[Bug c++/69797] New: ICE on invalid code on x86_64-linux-gnu in operator[], at vec.h:714

["su at cs dot ucdavis.edu" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69797

            Bug ID: 69797
           Summary: ICE on invalid code on x86_64-linux-gnu in operator[],
                    at vec.h:714
           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.  

This also affects 4.8.x and later releases, and is a regression from 4.7.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-trunk/configure --prefix=/usr/local/gcc-trunk
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 6.0.0 20160212 (experimental) [trunk revision 233377] (GCC) 
$ 
$ 
$ 
$ g++-4.7 -c small.cc
small.cc: In function âvoid fn1()â:
small.cc:4:23: error: too few arguments to function â__atomic_fetch_addâ
$ 
$ 
$ 
$ g++-trunk -c small.cc
small.cc: In function âvoid fn1()â:
small.cc:4:23: internal compiler error: in operator[], at vec.h:714
   __atomic_fetch_add ();
                       ^
0x8643c2 vec<tree_node*, va_gc, vl_embed>::operator[](unsigned int)
        ../../gcc-trunk/gcc/vec.h:714
0x8643c2 resolve_overloaded_atomic_exchange
        ../../gcc-trunk/gcc/c-family/c-common.c:11030
0x8643c2 resolve_overloaded_builtin(unsigned int, tree_node*, vec<tree_node*,
va_gc, vl_embed>*)
        ../../gcc-trunk/gcc/c-family/c-common.c:11305
0x781c2a finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**, bool,
bool, int)
        ../../gcc-trunk/gcc/cp/semantics.c:2381
0x6fe182 cp_parser_postfix_expression
        ../../gcc-trunk/gcc/cp/parser.c:6902
0x6fc28c cp_parser_unary_expression
        ../../gcc-trunk/gcc/cp/parser.c:7989
0x706557 cp_parser_cast_expression
        ../../gcc-trunk/gcc/cp/parser.c:8666
0x706aed cp_parser_binary_expression
        ../../gcc-trunk/gcc/cp/parser.c:8767
0x707390 cp_parser_assignment_expression
        ../../gcc-trunk/gcc/cp/parser.c:9054
0x709d6a cp_parser_expression
        ../../gcc-trunk/gcc/cp/parser.c:9223
0x70a313 cp_parser_expression_statement
        ../../gcc-trunk/gcc/cp/parser.c:10684
0x71958e cp_parser_statement
        ../../gcc-trunk/gcc/cp/parser.c:10535
0x719f94 cp_parser_statement_seq_opt
        ../../gcc-trunk/gcc/cp/parser.c:10807
0x71a09f cp_parser_compound_statement
        ../../gcc-trunk/gcc/cp/parser.c:10761
0x71a1fd cp_parser_function_body
        ../../gcc-trunk/gcc/cp/parser.c:20641
0x71a1fd cp_parser_ctor_initializer_opt_and_function_body
        ../../gcc-trunk/gcc/cp/parser.c:20677
0x71acb1 cp_parser_function_definition_after_declarator
        ../../gcc-trunk/gcc/cp/parser.c:25309
0x71b904 cp_parser_function_definition_from_specifiers_and_declarator
        ../../gcc-trunk/gcc/cp/parser.c:25221
0x71b904 cp_parser_init_declarator
        ../../gcc-trunk/gcc/cp/parser.c:18419
0x71bb1b cp_parser_simple_declaration
        ../../gcc-trunk/gcc/cp/parser.c:12359
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.
$ 


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


void
fn1 () 
{
  __atomic_fetch_add ();
}