[Bug c/111855] New: GCC: 14: internal compiler error: tree check: expected class 'type', have 'exceptional' (error_mark) in useless_type_conversion_p, at gimple-expr.cc:265

[141242068 at smail dot nju.edu.cn via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111855

            Bug ID: 111855
           Summary: GCC: 14: internal compiler error: tree check: expected
                    class 'type', have 'exceptional' (error_mark) in
                    useless_type_conversion_p, at gimple-expr.cc:265
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: 141242068 at smail dot nju.edu.cn
  Target Milestone: ---

When compile this program with GCC-14, gcc throws internal compiler error:
```
extern void *memmove(void [3], const void *, __SIZE_TYPE__);

void f(void)
{
 char s[] = "12345";
 memmove(s + 1, s, 4);
}
```

Compiler Explorer: https://gcc.godbolt.org/z/5zcnehhzo

The full stack:
```
<source>:1:27: error: declaration of type name as array of voids
    1 | extern void *memmove(void [3], const void *, __SIZE_TYPE__);
      |                           ^
<source>: In function 'f':
<source>:6:12: error: type of formal parameter 1 is incomplete
    6 |  memmove(s + 1, s, 4);
      |          ~~^~~
<source>:6:2: internal compiler error: tree check: expected class 'type', have
'exceptional' (error_mark) in useless_type_conversion_p, at gimple-expr.cc:265
    6 |  memmove(s + 1, s, 4);
      |  ^~~~~~~
0x230ff8e internal_error(char const*, ...)
        ???:0
0x8a8944 tree_class_check_failed(tree_node const*, tree_code_class, char
const*, int, char const*)
        ???:0
0xdb9a31 gimplify_expr(tree_node**, gimple**, gimple**, bool (*)(tree_node*),
int)
        ???:0
0xdb9247 gimplify_expr(tree_node**, gimple**, gimple**, bool (*)(tree_node*),
int)
        ???:0
0xdbc21a gimplify_stmt(tree_node**, gimple**)
        ???:0
0xdba1c3 gimplify_expr(tree_node**, gimple**, gimple**, bool (*)(tree_node*),
int)
        ???:0
0xdbc21a gimplify_stmt(tree_node**, gimple**)
        ???:0
0xdb926f gimplify_expr(tree_node**, gimple**, gimple**, bool (*)(tree_node*),
int)
        ???:0
0xdbc21a gimplify_stmt(tree_node**, gimple**)
        ???:0
0xdbe233 gimplify_body(tree_node*, bool)
        ???:0
0xdbe68f gimplify_function_tree(tree_node*)
        ???:0
0xbe7db7 cgraph_node::analyze()
        ???:0
0xbeb901 symbol_table::finalize_compilation_unit()
        ???:0
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
```