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digitalmars.D.bugs - [Issue 2172] New: bool add bool accepted?

reply d-bugmail puremagic.com writes:
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.


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Jun 25 2008
next sibling parent reply d-bugmail puremagic.com writes:
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.


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Jun 27 2008
parent "Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:
<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.
Jun 27 2008
prev sibling next sibling parent d-bugmail puremagic.com writes:
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.


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Jun 27 2008
prev sibling parent d-bugmail puremagic.com writes:
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


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Jun 29 2008