Add nullability annotations

PiperOrigin-RevId: 589842893
Change-Id: I9657761d1f71c665582406f278c6605f6d382f6d

10 files changed, 46 insertions, 26 deletions

diff --git a/absl/status/BUILD.bazel b/absl/status/BUILD.bazel
index 3cf0a5e1..a5fad4d4 100644
--- a/absl/status/BUILD.bazel
+++ b/absl/status/BUILD.bazel
@@ -54,6 +54,7 @@ cc_library(
         "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:no_destructor",
+        "//absl/base:nullability",
         "//absl/base:raw_logging_internal",
         "//absl/base:strerror",
         "//absl/container:inlined_vector",
@@ -100,6 +101,7 @@ cc_library(
         "//absl/base",
         "//absl/base:config",
         "//absl/base:core_headers",
+        "//absl/base:nullability",
         "//absl/base:raw_logging_internal",
         "//absl/meta:type_traits",
         "//absl/strings",
diff --git a/absl/status/CMakeLists.txt b/absl/status/CMakeLists.txt
index da789901..d9d16830 100644
--- a/absl/status/CMakeLists.txt
+++ b/absl/status/CMakeLists.txt
@@ -37,6 +37,7 @@ absl_cc_library(
     absl::inlined_vector
     absl::memory
     absl::no_destructor
+    absl::nullability
     absl::optional
     absl::raw_logging_internal
     absl::span
@@ -76,6 +77,7 @@ absl_cc_library(
     absl::base
     absl::config
     absl::core_headers
+    absl::nullability
     absl::raw_logging_internal
     absl::status
     absl::strings
diff --git a/absl/status/internal/status_internal.cc b/absl/status/internal/status_internal.cc
index 2307579b..a9156754 100644
--- a/absl/status/internal/status_internal.cc
+++ b/absl/status/internal/status_internal.cc
@@ -27,6 +27,7 @@
 #include "absl/base/attributes.h"
 #include "absl/base/config.h"
 #include "absl/base/macros.h"
+#include "absl/base/nullability.h"
 #include "absl/debugging/stacktrace.h"
 #include "absl/debugging/symbolize.h"
 #include "absl/memory/memory.h"
@@ -187,7 +188,7 @@ bool StatusRep::operator==(const StatusRep& other) const {
   return true;
 }
 
-StatusRep* StatusRep::CloneAndUnref() const {
+absl::Nonnull<StatusRep*> StatusRep::CloneAndUnref() const {
   // Optimization: no need to create a clone if we already have a refcount of 1.
   if (ref_.load(std::memory_order_acquire) == 1) {
     // All StatusRep instances are heap allocated and mutable, therefore this
@@ -233,8 +234,9 @@ absl::StatusCode MapToLocalCode(int value) {
   }
 }
 
-std::string* MakeCheckFailString(const absl::Status* status,
-                                 const char* prefix) {
+absl::Nonnull<std::string*> MakeCheckFailString(
+    absl::Nonnull<const absl::Status*> status,
+    absl::Nonnull<const char*> prefix) {
   return new std::string(
       absl::StrCat(prefix, " (",
                    status->ToString(StatusToStringMode::kWithEverything), ")"));
diff --git a/absl/status/internal/status_internal.h b/absl/status/internal/status_internal.h
index c84e626f..c9f43832 100644
--- a/absl/status/internal/status_internal.h
+++ b/absl/status/internal/status_internal.h
@@ -22,6 +22,7 @@
 
 #include "absl/base/attributes.h"
 #include "absl/base/config.h"
+#include "absl/base/nullability.h"
 #include "absl/container/inlined_vector.h"
 #include "absl/strings/cord.h"
 #include "absl/strings/string_view.h"
@@ -99,7 +100,7 @@ class StatusRep {
   // Returns an equivalent heap allocated StatusRep with refcount 1.
   //
   // `this` is not safe to be used after calling as it may have been deleted.
-  StatusRep* CloneAndUnref() const;
+  absl::Nonnull<StatusRep*> CloneAndUnref() const;
 
  private:
   mutable std::atomic<int32_t> ref_;
@@ -119,8 +120,9 @@ absl::StatusCode MapToLocalCode(int value);
 //
 // This is an internal implementation detail for Abseil logging.
 ABSL_ATTRIBUTE_PURE_FUNCTION
-std::string* MakeCheckFailString(const absl::Status* status,
-                                 const char* prefix);
+absl::Nonnull<std::string*> MakeCheckFailString(
+    absl::Nonnull<const absl::Status*> status,
+    absl::Nonnull<const char*> prefix);
 
 }  // namespace status_internal
 
diff --git a/absl/status/internal/statusor_internal.h b/absl/status/internal/statusor_internal.h
index 49cead7a..25c11474 100644
--- a/absl/status/internal/statusor_internal.h
+++ b/absl/status/internal/statusor_internal.h
@@ -18,6 +18,7 @@
 #include <utility>
 
 #include "absl/base/attributes.h"
+#include "absl/base/nullability.h"
 #include "absl/meta/type_traits.h"
 #include "absl/status/status.h"
 #include "absl/utility/utility.h"
@@ -123,7 +124,7 @@ using IsForwardingAssignmentValid = absl::disjunction<
 class Helper {
  public:
   // Move type-agnostic error handling to the .cc.
-  static void HandleInvalidStatusCtorArg(Status*);
+  static void HandleInvalidStatusCtorArg(absl::Nonnull<Status*>);
   ABSL_ATTRIBUTE_NORETURN static void Crash(const absl::Status& status);
 };
 
@@ -131,7 +132,8 @@ class Helper {
 // the constructor.
 // This abstraction is here mostly for the gcc performance fix.
 template <typename T, typename... Args>
-ABSL_ATTRIBUTE_NONNULL(1) void PlacementNew(void* p, Args&&... args) {
+ABSL_ATTRIBUTE_NONNULL(1)
+void PlacementNew(absl::Nonnull<void*> p, Args&&... args) {
   new (p) T(std::forward<Args>(args)...);
 }
 
diff --git a/absl/status/status.cc b/absl/status/status.cc
index 7c778ac0..4dd5ae06 100644
--- a/absl/status/status.cc
+++ b/absl/status/status.cc
@@ -29,6 +29,7 @@
 #include "absl/base/internal/strerror.h"
 #include "absl/base/macros.h"
 #include "absl/base/no_destructor.h"
+#include "absl/base/nullability.h"
 #include "absl/debugging/stacktrace.h"
 #include "absl/debugging/symbolize.h"
 #include "absl/status/internal/status_internal.h"
@@ -90,7 +91,7 @@ std::ostream& operator<<(std::ostream& os, StatusCode code) {
   return os << StatusCodeToString(code);
 }
 
-const std::string* Status::EmptyString() {
+absl::Nonnull<const std::string*> Status::EmptyString() {
   static const absl::NoDestructor<std::string> kEmpty;
   return kEmpty.get();
 }
@@ -99,7 +100,7 @@ const std::string* Status::EmptyString() {
 constexpr const char Status::kMovedFromString[];
 #endif
 
-const std::string* Status::MovedFromString() {
+absl::Nonnull<const std::string*> Status::MovedFromString() {
   static const absl::NoDestructor<std::string> kMovedFrom(kMovedFromString);
   return kMovedFrom.get();
 }
@@ -111,7 +112,8 @@ Status::Status(absl::StatusCode code, absl::string_view msg)
   }
 }
 
-status_internal::StatusRep* Status::PrepareToModify(uintptr_t rep) {
+absl::Nonnull<status_internal::StatusRep*> Status::PrepareToModify(
+    uintptr_t rep) {
   if (IsInlined(rep)) {
     return new status_internal::StatusRep(InlinedRepToCode(rep),
                                           absl::string_view(), nullptr);
@@ -412,7 +414,7 @@ Status ErrnoToStatus(int error_number, absl::string_view message) {
                 MessageForErrnoToStatus(error_number, message));
 }
 
-const char* StatusMessageAsCStr(const Status& status) {
+absl::Nonnull<const char*> StatusMessageAsCStr(const Status& status) {
   // As an internal implementation detail, we guarantee that if status.message()
   // is non-empty, then the resulting string_view is null terminated.
   auto sv_message = status.message();
diff --git a/absl/status/status.h b/absl/status/status.h
index d4f74140..9ce16db9 100644
--- a/absl/status/status.h
+++ b/absl/status/status.h
@@ -60,6 +60,7 @@
 #include "absl/base/attributes.h"
 #include "absl/base/config.h"
 #include "absl/base/macros.h"
+#include "absl/base/nullability.h"
 #include "absl/base/optimization.h"
 #include "absl/functional/function_ref.h"
 #include "absl/status/internal/status_internal.h"
@@ -622,14 +623,15 @@ class ABSL_ATTRIBUTE_TRIVIAL_ABI Status final {
 
   // REQUIRES: !ok()
   // Ensures rep is not inlined or shared with any other Status.
-  static status_internal::StatusRep* PrepareToModify(uintptr_t rep);
+  static absl::Nonnull<status_internal::StatusRep*> PrepareToModify(
+      uintptr_t rep);
 
   // MSVC 14.0 limitation requires the const.
   static constexpr const char kMovedFromString[] =
       "Status accessed after move.";
 
-  static const std::string* EmptyString();
-  static const std::string* MovedFromString();
+  static absl::Nonnull<const std::string*> EmptyString();
+  static absl::Nonnull<const std::string*> MovedFromString();
 
   // Returns whether rep contains an inlined representation.
   // See rep_ for details.
@@ -648,7 +650,8 @@ class ABSL_ATTRIBUTE_TRIVIAL_ABI Status final {
   // Converts between StatusRep* and the external uintptr_t representation used
   // by rep_. See rep_ for details.
   static uintptr_t PointerToRep(status_internal::StatusRep* r);
-  static const status_internal::StatusRep* RepToPointer(uintptr_t r);
+  static absl::Nonnull<const status_internal::StatusRep*> RepToPointer(
+      uintptr_t r);
 
   static std::string ToStringSlow(uintptr_t rep, StatusToStringMode mode);
 
@@ -899,12 +902,14 @@ constexpr uintptr_t Status::MovedFromRep() {
   return CodeToInlinedRep(absl::StatusCode::kInternal) | 2;
 }
 
-inline const status_internal::StatusRep* Status::RepToPointer(uintptr_t rep) {
+inline absl::Nonnull<const status_internal::StatusRep*> Status::RepToPointer(
+    uintptr_t rep) {
   assert(!IsInlined(rep));
   return reinterpret_cast<const status_internal::StatusRep*>(rep);
 }
 
-inline uintptr_t Status::PointerToRep(status_internal::StatusRep* rep) {
+inline uintptr_t Status::PointerToRep(
+    absl::Nonnull<status_internal::StatusRep*> rep) {
   return reinterpret_cast<uintptr_t>(rep);
 }
 
@@ -929,7 +934,7 @@ inline Status CancelledError() { return Status(absl::StatusCode::kCancelled); }
 // If the status's message is empty, the empty string is returned.
 //
 // StatusMessageAsCStr exists for C support. Use `status.message()` in C++.
-const char* StatusMessageAsCStr(
+absl::Nonnull<const char*> StatusMessageAsCStr(
     const Status& status ABSL_ATTRIBUTE_LIFETIME_BOUND);
 
 ABSL_NAMESPACE_END
diff --git a/absl/status/status_payload_printer.h b/absl/status/status_payload_printer.h
index 5e0937f6..f22255e1 100644
--- a/absl/status/status_payload_printer.h
+++ b/absl/status/status_payload_printer.h
@@ -16,6 +16,7 @@
 
 #include <string>
 
+#include "absl/base/nullability.h"
 #include "absl/strings/cord.h"
 #include "absl/strings/string_view.h"
 #include "absl/types/optional.h"
@@ -34,8 +35,8 @@ namespace status_internal {
 // NOTE: This is an internal API and the design is subject to change in the
 // future in a non-backward-compatible way. Since it's only meant for debugging
 // purpose, you should not rely on it in any critical logic.
-using StatusPayloadPrinter = absl::optional<std::string> (*)(absl::string_view,
-                                                             const absl::Cord&);
+using StatusPayloadPrinter = absl::Nullable<absl::optional<std::string> (*)(
+    absl::string_view, const absl::Cord&)>;
 
 // Sets the global payload printer. Only one printer should be set per process.
 // If multiple printers are set, it's undefined which one will be used.
diff --git a/absl/status/statusor.cc b/absl/status/statusor.cc
index bfad75ef..7e6b334c 100644
--- a/absl/status/statusor.cc
+++ b/absl/status/statusor.cc
@@ -19,6 +19,7 @@
 #include "absl/base/call_once.h"
 #include "absl/base/config.h"
 #include "absl/base/internal/raw_logging.h"
+#include "absl/base/nullability.h"
 #include "absl/status/internal/statusor_internal.h"
 #include "absl/status/status.h"
 #include "absl/strings/str_cat.h"
@@ -54,7 +55,7 @@ BadStatusOrAccess& BadStatusOrAccess::operator=(BadStatusOrAccess&& other) {
 BadStatusOrAccess::BadStatusOrAccess(BadStatusOrAccess&& other)
     : status_(std::move(other.status_)) {}
 
-const char* BadStatusOrAccess::what() const noexcept {
+absl::Nonnull<const char*> BadStatusOrAccess::what() const noexcept {
   InitWhat();
   return what_.c_str();
 }
@@ -69,7 +70,7 @@ void BadStatusOrAccess::InitWhat() const {
 
 namespace internal_statusor {
 
-void Helper::HandleInvalidStatusCtorArg(absl::Status* status) {
+void Helper::HandleInvalidStatusCtorArg(absl::Nonnull<absl::Status*> status) {
   const char* kMessage =
       "An OK status is not a valid constructor argument to StatusOr<T>";
 #ifdef NDEBUG
diff --git a/absl/status/statusor.h b/absl/status/statusor.h
index 54c7ce02..33a2cf31 100644
--- a/absl/status/statusor.h
+++ b/absl/status/statusor.h
@@ -44,6 +44,7 @@
 #include <utility>
 
 #include "absl/base/attributes.h"
+#include "absl/base/nullability.h"
 #include "absl/base/call_once.h"
 #include "absl/meta/type_traits.h"
 #include "absl/status/internal/statusor_internal.h"
@@ -88,7 +89,7 @@ class BadStatusOrAccess : public std::exception {
   //
   // The pointer of this string is guaranteed to be valid until any non-const
   // function is invoked on the exception object.
-  const char* what() const noexcept override;
+  absl::Nonnull<const char*> what() const noexcept override;
 
   // BadStatusOrAccess::status()
   //
@@ -750,13 +751,13 @@ T&& StatusOr<T>::operator*() && {
 }
 
 template <typename T>
-const T* StatusOr<T>::operator->() const {
+absl::Nonnull<const T*> StatusOr<T>::operator->() const {
   this->EnsureOk();
   return &this->data_;
 }
 
 template <typename T>
-T* StatusOr<T>::operator->() {
+absl::Nonnull<T*> StatusOr<T>::operator->() {
   this->EnsureOk();
   return &this->data_;
 }