[lld] [LLD][COFF] Don't dllimport from static libraries (PR #134443)

[Alexandre Ganea via llvm-commits]

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@@ -231,6 +231,17 @@ void SymbolTable::reportUndefinedSymbol(const UndefinedDiag &undefDiag) {
   }
   if (numDisplayedRefs < numRefs)
     diag << "\n>>> referenced " << numRefs - numDisplayedRefs << " more times";
+
+  // Hints
+  StringRef name = undefDiag.sym->getName();
+  if (name.starts_with("__imp_")) {
+    Symbol *imp = find(name.substr(strlen("__imp_")));
+    if (imp && imp->isLazy()) {
+      diag << "\nNOTE: a relevant symbol '" << imp->getName()
+           << "' is available in " << toString(imp->getFile())
+           << " but cannot be used because it is not a import library.";
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aganea wrote:

Please see updated version. I've added another testcase to also validate your test case in https://github.com/llvm/llvm-project/issues/131807#issuecomment-2760632883 -- which happens to only generate a warning.

https://github.com/llvm/llvm-project/pull/134443