[ELF] Add a comment for ARMExidxSentinelSection::Highest; Use "= nullptr" instead of "= 0". NFC.

igorkudrin · igorkudrin · commit 5e9da2d06bf3 · 2018-01-09T09:44:27.000Z
Differential Revision: https://reviews.llvm.org/D41234 llvm-svn: 322066
diff --git a/lld/ELF/SyntheticSections.h b/lld/ELF/SyntheticSections.h
@@ -790,7 +790,10 @@ class ARMExidxSentinelSection : public SyntheticSection {
   void writeTo(uint8_t *Buf) override;
   bool empty() const override;
 
-  InputSection *Highest = 0;
+  // The last section referenced by a regular .ARM.exidx section.
+  // It is found and filled in Writer<ELFT>::resolveShfLinkOrder().
+  // The sentinel points at the end of that section.
+  InputSection *Highest = nullptr;
 };
 
 // A container for one or more linker generated thunks. Instances of these
