[lld] wasm-ld: Add allow-multiple-definition flag (PR #97699)

[Sam Clegg via llvm-commits]

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@@ -310,9 +310,14 @@ static bool shouldReplace(const Symbol *existing, InputFile *newFile,
   }
 
   // Neither symbol is week. They conflict.
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sbc100 wrote:

It looks like `reportDuplicate` in the ELF linker simple returns early when `allowMultipleDefinition` is set.  I guess we should do the same?

https://github.com/llvm/llvm-project/pull/97699