lldb more verbose "invalid frame" error

[pawelo]

Summary

Many times during my recent activities I saw invalid frame error message. I found it totally useless - it does not give any clue why the error happened. It turned out that it can occur due to obvious reasons: no target selected, no process launched etc. With this patch it is easier to guess root cause of this error and save hours of unnecessary investigation.

[jasonmolenda]

This looks like a good change, thank you for coming up with it. Could you put the statements on separate lines from the conditional expressions? Instead of

if (!m_exe_ctx.HasTargetScope()) result.AppendError (GetInvalidTargetDescription());

more like this -

if (!m_exe_ctx.HasTargetScope())

result.AppendError (GetInvalidTargetDescription());

or

if (!m_exe_ctx.HasTargetScope())
{

result.AppendError (GetInvalidTargetDescription());

}

(in this case I think not using the braces will look cleaner). I know we have a few examples of the if (cond) stmt; in lldb already but they are something we need to clean up at some point.

J

[pawelo]

changed as requested

[tfiala]

Jason, do you want to submit this or do you want me to run it through over
here?

[jasonmolenda]

I applied the patch and was going to commit it, then I realized I don't clearly understand what behavior we're fixing. e.g. these commands all report a reasonable error msg when a thread/process/frame is missing before the patch is applied.

% lldb
(lldb) f
error: invalid thread
(lldb) bt
error: invalid process
(lldb) reg read pc
error: invalid frame
(lldb) c
error: invalid process
(lldb)

[pawelo]

Maybe this looks better?

[jasonmolenda]

Looks good to me! Anyone else?

[emaste]

This looks good to me.

[tfiala]

Yep good here too.

source/Interpreter/CommandObject.cpp

if (flags & (eFlagRequiresTarget   |
         if ((flags & eFlagRequiresThread) && !m_exe_ctx.HasThreadScope())
         {
             result.AppendError (GetInvalidThreadDescription());
             return false;
         }
         
         if ((flags & eFlagRequiresFrame) && !m_exe_ctx.HasFrameScope())
         {
+            if (!m_exe_ctx.HasTargetScope())
+                result.AppendError (GetInvalidTargetDescription());
+            else if (!m_exe_ctx.HasProcessScope())
+                result.AppendError (GetInvalidProcessDescription());
+            else if (!m_exe_ctx.HasThreadScope())
+                result.AppendError (GetInvalidThreadDescription());
+            else
                 result.AppendError (GetInvalidFrameDescription());
             return false;
         }
         
         if ((flags & eFlagRequiresRegContext) && (m_exe_ctx.GetRegisterContext() == nullptr))
         {
             result.AppendError (GetInvalidRegContextDescription());
             return false;
         }