[clang] [Sema] Enforce parameter match for ownership_returns attribute (PR #192339)

[Aaron Ballman via cfe-commits]

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@@ -1558,24 +1572,30 @@ static void handleOwnershipAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
       // Cannot have two ownership attributes of different kinds for the same
       // index.
       if (I->getOwnKind() != K && llvm::is_contained(I->args(), Idx)) {
-          S.Diag(AL.getLoc(), diag::err_attributes_are_not_compatible)
-              << AL << I
-              << (AL.isRegularKeywordAttribute() ||
-                  I->isRegularKeywordAttribute());
-          return;
-      } else if (K == OwnershipAttr::Returns &&
+        S.Diag(AL.getLoc(), diag::err_attributes_are_not_compatible)
+            << AL << I
+            << (AL.isRegularKeywordAttribute() ||
+                I->isRegularKeywordAttribute());
+        return;
+      }
+
+      if (K == OwnershipAttr::Returns &&
                  I->getOwnKind() == OwnershipAttr::Returns) {
-        // A returns attribute conflicts with any other returns attribute using
-        // a different index.
-        if (!llvm::is_contained(I->args(), Idx)) {
+        bool IHasArgs = I->args_size() > 0;
+
+        if (!IHasArgs || !llvm::is_contained(I->args(), Idx)) {
+          unsigned IIdx = IHasArgs ? I->args_begin()->getSourceIndex() : 0;
+
           S.Diag(I->getLocation(), diag::err_ownership_returns_index_mismatch)
-              << I->args_begin()->getSourceIndex();
-          if (I->args_size())
-            S.Diag(AL.getLoc(), diag::note_ownership_returns_index_mismatch)
-                << Idx.getSourceIndex() << Ex->getSourceRange();
+              << IIdx << (IHasArgs ? 0 : 1);
+
+          S.Diag(AL.getLoc(), diag::note_ownership_returns_index_mismatch)
+              << Idx.getSourceIndex() << 0 << Ex->getSourceRange();
           return;
         }
-      } else if (K == OwnershipAttr::Takes &&
+      }
+      
+      if (K == OwnershipAttr::Takes &&
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AaronBallman wrote:

I think this one is still an `else if` situation because there's not an unconditional return before it.

https://github.com/llvm/llvm-project/pull/192339