[m-users.] Debugger, setting initial breakpoint not triggering

[Sean Charles (emacstheviking)]

Hi Julien,

Yes, I figured it all out in the end! I installed the none.gc and added --debug and it was all good. The only change I had to make was to replace string-to-int with string-to-number in the gud.el scripts folder and it was all good to go. I raised a PR for that but then I found a better way, emacs has a means to alias out old functions for new which I added to the ticket comment I might try to do it in a cleaner way myself so it is backwards compatible with emacs older than 26.1

Thanks again everybody.
Sean.





> On 14 Dec 2022, at 01:11, Julien Fischer <jfischer at opturion.com> wrote:
> 
> 
> Hi Sean,
> 
> On Tue, 13 Dec 2022, Sean Charles (emacstheviking) wrote:
> 
>> So according to the documentation then, what
>> does --enable-hlc-low-level-debug-grades actually do for me if it
>> isn't provding me with a debug grade for hlc?
> 
> The .ll_debug grades prepare the C code generated by the Mercury
> compiler for debugging with a C debugger (e.g. gdb).  As Zoltan
> mentioned the main use for this is debugging issues in the Mercury->C
> code generator.
> 
> The other use case for them, and this is probably why the option
> --enable-hlc-low-level-debug-grades exists, is debugging Mercury code
> that contains substantial amounts of C code (e.g. via pragma
> foreign_proc) at the C level.
> 
> Mercury-level debugging is not supported by the high-level C backend at
> all. In order to use the Mercury debugger you will need to compile your
> code using a debug grade with the the low-level C backend, e.g.:
> 
>     asm_fast.gc.debug
>     reg.gc.debug
>     none.gc.debug
> 
> etc.
> 
> (Since you appear to be using clang, only the last of those will work.)
> 
> ...
> 
>> After some playing around I came up with this configuration line:
>> ./configure --enable-hlc-low-level-debug-grades --disable-java-grade --enable-additional-libgrades=none.gc,none.gc.debug
>> and then managed to select none.gc coupled with the --debug flag, resulting in a build that now triggers the expected operation of mdb:
> 
> 
> The '--debug' flag is an endless source of confusion and we have been
> intending to change its behaviour.
> 
> What it currently does is paste ".debug" on to the current grade.
> So for example, if your Mercury installation has been configured to use
> "hlc.gc" as its default grade and you do this:
> 
>    $ mmc --debug foo.m
> 
> Then the compiler will attempt to compile that program in the grade
> hlc.gc.debug (which will result in a error somewhere along the process
> since that is not supported).
> 
> I suggest instead outputting the installed grades using
> --output-stdlib-grades (as you have done) and then picking
> one that contains either the "debug" or "decldebug" component
> (But not "ll_debug!) and then explitily invoke the compiler with
> that.
> 
> (Or install a debug grade if one is not present.)
> 
> Julien.