related to PR 46526 ?

It is caused by revision 166167:

http://gcc.gnu.org/ml/gcc-cvs/2010-11/msg00053.html

(In reply to comment #1)
> related to PR 46526 ?

Revision 167049 still fails.

This seems to cause FAILs in libstdc++ testsuite with -O0, for example:
$ g++ 42819.ii -std=gnu++0x
$ ./a.out
terminate called after throwing an instance of 'std::system_error'
  what():  Unknown error 18446744073709551615
Aborted

(all failures I encountered are from 30_threads)

Most of the 30_threads tests will abort without -pthread

Thank you, I did my flag reduction wrongly. It seems using of precompiled headers sometimes causes wrong code, but it's unrelated to this PR.

Created attachment 22846 [details]
gcc46-pr46626.patch

Untested fix.  The problem seems to be that the B::B() ctor body, which is constexpr (and g++ generated) has a CLEANUP_STMT in it, and build_data_member_initialization ignores CLEANUP_STMT, which means the setting of vtable pointer to _ZTV1B + 16 is ignored, thus it stays to be _ZTV1A + 16.

The attached patch handles CLEANUP_BODY of CLEANUP_STMT by recursing into it.

With the patch applied to r168236:

$ cat test.cpp 
struct X {
    virtual int& x(int&)=0;
    virtual ~X() {}
};

struct Y {
    virtual int& y(int&)=0;
    virtual ~Y() {}
};

struct Z: X, Y {
    int& x(int&);
    int& y(int&);
};

void func() {
    Z z;
}

$ g++ -c -std=c++0x test.cpp
test.cpp: In function 'void func()':
test.cpp:17:7:   in constexpr expansion of 'z.Z::Z()'
test.cpp:17:7: internal compiler error: in cxx_eval_bare_aggregate, at cp/semantics.c:6352
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

Without the patch, with the same test.cpp:

$ g++ -c -std=c++0x test.cpp; echo $?
0

Without the patch, with slightly different test1.cpp:

0 rk@wata:~/tmp/qqq>cat test1.cpp 
struct X {
    virtual int& x(int&)=0;
//  virtual ~X() {}
};

struct Y {
    virtual int& y(int&)=0;
//  virtual ~Y() {}
};

struct Z: X, Y {
    int& x(int&);
    int& y(int&);
};

void func() {
    Z z;
}

0 rk@wata:~/tmp/qqq>g++ -c -std=c++0x test1.cpp
test1.cpp: In function 'void func()':
test1.cpp:17:7:   in constexpr expansion of 'z.Z::Z()'
test1.cpp:17:7: internal compiler error: in cxx_eval_bare_aggregate, at cp/semantics.c:6338
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

Author: jakub
Date: Mon Dec 27 12:54:30 2010
New Revision: 168271

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=168271
Log:
	PR c++/46626
	* semantics.c (build_data_member_initialization): For CLEANUP_STMT
	recurse into CLEANUP_BODY.

	* g++.dg/cpp0x/constexpr-base4.C: New test.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-base4.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/semantics.c
    trunk/gcc/testsuite/ChangeLog

I see the ICE with the second testcase from #c8 back till r166167, therefore please file it as a separate bugreport, it is not related to this one.