• via D.gnu (58/58) Dec 10 2016 http://bugzilla.gdcproject.org/show_bug.cgi?id=248

" via D.gnu" <d.gnu puremagic.com> writes:

http://bugzilla.gdcproject.org/show_bug.cgi?id=248

            Bug ID: 248
           Summary: Regression: Call result not properly saved when
                    calling a vtbl function
           Product: GDC
           Version: development
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: Normal
         Component: gdc
          Assignee: ibuclaw gdcproject.org
          Reporter: johannespfau gmail.com

Reduced from a DDMD build regression:

We've got a function getMemtype which has side effects and returns a class
object Bar which has a virtual function isintegral. The function is called in
this way: getMemtype().isintegral(). In this call the return value of
getMemtype, the reference to a Bar object, is needed twice: Once to get the
vtbl entry for isintegral and once to pass the object reference as the this
pointer for isintegral. I guess the result of the getMemtype call is not saved
properly. We can certainly see that the getMemType function executes twice.

 Iain I'll assign this to you as you are more familiar with this code.

---------------------------------------------------
import std.stdio;

class Bar
{
    bool isintegral()
    {
        return false;
    }
}

class Symbol
{
    Bar getMemtype()
    {
        writeln("foo");
        return new Bar();
    }
}

class Enum
{
    Symbol sym;
    bool isintegral()
    {
        return sym.getMemtype().isintegral();
    }
}

void main()
{
    Enum e = new Enum();
    e.sym = new Symbol();
    e.isintegral();
}
---------------------------------------------------

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