[clang] Thread Safety Analysis: Check managed capabilities of returned scoped capability (PR #131831)

[Aaron Puchert via cfe-commits]

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@@ -2316,6 +2337,49 @@ void BuildLockset::VisitReturnStmt(const ReturnStmt *S) {
         ReturnType->getPointeeType().isConstQualified() ? AK_Read : AK_Written,
         POK_ReturnPointer);
   }
+
+  if (!checkRecordTypeForScopedCapability(ReturnType))
+    return;
+
+  if (const auto *CBTE = dyn_cast<ExprWithCleanups>(RetVal))
+    RetVal = CBTE->getSubExpr();
+  RetVal = RetVal->IgnoreCasts();
+  if (const auto *CBTE = dyn_cast<CXXBindTemporaryExpr>(RetVal))
+    RetVal = CBTE->getSubExpr();
+  CapabilityExpr Cp;
+  if (auto Object = Analyzer->ConstructedObjects.find(RetVal);
+      Object != Analyzer->ConstructedObjects.end()) {
+    Cp = CapabilityExpr(Object->second, StringRef(), false);
+    Analyzer->ConstructedObjects.erase(Object);
+  }
+  if (!Cp.shouldIgnore()) {
+    const FactEntry *Fact = FSet.findLock(Analyzer->FactMan, Cp);
+    if (const ScopedLockableFactEntry *Scope =
+            cast_or_null<ScopedLockableFactEntry>(Fact)) {
+      CapExprSet LocksInReturnVal = Scope->getUnderlyingMutexes();
+      for (const auto &[a, b] : zip_longest(
+               Analyzer->ExpectedReturnedCapabilities, LocksInReturnVal)) {
+        if (!a.has_value()) {
+          Analyzer->Handler.handleExpectFewerUnderlyingMutexes(
+              RetVal->getExprLoc(), Analyzer->CurrentFunction->getLocation(),
+              Scope->toString(), b.value().getKind(), b.value().toString(),
+              false);
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aaronpuchert wrote:

Also here: add comments on the parameter.

https://github.com/llvm/llvm-project/pull/131831