[clang][dataflow] When analyzing ctors, don't initialize fields of `*this` with values. (#84164)

This is the constructor's job, and we want to be able to test that it
does this.

1 files changed, 63 insertions, 0 deletions

diff --git a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
index f534ccb..9fde417 100644
--- a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
@@ -1476,6 +1476,69 @@ TEST(TransferTest, BaseClassInitializer) {
       llvm::Succeeded());
 }
 
+TEST(TransferTest, FieldsDontHaveValuesInConstructor) {
+  // In a constructor, unlike in regular member functions, we don't want fields
+  // to be pre-initialized with values, because doing so is the job of the
+  // constructor.
+  std::string Code = R"(
+    struct target {
+      target() {
+        0;
+        // [[p]]
+        // Mention the field so it is modeled;
+        Val;
+      }
+
+      int Val;
+    };
+ )";
+  runDataflow(
+      Code,
+      [](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
+         ASTContext &ASTCtx) {
+        const Environment &Env = getEnvironmentAtAnnotation(Results, "p");
+        EXPECT_EQ(getFieldValue(Env.getThisPointeeStorageLocation(), "Val",
+                                ASTCtx, Env),
+                  nullptr);
+      });
+}
+
+TEST(TransferTest, FieldsDontHaveValuesInConstructorWithBaseClass) {
+  // See above, but for a class with a base class.
+  std::string Code = R"(
+    struct Base {
+        int BaseVal;
+    };
+
+    struct target  : public Base {
+      target() {
+        0;
+        // [[p]]
+        // Mention the fields so they are modeled.
+        BaseVal;
+        Val;
+      }
+
+      int Val;
+    };
+ )";
+  runDataflow(
+      Code,
+      [](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
+         ASTContext &ASTCtx) {
+        const Environment &Env = getEnvironmentAtAnnotation(Results, "p");
+        // FIXME: The field of the base class should already have been
+        // initialized with a value by the base constructor. This test documents
+        // the current buggy behavior.
+        EXPECT_EQ(getFieldValue(Env.getThisPointeeStorageLocation(), "BaseVal",
+                                ASTCtx, Env),
+                  nullptr);
+        EXPECT_EQ(getFieldValue(Env.getThisPointeeStorageLocation(), "Val",
+                                ASTCtx, Env),
+                  nullptr);
+      });
+}
+
 TEST(TransferTest, StructModeledFieldsWithAccessor) {
   std::string Code = R"(
     class S {