[llvm-dlltool] Respect the DATA flag when creating aliases (#98225)

Author: mstorsjo

llvm/lib/Object/COFFImportFile.cpp

@@ -691,7 +691,9 @@ Error writeImportLibrary(StringRef ImportName, StringRef Path,
       }
 
       if (!E.ImportName.empty() && Name != E.ImportName) {
-        Members.push_back(OF.createWeakExternal(E.ImportName, Name, false, M));
+        if (ImportType == IMPORT_CODE)
+          Members.push_back(
+              OF.createWeakExternal(E.ImportName, Name, false, M));
         Members.push_back(OF.createWeakExternal(E.ImportName, Name, true, M));
         continue;
       }

llvm/test/tools/llvm-dlltool/coff-weak-exports.def

@@ -6,6 +6,7 @@
 LIBRARY test.dll
 EXPORTS
 TestFunction==AltTestFunction
+TestData DATA == AltTestData
 ; When creating an import library, the DLL internal function name of
 ; the implementation of a function isn't visible at all.
 ImpLibName = Implementation
@@ -20,6 +21,9 @@ ImpLibName3 = kernel32.Sleep
 ; CHECK-NEXT: W TestFunction
 ; CHECK:      U __imp_AltTestFunction
 ; CHECK-NEXT: W __imp_TestFunction
+; CHECK-NOT:  W TestData
+; CHECK:      U __imp_AltTestData
+; CHECK-NEXT: W __imp_TestData
 ; CHECK:      T ImpLibName
 ; CHECK-NEXT: T __imp_ImpLibName
 ; CHECK:      U AltTestFunction2