[LLVMbugs] [Bug 11745] New: incorrect class layout with duplicate empty base classes of small nonempty class

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=11745

             Bug #: 11745
           Summary: incorrect class layout with duplicate empty base
                    classes of small nonempty class
           Product: clang
           Version: unspecified
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: C++
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: richard-llvm at metafoo.co.uk
                CC: dgregor at apple.com, llvmbugs at cs.uiuc.edu
    Classification: Unclassified


Given:

template<typename T, unsigned> struct X : T {};
struct E {};
struct Test1 : X<E,0>, X<E,1>, X<E,2>, X<E,3> {};
struct Test2 : X<E,0>, X<E,1>, X<E,2>, X<E,3> { char c; };

sizeof(Test1) is 4, as expected, and the E base subobjects all have distinct
addresses. sizeof(Test2) is 1, and the second, third and fourth E base
subobjects lie outside the full-object!

In particular, this static assert fails:

Test2 a[2];
static_assert((E*)(X<E,1>*)&a[0] != (E*)(X<E,0>*)&a[1], "should not happen");

-- 
Configure bugmail: http://llvm.org/bugs/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.