Incorrect behavior in case of watchpoint

[Aetf]

Hi,

I can see a few issues here.

1. BreakpointModel gets updated when user creating watch points directly
using command. The location reported by GDB includes the "-location " part,
but since we are quoting the entire string, GDB interprets the entire
string as an option, rather than only the "-location" part.
2. Even though we recognize the location and only quote remaining
expression, GDB/MI which is the protocol we use to communicate with GDB
actually doesn't support "-l/-location" option. see [1]
3. When starts new session, KDevelop tries to automatically reapply all
break/watch points saved in BreakpointModel. But the command fails due to
above reason. However there shouldn't be an endless loop. Once the command
fails, it should set the error message in the Breakpoint toolview and
continue. But maybe I'm just missing something.

The fix would be
1. In mibreakpointcontroller.cpp:358, detect and quote only the expression
part, this is easy.
2. Find a way to emulate the "-location" option. Possible solutions:
    2.1 Take the address of the expression when watch point got set and
save that in BreakpointModel. But addresses are likely to change between
runs
    2.2 Simply remove "-location" part and set it as a normal watch point.
But likely at the very begining of the program, the expression is out of
scope.
    2.3 Skip it. IMHO even normal watchpoints should be skipped. As they
rely on expressions that are hardly valid at this time.
3. Desired behavior should be display the error in Breakpoint toolview,
rather than entering an endless loop. However I didn't find which part of
the code is causing the loop after a quick of the codebase. And the desired
behavior is already implemented. This will need more investigate.

[1]
https://sourceware.org/gdb/onlinedocs/gdb/GDB_002fMI-Breakpoint-Commands.html#GDB_002fMI-Breakpoint-Commands

Cheers,
Aetf

On Mon, Sep 4, 2017 at 7:48 AM Aleix Pol <aleixpol at kde.org> wrote:

> On Fri, Sep 1, 2017 at 6:32 PM, Aetf <7437103 at gmail.com> wrote:
> > Hi,
> >
> > I'm afraid I don't have much time for this at the moment. Actually this
> has
> > been on my todo list for a while... I'll take a look at it soon.
> >
> > Cheers,
> > Aetf
> >
> > On Fri, Sep 1, 2017 at 7:55 AM Aleix Pol <aleixpol at kde.org> wrote:
> >>
> >> On Mon, Aug 21, 2017 at 1:54 PM, Aleksey Midenkov <midenok at gmail.com>
> >> wrote:
> >> > I've set watchpoint with command `watch -l` and it was saved in
> >> > KDevelop session. Now it doesn't start debug session because it ends
> >> > up in endless loop:
> >> >
> >> > (gdb) 2106-break-watch "-location m_part_spec.start_part"
> >> > 2106^error,msg="-break-watch: Unknown option ``location
> >> > m_part_spec.start_part''"
> >> > (gdb) 2107-break-watch "-location m_part_spec.start_part"
> >> > 2107^error,msg="-break-watch: Unknown option ``location
> >> > m_part_spec.start_part''"
> >> > (gdb) 2108-break-watch "-location m_part_spec.start_part"
> >> > 2108^error,msg="-break-watch: Unknown option ``location
> >> > m_part_spec.start_part''"
> >> > (gdb) 2109-break-watch "-location m_part_spec.start_part"
> >> > 2109^error,msg="-break-watch: Unknown option ``location
> >> > m_part_spec.start_part''"
> >> > (gdb) 2110-break-watch "-location m_part_spec.start_part"
> >> > 2110^error,msg="-break-watch: Unknown option ``location
> >> > m_part_spec.start_part''"
> >> > ...
> >> >
> >> > Though I've managed to delete breakpoint from Breakpoints tab and
> start
> >> > again.
> >>
> >> Hey Aetf,
> >> Any idea why that could be?
> >>
> >> Aleix
> >>
> >> PS: Aleksey, can you make sure this is reported in bugs.kde.org?
>
> Hi Aetf,
> Maybe you can give us some pointers in case someone else can/wants to fix
> it?
>
> Aleix
>
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