Re: Blog post about printing associative arrays from GDB
I'd also be very interested in how to get this working with dmd.
Re: Blog post about printing associative arrays from GDB
I created an initial version and would be glad to get some feedback. I couldn't figure out how to call the _AAGetX-style functions, so I just went with the approach in my blog post to get something working that can be refactored later. Here is the code. It currently works with gdc, but not with dmd, because dmd calls the type like _AArray_int_int, not int[int]. Also note that it creates (or overwrites) two files in the directory, libhelpers.so and helpers.d: https://github.com/johannes-riecken-dunnhumby/pretty I kept the generated files in there to ease experimentation (which I would take out later) and still it's very little code. To get it working I had to add the directory containing the code to my .gdbinit with `add-auto-load-safe-path ~/workspace/pretty` gdb can auto-load python files related to an executable if they are named as -gdb.py, so I did that for my example executable foo (which i create with `gdc-9 -g -o foo foo.d`. To check if my code works I used the command PYTHONPATH=. gdb ./foo -ex 'b 3' -ex run -ex 'p dict' For troubleshooting, check the output of `info pretty-printer` in gdb. Support for custom structs should be easy enough to add, but I need to work now. Cheers!
Re: Blog post about printing associative arrays from GDB
On Thursday, 24 October 2019 at 14:20:42 UTC, Mihails wrote: On Thursday, 24 October 2019 at 13:16:39 UTC, Johannes Riecken wrote: GDB uses internal functions of C++'s runtime to do the pretty-printing for C++. Implementing that for D's runtime library in its current form would seem like a considerable effort to me, since D's runtime library seems to be a bit hairier with respect to the internal fields, no? That wouldn't be a considerable effort on its own (I think all necessary machinery is already part of druntime.rt package) but right now you would need to have druntime built with debugging symbols to get anything done. For C++ standard containers it is not a problem because those are defined in header files. If AA implementation was switched to templates, it would "just work" for druntime too. Cool, if you (or someone else) can give me the fields or functions in the druntime.rt package that can be used to print associative arrays from GDB, then I can try my hand at building a pretty-printer using GDB's Python API next week.
Re: Blog post about printing associative arrays from GDB
On Thursday, 24 October 2019 at 11:20:07 UTC, Mihails wrote: GDB has some dedicated functionality to improve pretty-printing and expression evaluation of things that too complex to figure out automatically: - https://sourceware.org/gdb/onlinedocs/gdb/Pretty-Printing.html - https://sourceware.org/gdb/onlinedocs/gdb/Writing-an-Xmethod.html GCC, for example, provides such scripts for improved debugging of C++ standard library as part of its distribution. Writing something similar for DMD/GDC/LDC shouldn't be too hard. GDB uses internal functions of C++'s runtime to do the pretty-printing for C++. Implementing that for D's runtime library in its current form would seem like a considerable effort to me, since D's runtime library seems to be a bit hairier with respect to the internal fields, no?
Re: Blog post about printing associative arrays from GDB
On Wednesday, 23 October 2019 at 21:07:24 UTC, Dennis wrote:
Thanks for spitting through the GDB manual so I don't have to!
I would've guessed something like this was possible with GDB,
but never bothered until now.
On Wednesday, 23 October 2019 at 20:52:55 UTC, Johannes Riecken
wrote:
is there a Phobos function to automatically print expected and
actual values for failed assertions? In our company we use
ocean's test!("==").
Not a phobos function, a compiler switch. In recent LDC and
DMD, you can use -checkaction=context and an attempt is made to
print the actual values involved in the assertion. It is still
young so you might still encounter bugs or limitations, but it
does the job really well for most asserts.
That looks promising. In the version I have installed (dmd
2.087.0) compilation crashes when using the flag and also
stdio.writeln, but playing around with the newest version in
run.dlang.io, it seems to work well with the cases I've tried,
cool!
Blog post about printing associative arrays from GDB
I've written a blog post about printing custom data structures
from GDB using dlopen that I hope some of you find interesting
and I'd also be happy to discuss it:
https://medium.com/dunnhumby-data-science-engineering/how-to-simplify-debugging-unit-tests-in-d-a2b52c5c1fa
Please let me know if there are any better ways to print data
structures like associative arrays from GDB, maybe by using
functions from the runtime library. Another exciting idea would
be to automate the pretty printing, maybe also by looking how the
pretty-printers for C++ in GDB 7+ are defined. I sadly haven't
read much D code from outside our company; is there a Phobos
function to automatically print expected and actual values for
failed assertions? In our company we use ocean's test!("==").
