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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Erroneous errors for multiline statements that include BigInt literal suffix","articleBody":"\u003c!--\r\nThank you for reporting a possible bug in Node.js.\r\n\r\nPlease fill in as much of the template below as you can.\r\n\r\nVersion: output of `node -v`\r\nPlatform: output of `uname -a` (UNIX), or version and 32 or 64-bit (Windows)\r\nSubsystem: if known, please specify the affected core module name\r\n\r\nIf possible, please provide code that demonstrates the problem, keeping it as\r\nsimple and free of external dependencies as you can.\r\n--\u003e\r\n\r\n* **Version**: v10.15.0, v10.15.1, v11.8.0\r\n* **Platform**: Linux \u003cname redacted\u003e 4.15.0-43-generic  # 46~16.04.1-Ubuntu SMP Fri Dec 7 13:31:08 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux\r\n* **Subsystem**: REPL\r\n\r\n\u003c!-- Please provide more details below this comment. --\u003e\r\n## Possibly related to the issues discussed in #24231\r\n\r\nWhen attempting to create a multiline statement that includes the BigInt literal suffix syntax (i.e. Number followed by `n` to denote a BigInt) causes an erroneous `SyntaxError: Invalid or unexpected token` to be thrown. This behavior appears to occur only when the end of the statement is not on the same line as the BigInt. For example, the following seems to be erroneous behavior:\r\n\r\n```\r\n\u003e let a = [\r\n... 4,\r\n... 'hello',\r\n... 0xffn,\r\nThrown:\r\n0xffn,\r\n     ^\r\n\r\nSyntaxError: Unexpected end of input\r\n```\r\n\r\nWhereas if the statement ends on the same line, it seems to behave as expected:\r\n\r\n```\r\n\u003e [\r\n... 4,\r\n... 'hello',\r\n... 0xffn]\r\n[ 4, 'hello', 255n ]\r\n```\r\n\r\nThe same behavior seems to extend to any multiline statements regardless of whether or not the BigNum is the last thing on the line:\r\n\r\nWith BigNum:\r\n```\r\n\u003e function fun(){\r\n... let m = 0xffn; return m;\r\nThrown:\r\nlet m = 0xffn; return m;\r\n                       ^\r\n\r\nSyntaxError: Unexpected end of input\r\n```\r\nWithout BigNum:\r\n```\r\nfunction fun(){\r\n... let m = 0xff; return m;\r\n... }\r\nundefined\r\n```\r\nBigNum on same line as closing bracket:\r\n```\r\n\u003e function fun(){\r\n... let m = 0xffn; return m;}\r\nundefined\r\n\u003e fun()\r\n255n\r\n```\r\n\r\n### Edit (Not sure if helpful):\r\n\r\nBigInt suffix seems to be picked up as an identifier. Given the following input into REPL:\r\n```\r\n\u003e [\r\n... 0xffn,\r\n\r\n\u003cdebugger paused on pressing return key\u003e\r\n```\r\n\r\n`pp$4.raise()` at line 2753 in `internal/deps/acorn/dist/acorn.js` is receiving `pos = 6, message = \"Identifier directly after number (2:4)`\r\n\r\nThat in turn seems to be coming from `pp$8.readRadixNumber()` at line 4981 in `internal/deps/acorn/dist/acorn.js`\r\n\r\nThe issue seems to originate at `isIdentifierStart()` (internal/deps/acorn/dist/acorn.js:71), which does in fact pick up `n` as the start of an identifier.\r\n\r\n`isIdentifierStart()` is also called by `pp$8.readNumber()` when using a normal, non-radix-prefixed number, producing the same result.\r\n\r\n`isIdentifierStart()` is bypassed when the statement is terminated on the same line as the BigInt, which explains why this scenario does not trigger the error:\r\n```\r\n\u003e [\r\n... 0xffn]\r\n[ 255n ]\r\n\u003e\r\n```","author":{"url":"https://github.com/MatteBru","@type":"Person","name":"MatteBru"},"datePublished":"2019-01-30T23:09:12.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/25835/node/issues/25835"}