www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.bugs - [Issue 9932] New: CTFE cannot be used when a struct has "uninitialized" static array union members?

http://d.puremagic.com/issues/show_bug.cgi?id=9932

           Summary: CTFE cannot be used when a struct has "uninitialized"
                    static array union members?
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: simendsjo gmail.com


--- Comment #0 from simendsjo <simendsjo gmail.com> 2013-04-14 11:22:16 PDT ---
Ref: http://forum.dlang.org/thread/gegwzcaswemphdlcahfl forum.dlang.org
Related to http://d.puremagic.com/issues/show_bug.cgi?id=8543 ?
----
This is probably not a minimal test-case, and I haven't tested 
with more types, but it shows the problem.

// This works
struct S {
    this(int i) {
        a = i;
    }
    union {
        int a = void;
        int b = void;
    }
}
unittest
{
    auto s = S(1);
    assert(&s.a == &s.b);
    enum s2 = S(1);
    static assert(S(1).a == 1);
}

// But this doesn't
struct S2 {
    this(int i) { // error at this line
        a[] = i;
    }
    union {
        int[1] a = void;
        int[1] b = void;
    }
}
unittest
{
    auto s = S2(1);
    assert(s.a.ptr == s.b.ptr);
    // bug.d(19): Error: uninitialized variable 'b' cannot be 
returned from CTFE
    enum s2 = S2(1);
}

void main() {
}

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
Apr 14 2013