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LibJS: Tweak generated source in 'new Function()' to match ES 2015 spec

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ES 5(.1) described parsing of the function body string as:

https://www.ecma-international.org/ecma-262/5.1/#sec-15.3.2.1

7. If P is not parsable as a FormalParameterList[opt] then throw a SyntaxError exception.
8. If body is not parsable as FunctionBody then throw a SyntaxError exception.

We implemented it as building the source string of a complete function
and feeding that to the parser, with the same outcome. ES 2015+ does
exactly that, but with newlines at certain positions:

https://tc39.es/ecma262/#sec-createdynamicfunction

16. Let bodyString be the string-concatenation of 0x000A (LINE FEED), ? ToString(bodyArg), and 0x000A (LINE FEED).
17. Let prefix be the prefix associated with kind in Table 49.
18. Let sourceString be the string-concatenation of prefix, " anonymous(", P, 0x000A (LINE FEED), ") {", bodyString, and "}".

This patch updates the generated source string to match these
requirements. This will make certain edge cases work, e.g.
'new Function("-->")', where the user supplied input must be placed on
its own line to be valid syntax.
This commit is contained in:
Linus Groh 2020-10-29 18:11:35 +00:00 • committed by Andreas Kling
parent bed270ca47
commit a10d09faba
3 changed files with 16 additions and 8 deletions
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4
Libraries/LibJS/Tests/builtins/Function/Function.js
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@ -30,6 +30,8 @@ describe("correct behavior", () => {
expect(new Function("return typeof Function()")()).toBe("function");
expect(new Function("x", "return function (y) { return x + y };")(1)(2)).toBe(3);
expect(new Function("-->")()).toBeUndefined();
expect(new Function().name).toBe("anonymous");
expect(new Function().toString()).toBe("function anonymous() {\n ???\n}");
});
@ -45,7 +47,7 @@ describe("errors", () => {
// This is in line with what other engines are reporting.
.toThrowWithMessage(
SyntaxError,
"Unexpected token CurlyClose. Expected BracketClose (line: 1, column: 26)"
"Unexpected token CurlyClose. Expected BracketClose (line: 4, column: 1)"
);
});
});