[ELF] Skip non-InputSection's in getErrPlace

[MaskRay]

Summary

Otherwise MergeInputSection's can also be iterated and will cause cast error.

[ikudrin]

Is it possible to add a test case?

[grimar]

It seems caused by rL336106. But I really do not understand how it can happen.

As my comment for the commit says:
"We should only have InputSection type of the sections in the vector.
(because we already converted MergeInputSection in mergeSections()
and combined EhInputSections in combineEhFrameSections())."

What am I missing?

[MaskRay]

In D50419#1198702, @grimar wrote:

It seems caused by rL336106. But I really do not understand how it can happen.

As my comment for the commit says:
"We should only have InputSection type of the sections in the vector.
(because we already converted MergeInputSection in mergeSections()
and combined EhInputSections in combineEhFrameSections())."

What am I missing?

Thanks for the information! I find that mergeSections() does not remove non-alive sections as its comment says. I have created D50742

In an internal target, both revisions will fix the invalid cast but D50742 is obviously the way to go.

ELF/Target.cpp

if (Config->EKind == ELF32LEKind)
       return getX32TargetInfo();
     return getX86_64TargetInfo();
   }
   fatal("unknown target machine");
 }
 
 template <class ELFT> static ErrorPlace getErrPlace(const uint8_t *Loc) {
   for (InputSectionBase *D : InputSections) {
-    auto *IS = cast<InputSection>(D);
-    if (!IS->getParent())
+    auto *IS = dyn_cast<InputSection>(D);
+    if (!IS || !IS->getParent())
       continue;
 
     uint8_t *ISLoc = IS->getParent()->Loc + IS->OutSecOff;
     if (ISLoc <= Loc && Loc < ISLoc + IS->getSize())
       return {IS, IS->template getLocation<ELFT>(Loc - ISLoc) + ": "};
   }
   return {};
 }