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octal escapes are not handled correctly in string literal types #24209

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octal escapes are not handled correctly in string literal types#24209
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Description

@ajafff
Klaus Meinhardt (ajafff)
opened on May 17, 2018

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.

Playground Link: https://agentcooper.github.io/typescript-play/?target=5#code/MYewdgzgLgBAhgLhgcgDoEZkwLwswbhgHoiU4sBLCGEAMxigE8AHAUzyzjABMZQwocCpA4AoftBgAjJGkw4UGZIRIoplanQYt2yTABppAV1j9Bw6miMAGW5nHhJwBXOXFSEOAFt2cS+qA

Related Issues:

Activity

  1. ajafff commented on May 17, 2018

    @ajafff
    Klaus Meinhardt (ajafff)
    on May 17, 2018
    ContributorAuthor

    It seems like this is not specific to literal types. This is caused by incorrect parsing of octal escape sequences in every StringLiteral.

  2. DanielRosenwasser commented on May 17, 2018

    @DanielRosenwasser
    Daniel Rosenwasser (DanielRosenwasser)
    on May 17, 2018
    Member

    Duplicate of #396.

  3. Daniel Rosenwasser (DanielRosenwasser)
    added
    DuplicateAn existing issue was already created
    on May 17, 2018

  4. ajafff commented on May 17, 2018

    @ajafff
    Klaus Meinhardt (ajafff)
    on May 17, 2018
    ContributorAuthor

    #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.

  5. typescript-bot commented on Jun 2, 2018

    @typescript-bot
    TypeScript Bot (typescript-bot)
    on Jun 2, 2018
    Contributor

    Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.

  6. TypeScript Bot (typescript-bot)
    closed this as completedon Jun 2, 2018
  7. microsoft
    locked and limited conversation to collaborators on Aug 2, 2018
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