[RFC][Python] gdbpy_frame_stop_reason_string bug

[Kevin Pouget <kevin.pouget@gmail.com>]

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Hi,

I wanted to discuss the best way to solve this bug before going any
further in the development:

> (gdb) py print gdb.frame_stop_reason_string(2)
> /home/kevin/travail/git/gdb/gdb/frame.c:2372: internal-error: Invalid frame stop reason
> A problem internal to GDB has been detected,further debugging may prove unreliable.


I prepared the attached patch, which requires to change
'internal_error' to a simple 'error' (I assume that it can't break
anything because it ends up calling `exit()', but I didn't check yet),

but "Frame.unwind_stop_reason ()" easily returns 'invalid frame stop
reason', for instance

> (gdb) start
> ...
> (gdb) pp gdb.newest_frame().unwind_stop_reason()
> 0

so I'm not convinced that it's the best solution.

Would it be better to return (in frame_stop_reason_string) a reason
for each value of "enum unwind_stop_reason reason", but breaking the
original intend of the `internal_error' call?

thanks for your comments,

Kevin

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diff --git a/gdb/frame.c b/gdb/frame.c
index 5824020..1c1a18b 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -2369,8 +2369,7 @@ frame_stop_reason_string (enum unwind_stop_reason reason)
     case UNWIND_NO_REASON:
     case UNWIND_FIRST_ERROR:
     default:
-      internal_error (__FILE__, __LINE__,
-		      "Invalid frame stop reason");
+      error (_("Invalid frame stop reason"));
     }
 }
 
diff --git a/gdb/python/py-frame.c b/gdb/python/py-frame.c
index 75aa44e..2b95112 100644
--- a/gdb/python/py-frame.c
+++ b/gdb/python/py-frame.c
@@ -538,19 +538,20 @@ gdbpy_frame_stop_reason_string (PyObject *self, PyObject *args)
 {
   int reason;
   const char *str;
+  PyObject *py_str_reason = NULL;
+  volatile struct gdb_exception except;
 
   if (!PyArg_ParseTuple (args, "i", &reason))
     return NULL;
 
-  if (reason < 0 || reason > UNWIND_NO_SAVED_PC)
+  TRY_CATCH (except, RETURN_MASK_ALL)
     {
-      PyErr_SetString (PyExc_ValueError, 
-		       _("Invalid frame stop reason."));
-      return NULL;
+      str = frame_stop_reason_string (reason);
+      py_str_reason = PyUnicode_Decode (str, strlen (str), host_charset (), NULL);
     }
+  GDB_PY_HANDLE_EXCEPTION (except);
 
-  str = frame_stop_reason_string (reason);
-  return PyUnicode_Decode (str, strlen (str), host_charset (), NULL);
+  return py_str_reason;
 }
 
 /* Implements the equality comparison for Frame objects.