https://github.com/martinboehme created
https://github.com/llvm/llvm-project/pull/96731
We were previously treating the operand of `typeid()` as being definitely
unevaluated, but it can be evaluated if it is a glvalue of polymorphic type.
This patch includes a test that fails without the fix.
>From 2e80e59fccc7ced7539fa2ee70e33545ce0e1441 Mon Sep 17 00:00:00 2001
From: Martin Braenne <mboe...@google.com>
Date: Wed, 26 Jun 2024 04:44:53 +0000
Subject: [PATCH] [clang][dataflow] Teach `AnalysisASTVisitor` that `typeid()`
can be evaluated.
We were previously treating the operand of `typeid()` as being definitely
unevaluated, but it can be evaluated if it is a glvalue of polymorphic type.
This patch includes a test that fails without the fix.
---
.../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 2a74d7fa63fd7..10d7ec9380ab8 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 {
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