xref: /llvm-project/clang-tools-extra/docs/clang-tidy/checks/readability/else-after-return.rst (revision 6e566bc5523f743bc34a7e26f050f1f2b4d699a8) 
1.. title:: clang-tidy - readability-else-after-return
2
3readability-else-after-return
4=============================
5
6`LLVM Coding Standards <https://llvm.org/docs/CodingStandards.html>`_ advises to
7reduce indentation where possible and where it makes understanding code easier.
8Early exit is one of the suggested enforcements of that. Please do not use
9``else`` or ``else if`` after something that interrupts control flow - like
10``return``, ``break``, ``continue``, ``throw``.
11
12The following piece of code illustrates how the check works. This piece of code:
13
14.. code-block:: c++
15
16    void foo(int Value) {
17      int Local = 0;
18      for (int i = 0; i < 42; i++) {
19        if (Value == 1) {
20          return;
21        } else {
22          Local++;
23        }
24
25        if (Value == 2)
26          continue;
27        else
28          Local++;
29
30        if (Value == 3) {
31          throw 42;
32        } else {
33          Local++;
34        }
35      }
36    }
37
38
39Would be transformed into:
40
41.. code-block:: c++
42
43    void foo(int Value) {
44      int Local = 0;
45      for (int i = 0; i < 42; i++) {
46        if (Value == 1) {
47          return;
48        }
49        Local++;
50
51        if (Value == 2)
52          continue;
53        Local++;
54
55        if (Value == 3) {
56          throw 42;
57        }
58        Local++;
59      }
60    }
61
62Options
63-------
64
65.. option:: WarnOnUnfixable
66
67   When `true`, emit a warning for cases where the check can't output a
68   Fix-It. These can occur with declarations inside the ``else`` branch that
69   would have an extended lifetime if the ``else`` branch was removed.
70   Default value is `true`.
71
72.. option:: WarnOnConditionVariables
73
74   When `true`, the check will attempt to refactor a variable defined inside
75   the condition of the ``if`` statement that is used in the ``else`` branch
76   defining them just before the ``if`` statement. This can only be done if
77   the ``if`` statement is the last statement in its parent's scope.
78   Default value is `true`.
79
80
81LLVM alias
82----------
83
84There is an alias of this check called llvm-else-after-return.
85In that version the options :option:`WarnOnUnfixable` and
86:option:`WarnOnConditionVariables` are both set to `false` by default.
87
88This check helps to enforce this `LLVM Coding Standards recommendation
89<https://llvm.org/docs/CodingStandards.html#don-t-use-else-after-a-return>`_.
90