490](https://github.com/evanw/esbuild/issues/3490), [#3491](https://github.com/evanw/esbuild/pull/3491))
+* Parse upcoming changes to TypeScript syntax ([#3490](https://github.com/evanw/esbuild/issues/3490), [#3491](https://github.com/evanw/esbuild/pull/3491))
 
-    With this release, you can now use `from` as the name of a default type-only import in TypeScript code:
+    With this release, you can now use `from` as the name of a default type-only import in TypeScript code, as well as `of` as the name of an `await using` loop iteration variable:
 
     ```ts
     import type from from 'from'
+    for (await using of of of) ;
     ```
 
-    This matches a similar [change in the TypeScript compiler](https://github.com/microsoft/TypeScript/issues/56376) which will start allowing this syntax in an upcoming version of TypeScript.
+    This matches similar changes in the TypeScript compiler ([#56376](https://github.com/microsoft/TypeScript/issues/56376) and [#55555](https://github.com/microsoft/TypeScript/issues/55555)) which will start allowing this syntax in an upcoming version of TypeScript. Please never actually write code like this.
 
-    This change was contributed by [@magic-akari](https://github.com/magic-akari).
+    The type-only import syntax change was contributed by [@magic-akari](https://github.com/magic-akari).
 
 ## 0.19.5
 

diff --git a/internal/js_parser/js_parser.go b/internal/js_parser/js_parser.go
@@ -4817,7 +4817,7 @@ func (p *parser) parseExprOrLetOrUsingStmt(opts parseStmtOpts) (js_ast.Expr, js_
 			usingLoc := p.saveExprCommentsHere()
 			usingRange := p.lexer.Range()
 			p.lexer.Next()
-			if p.lexer.Token == js_lexer.TIdentifier && !p.lexer.HasNewlineBefore && (!opts.isForLoopInit || p.lexer.Raw() != "of") {
+			if p.lexer.Token == js_lexer.TIdentifier && !p.lexer.HasNewlineBefore {
 				// It's an "await using" declaration if we get here
 				if opts.lexicalDecl != lexicalDeclAllowAll {
 					p.forbidLexicalDecl(usingRange.Loc)
@@ -7447,6 +7447,8 @@ func (p *parser) parseStmt(opts parseStmtOpts) js_ast.Stmt {
 			return js_ast.Stmt{Loc: loc, Data: &js_ast.SForIn{Init: initOrNil, Value: value, Body: body}}
 		}
 
+		p.lexer.Expect(js_lexer.TSemicolon)
+
 		// "await using" declarations are only allowed in for-of loops
 		if local, ok := initOrNil.Data.(*js_ast.SLocal); ok && local.Kind == js_ast.LocalAwaitUsing {
 			p.log.AddError(&p.tracker, js_lexer.RangeOfIdentifier(p.source, initOrNil.Loc), "\"await using\" declarations are not allowed here")
@@ -7457,8 +7459,6 @@ func (p *parser) parseStmt(opts parseStmtOpts) js_ast.Stmt {
 			p.requireInitializers(local.Kind, decls)
 		}
 
-		p.lexer.Expect(js_lexer.TSemicolon)
-
 		if p.lexer.Token != js_lexer.TSemicolon {
 			testOrNil = p.parseExpr(js_ast.LLowest)
 		}

diff --git a/internal/js_parser/js_parser_test.go b/internal/js_parser/js_parser_test.go
@@ -6399,8 +6399,13 @@ func TestUsing(t *testing.T) {
 	expectPrinted(t, "for (using x = y;;) ;", "for (using x = y; ; )\n  ;\n")
 	expectPrinted(t, "for (using x of y) ;", "for (using x of y)\n  ;\n")
 	expectPrinted(t, "for (using of x) ;", "for (using of x)\n  ;\n")
+	expectPrinted(t, "for (using of of) ;", "for (using of of)\n  ;\n")
+	expectPrinted(t, "for (await using of of x) ;", "for (await using of of x)\n  ;\n")
+	expectPrinted(t, "for (await using of of of) ;", "for (await using of of of)\n  ;\n")
 	expectPrinted(t, "for await (using x of y) ;", "for await (using x of y)\n  ;\n")
 	expectPrinted(t, "for await (using of x) ;", "for await (using of x)\n  ;\n")
+	expectParseError(t, "for (using of of x) ;", "<stdin>: ERROR: Expected \")\" but found \"x\"\n")
+	expectParseError(t, "for (using of of of) ;", "<stdin>: ERROR: Expected \")\" but found \"of\"\n")
 	expectParseError(t, "for (using x in y) ;", "<stdin>: ERROR: \"using\" declarations are not allowed here\n")
 	expectParseError(t, "for (using x;;) ;", "<stdin>: ERROR: The declaration \"x\" must be initialized\n")
 	expectParseError(t, "for (using x = y of z) ;", "<stdin>: ERROR: for-of loop variables cannot have an initializer\n")
@@ -6416,10 +6421,10 @@ func TestUsing(t *testing.T) {
 	expectParseError(t, "await using [x] = y", "<stdin>: ERROR: Invalid assignment target\n")
 	expectParseError(t, "for (await using x in y) ;", "<stdin>: ERROR: \"await using\" declarations are not allowed here\n")
 	expectParseError(t, "for (await using x = y;;) ;", "<stdin>: ERROR: \"await using\" declarations are not allowed here\n")
-	expectParseError(t, "for (await using of x) ;", "<stdin>: ERROR: Invalid assignment target\n")
+	expectParseError(t, "for (await using of x) ;", "<stdin>: ERROR: Expected \";\" but found \"x\"\n")
 	expectParseError(t, "for (await using x = y of z) ;", "<stdin>: ERROR: for-of loop variables cannot have an initializer\n")
 	expectParseError(t, "for (await using \n x of y) ;", "<stdin>: ERROR: Expected \";\" but found \"x\"\n")
-	expectParseError(t, "for await (await using of x) ;", "<stdin>: ERROR: Invalid assignment target\n")
+	expectParseError(t, "for await (await using of x) ;", "<stdin>: ERROR: Expected \"of\" but found \"x\"\n")
 	expectParseError(t, "for await (await using x = y of z) ;", "<stdin>: ERROR: for-of loop variables cannot have an initializer\n")
 	expectParseError(t, "for await (await using \n x of y) ;", "<stdin>: ERROR: Expected \"of\" but found \"x\"\n")