[Rd] [External] Re: Operations with long altrep vectors cause segfaults on Windows

[Tomas Kalibera]

On 9/9/20 8:48 AM, Hugh Parsonage wrote:
> I am unable to set break or use gdb with any success when I use that version.
>
> On linux I would do R -d gdb but this gives "unknown option '-d' "
> while gdb R.exe (in the same directory as the debug version) gives the
> same output as before.
>
> I'm happy to help but I appreciate this list might not be the best
> place to get a tutorial on using gdb on Windows.

Essentially, the steps are: build with DEBUG=T (to have debug symbols), 
possibly updating EOPTS in MkRules.local to disable optimizations, then 
run gdb loading RGui, "set solib-search-path", run RGui from gdb. Then 
you can break to debugger from RGui menu, or just run the code that 
segfaults, and you get to gdb and can print the stacktrace, etc. You can 
find some information in rw-FAQ (R for Windows FAQ), but yes, it is 
harder than on Linux. We can take care of this report, but of course in 
the longer term it would help if more people could take their time to 
setup debugging and analyze bugs even on Windows.

Tomas

>
> On Wed, 9 Sep 2020 at 07:47, Jeroen Ooms <jeroenooms using gmail.com> wrote:
>> On Tue, Sep 8, 2020 at 11:44 PM Jeroen Ooms <jeroenooms using gmail.com> wrote:
>>> On Tue, Sep 8, 2020 at 5:20 PM Tomas Kalibera <tomas.kalibera using gmail.com> wrote:
>>>> On 9/8/20 4:48 PM, Hugh Parsonage wrote:
>>>>> Unfortunately I only get
>>>>>
>>>>> [Thread 21752.0x4aa8 exited with code 3221225477]
>>>>> [Thread 21752.0x4514 exited with code 3221225477]
>>>>> [Thread 21752.0x3f10 exited with code 3221225477]
>>>>> [Inferior 1 (process 21752) exited with code 030000000005]
>>>>>
>>>>> (I'm guessing I would need to build an instrumented version of R, or
>>>>> can R be debugged using gdb with an off-the-shelf installation?)
>>>> No, the default build lacks debug symbols. You need a build with debug
>>>> symbols, and if you can reproduce in a build without compiler
>>>> optimizations (-O0), the backtrace may be easier to interpret. Some bugs
>>>> however "disappear" when optimizations are disabled. You can build R
>>>> from source (and there may be debug builds provided by someone else
>>>> (Jeroen?)).
>>> Debug builds for each revision are available from
>>> https://r-devel.github.io . To download the installer you need to
>>> click the github icon in the last column in the table. You need to be
>>> signed in with a (free) Github account in order to download builds
>>> (artifacts) from Github actions. It will show download links for both
>>> the regular installer and installer with debug symbols.
>>>
>>> In other news, the https://r-devel.github.io table also shows that the
>>> fix that martin committed is segfaulting on 32-bit.
>> Sorry that was inaccurate, it is not segfaulting at all, but the unit
>> test is raising an error on 32-bit.