[clang][dataflow] Model variables / fields / funcs used in default initializers.

[mboehme]

Summary

The newly added test fails without the other changes in this patch.

[mboehme]

pre-merge failure looks unrelated

clang/lib/Analysis/FlowSensitive/DataflowEnvironment.cpp

 static void
 getFieldsGlobalsAndFuncs(const Stmt &S,
                          llvm::DenseSet<const FieldDecl *> &Fields,
                          llvm::DenseSet<const VarDecl *> &Vars,
                          llvm::DenseSet<const FunctionDecl *> &Funcs) {
   for (auto *Child : S.children())
     if (Child != nullptr)
       getFieldsGlobalsAndFuncs(*Child, Fields, Vars, Funcs);
+  if (const auto *DefaultInit = dyn_cast<CXXDefaultInitExpr>(&S))
+    getFieldsGlobalsAndFuncs(*DefaultInit->getExpr(), Fields, Vars, Funcs);
 
   if (auto *DS = dyn_cast<DeclStmt>(&S)) {
     if (DS->isSingleDecl())
       getFieldsGlobalsAndFuncs(*DS->getSingleDecl(), Fields, Vars, Funcs);
     else
       for (auto *D : DS->getDeclGroup())
         getFieldsGlobalsAndFuncs(*D, Fields, Vars, Funcs);
   } else if (auto *E = dyn_cast<DeclRefExpr>(&S)) {

clang/unittests/Analysis/FlowSensitive/TransferTest.cpp

runDataflow(
         auto &AnonStruct = cast<AggregateStorageLocation>(ThisLoc->getChild(
             *cast<ValueDecl>(IndirectField->chain().front())));
 
         auto *B = cast<BoolValue>(Env.getValue(AnonStruct.getChild(*BDecl)));
         ASSERT_TRUE(Env.flowConditionImplies(*B));
       });
 }
 
+TEST(TransferTest, AnonymousStructWithReferenceField) {
+  std::string Code = R"(
+    int global_i = 0;
+    struct target {
+      target() {
+        (void)0;
+        // [[p]]
+      }
+      struct {
+        int &i = global_i;
+      };
+    };
+  )";
+  runDataflow(
+      Code,
+      [](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
+         ASTContext &ASTCtx) {
+        const Environment &Env = getEnvironmentAtAnnotation(Results, "p");
+        const ValueDecl *GlobalIDecl = findValueDecl(ASTCtx, "global_i");
+        const ValueDecl *IDecl = findValueDecl(ASTCtx, "i");
+        const IndirectFieldDecl *IndirectField =
+            findIndirectFieldDecl(ASTCtx, "i");
+
+        auto *ThisLoc =
+            cast<AggregateStorageLocation>(Env.getThisPointeeStorageLocation());
+        auto &AnonStruct = cast<AggregateStorageLocation>(ThisLoc->getChild(
+            *cast<ValueDecl>(IndirectField->chain().front())));
+
+        auto *RefVal =
+            cast<ReferenceValue>(Env.getValue(AnonStruct.getChild(*IDecl)));
+
+        ASSERT_EQ(&RefVal->getReferentLoc(),
+                  Env.getStorageLocation(*GlobalIDecl));
+      });
+}
+
 } // namespace