[clang] [LifetimeSafety] Add warning for member functions returning field origins (PR #229784)

[Utkarsh Saxena via cfe-commits]

================
@@ -700,3 +700,94 @@ S foo() {
   return S(create_up());
 }
 } // namespace GH193747
+
+namespace field_origin_escape {
+
+class Context {
+public:
+  // This method should be annotated with lifetimebound.
+  std::string_view method() const { // expected-warning {{implicit this in intra-TU function should be marked [[clang::lifetimebound]]}}
+    return method_;                 // expected-note {{param returned here}}
+  }
+
+private:
+  std::string method_ = "42";
+};
+
+class ContextAnnotated {
+public:
+  std::string_view method() const [[clang::lifetimebound]] {
+    return method_;
+  }
+
+private:
+  std::string method_ = "42";
+};
+
+class ContextWrapper {
+public:
+  explicit ContextWrapper(Context &inner,          // expected-warning {{parameter in intra-TU constructor should be marked [[clang::lifetimebound]]}}
+                          ContextAnnotated &annot) // expected-warning {{parameter in intra-TU constructor should be marked [[clang::lifetimebound]]}}
+      : inner_(inner), annot_(annot) {}
+
+  Context &inner() const { // expected-warning {{return value depends on the lifetime of the object referenced by field 'inner_', which cannot be expressed with [[clang::lifetimebound]]}}
+    return inner_;         // expected-note {{returned here}}
+  }
+
+  // This method should NOT be annotated with lifetimebound.
+  std::string_view method() const { // expected-warning {{return value depends on the lifetime of the object referenced by field 'inner_', which cannot be expressed with [[clang::lifetimebound]]}}
+    return inner_.method();         // expected-note {{returned here}}
+  }
+
+  std::string_view annot_method() const { // expected-warning {{return value depends on the lifetime of the object referenced by field 'annot_', which cannot be expressed with [[clang::lifetimebound]]}}
+    return annot_.method();               // expected-note {{returned here}}
+  }
+
+private:
+  Context &inner_;          // expected-note {{escapes to this field}}
+  ContextAnnotated &annot_; // expected-note {{escapes to this field}}
+};
+
+struct FieldTypes {
+  int val_;
+  int *ptr_;
+  int &ref_;
+  std::string str_;
----------------
usx95 wrote:

Added.

https://github.com/llvm/llvm-project/pull/229784