[clang] [clang][CrossTU] Indicate weak link attribute in ExternalDefMap. (PR #204188)

[Balázs Benics via cfe-commits]

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@@ -279,6 +306,8 @@ CrossTranslationUnitContext::~CrossTranslationUnitContext() {}
 std::optional<std::string>
 CrossTranslationUnitContext::getLookupName(const Decl *D) {
   SmallString<128> DeclUSR;
+  if (D->hasAttr<WeakAttr>())
+    DeclUSR.push_back('-');
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steakhal wrote:

Just posed: https://discourse.llvm.org/t/should-weak-strong-symbols-have-the-same-usr/91177

https://github.com/llvm/llvm-project/pull/204188