[PATCH] D81988: [ELF] Fix a dyn_cast<Defined>(nullptr) crash if a local symbol appears in InputFile::symbols

[George Rimar via Phabricator via llvm-commits]

grimar added a comment.

In D81988#2098351 <https://reviews.llvm.org/D81988#2098351>, @MaskRay wrote:

> In D81988#2097630 <https://reviews.llvm.org/D81988#2097630>, @grimar wrote:
>
> > In D81988#2097485 <https://reviews.llvm.org/D81988#2097485>, @jhenderson wrote:
> >
> > > would we be better off emitting some kind of warning or error about the out-of-order list earlier on?
> >
> >
> > +1 to this question.
>
>
> This should be a separate change. llvm-readobj -s should emit a warning as well (like GNU readelf).


Shouldn't we just error out early?

We have a few more places where we have this code pattern:

1. MapFile.cpp

https://github.com/llvm/llvm-project/blob/master/lld/ELF/MapFile.cpp#L54

2. InputSectionBase::getEnclosingFunction:

https://github.com/llvm/llvm-project/blob/master/lld/ELF/InputSection.cpp#L285

That code also uses `dyn_cast<Defined>(b)` and makes me wondering why do you want to support
this broken case instead of reporting an error much earlier? This ways seems we will not need to
fix all other places.


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