[Issue 5899] New: auto-return function cannot match 'null' with reference type.

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=5899

           Summary: auto-return function cannot match 'null' with
                    reference type.
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: rejects-valid
          Severity: minor
          Priority: P2
         Component: DMD
        AssignedTo: nobody at puremagic.com
        ReportedBy: kennytm at gmail.com


--- Comment #0 from kennytm at gmail.com 2011-04-27 08:46:39 PDT ---
Test code 1:
---------------------------
class K {}
auto f(bool b) {
    if (b)
        return new K;
    else
        return null;
}
---------------------------
x.d(6): Error: mismatched function return type inference of void* and x.K
---------------------------



Test code 2:
---------------------------
auto f(bool b) {
    if (b)
        return new int;
    else
        return null;
}
---------------------------
x.d(5): Error: mismatched function return type inference of void* and int*
---------------------------



DMD should know that 'null' is a valid value for any reference types.

A workaround is to give an exact type, e.g.
---------------------------
auto f(bool b) {
    if (b)
        return new int; // or new K;
    else {
        typeof(return) n = null;
        return n;
    }
}
---------------------------
but this should not be necessary.


(Perhaps the D spec should give a specific type e.g. 'nullptr_t' for 'null'?)

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