1 // Copyright 2022 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "base/check.h"
6 #include "base/compiler_specific.h"
7
8 #if CHECK_WILL_STREAM()
9 #include "base/logging.h"
10 #endif // CHECK_WILL_STREAM()
11
12 #ifndef BASE_CHECK_DEREF_H_
13 #define BASE_CHECK_DEREF_H_
14
15 namespace logging {
16
17 // Returns a reference to pointee of `ptr` if `ptr` is not null, or dies if
18 // `ptr` is null.
19 //
20 // It is useful in initializers and direct assignments, where a direct `CHECK`
21 // call can't be used:
22 //
23 // MyType& type_ref = CHECK_DEREF(MethodReturningAPointer());
24 //
25 // If your raw pointer is stored in a wrapped type like `unique_ptr` or
26 // `raw_ptr`, you should use their `.get()` methods to get the raw pointer
27 // before calling `CHECK_DEREF()`:
28 //
29 // MyType& type_ref = CHECK_DEREF(your_wrapped_pointer.get());
30 //
31 #define CHECK_DEREF(ptr) \
32 ::logging::CheckDeref(ptr, #ptr " != nullptr", __FILE__, __LINE__)
33
34 template <typename T>
CheckDeref(T * ptr,const char * message,const char * file,int line)35 T& CheckDeref(T* ptr, const char* message, const char* file, int line) {
36 // Note: we can't just call `CHECK_NE(ptr, nullptr)` here, as that would
37 // cause the error to be reported from this header, and we want the error
38 // to be reported at the file and line of the caller.
39 if (UNLIKELY(ptr == nullptr)) {
40 #if !CHECK_WILL_STREAM()
41 CheckFailure();
42 #else
43 // `LogMessage` will die with a fatal error in its destructor.
44 LogMessage(file, line, message);
45 #endif // !CHECK_WILL_STREAM()
46 }
47 return *ptr;
48 }
49
50 } // namespace logging
51
52 #endif // BASE_CHECK_DEREF_H_
53