[dune-functions] Bug in DiscreteGlobalBasisFunction

[Carsten Gräser]

Hi Simon,

Am 13.08.21 um 10:42 schrieb Simon Praetorius:
> I have implemented an own DiscreteFunction representation, inspired
> by the DiscreteGlobalBasisFunction but with some additional
> functionality and something made differently. But, I will have a look
> whether I have adopted this part of the code. So far, I've not found
> a situation with strange results in some sub-components that I
> couldn't explain.
> 
> How to detect such errors in the future? An extended test is probably
> a good idea. Thanks for implementing this. Would it make sense to
> include valgrind in the testsuite, i.e., run the examples through a
> memory debugger? Maybe also a static code analyzer. There exist lost
in the present case a plain test found this. Unfortunately
this was missing before.

I don't know how much work it is to use valgrind in the CI.
Instead of this one could use a debug build configuration
with some enabled sanitizers (maybe address and ub). But I'm
not sure if this would also catch read before write issues
like valgrid does.

Best,
Carsten