1.. title:: clang-tidy - readability-qualified-auto
2
3readability-qualified-auto
4==========================
5
6Adds pointer qualifications to ``auto``-typed variables that are deduced to
7pointers.
8
9`LLVM Coding Standards <https://llvm.org/docs/CodingStandards.html#beware-unnecessary-copies-with-auto>`_
10advises to make it obvious if a ``auto`` typed variable is a pointer. This
11check will transform ``auto`` to ``auto *`` when the type is deduced to be a
12pointer.
13
14.. code-block:: c++
15
16  for (auto Data : MutatablePtrContainer) {
17    change(*Data);
18  }
19  for (auto Data : ConstantPtrContainer) {
20    observe(*Data);
21  }
22
23Would be transformed into:
24
25.. code-block:: c++
26
27  for (auto *Data : MutatablePtrContainer) {
28    change(*Data);
29  }
30  for (const auto *Data : ConstantPtrContainer) {
31    observe(*Data);
32  }
33
34Note ``const`` ``volatile`` qualified types will retain their ``const`` and
35``volatile`` qualifiers. Pointers to pointers will not be fully qualified.
36
37.. code-block:: c++
38
39  const auto Foo = cast<int *>(Baz1);
40  const auto Bar = cast<const int *>(Baz2);
41  volatile auto FooBar = cast<int *>(Baz3);
42  auto BarFoo = cast<int **>(Baz4);
43
44Would be transformed into:
45
46.. code-block:: c++
47
48  auto *const Foo = cast<int *>(Baz1);
49  const auto *const Bar = cast<const int *>(Baz2);
50  auto *volatile FooBar = cast<int *>(Baz3);
51  auto *BarFoo = cast<int **>(Baz4);
52
53Options
54-------
55
56.. option:: AddConstToQualified
57
58   When set to `1` the check will add const qualifiers variables defined as
59   ``auto *`` or ``auto &`` when applicable.
60   Default value is '1'.
61
62.. code-block:: c++
63
64   auto Foo1 = cast<const int *>(Bar1);
65   auto *Foo2 = cast<const int *>(Bar2);
66   auto &Foo3 = cast<const int &>(Bar3);
67
68If AddConstToQualified is set to `0`,  it will be transformed into:
69
70.. code-block:: c++
71
72   const auto *Foo1 = cast<const int *>(Bar1);
73   auto *Foo2 = cast<const int *>(Bar2);
74   auto &Foo3 = cast<const int &>(Bar3);
75
76Otherwise it will be transformed into:
77
78.. code-block:: c++
79
80   const auto *Foo1 = cast<const int *>(Bar1);
81   const auto *Foo2 = cast<const int *>(Bar2);
82   const auto &Foo3 = cast<const int &>(Bar3);
83
84Note in the LLVM alias, the default value is `0`.
85