[Issue 2713] New: Error resolving types with ? : and const

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=2713

           Summary: Error resolving types with ? : and const
           Product: D
           Version: 2.025
          Platform: PC
               URL: http://www.digitalmars.com/webnews/newsgroups.php?art_gr
                    oup=digitalmars.D&article_id=85423
        OS/Version: All
            Status: NEW
          Keywords: rejects-valid
          Severity: minor
          Priority: P3
         Component: DMD
        AssignedTo: bugzilla at digitalmars.com
        ReportedBy: zildjohn01 at gmail.com


The following fails to compile:

bool flag() {
        bool left, right;
        return true ? cast(const bool)left : cast(bool)right;
}

with the error "cannot implicitly convert expression (cast(int)left) of type
int to bool".  It seems to happen whenever the left and right sides differ in
const-ness or invariant-ness.

This becomes an issue when trying to write const-correct class functions which
return bool, for example:

class C {
    private int mask;

    private bool readyYet() const {return true;}

    public bool ExtractStateBit() const {
        return readyYet() ? (mask & 1) : false;
    }
}


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