[clang][dataflow] Add a transfer function for CXXBoolLiteralExpr

[sgatev]

Summary

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

clang/lib/Analysis/FlowSensitive/Transfer.cpp

if (Type->isStructureOrClassType()) {
 
         if (Value *InitVal = Env.getValue(*Init, SkipPast::None))
           cast<StructValue>(Val)->setChild(*Field, *InitVal);
       }
     }
     // FIXME: Implement array initialization.
   }
 
-  // FIXME: Add support for:
-  // - CXXBoolLiteralExpr
+  void VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *S) {
+    auto &Loc = Env.createStorageLocation(*S);
+    Env.setStorageLocation(*S, Loc);
+    Env.setValue(Loc, Env.getBoolLiteralValue(S->getValue()));
+  }
 
 private:
   Environment &Env;
 };
 
 void transfer(const Stmt &S, Environment &Env) {
   assert(!isa<ParenExpr>(&S));
   TransferVisitor(Env).Visit(&S);
 }
 
 } // namespace dataflow
 } // namespace clang

clang/unittests/Analysis/FlowSensitive/TransferTest.cpp

runDataflow(Code,
                     Env.getStorageLocation(*BazDecl, SkipPast::None));
                 ASSERT_THAT(BazLoc, NotNull());
 
                 // FIXME: Add support for union types.
                 EXPECT_THAT(Env.getValue(*BazLoc), IsNull());
               });
 }
 
+TEST_F(TransferTest, AssignFromBoolLiteral) {
+  std::string Code = R"(
+    void target() {
+      bool Foo = true;
+      bool Bar = false;
+      // [[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 auto *FooVal =
+            dyn_cast_or_null<BoolValue>(Env.getValue(*FooDecl, SkipPast::None));
+        ASSERT_THAT(FooVal, NotNull());
+
+        const ValueDecl *BarDecl = findValueDecl(ASTCtx, "Bar");
+        ASSERT_THAT(BarDecl, NotNull());
+
+        const auto *BarVal =
+            dyn_cast_or_null<BoolValue>(Env.getValue(*BarDecl, SkipPast::None));
+        ASSERT_THAT(BarVal, NotNull());
+
+        EXPECT_EQ(FooVal, &Env.getBoolLiteralValue(true));
+        EXPECT_EQ(BarVal, &Env.getBoolLiteralValue(false));
+      });
+}
+
 } // namespace