[Issue 2172] New: bool add bool accepted?

[Issue 2172] statically disallow bool + bool

Jan 30, 2012

http://d.puremagic.com/issues/show_bug.cgi?id=2172 Summary: bool add bool accepted? Product: D Version: 1.030 Platform: PC OS/Version: Windows Status: NEW Severity: normal Priority: P2 Component: DMD AssignedTo: bugzilla@digitalmars.com ReportedBy: davidl@126.com BugsThisDependsOn: 1511 bool t; t= true+false; // this accepted t= true+true; // Error: cannot implicitly convert expression (2) of type int to bool bool type shouldn't be addable. and error message is confusing. --

http://d.puremagic.com/issues/show_bug.cgi?id=2172 bugzilla@digitalmars.com changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution| |INVALID ------- Comment #1 from bugzilla@digitalmars.com 2008-06-27 17:15 ------- bool follows the same integral promotion rules that C has, and this is working as designed. I also do not understand why the error message is confusing - 2 cannot be implicitly converted to bool, as it says. --

http://d.puremagic.com/issues/show_bug.cgi?id=2172 ------- Comment #2 from shro8822@vandals.uidaho.edu 2008-06-27 17:29 ------- I think the confusion comes from the cast failure being value dependent rather than just type dependent. --

June 27, 2008

Re: [Issue 2172] bool add bool accepted?

Posted by Jarrett Billingsley
in reply to d-bugmail

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Jarrett Billingsley

Posted in reply to d-bugmail

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<d-bugmail@puremagic.com> wrote in message news:g43oq2$2k82$1@digitalmars.com...
> http://d.puremagic.com/issues/show_bug.cgi?id=2172
>
>
> bugzilla@digitalmars.com changed:
>
>           What    |Removed                     |Added
> ----------------------------------------------------------------------------
>             Status|NEW                         |RESOLVED
>         Resolution|                            |INVALID
>
>
>
>
> ------- Comment #1 from bugzilla@digitalmars.com  2008-06-27 17:15 -------
> bool follows the same integral promotion rules that C has, and this is
> working
> as designed. I also do not understand why the error message is confusing -
> 2
> cannot be implicitly converted to bool, as it says.

I can understand the OP's confusion.

http://www.digitalmars.com/d/1.0/type.html

"The only operators that can accept operands of type bool are: & | ^ &= |= ^= ! && || ?:. A bool value can be implicitly converted to any integral type, with false becoming 0 and true becoming 1."

Which one is it?  It seems that promotion to an int makes the first rule unnecessary.

Also, keep in mind that D *is* your language and you don't *have* to do everything the same way as C.  I think that having boolean types not implicitly convertible to ints makes a lot more sense.

http://d.puremagic.com/issues/show_bug.cgi?id=2172 davidl@126.com changed: What |Removed |Added ---------------------------------------------------------------------------- Status|RESOLVED |REOPENED Resolution|INVALID | ------- Comment #3 from davidl@126.com 2008-06-29 22:11 ------- I don't think we still need to keep consistent with C on that exactly point. Compiler can at least giving a waring on this. And adding code to BinExp::semantic , and provide a table like implicitconv table [op, e1->type, e2->type] mapping to bin op allow for TOK.TOKadd, bool, bool -> false TOK.TOKmul, bool, bool -> false and this naturally fix issue 1511 --

http://d.puremagic.com/issues/show_bug.cgi?id=2172 bearophile_hugs@eml.cc changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bearophile_hugs@eml.cc --- Comment #4 from bearophile_hugs@eml.cc 2012-01-30 04:28:27 PST --- The error message looks clear. And and this point I don't think D boolean semantics will change. So I think this bug report needs to be closed. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=2172 yebblies <yebblies@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|REOPENED |RESOLVED Resolution| |FIXED --- Comment #5 from yebblies <yebblies@gmail.com> 2012-01-31 02:17:02 EST --- I tend to agree. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

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