1.. title:: clang-tidy - modernize-replace-auto-ptr 2 3modernize-replace-auto-ptr 4========================== 5 6This check replaces the uses of the deprecated class ``std::auto_ptr`` by 7``std::unique_ptr`` (introduced in C++11). The transfer of ownership, done 8by the copy-constructor and the assignment operator, is changed to match 9``std::unique_ptr`` usage by using explicit calls to ``std::move()``. 10 11Migration example: 12 13.. code-block:: c++ 14 15 -void take_ownership_fn(std::auto_ptr<int> int_ptr); 16 +void take_ownership_fn(std::unique_ptr<int> int_ptr); 17 18 void f(int x) { 19 - std::auto_ptr<int> a(new int(x)); 20 - std::auto_ptr<int> b; 21 + std::unique_ptr<int> a(new int(x)); 22 + std::unique_ptr<int> b; 23 24 - b = a; 25 - take_ownership_fn(b); 26 + b = std::move(a); 27 + take_ownership_fn(std::move(b)); 28 } 29 30Since ``std::move()`` is a library function declared in ``<utility>`` it may be 31necessary to add this include. The check will add the include directive when 32necessary. 33 34Known Limitations 35----------------- 36* If headers modification is not activated or if a header is not allowed to be 37 changed this check will produce broken code (compilation error), where the 38 headers' code will stay unchanged while the code using them will be changed. 39 40* Client code that declares a reference to an ``std::auto_ptr`` coming from 41 code that can't be migrated (such as a header coming from a 3\ :sup:`rd` 42 party library) will produce a compilation error after migration. This is 43 because the type of the reference will be changed to ``std::unique_ptr`` but 44 the type returned by the library won't change, binding a reference to 45 ``std::unique_ptr`` from an ``std::auto_ptr``. This pattern doesn't make much 46 sense and usually ``std::auto_ptr`` are stored by value (otherwise what is 47 the point in using them instead of a reference or a pointer?). 48 49.. code-block:: c++ 50 51 // <3rd-party header...> 52 std::auto_ptr<int> get_value(); 53 const std::auto_ptr<int> & get_ref(); 54 55 // <calling code (with migration)...> 56 -std::auto_ptr<int> a(get_value()); 57 +std::unique_ptr<int> a(get_value()); // ok, unique_ptr constructed from auto_ptr 58 59 -const std::auto_ptr<int> & p = get_ptr(); 60 +const std::unique_ptr<int> & p = get_ptr(); // won't compile 61 62* Non-instantiated templates aren't modified. 63 64.. code-block:: c++ 65 66 template <typename X> 67 void f() { 68 std::auto_ptr<X> p; 69 } 70 71 // only 'f<int>()' (or similar) will trigger the replacement. 72 73Options 74------- 75 76.. option:: IncludeStyle 77 78 A string specifying which include-style is used, `llvm` or `google`. Default 79 is `llvm`. 80