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Literal overflow warnings should only apply to decimal. #24361

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@theemathas

E.g. 0x8888i16 should not warn. Similar to binary operations | and &, hexadecimal, binary, and octal literals are often used to specify the concrete representation in memory whereas decimal literals are used to represent abstract values.

Also note that -(0x8000i16) which evaluates to -32768 (hex: 0x8000i16, which is the minimum value of i16) currently does not warn.

cc #22020

reincarnation of #23463

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  1. steveklabnik commented on Jun 27, 2016

    @steveklabnik
    Contributor

    Triage: @rust-lang/lang , what do you think about this? This does still warn today, and I'm not sure where i stand, personally.

  2. eddyb commented on Jun 27, 2016

    @eddyb
    Contributor

    I would say that 0x8888u16 as i16 is the "correct" form, but I'm a bit torn.

  3. pnkfelix commented on Jul 4, 2016

    @pnkfelix
    Contributor

    I agree with @eddyb

    Also, regarding the -(0x8000i16) that does not warn: that falls at runtime on builds with overflow checking. E.g. debug builds.

  4. estebank commented on Aug 15, 2018

    @estebank
    Contributor

    @rust-lang/lang should we close this given the resolution of #48073? There's no suggestion to write 0x8888u16 as i16, but #48432 could be expanded to do so. Otherwise, if we're not suggesting that, then we we should close this in my opinion.

  5. Mark-Simulacrum commented on Sep 8, 2019

    @Mark-Simulacrum
    Member

    I'm going to go ahead and close this as I think we've essentially intentionally chosen a path here and I believe the suggestion has been implemented, if indirectly, by showing what the literal in i16 would be. It seems like largely writing the "end result" or allowing the lint is an acceptable tradeoff.

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    A-diagnosticsArea: Messages for errors, warnings, and lintsC-feature-requestCategory: A feature request, i.e: not implemented / a PR.T-langRelevant to the language team

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