Adds template specialization for nullptr assertion of absl::AnyInvocable types.

PiperOrigin-RevId: 526644558
Change-Id: I050162c2c0d667c32f7e11f51201054cca52667d

absl/functional/BUILD.bazel

@@ -92,6 +92,7 @@ cc_library(
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
+        ":any_invocable",
         "//absl/base:base_internal",
         "//absl/base:core_headers",
         "//absl/meta:type_traits",
@@ -104,6 +105,7 @@ cc_test(
     srcs = ["function_ref_test.cc"],
     copts = ABSL_TEST_COPTS,
     deps = [
+        ":any_invocable",
         ":function_ref",
         "//absl/container:test_instance_tracker",
         "//absl/memory",

absl/functional/CMakeLists.txt

@@ -90,6 +90,7 @@ absl_cc_library(
   DEPS
     absl::base_internal
     absl::core_headers
+    absl::any_invocable
     absl::meta
   PUBLIC
 )

absl/functional/function_ref_test.cc

@@ -20,6 +20,7 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include "absl/container/internal/test_instance_tracker.h"
+#include "absl/functional/any_invocable.h"
 #include "absl/memory/memory.h"
 
 namespace absl {
@@ -157,6 +158,25 @@ TEST(FunctionRef, NullMemberPtrAssertFails) {
   EXPECT_DEBUG_DEATH({ FunctionRef<int(const S& s)> ref(mem_ptr); }, "");
 }
 
+TEST(FunctionRef, NullStdFunctionAssertPasses) {
+  std::function<void()> function = []() {};
+  FunctionRef<void()> ref(function);
+}
+
+TEST(FunctionRef, NullStdFunctionAssertFails) {
+  std::function<void()> function = nullptr;
+  EXPECT_DEBUG_DEATH({ FunctionRef<void()> ref(function); }, "");
+}
+
+TEST(FunctionRef, NullAnyInvocableAssertPasses) {
+  AnyInvocable<void() const> invocable = []() {};
+  FunctionRef<void()> ref(invocable);
+}
+TEST(FunctionRef, NullAnyInvocableAssertFails) {
+  AnyInvocable<void() const> invocable = nullptr;
+  EXPECT_DEBUG_DEATH({ FunctionRef<void()> ref(invocable); }, "");
+}
+
 #endif  // GTEST_HAS_DEATH_TEST
 
 TEST(FunctionRef, CopiesAndMovesPerPassByValue) {

absl/functional/internal/function_ref.h

@@ -20,6 +20,7 @@
 #include <type_traits>
 
 #include "absl/base/internal/invoke.h"
+#include "absl/functional/any_invocable.h"
 #include "absl/meta/type_traits.h"
 
 namespace absl {
@@ -90,6 +91,12 @@ void AssertNonNull(const std::function<Sig>& f) {
   (void)f;
 }
 
+template <typename Sig>
+void AssertNonNull(const AnyInvocable<Sig>& f) {
+  assert(f != nullptr);
+  (void)f;
+}
+
 template <typename F>
 void AssertNonNull(const F&) {}