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octal escapes are not handled correctly in string literal types #24209
Description
TypeScript Version: 2.9.0-rc
Search Terms: type octal
Code
const a: '\1' = '1'; // 'a' is of type '1' and contains '1'
const b: '\1' = '\1'; // 'b' is of type '1', but contains '\u0001'
const c = '\1'; // same as 'b'Expected behavior:
Octal escapes in string literals are handled correctly.
For LiteralTypeNodes I would probably prefer a grammar error, but type inference also needs to handle octal escapes.
Actual behavior:
Octal escapes are ignored when converting a StringLiteral to a LiteralType.
Related Issues:
Activity
ajafff commentedon May 17, 2018
It seems like this is not specific to literal types. This is caused by incorrect parsing of octal escape sequences in every StringLiteral.
DanielRosenwasser commentedon May 17, 2018
Duplicate of #396.
ajafff commentedon May 17, 2018
#396 is about making octal escape sequences an error. Only #396 (comment) mentions some difficulties with the scanner / parser.
However, I'm ok with closing this as duplicate. I hope nobody uses octal escape sequences anymore so the type checking inconsistencies are not a problem in real world code.
typescript-bot commentedon Jun 2, 2018
Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.