[clang] reland (PR #98896)

[via cfe-commits]

https://github.com/martinboehme created https://github.com/llvm/llvm-project/pull/98896

- **Reapply "[clang][dataflow] Teach `AnalysisASTVisitor` that `typeid()` can be evaluated." (#96766)**
- **Turn on RTTI explicitly in `checkDataflowWithNoopAnalysis()`.**


>From b7dbf7d24e536c22c2a380d7b6de9bf7b4fc5ef7 Mon Sep 17 00:00:00 2001
From: Martin Braenne <mboehme at google.com>
Date: Thu, 27 Jun 2024 07:30:02 +0000
Subject: [PATCH 1/2] Reapply "[clang][dataflow] Teach `AnalysisASTVisitor`
 that `typeid()` can be evaluated." (#96766)

This reverts commit 6e96e5ab8a0e40fba0302a5c32574be41ef57354.
---
 .../clang/Analysis/FlowSensitive/ASTOps.h     |  6 ++-
 .../Analysis/FlowSensitive/TransferTest.cpp   | 43 +++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/clang/include/clang/Analysis/FlowSensitive/ASTOps.h b/clang/include/clang/Analysis/FlowSensitive/ASTOps.h
index 925b99af9141a..f9c923a36ad22 100644
--- a/clang/include/clang/Analysis/FlowSensitive/ASTOps.h
+++ b/clang/include/clang/Analysis/FlowSensitive/ASTOps.h
@@ -113,7 +113,11 @@ class AnalysisASTVisitor : public RecursiveASTVisitor<Derived> {
   // nevertheless it appears in the Clang CFG, so we don't exclude it here.
   bool TraverseDecltypeTypeLoc(DecltypeTypeLoc) { return true; }
   bool TraverseTypeOfExprTypeLoc(TypeOfExprTypeLoc) { return true; }
-  bool TraverseCXXTypeidExpr(CXXTypeidExpr *) { return true; }
+  bool TraverseCXXTypeidExpr(CXXTypeidExpr *TIE) {
+    if (TIE->isPotentiallyEvaluated())
+      return RecursiveASTVisitor<Derived>::TraverseCXXTypeidExpr(TIE);
+    return true;
+  }
   bool TraverseUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *) {
     return true;
   }
diff --git a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
index e743eefa5d458..39e7001393e5e 100644
--- a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp
@@ -1637,6 +1637,49 @@ TEST(TransferTest, StructModeledFieldsWithAccessor) {
       });
 }
 
+TEST(TransferTest, StructModeledFieldsInTypeid) {
+  // Test that we model fields mentioned inside a `typeid()` expression only if
+  // that expression is potentially evaluated -- i.e. if the expression inside
+  // `typeid()` is a glvalue of polymorphic type (see
+  // `CXXTypeidExpr::isPotentiallyEvaluated()` and [expr.typeid]p3).
+  std::string Code = R"(
+    // Definitions needed for `typeid`.
+    namespace std {
+      class type_info {};
+      class bad_typeid {};
+    }  // namespace std
+
+    struct NonPolymorphic {};
+
+    struct Polymorphic {
+      virtual ~Polymorphic() = default;
+    };
+
+    struct S {
+      NonPolymorphic *NonPoly;
+      Polymorphic *Poly;
+    };
+
+    void target(S &s) {
+      typeid(*s.NonPoly);
+      typeid(*s.Poly);
+      // [[p]]
+    }
+  )";
+  runDataflow(
+      Code,
+      [](const llvm::StringMap<DataflowAnalysisState<NoopLattice>> &Results,
+         ASTContext &ASTCtx) {
+        const Environment &Env = getEnvironmentAtAnnotation(Results, "p");
+        auto &SLoc = getLocForDecl<RecordStorageLocation>(ASTCtx, Env, "s");
+        std::vector<const ValueDecl *> Fields;
+        for (auto [Field, _] : SLoc.children())
+          Fields.push_back(Field);
+        EXPECT_THAT(Fields,
+                    UnorderedElementsAre(findValueDecl(ASTCtx, "Poly")));
+      });
+}
+
 TEST(TransferTest, StructModeledFieldsWithComplicatedInheritance) {
   std::string Code = R"(
     struct Base1 {

>From 273098962e7740331f46154bf4ed67d68b52c5bc Mon Sep 17 00:00:00 2001
From: Martin Braenne <mboehme at google.com>
Date: Thu, 27 Jun 2024 08:04:30 +0000
Subject: [PATCH 2/2] Turn on RTTI explicitly in
 `checkDataflowWithNoopAnalysis()`.

---
 clang/unittests/Analysis/FlowSensitive/TestingSupport.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/clang/unittests/Analysis/FlowSensitive/TestingSupport.cpp b/clang/unittests/Analysis/FlowSensitive/TestingSupport.cpp
index 5c4d42c6ccdcf..622de6323ad33 100644
--- a/clang/unittests/Analysis/FlowSensitive/TestingSupport.cpp
+++ b/clang/unittests/Analysis/FlowSensitive/TestingSupport.cpp
@@ -176,13 +176,18 @@ llvm::Error test::checkDataflowWithNoopAnalysis(
     DataflowAnalysisOptions Options, LangStandard::Kind Std,
     std::function<llvm::StringMap<QualType>(QualType)> SyntheticFieldCallback) {
   llvm::SmallVector<std::string, 3> ASTBuildArgs = {
+      "-fsyntax-only",
       // -fnodelayed-template-parsing is the default everywhere but on Windows.
       // Set it explicitly so that tests behave the same on Windows as on other
       // platforms.
+      "-fno-delayed-template-parsing",
       // Set -Wno-unused-value because it's often desirable in tests to write
       // expressions with unused value, and we don't want the output to be
       // cluttered with warnings about them.
-      "-fsyntax-only", "-fno-delayed-template-parsing", "-Wno-unused-value",
+      "-Wno-unused-value",
+      // Some build environments don't have RTTI enabled by default.
+      // Enable it explicitly to make sure tests work in all environments.
+      "-frtti",
       "-std=" +
           std::string(LangStandard::getLangStandardForKind(Std).getName())};
   AnalysisInputs<NoopAnalysis> AI(