try_finally_expr in must_not_throw_expr

[Philipp Rimmele <ph_rimmele@hotmail.com>]

Hi,

i'm developing a GCC-Plugin. And i don't understand why there is a "try_finally_expr" in a must_not_throw-Area in my AST. It happens in the destructors.
Here is my AST:
function_decl Exception::__dt_base
  1: must_not_throw_expr(->void_type{void})[42]
    0: statement_list(->void_type{void})
      0: bind_expr(->void_type{void})[42]
        1: statement_list(->void_type{void})
          0: cleanup_point_expr(->void_type{void})[42]
            0: expr_stmt(->void_type{void})
              0: convert_expr(->void_type{void})
                0: modify_expr(->pointer_type->pointer_type{__vtbl_ptr_type}->function_type->integer_type{int})
                  0: component_ref(->pointer_type->pointer_type{__vtbl_ptr_type}->function_type->integer_type{int})
                    0: indirect_ref(->record_type{Exception})
                      0: nop_expr(->pointer_type->record_type{Exception})
                        0: parm_decl(->pointer_type->record_type{Exception}) : this
                    1: field_decl(->pointer_type->pointer_type{__vtbl_ptr_type}->function_type->integer_type{int})
                  1: pointer_plus_expr(->pointer_type->pointer_type{__vtbl_ptr_type}->function_type->integer_type{int})
                    0: addr_expr(->pointer_type->pointer_type{__vtbl_ptr_type}->function_type->integer_type{int})
                      0: var_decl(->array_type->pointer_type{__vtbl_ptr_type}->function_type->integer_type{int}) : _ZTV9Exception
                    1: integer_cst : 16 : 1
          0: try_finally(->void_type{void})[42]
            0: statement_list(->void_type{void})
            1: modify_expr(->void_type{void})
              0: indirect_ref(->record_type)
                0: nop_expr(->reference_type->record_type)
                  0: parm_decl(->pointer_type->record_type{Exception}) : this
              1: constructor(->record_type)
        2: block
      0: label_expr(->void_type{void})[42]
        0: label_decl(->void_type{void}) : <unnamed>

What is the reason for this? There should no Exception be thrown, so why handle it with a try_finally-Expression? I'm currently using GCC-8.2.0.
I would be realy glad if you could answer me this question. And if you can give me some examples, where the try_finally-expression is also used, it would be realy helpfull.


Thank you and kind regards,

Philipp Rimmele