Rename /nullability_verification to /nullability in preparation for adding/relocating inference functionality here.

PiperOrigin-RevId: 528495113

nullability/test/function_pointers.cc

diff --git a/nullability/test/function_pointers.cc b/nullability/test/function_pointers.cc
new file mode 100644
index 0000000..290ba15
--- /dev/null
+++ b/nullability/test/function_pointers.cc
@@ -0,0 +1,101 @@
+// Part of the Crubit project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+// Tests for nullability of function pointers.
+
+#include "nullability/test/check_diagnostics.h"
+#include "third_party/llvm/llvm-project/third-party/unittest/googletest/include/gtest/gtest.h"
+
+namespace clang {
+namespace tidy {
+namespace nullability {
+namespace {
+
+TEST(PointerNullabilityTest, FunctionToPointerDecayIsNonnull) {
+  EXPECT_TRUE(checkDiagnostics(R"cc(
+    void target() {
+      // Use `static_cast` to force function-to-pointer decay.
+      __assert_nullability<NK_nonnull>(static_cast<void (*)()>(target));
+    }
+  )cc"));
+}
+
+TEST(PointerNullabilityTest, CallExplicitlyDereferencedDirectCallee) {
+  EXPECT_TRUE(checkDiagnostics(R"cc(
+    void callee();
+    void target() { (*callee)(); }
+  )cc"));
+}
+
+TEST(PointerNullabilityTest, AnnotationsInReturnType) {
+  EXPECT_TRUE(checkDiagnostics(R"cc(
+    int* _Nullable target() {
+      // Use `static_cast` to force function-to-pointer decay.
+      __assert_nullability<NK_nonnull, NK_nullable>(
+          static_cast<int* (*)()>(target));
+      return nullptr;
+    }
+  )cc"));
+}
+
+TEST(PointerNullabilityTest, AnnotationsInParameters) {
+  EXPECT_TRUE(checkDiagnostics(R"cc(
+    void target(int *_Nullable) {
+      // Use `static_cast` to force function-to-pointer decay.
+      __assert_nullability<NK_nonnull, NK_nullable>(
+          static_cast<void (*)(int *)>(target));
+    }
+  )cc"));
+}
+
+TEST(PointerNullabilityTest, NonnullCallback) {
+  EXPECT_TRUE(checkDiagnostics(R"cc(
+    void target(void (*_Nonnull callback)()) {
+      // Both an explicit dereference and an implicit dereference done by a
+      // function call should be allowed.
+      (*callback)();
+      callback();
+    }
+  )cc"));
+}
+
+TEST(PointerNullabilityTest, NullableCallback) {
+  EXPECT_TRUE(checkDiagnostics(R"cc(
+    void target(void (*_Nullable callback)()) {
+      // Both an explicit dereference and an implicit dereference done by a
+      // function call should be marked as unsafe.
+      (*callback)();  // [[unsafe]]
+      callback();     // [[unsafe]]
+    }
+  )cc"));
+}
+
+TEST(PointerNullabilityTest, NonnullCallbackWithoutCalleeDecl) {
+  EXPECT_TRUE(checkDiagnostics(R"cc(
+    using NonnullCallbackType = void (*_Nonnull)();
+    NonnullCallbackType getCallback();
+    void target() {
+      __assert_nullability<NK_nonnull>(getCallback());
+      (*getCallback())();
+      getCallback()();
+    }
+  )cc"));
+}
+
+TEST(PointerNullabilityTest, NullableCallbackWithoutCalleeDecl) {
+  EXPECT_TRUE(checkDiagnostics(R"cc(
+    using NullableCallbackType = void (*_Nullable)();
+    NullableCallbackType getCallback();
+    void target(bool b) {
+      __assert_nullability<NK_nullable>(getCallback());
+      (*getCallback())();  // [[unsafe]]
+      getCallback()();     // [[unsafe]]
+    }
+  )cc"));
+}
+
+}  // namespace
+}  // namespace nullability
+}  // namespace tidy
+}  // namespace clang