[llvm-branch-commits] [clang] [LifetimeSafety] Detect dangling field of base class (PR #191831)

[via llvm-branch-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-analysis

Author: Utkarsh Saxena (usx95)

<details>
<summary>Changes</summary>

Fixes: https://github.com/llvm/llvm-project/issues/191823

---
Full diff: https://github.com/llvm/llvm-project/pull/191831.diff


4 Files Affected:

- (modified) clang/lib/Analysis/LifetimeSafety/Origins.cpp (+1-1) 
- (modified) clang/test/Sema/warn-lifetime-safety-dangling-field.cpp (+12) 
- (modified) clang/test/Sema/warn-lifetime-safety-suggestions.cpp (+15) 
- (modified) clang/test/Sema/warn-lifetime-safety.cpp (+15) 


``````````diff
diff --git a/clang/lib/Analysis/LifetimeSafety/Origins.cpp b/clang/lib/Analysis/LifetimeSafety/Origins.cpp
index abf9890b08522..fdd2671dee2e0 100644
--- a/clang/lib/Analysis/LifetimeSafety/Origins.cpp
+++ b/clang/lib/Analysis/LifetimeSafety/Origins.cpp
@@ -236,7 +236,7 @@ OriginList *OriginManager::getOrCreateList(const Expr *E) {
     ReferencedDecl = DRE->getDecl();
   else if (auto *ME = dyn_cast<MemberExpr>(E))
     if (auto *Field = dyn_cast<FieldDecl>(ME->getMemberDecl());
-        Field && isa<CXXThisExpr>(ME->getBase()))
+        Field && isa<CXXThisExpr>(ME->getBase()->IgnoreParenImpCasts()))
       ReferencedDecl = Field;
   if (ReferencedDecl) {
     OriginList *Head = nullptr;
diff --git a/clang/test/Sema/warn-lifetime-safety-dangling-field.cpp b/clang/test/Sema/warn-lifetime-safety-dangling-field.cpp
index fa45458371012..79b0183ed91ec 100644
--- a/clang/test/Sema/warn-lifetime-safety-dangling-field.cpp
+++ b/clang/test/Sema/warn-lifetime-safety-dangling-field.cpp
@@ -184,3 +184,15 @@ struct IndirectEscape2 {
     p = s.data();
   }
 };
+
+namespace DanglingPointerFieldInBaseClass {
+struct BaseWithPointer {
+  std::string_view view; // expected-note {{this field dangles}}
+};
+
+struct DerivedWithCtor : BaseWithPointer {
+  DerivedWithCtor(std::string s) {
+    view = s; // expected-warning {{address of stack memory escapes to a field}}
+  }
+};
+} // namespace DanglingPointerFieldInBaseClass
diff --git a/clang/test/Sema/warn-lifetime-safety-suggestions.cpp b/clang/test/Sema/warn-lifetime-safety-suggestions.cpp
index c96b92cfe0b5b..b3b13038dc344 100644
--- a/clang/test/Sema/warn-lifetime-safety-suggestions.cpp
+++ b/clang/test/Sema/warn-lifetime-safety-suggestions.cpp
@@ -513,4 +513,19 @@ CaptureRefToRef test_ref_to_ref() {
   CaptureRefToRef x(obj); // expected-warning {{address of stack memory is returned later}}
   return x; // expected-note {{returned here}}
 }
+
+struct BaseWithView {
+  View v; // expected-note {{escapes to this field}}
+};
+struct CaptureRefToBaseView : BaseWithView {
+  CaptureRefToBaseView(const MyObj& obj) { // expected-warning {{parameter in intra-TU function should be marked [[clang::lifetimebound]]}}
+    v = obj;
+  }
+};
+
+CaptureRefToBaseView test_ref_to_base_view() {
+  MyObj obj;
+  CaptureRefToBaseView x(obj); // expected-warning {{address of stack memory is returned later}}
+  return x; // expected-note {{returned here}}
+}
 } // namespace capturing_constructor
diff --git a/clang/test/Sema/warn-lifetime-safety.cpp b/clang/test/Sema/warn-lifetime-safety.cpp
index b1dea7f7340b3..9c8df51833a0a 100644
--- a/clang/test/Sema/warn-lifetime-safety.cpp
+++ b/clang/test/Sema/warn-lifetime-safety.cpp
@@ -2531,3 +2531,18 @@ int *noreturn_dead_nested(bool cond, bool cond2, int *num) {
 }
 
 } // namespace conditional_operator_control_flow
+
+namespace base_class_fields {
+struct X { int* x; }; // expected-note {{this field dangles}}
+struct Y : X {
+  int* y;
+  void bar() {
+    {
+      int a;
+      x = &a; // expected-warning {{address of stack memory escapes to a field}}
+    }
+    (void)x;
+  }
+};
+} // namespace base_class_fields
+

``````````

</details>


https://github.com/llvm/llvm-project/pull/191831