Remove absl_nullability_compatible tag.

As of [this
change](abseil/abseil-cpp@485f2be),
this no longer has any effect; instead, the `ABSL_NULLABILITY_COMPATIBLE`
attribute  (which is already present on the classes in question) determines
whether a class is compatible with nullability annotations.

PiperOrigin-RevId: 688111839

riegeli/base/BUILD

@@ -246,6 +246,7 @@ cc_library(
         ":type_id",
         ":type_traits",
         "@com_google_absl//absl/base:core_headers",
+        "@com_google_absl//absl/base:nullability",
         "@com_google_absl//absl/meta:type_traits",
         "@com_google_absl//absl/strings",
         "@com_google_absl//absl/types:optional",
@@ -272,6 +273,7 @@ cc_library(
         ":initializer",
         ":type_traits",
         "@com_google_absl//absl/base:core_headers",
+        "@com_google_absl//absl/base:nullability",
         "@com_google_absl//absl/meta:type_traits",
     ],
 )
@@ -295,6 +297,7 @@ cc_library(
         ":type_traits",
         "@com_google_absl//absl/base",
         "@com_google_absl//absl/base:core_headers",
+        "@com_google_absl//absl/base:nullability",
         "@com_google_absl//absl/meta:type_traits",
         "@com_google_absl//absl/strings",
     ],

riegeli/base/any.h

@@ -26,6 +26,7 @@
 #include <utility>
 
 #include "absl/base/attributes.h"
+#include "absl/base/nullability.h"
 #include "absl/base/optimization.h"
 #include "absl/meta/type_traits.h"
 #include "absl/strings/string_view.h"
@@ -231,8 +232,6 @@ class
   };
 
  public:
-  using absl_nullability_compatible = void;
-
   // `Any<Handle>::Inlining<InlineManagers...>` enlarges inline storage of
   // `Any<Handle>`.
   //
@@ -386,7 +385,11 @@ class DependencyManagerImpl<
 // an owned dependency by rvalue reference instead of by value, which avoids
 // moving it.
 template <typename Handle>
-class AnyRef : public any_internal::AnyBase<Handle, 0, 0> {
+class
+#ifdef ABSL_NULLABILITY_COMPATIBLE
+    ABSL_NULLABILITY_COMPATIBLE
+#endif
+        AnyRef : public any_internal::AnyBase<Handle, 0, 0> {
  public:
   // Creates an empty `AnyRef`.
   AnyRef() noexcept { this->Initialize(); }

riegeli/base/dependency.h

@@ -20,6 +20,7 @@
 #include <utility>
 
 #include "absl/base/attributes.h"
+#include "absl/base/nullability.h"
 #include "absl/meta/type_traits.h"
 #include "absl/strings/string_view.h"
 #include "absl/types/span.h"
@@ -934,8 +935,6 @@ class
                          dependency_internal::DependencyDeref<Handle, Manager>,
                          Handle, Manager> {
  public:
-  using absl_nullability_compatible = void;
-
   using Dependency::DependencyDerived::DependencyDerived;
 
   Dependency(const Dependency& that) = default;

riegeli/base/intrusive_shared_ptr.h

@@ -293,9 +293,6 @@ class
     return a.get() == nullptr;
   }
 
-  // Allow Nullability annotations on `IntrusiveSharedPtr`.
-  using absl_nullability_compatible = void;
-
   // Indicate support for:
   //  * `ExternalRef(const IntrusiveSharedPtr&, substr)`
   //  * `ExternalRef(IntrusiveSharedPtr&&, substr)`

riegeli/base/shared_ptr.h

@@ -222,9 +222,6 @@ class
     return a.ptr_ == nullptr;
   }
 
-  // Allow Nullability annotations on `IntrusiveSharedPtr`.
-  using absl_nullability_compatible = void;
-
   // Indicate support for:
   //  * `ExternalRef(const SharedPtr&, substr)`
   //  * `ExternalRef(SharedPtr&&, substr)`

riegeli/base/stable_dependency.h

@@ -21,6 +21,7 @@
 #include <utility>
 
 #include "absl/base/attributes.h"
+#include "absl/base/nullability.h"
 #include "absl/base/optimization.h"
 #include "absl/meta/type_traits.h"
 #include "riegeli/base/dependency.h"
@@ -176,8 +177,6 @@ class
             std::enable_if_t<Dependency<Handle, Manager>::kIsStable>>
     : public Dependency<Handle, Manager> {
  public:
-  using absl_nullability_compatible = void;
-
   using StableDependency::Dependency::Dependency;
 
   StableDependency(StableDependency&& that) = default;

riegeli/bytes/cfile_handle.h

@@ -68,9 +68,6 @@ class
 
   friend bool operator==(const OwnedCFile& a, FILE* b) { return a.get() == b; }
 
-  // Allow Nullability annotations on `OwnedCFile`.
-  using absl_nullability_compatible = void;
-
   // Opens a new `FILE*`, like with `fopen()` but taking
   // `absl::string_view filename`, `absl::string_view mode`, and returning
   // `absl::Status`.
@@ -161,9 +158,6 @@ class
   }
   friend bool operator==(UnownedCFile a, FILE* b) { return a.get() == b; }
 
-  // Allow Nullability annotations on `UnownedCFile`.
-  using absl_nullability_compatible = void;
-
  private:
   FILE* file_ = nullptr;
 };
@@ -251,9 +245,6 @@ class
     return a.target_ == b.target_;
   }
 
-  // Allow Nullability annotations on `CFileHandle`.
-  using absl_nullability_compatible = void;
-
   // Returns `true` if the `CFileHandle` owns the `FILE*`, i.e. is responsible
   // for closing it and the `FILE*` is present.
   bool IsOwning() const { return methods_->is_owning(target_); }

riegeli/bytes/fd_handle.h

@@ -265,9 +265,6 @@ class
     return a.target_ == b.target_;
   }
 
-  // Allow Nullability annotations on `FdHandle`.
-  using absl_nullability_compatible = void;
-
   // Returns `true` if the `FdHandle` owns the fd, i.e. is responsible for
   // closing it and the fd is present.
   bool IsOwning() const { return methods_->is_owning(target_); }

riegeli/digests/digester_handle.h

@@ -148,9 +148,6 @@ class
     return a.target() == b.target();
   }
 
-  // Allow Nullability annotations on `DigesterBaseHandle`.
-  using absl_nullability_compatible = void;
-
   // If `write_size_hint` is not `absl::nullopt`, hints that this amount of data
   // will be written from the current position. This may improve performance and
   // memory usage.