[clang-tidy] Allow bugprone-unchecked-optional-access to handle calls to `std::forward`

The check now understands that calling `std::forward`
will not modify the underlying optional value.

This fixes llvm#59705

Reviewed By: PiotrZSL

Differential Revision: https://reviews.llvm.org/D147383

1 files changed, 47 insertions, 0 deletions

diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/unchecked-optional-access.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/unchecked-optional-access.cpp
index 6c79dad93e90..c1e731f41171 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/bugprone/unchecked-optional-access.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/bugprone/unchecked-optional-access.cpp
@@ -110,3 +110,50 @@ class C4 {
   }
   int foo_;
 };
+
+// llvm#59705
+namespace std
+{
+  template <typename T>
+  constexpr T&& forward(T& type) noexcept {
+    return static_cast<T&&>(type);
+  }
+
+  template <typename T>
+  constexpr T&& forward(T&& type) noexcept {
+    return static_cast<T&&>(type);
+  }
+}
+
+void std_forward_copy(absl::optional<int> opt) {
+  std::forward<absl::optional<int>>(opt).value();
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: unchecked access to optional
+}
+
+void std_forward_copy_safe(absl::optional<int> opt) {
+  if (!opt) return;
+
+  std::forward<absl::optional<int>>(opt).value();
+}
+
+void std_forward_copy(absl::optional<int>& opt) {
+  std::forward<absl::optional<int>>(opt).value();
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: unchecked access to optional
+}
+
+void std_forward_lvalue_ref_safe(absl::optional<int>& opt) {
+  if (!opt) return;
+
+  std::forward<absl::optional<int>>(opt).value();
+}
+
+void std_forward_copy(absl::optional<int>&& opt) {
+  std::forward<absl::optional<int>>(opt).value();
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: unchecked access to optional
+}
+
+void std_forward_rvalue_ref_safe(absl::optional<int>&& opt) {
+  if (!opt) return;
+
+  std::forward<absl::optional<int>>(opt).value();
+}