1.. title:: clang-tidy - modernize-use-designated-initializers 2 3modernize-use-designated-initializers 4===================================== 5 6Finds initializer lists for aggregate types which could be written as designated 7initializers instead. 8 9With plain initializer lists, it is very easy to introduce bugs when adding new 10fields in the middle of a struct or class type. The same confusion might arise 11when changing the order of fields. 12 13C++20 supports the designated initializer syntax for aggregate types. By 14applying it, we can always be sure that aggregates are constructed correctly, 15because every variable being initialized is referenced by its name. 16 17Example: 18 19.. code-block:: 20 21 struct S { int i, j; }; 22 23is an aggregate type that should be initialized as 24 25.. code-block:: 26 27 S s{.i = 1, .j = 2}; 28 29instead of 30 31.. code-block:: 32 33 S s{1, 2}; 34 35which could easily become an issue when ``i`` and ``j`` are swapped in the 36declaration of ``S``. 37 38Even when compiling in a language version older than C++20, depending on your 39compiler, designated initializers are potentially supported. Therefore, the 40check is by default restricted to C99/C++20 and above. Check out the options 41``-Wc99-designator`` to get support for mixed designators in initializer list in 42C and ``-Wc++20-designator`` for support of designated initializers in older C++ 43language modes. 44 45Options 46------- 47 48.. option:: IgnoreMacros 49 50 The value `false` specifies that components of initializer lists expanded from 51 macros are not checked. The default value is `true`. 52 53.. option:: IgnoreSingleElementAggregates 54 55 The value `false` specifies that even initializers for aggregate types with 56 only a single element should be checked. The default value is `true`. 57 58.. option:: RestrictToPODTypes 59 60 The value `true` specifies that only Plain Old Data (POD) types shall be 61 checked. This makes the check applicable to even older C++ standards. The 62 default value is `false`. 63 64.. option:: StrictCStandardCompliance 65 66 When set to `false`, the check will not restrict itself to C99 and above. 67 The default value is `true`. 68 69.. option:: StrictCppStandardCompliance 70 71 When set to `false`, the check will not restrict itself to C++20 and above. 72 The default value is `true`. 73