[lld] [lld][ELF] Demote symbols in discarded sections to Undefined. (PR #68777)

[Fangrui Song via llvm-commits]

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@@ -3062,6 +3062,31 @@ void LinkerDriver::link(opt::InputArgList &args) {
     script->addOrphanSections();
   }
 
+  // Explicitly demote symbols which didn't get placed. If we don't, any
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MaskRay wrote:

"Explicitly" is redundant.

Suggest: Demote symbols defined relative to input sections that are discarded by /DISCARD/ so that relocations referencing them will get reported.

https://github.com/llvm/llvm-project/pull/68777