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LibJS: Implement rules for duplicate function parameters

- A regular function can have duplicate parameters except in strict mode
  or if its parameter list is not "simple" (has a default or rest
  parameter)
- An arrow function can never have duplicate parameters

Compared to other engines I opted for more useful syntax error messages
than a generic "duplicate parameter name not allowed in this context":

    "use strict"; function test(foo, foo) {}
                                     ^
    Uncaught exception: [SyntaxError]: Duplicate parameter 'foo' not allowed in strict mode (line: 1, column: 34)

    function test(foo, foo = 1) {}
                       ^
    Uncaught exception: [SyntaxError]: Duplicate parameter 'foo' not allowed in function with default parameter (line: 1, column: 20)

    function test(foo, ...foo) {}
                          ^
    Uncaught exception: [SyntaxError]: Duplicate parameter 'foo' not allowed in function with rest parameter (line: 1, column: 23)

    (foo, foo) => {}
          ^
    Uncaught exception: [SyntaxError]: Duplicate parameter 'foo' not allowed in arrow function (line: 1, column: 7)
This commit is contained in:
Linus Groh 2020-10-25 11:14:04 +00:00 committed by Andreas Kling
parent b1eeb15129
commit dca9e4ec10
4 changed files with 83 additions and 7 deletions

View file

@ -47,6 +47,7 @@ struct FunctionNodeParseOptions {
AllowSuperConstructorCall = 1 << 2,
IsGetterFunction = 1 << 3,
IsSetterFunction = 1 << 4,
IsArrowFunction = 1 << 5,
};
};