[clang-tools-extra] Enforce SL.con.3: Add check to replace operator[] with at() [Cont.] (PR #95220)

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Paul =?utf-8?q?Heidekrüger?= <paul.heidekrueger at tum.de>,
Paul =?utf-8?q?Heidekrüger?= <paul.heidekrueger at tum.de>,
Paul =?utf-8?q?Heidekrüger?= <paul.heidekrueger at tum.de>,
Paul =?utf-8?q?Heidekrüger?= <paul.heidekrueger at tum.de>,
Paul =?utf-8?q?Heidekrüger?= <paul.heidekrueger at tum.de>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/95220 at github.com>


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@@ -0,0 +1,31 @@
+.. title:: clang-tidy - cppcoreguidelines-prefer-at-over-subscript-operator
+
+cppcoreguidelines-prefer-at-over-subscript-operator
+=====================================
+
+This check flags all uses of ``operator[]`` where an equivalent (same parameter and return types) ``at()`` method exists and suggest using that instead.
+
+For example the code
+
+.. code-block:: c++
+  std::array<int, 3> a;
+  int b = a[4];
+
+will generate a warning but 
+
+.. code-block:: c++
+  std::unique_ptr<int> a;
+  int b = a[0];
+
+will not.
+
+The classes ``std::map``, ``std::unordered_map`` and ``std::flat_map`` are excluded from this check, because for them the subscript operator has a defined behaviour when a key does not exist (inserting a new element).
----------------
EugeneZelenko wrote:

Please follow 80 characters limit. Same in other places in this file.

https://github.com/llvm/llvm-project/pull/95220