[PATCH] D153409: BEGIN_PUBLIC [clang][dataflow] Treat fields of anonymous records as being part of their parent.

[Martin Böhme via Phabricator via cfe-commits]

mboehme created this revision.
Herald added subscribers: martong, xazax.hun.
Herald added a reviewer: NoQ.
Herald added a project: All.
mboehme requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

See https://en.cppreference.com/w/c/language/struct.

Adds a test that fails without the other changes in the patch.
END_PUBLIC


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D153409

Files:
  clang/lib/Analysis/FlowSensitive/DataflowAnalysisContext.cpp
  clang/lib/Analysis/FlowSensitive/Transfer.cpp
  clang/unittests/Analysis/FlowSensitive/TestingSupport.cpp
  clang/unittests/Analysis/FlowSensitive/TransferTest.cpp


Index: clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
===================================================================
--- clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
+++ clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
@@ -5403,4 +5403,35 @@
       });
 }
 
+// Check that fields of anonymous records are modeled and treated as children
+// of the enclosing record.
+TEST(TransferTest, AnonymousStruct) {
+  std::string Code = R"(
+    struct S {
+      struct {
+        int i;
+      };
+    };
+    void target() {
+      S s;
+      (void)s.i;
+      // [[p]]
+    }
+  )";
+  runDataflow(
+      Code,
+      [](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
+         ASTContext &ASTCtx) {
+        const Environment &Env = getEnvironmentAtAnnotation(Results, "p");
+        const ValueDecl *SDecl = findValueDecl(ASTCtx, "s");
+        const ValueDecl *IDecl = findValueDecl(ASTCtx, "i");
+
+        auto *S =
+            cast<AggregateStorageLocation>(Env.getStorageLocation(*SDecl));
+        // If we can call getChild() without an assertion failure, it means
+        // that `i` is modeled.
+        S->getChild(*IDecl);
+      });
+}
+
 } // namespace
Index: clang/unittests/Analysis/FlowSensitive/TestingSupport.cpp
===================================================================
--- clang/unittests/Analysis/FlowSensitive/TestingSupport.cpp
+++ clang/unittests/Analysis/FlowSensitive/TestingSupport.cpp
@@ -154,7 +154,8 @@
 }
 
 const ValueDecl *test::findValueDecl(ASTContext &ASTCtx, llvm::StringRef Name) {
-  auto TargetNodes = match(valueDecl(hasName(Name)).bind("v"), ASTCtx);
+  auto TargetNodes = match(
+      valueDecl(unless(indirectFieldDecl()), hasName(Name)).bind("v"), ASTCtx);
   assert(TargetNodes.size() == 1 && "Name must be unique");
   auto *const Result = selectFirst<ValueDecl>("v", TargetNodes);
   assert(Result != nullptr);
Index: clang/lib/Analysis/FlowSensitive/Transfer.cpp
===================================================================
--- clang/lib/Analysis/FlowSensitive/Transfer.cpp
+++ clang/lib/Analysis/FlowSensitive/Transfer.cpp
@@ -543,6 +543,16 @@
     if (BaseLoc == nullptr)
       return;
 
+    // Fields on anonymous records are treated as being part of the enclosing
+    // records. So if we see a member access for an anonymous record, just pass
+    // through the storage location of the base object.
+    if (auto *Field = dyn_cast<FieldDecl>(Member)) {
+      if (Field->isAnonymousStructOrUnion()) {
+        Env.setStorageLocation(*S, *BaseLoc);
+        return;
+      }
+    }
+
     auto &MemberLoc = BaseLoc->getChild(*Member);
     if (MemberLoc.getType()->isReferenceType()) {
       // Based on its type, `MemberLoc` must be mapped either to nothing or to a
Index: clang/lib/Analysis/FlowSensitive/DataflowAnalysisContext.cpp
===================================================================
--- clang/lib/Analysis/FlowSensitive/DataflowAnalysisContext.cpp
+++ clang/lib/Analysis/FlowSensitive/DataflowAnalysisContext.cpp
@@ -300,8 +300,12 @@
       !Type->isRecordType())
     return;
 
-  for (const FieldDecl *Field : Type->getAsRecordDecl()->fields())
-    Fields.insert(Field);
+  for (const FieldDecl *Field : Type->getAsRecordDecl()->fields()) {
+    if (Field->isAnonymousStructOrUnion())
+      getFieldsFromClassHierarchy(Field->getType(), Fields);
+    else
+      Fields.insert(Field);
+  }
   if (auto *CXXRecord = Type->getAsCXXRecordDecl())
     for (const CXXBaseSpecifier &Base : CXXRecord->bases())
       getFieldsFromClassHierarchy(Base.getType(), Fields);


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