[Bug c++/59646] New: [4.7/4.8/4.9 Regression] ICE with volatile in initializer list

[reichelt at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59646

            Bug ID: 59646
           Summary: [4.7/4.8/4.9 Regression] ICE with volatile in
                    initializer list
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: reichelt at gcc dot gnu.org

The following (invalid?) code snippet triggers an ICE since GCC 4.7.0:

===========================================================
#include <initializer_list>

struct A {};

std::initializer_list<volatile A> x = {{}};
===========================================================

bug.cc:5:42: error: no matching function for call to 'A::A(volatile A)'
 std::initializer_list<volatile A> x = {{}};
                                          ^
bug.cc:5:42: note: candidates are:
bug.cc:3:8: note: constexpr A::A()
 struct A {};
        ^
bug.cc:3:8: note:   candidate expects 0 arguments, 1 provided
bug.cc:3:8: note: constexpr A::A(const A&)
bug.cc:3:8: note:   no known conversion for argument 1 from 'volatile A' to
'const A&'
bug.cc:3:8: note: constexpr A::A(A&&)
bug.cc:3:8: note:   no known conversion for argument 1 from 'volatile A' to
'A&&'
bug.cc: In function 'void __static_initialization_and_destruction_0(int, int)':
bug.cc:5:42: internal compiler error: tree check: expected class 'type', have
'exceptional' (error_mark) in useless_type_conversion_p, at gimple-expr.c:80
 std::initializer_list<volatile A> x = {{}};
                                          ^
0xd8f855 tree_class_check_failed(tree_node const*, tree_code_class, char
const*, int, char const*)
        ../../gcc/gcc/tree.c:9243
0x9a5f05 tree_class_check
        ../../gcc/gcc/tree.h:2830
0x9a5f05 useless_type_conversion_p(tree_node*, tree_node*)
        ../../gcc/gcc/gimple-expr.c:80
0x9d2cf9 gimplify_modify_expr
        ../../gcc/gcc/gimplify.c:4446
0x9c72fc gimplify_expr(tree_node**, gimple_statement_base**,
gimple_statement_base**, bool (*)(tree_node*), int)
        ../../gcc/gcc/gimplify.c:7431
0x9cb7b6 gimplify_stmt(tree_node**, gimple_statement_base**)
        ../../gcc/gcc/gimplify.c:5334
0x9c74ec gimplify_cleanup_point_expr
        ../../gcc/gcc/gimplify.c:5110
0x9c74ec gimplify_expr(tree_node**, gimple_statement_base**,
gimple_statement_base**, bool (*)(tree_node*), int)
        ../../gcc/gcc/gimplify.c:7787
0x9cb7b6 gimplify_stmt(tree_node**, gimple_statement_base**)
        ../../gcc/gcc/gimplify.c:5334
0x9c7aab gimplify_statement_list
        ../../gcc/gcc/gimplify.c:1405
0x9c7aab gimplify_expr(tree_node**, gimple_statement_base**,
gimple_statement_base**, bool (*)(tree_node*), int)
        ../../gcc/gcc/gimplify.c:7839
0x9cb7b6 gimplify_stmt(tree_node**, gimple_statement_base**)
        ../../gcc/gcc/gimplify.c:5334
0x9cf6d3 gimplify_cond_expr
        ../../gcc/gcc/gimplify.c:3052
0x9c7333 gimplify_expr(tree_node**, gimple_statement_base**,
gimple_statement_base**, bool (*)(tree_node*), int)
        ../../gcc/gcc/gimplify.c:7387
0x9cb7b6 gimplify_stmt(tree_node**, gimple_statement_base**)
        ../../gcc/gcc/gimplify.c:5334
0x9cf6d3 gimplify_cond_expr
        ../../gcc/gcc/gimplify.c:3052
0x9c7333 gimplify_expr(tree_node**, gimple_statement_base**,
gimple_statement_base**, bool (*)(tree_node*), int)
        ../../gcc/gcc/gimplify.c:7387
0x9cb7b6 gimplify_stmt(tree_node**, gimple_statement_base**)
        ../../gcc/gcc/gimplify.c:5334
0x9ccf7a gimplify_body(tree_node*, bool)
        ../../gcc/gcc/gimplify.c:8531
0x9cd579 gimplify_function_tree(tree_node*)
        ../../gcc/gcc/gimplify.c:8684
Please submit a full bug report, [etc.]

Btw, clang 3.2 accepts the above code snippet.
Also the code is accepted if 'A' is replaced by 'int'.