APAR status
Closed as program error.
Error description
COMPILER PRODUCES INCORRECT RESULTS FOR CLASS MEMBER VARIABLE OFFSETS W.R.T. POLYMORPHISM AND TEMPLATING ---------------------------------------------------------------- xlC -std=c++11 testcode.C $ ./a.out Actual results: C: &B::data2=0x7fffc9d1f910, &A2::data2=0x7fffc9d1f908, &B::getData2()=0x7fffc9d1f908, &A2::getData2()=0x7fffc9d1f908 B: &data2=0x7fffc9d1f908, &getData2()=0x7fffc9d1f908 The expected results: C: &B::data2=0x7fffcaf71478, &A2::data2=0x7fffcaf71478, &B::getData2()=0x7fffcaf71478, &A2::getData2()=0x7fffcaf71478 B: &data2=0x7fffcaf71478, &getData2()=0x7fffcaf71478 ================================================================ Test Case: #include<stdio.h> #include<vector> template<typename TV> struct myvec { protected: std::vector<TV> vec_data; }; template<typename TA> struct A1 { virtual ~A1() = default; }; struct A2 { virtual ~A2() = default; protected: myvec<int> data1; myvec<int> data2; myvec<int> &getData1(){ return data1; } myvec<int> &getData2(){ return data2; } }; template<typename T> struct B : public A1<T>, public A2 { virtual ~B() = default; void testB(){ printf("B: &data2=%p, &getData2()=%p\n", &(A2::data2), &getData2()); } }; template<typename T2> struct C : public B<T2> { using Parent = B<T2>; virtual ~C() = default; void testC(){ printf("C: &B::data2=%p, &A2::data2=%p, &B::getData2()=%p, &A2::getData2()=%p\n", &(Parent::data2), &(A2::data2), &(Parent::getData2()), &(A2::getData2())); } }; int main(void){ C<double> c; c.testC(); c.testB(); return 0; }
Local fix
N/A
Problem summary
USERS AFFECTED: Users who have test cases similar to the one mentioned in the APAR are affected by this issue. PROBLEM DESCRIPTION: The root cause is that the compiler was incorrectly handling qualified base class members, where the qualified name is more derived than the subobject in which the member resides.
Problem conclusion
The compiler has been fixed to handle this scenario.
Temporary fix
Comments
APAR Information
APAR number
LI81681
Reported component name
XL C/C++ LINUX
Reported component ID
5725C7310
Reported release
G11
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2020-08-24
Closed date
2020-11-03
Last modified date
2020-11-03
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
IJ32578
Fix information
Fixed component name
XL C/C++ LINUX
Fixed component ID
5725C7310
Applicable component levels
[{"Line of Business":{"code":"LOB57","label":"Power"},"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSXVZZ","label":"XL C\/C++ for Linux"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"G11"}]
Document Information
Modified date:
08 May 2021