[Guideline] Add do not divide by 0

src/coding-guidelines/expressions.rst

@@ -81,3 +81,54 @@ Expressions
          }
 
          fn with_base(_: &Base) { ... }
+
+.. guideline:: Do not divide by 0
+   :id: gui_kMbiWbn8Z6g5
+   :category: mandatory
+   :status: draft
+   :release: latest
+   :fls: fls_Q9dhNiICGIfr
+   :decidability: undecidable
+   :scope: system
+   :tags: numerics
+
+   This guideline applies when unsigned integer or two’s complement division is performed during the
+   evaluation of an `ArithmeticExpression
+   <https://rust-lang.github.io/fls/expressions.html#arithmetic-expressions>`_.
+
+   Note that this includes the evaluation of a `RemainderExpression
+   <https://rust-lang.github.io/fls/expressions.html#syntax_remainderexpression>`_, which uses unsigned integer or two's
+   complement division.
+
+   This rule does not apply to evaluation of a :std:`core::ops::Div` trait on types other than `integer
+   types <https://rust-lang.github.io/fls/types-and-traits.html#integer-types>`_. The use of
+   :std:`std::num::NonZero` or is therefore a recommended way to avoid the undecidability of this
+   guideline.
+
+   .. rationale::
+      :id: rat_h84NjY2tLSBW
+      :status: draft
+
+      Integer division by zero results in a panic, which is an abnormal program state and may terminate the process.
+
+   .. non_compliant_example::
+      :id: non_compl_ex_LLs3vY8aGz0F
+      :status: draft
+
+      When the division is performed, the right operand is evaluated to zero and the program panics.
+
+      .. code-block:: rust
+
+         let x = 0;
+         let x = 5 / x;
+
+   .. compliant_example::
+      :id: compl_ex_Ri9pP5Ch3kbb
+      :status: draft
+
+      There is no compliant way to perform integer division by zero. A checked division will prevent any
+      division by zero from happening. The programmer can then handle the returned :std:``std::option::Option``.
+
+      .. code-block:: rust
+
+         let x = 5u8.checked_div(0);