Changeset 276942 in webkit

Timestamp:

May 3, 2021 7:37:17 PM (3 years ago)

Author:

mark.lam@apple.com

Message:

Fix syntax error message for AUTOPLUSPLUS token.
​https://bugs.webkit.org/show_bug.cgi?id=225308
rdar://76830934

Reviewed by Saam Barati.

JSTests:

• stress/prefix-plusplus-syntax-error-should-say-plusplus.js: Added.

Source/JavaScriptCore:

For the record, it's not easy to tell from the code why AUTOPLUSPLUS is needed.
It's needed to distinguish this:

`
statement ++ stuff ++ is a postfix operator applied to statement.
`

from this:

`
statement
++stuff The \n before the ++ makes it a prefix operator applied to stuff`.
`

If we merely tokenize the ++ as a PLUSPLUS token, then it's unclear whether it acts
as a postfix or prefix token in the 2nd case above.

This is why the correct fix is not to get rid of the AUTOPLUSPLUS token, but to
teach the syntax error message to be aware of the AUTOPLUSPLUS token.

• parser/Parser.cpp:

(JSC::Parser<LexerType>::parseUnaryExpression):

Location:

trunk

Files:

• JSTests/ChangeLog (modified) (1 diff)
• JSTests/stress/prefix-plusplus-syntax-error-should-say-plusplus.js (added)
• Source/JavaScriptCore/ChangeLog (modified) (1 diff)
• Source/JavaScriptCore/parser/Parser.cpp (modified) (2 diffs)

trunk/JSTests/ChangeLog

@@ +1 @@
+2021-05-03  Mark Lam  <mark.lam@apple.com>
+
+        Fix syntax error message for AUTOPLUSPLUS token.
+        https://bugs.webkit.org/show_bug.cgi?id=225308
+        rdar://76830934
+
+        Reviewed by Saam Barati.
+
+        * stress/prefix-plusplus-syntax-error-should-say-plusplus.js: Added.
+
 2021-05-03  Dmitry Bezhetskov  <dbezhetskov@igalia.com>
 

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2021-05-03  Mark Lam  <mark.lam@apple.com>
+
+        Fix syntax error message for AUTOPLUSPLUS token.
+        https://bugs.webkit.org/show_bug.cgi?id=225308
+        rdar://76830934
+
+        Reviewed by Saam Barati.
+
+        For the record, it's not easy to tell from the code why AUTOPLUSPLUS is needed.
+        It's needed to distinguish this:
+            ```
+            statement ++ stuff  // ++ is a postfix operator applied to `statement`.
+            ```
+        from this:
+            ```
+            statement
+            ++stuff    // The `\n` before the ++ makes it a prefix operator applied to `stuff``.
+            ```
+
+        If we merely tokenize the ++ as a PLUSPLUS token, then it's unclear whether it acts
+        as a postfix or prefix token in the 2nd case above.
+
+        This is why the correct fix is not to get rid of the AUTOPLUSPLUS token, but to
+        teach the syntax error message to be aware of the AUTOPLUSPLUS token.
+
+        * parser/Parser.cpp:
+        (JSC::Parser<LexerType>::parseUnaryExpression):
+
 2021-05-03  Chris Dumez  <cdumez@apple.com>
 

trunk/Source/JavaScriptCore/parser/Parser.cpp

@@ -2 +2 @@
  *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
  *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
- *  Copyright (C) 2003-2019 Apple Inc. All rights reserved.
+ *  Copyright (C) 2003-2021 Apple Inc. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
@@ -5393 +5393 @@
     if (isUpdateOp(static_cast<JSTokenType>(lastOperator))) {
         semanticFailIfTrue(context.isMetaProperty(expr), metaPropertyName(context, expr), " can't come after a prefix operator");
-        semanticFailIfFalse(isSimpleAssignmentTarget(context, expr), "Prefix ", lastOperator == PLUSPLUS ? "++" : "--", " operator applied to value that is not a reference");
+        semanticFailIfFalse(isSimpleAssignmentTarget(context, expr), "Prefix ", lastOperator == PLUSPLUS || lastOperator == AUTOPLUSPLUS ? "++" : "--", " operator applied to value that is not a reference");
     }
     bool isEvalOrArguments = false;