Rewrite stack handling

Problems with the current stack implementation:

* The GUI assumes that the stack frame pushed on the stack
is level 2. If the 'no_tail' option is set for the process,
there may not be an entry for level 2.

* In each stack entry, the line number is the line number of
the caller, not the line number for the function in the 'mfa'
field as might be expected. That complicates generation of
a stacktrace with line number information.

Change the implementation as follows:

* Keep the information for the current function (its MFA and
current line number) in the #ieval{} record. Don't push it
onto the stack. Only push the information when another function
is called. That will ensure that the MFA and the line number
is found in the same stack entry. That also has the advantage
that if the 'no_tail' option is set, the stack not need to
be modified for tail-recursive calls.

* Make sure that there always is an entry for level two.

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/debugger/src/dbg_icmd.erl b/lib/debugger/src/dbg_icmd.erl
index c158aad1cf..b230efaa7a 100644
--- a/lib/debugger/src/dbg_icmd.erl
+++ b/lib/debugger/src/dbg_icmd.erl
@@ -345,8 +345,8 @@ handle_user_msg({get,stack_frame,From,{Dir,SP}}, _Status, _Bs,_Ieval) ->
     reply(From, stack_frame, dbg_istk:stack_frame(Dir, SP));
 handle_user_msg({get,messages,From,_}, _Status, _Bs, _Ieval) ->
     reply(From, messages, messages());
-handle_user_msg({get,backtrace,From,N}, _Status, _Bs, _Ieval) ->
-    reply(From, backtrace, dbg_istk:backtrace(N)).
+handle_user_msg({get,backtrace,From,N}, _Status, _Bs, Ieval) ->
+    reply(From, backtrace, dbg_istk:backtrace(N, Ieval)).
 
 set_stack_trace(true) ->
     set_stack_trace(all);