[Bug c++/70512] New: ICE on valid code on x86_64-linux-gnu: canonical types differ for identical types

[su at cs dot ucdavis.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70512

            Bug ID: 70512
           Summary: ICE on valid code on x86_64-linux-gnu: canonical types
                    differ for identical types
           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 in both 32-bit and 64-bit modes.  

This is a regression from 5.3.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 20160401 (experimental) [trunk revision 234665] (GCC) 
$ 
$ g++-5.3 -c small.cpp
$ 
$ g++-trunk -c small.cpp
small.cpp: In member function ‘S& S::operator=(int)’:
small.cpp:5:13: internal compiler error: canonical types differ for identical
types S* and S*
     return *this;
             ^~~~
0x76ac7f comptypes(tree_node*, tree_node*, int)
        ../../gcc-source-trunk/gcc/cp/typeck.c:1428
0x786c1e ocp_convert(tree_node*, tree_node*, int, int, int)
        ../../gcc-source-trunk/gcc/cp/cvt.c:697
0x615753 convert_like_real
        ../../gcc-source-trunk/gcc/cp/call.c:6695
0x62197b initialize_reference(tree_node*, tree_node*, int, int)
        ../../gcc-source-trunk/gcc/cp/call.c:9958
0x775bdb check_return_expr(tree_node*, bool*)
        ../../gcc-source-trunk/gcc/cp/typeck.c:8920
0x7b609e finish_return_stmt(tree_node*)
        ../../gcc-source-trunk/gcc/cp/semantics.c:870
0x732aea cp_parser_jump_statement
        ../../gcc-source-trunk/gcc/cp/parser.c:11808
0x732aea cp_parser_statement
        ../../gcc-source-trunk/gcc/cp/parser.c:10414
0x73315c cp_parser_statement_seq_opt
        ../../gcc-source-trunk/gcc/cp/parser.c:10806
0x73324f cp_parser_compound_statement
        ../../gcc-source-trunk/gcc/cp/parser.c:10760
0x751a8f cp_parser_function_body
        ../../gcc-source-trunk/gcc/cp/parser.c:20653
0x751a8f cp_parser_ctor_initializer_opt_and_function_body
        ../../gcc-source-trunk/gcc/cp/parser.c:20689
0x752531 cp_parser_function_definition_after_declarator
        ../../gcc-source-trunk/gcc/cp/parser.c:25351
0x757960 cp_parser_late_parsing_for_member
        ../../gcc-source-trunk/gcc/cp/parser.c:26191
0x730039 cp_parser_class_specifier_1
        ../../gcc-source-trunk/gcc/cp/parser.c:21524
0x730039 cp_parser_class_specifier
        ../../gcc-source-trunk/gcc/cp/parser.c:21550
0x730039 cp_parser_type_specifier
        ../../gcc-source-trunk/gcc/cp/parser.c:15834
0x749ea3 cp_parser_decl_specifier_seq
        ../../gcc-source-trunk/gcc/cp/parser.c:12758
0x753296 cp_parser_simple_declaration
        ../../gcc-source-trunk/gcc/cp/parser.c:12301
0x753721 cp_parser_block_declaration
        ../../gcc-source-trunk/gcc/cp/parser.c:12248
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.
$ 


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


struct S 
{
  S& operator= (int)
  {
    return *this;
  }
} __attribute__ ((__may_alias__));