[clang] 68226e5 - [clang][dataflow] Add a test to justify skipping past references in UO_Deref

[Stanislav Gatev via cfe-commits]

Author: Stanislav Gatev
Date: 2022-01-18T21:27:43Z
New Revision: 68226e572f41105446413b12ee95ab5540b2b6ac

URL: https://github.com/llvm/llvm-project/commit/68226e572f41105446413b12ee95ab5540b2b6ac
DIFF: https://github.com/llvm/llvm-project/commit/68226e572f41105446413b12ee95ab5540b2b6ac.diff

LOG: [clang][dataflow] Add a test to justify skipping past references in UO_Deref

This is part of the implementation of the dataflow analysis framework.
See "[RFC] A dataflow analysis framework for Clang AST" on cfe-dev.

Reviewed-by: xazax.hun

Differential Revision: https://reviews.llvm.org/D117567

Added: 
    

Modified: 
    clang/lib/Analysis/FlowSensitive/Transfer.cpp
    clang/unittests/Analysis/FlowSensitive/TransferTest.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Analysis/FlowSensitive/Transfer.cpp b/clang/lib/Analysis/FlowSensitive/Transfer.cpp
index 0979f55c5a5c8..865191916e502 100644
--- a/clang/lib/Analysis/FlowSensitive/Transfer.cpp
+++ b/clang/lib/Analysis/FlowSensitive/Transfer.cpp
@@ -182,6 +182,7 @@ class TransferVisitor : public ConstStmtVisitor<TransferVisitor> {
 
     switch (S->getOpcode()) {
     case UO_Deref: {
+      // Skip past a reference to handle dereference of a dependent pointer.
       const auto *SubExprVal = cast_or_null<PointerValue>(
           Env.getValue(*SubExpr, SkipPast::Reference));
       if (SubExprVal == nullptr)

diff  --git a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
index ea035ba013daf..d1d8705d26c0a 100644
--- a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
@@ -1758,4 +1758,34 @@ TEST_F(TransferTest, AddrOfReference) {
               });
 }
 
+TEST_F(TransferTest, DerefDependentPtr) {
+  std::string Code = R"(
+    template <typename T>
+    void target(T *Foo) {
+      T &Bar = *Foo;
+      /*[[p]]*/
+    }
+  )";
+  runDataflow(
+      Code, [](llvm::ArrayRef<
+                   std::pair<std::string, DataflowAnalysisState<NoopLattice>>>
+                   Results,
+               ASTContext &ASTCtx) {
+        ASSERT_THAT(Results, ElementsAre(Pair("p", _)));
+        const Environment &Env = Results[0].second.Env;
+
+        const ValueDecl *FooDecl = findValueDecl(ASTCtx, "Foo");
+        ASSERT_THAT(FooDecl, NotNull());
+
+        const ValueDecl *BarDecl = findValueDecl(ASTCtx, "Bar");
+        ASSERT_THAT(BarDecl, NotNull());
+
+        const auto *FooVal =
+            cast<PointerValue>(Env.getValue(*FooDecl, SkipPast::None));
+        const auto *BarVal =
+            cast<ReferenceValue>(Env.getValue(*BarDecl, SkipPast::None));
+        EXPECT_EQ(&BarVal->getPointeeLoc(), &FooVal->getPointeeLoc());
+      });
+}
+
 } // namespace