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

[Fangrui Song via llvm-commits]

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@@ -319,9 +319,12 @@ static bool shouldReplace(const Symbol *existing, InputFile *newFile,
   }
 
   // Neither symbol is week. They conflict.
-  error("duplicate symbol: " + toString(*existing) + "\n>>> defined in " +
-        toString(existing->getFile()) + "\n>>> defined in " +
-        toString(newFile));
+  if (config->allowMultipleDefinition) {
+    return false;
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MaskRay wrote:

https://llvm.org/docs/CodingStandards.html#don-t-use-braces-on-simple-single-statement-bodies-of-if-else-loop-statements

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