[clang][dataflow] Support StmtExpr in PropagateResultObject(). (#88872)

This patch adds a test that assert-fails without the fix.

Author: martinboehme

clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp

@@ -470,6 +470,11 @@ class ResultObjectVisitor : public RecursiveASTVisitor<ResultObjectVisitor> {
       return;
     }
 
+    if (auto *SE = dyn_cast<StmtExpr>(E)) {
+      PropagateResultObject(cast<Expr>(SE->getSubStmt()->body_back()), Loc);
+      return;
+    }
+
     // All other expression nodes that propagate a record prvalue should have
     // exactly one child.
     SmallVector<Stmt *, 1> Children(E->child_begin(), E->child_end());

clang/unittests/Analysis/FlowSensitive/TransferTest.cpp

@@ -3182,6 +3182,32 @@ TEST(TransferTest, ResultObjectLocationForStdInitializerListExpr) {
       });
 }
 
+TEST(TransferTest, ResultObjectLocationForStmtExpr) {
+  std::string Code = R"(
+    struct S {};
+    void target() {
+      S s = ({ S(); });
+      // [[p]]
+    }
+  )";
+  using ast_matchers::cxxConstructExpr;
+  using ast_matchers::match;
+  using ast_matchers::selectFirst;
+  using ast_matchers::traverse;
+  runDataflow(
+      Code,
+      [](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
+         ASTContext &ASTCtx) {
+        const Environment &Env = getEnvironmentAtAnnotation(Results, "p");
+
+        auto *Construct = selectFirst<CXXConstructExpr>(
+            "construct", match(cxxConstructExpr().bind("construct"), ASTCtx));
+
+        EXPECT_EQ(&Env.getResultObjectLocation(*Construct),
+                  &getLocForDecl<RecordStorageLocation>(ASTCtx, Env, "s"));
+      });
+}
+
 TEST(TransferTest, ResultObjectLocationPropagatesThroughConditionalOperator) {
   std::string Code = R"(
     struct A {