• d-bugmail puremagic.com (60/60) Dec 29 2021 https://issues.dlang.org/show_bug.cgi?id=22636

d-bugmail puremagic.com writes:

https://issues.dlang.org/show_bug.cgi?id=22636

          Issue ID: 22636
           Summary: Wrong C++ constructor called for abstract class
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: tim.dlang t-online.de

Wrong C++ constructor called for abstract class

//////////////// testabstractcpp.cpp ////////////////

class C
{
public:
    C();
    virtual void f() = 0;
    int i;
};

C::C()
{
    i = 5;
}

////////////////// testabstractd.d //////////////////

extern(C++) abstract class C
{
    this();
    abstract void f();
    int i;
}

extern(C++) class D : C
{
    override void f()
    {
        assert(i == 5);
    }
}

void main()
{
    D d = new D();
    d.f();
}

/////////////////////////////////////////////////////

The files can be compiled with the following commands:
clang++ -c testabstractcpp.cpp
dmd -L-lstdc++ testabstractd.d testabstractcpp.o

The second command results in a linker error:
/usr/bin/ld: testabstractd.o:(.data._D13testabstractd1C7__ClassZ+0x88):
undefined reference to `C::C()'
/usr/bin/ld: testabstractd.o: in function `D::D()':
testabstractd.d:(.text._ZN1DC1Ev[_ZN1DC1Ev]+0x14): undefined reference to
`C::C()'

The Itanium C++ ABI has different constructors. Clang seems to only emit the
base object constructor (_ZN1CC2Ev) for abstract class C, but dmd tries to use
the complete object constructor (_ZN1DC1Ev).
The example work with GCC, because it emits both constructors.

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