[Bug c++/70202] New: ICE on invalid code on x86_64-linux-gnu in build_simple_base_path, at cp/class.c:579

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70202

            Bug ID: 70202
           Summary: ICE on invalid code on x86_64-linux-gnu in
                    build_simple_base_path, at cp/class.c:579
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

The following code causes an ICE when compiled with the current GCC trunk on
x86_64-linux-gnu.

It also seems to affect all earlier versions of GCC since as early as 4.4.x. 


$ g++-trunk -v
Using built-in specs.
COLLECT_GCC=g++-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto
--prefix=/usr/local/gcc-trunk --disable-bootstrap
Thread model: posix
gcc version 6.0.0 20160311 (experimental) [trunk revision 234134] (GCC) 
$ 
$ g++-trunk small.cpp
small.cpp:6:21: error: duplicate base type ‘A’ invalid
 class B : public A, A
                     ^
small.cpp: In function ‘int main()’:
small.cpp:13:5: error: aggregate ‘B b1’ has incomplete type and cannot be
defined
   B b1, &b2 = b1;
     ^~
small.cpp:14:9: internal compiler error: in build_simple_base_path, at
cp/class.c:579
   A a = b2;
         ^~
0x6d5c82 build_simple_base_path
        ../../gcc-source-trunk/gcc/cp/class.c:579
0x6f273d build_base_path(tree_code, tree_node*, tree_node*, int, int)
        ../../gcc-source-trunk/gcc/cp/class.c:409
0x6149e5 convert_like_real
        ../../gcc-source-trunk/gcc/cp/call.c:6568
0x613978 convert_like_real
        ../../gcc-source-trunk/gcc/cp/call.c:6538
0x610c3f build_over_call
        ../../gcc-source-trunk/gcc/cp/call.c:7493
0x61d3a5 build_new_method_call_1
        ../../gcc-source-trunk/gcc/cp/call.c:8410
0x61d3a5 build_new_method_call(tree_node*, tree_node*, vec<tree_node*, va_gc,
vl_embed>**, tree_node*, int, tree_node**, int)
        ../../gcc-source-trunk/gcc/cp/call.c:8480
0x61e349 build_special_member_call(tree_node*, tree_node*, vec<tree_node*,
va_gc, vl_embed>**, tree_node*, int, int)
        ../../gcc-source-trunk/gcc/cp/call.c:8017
0x786510 ocp_convert(tree_node*, tree_node*, int, int, int)
        ../../gcc-source-trunk/gcc/cp/cvt.c:887
0x7952a5 expand_default_init
        ../../gcc-source-trunk/gcc/cp/init.c:1689
0x7952a5 expand_aggr_init_1
        ../../gcc-source-trunk/gcc/cp/init.c:1858
0x795be4 build_aggr_init(tree_node*, tree_node*, int, int)
        ../../gcc-source-trunk/gcc/cp/init.c:1606
0x62ef8a build_aggr_init_full_exprs
        ../../gcc-source-trunk/gcc/cp/decl.c:5964
0x62ef8a check_initializer
        ../../gcc-source-trunk/gcc/cp/decl.c:6108
0x658a0c cp_finish_decl(tree_node*, tree_node*, bool, tree_node*, int)
        ../../gcc-source-trunk/gcc/cp/decl.c:6783
0x751a4f cp_parser_init_declarator
        ../../gcc-source-trunk/gcc/cp/parser.c:18644
0x752200 cp_parser_simple_declaration
        ../../gcc-source-trunk/gcc/cp/parser.c:12365
0x752511 cp_parser_block_declaration
        ../../gcc-source-trunk/gcc/cp/parser.c:12234
0x752f68 cp_parser_declaration_statement
        ../../gcc-source-trunk/gcc/cp/parser.c:11846
0x73162b cp_parser_statement
        ../../gcc-source-trunk/gcc/cp/parser.c:10528
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
$ 


---------------------------------


class A
{
  virtual void foo () { }
}; 

class B : public A, A
{
}; 

int 
main ()
{
  B b1, &b2 = b1; 
  A a = b2;
  return 0; 
}