ada - 确定 Ada 断言失败的原因

Question

如果断言失败，我会得到以下输出：

引发 SYSTEM.ASSERTIONS.ASSERT_FAILURE ：Dynamic_Predicate 在 file.adb:36 失败

我能得到更多细节吗？例如输入是什么，或者可能是堆栈跟踪，或者任何其他可能帮助我确定断言失败的原因？

Answer 1

您可以使用 GNAT.Traceback（如果您使用 GNAT）包或打印值来捕获 System.Assertions.Assert_Failure 以打印堆栈跟踪。

像这里的东西

pragma Assertion_Policy(CHECK);

with Ada.Text_IO; use Ada.Text_IO;
with GNAT.Traceback;
with System.Assertions;
with GNAT.Traceback.Symbolic;
procedure Main is
   procedure Call_Stack is
      Trace  : GNAT.Traceback.Tracebacks_Array (1..1_000);
      Length : Natural;
   begin
      GNAT.Traceback.Call_Chain (Trace, Length);
      Put_Line (GNAT.Traceback.Symbolic.Symbolic_Traceback (Trace (1..Length)));
   end Call_Stack; 
   type Day is new String (1 .. 10);
   type Message is record
      Sent     : Day;
      Received : Day;
   end record with
     Dynamic_Predicate => Message.Sent <= Message.Received;
   M : Message;
begin
   M  := (Received => "1776-07-04", Sent => "1783-09-03");
exception
   when System.Assertions.Assert_Failure =>
      Call_Stack;
      Put_Line(String(M.Sent));
      Put_Line(String(M.Received));
end Main;

或者你可以调试你的程序，正如我在评论中提到的那样