================
@@ -27,6 +27,29 @@ This check will flag:
- All applications of binary operators with a narrowing conversions.
For example: ``int i; i+= 0.1;``.
+Note that arithmetic with integer types may perform implicit conversions if
the used integer types are smaller than ``int``.
+These rules are documented under `"Integral Promotion" on this
cppreference.com
<https://en.cppreference.com/w/cpp/language/implicit_conversion>`_
+page. The following example demonstrates this behavior and can be explored
with `cppinsights.io <https://cppinsights.io/s/68553908>`_.
+
+.. code-block:: c++
+
+ // The following function definition demonstrates usage of arithmetic with
integer types smaller than `int`
+ // and how the narrowing conversion happens implicitly.
+ void computation(short argument1, short argument2) {
+ // Arithmetic written by humans:
+ short result = argument1 + argument2;
+ // Arithmetic actually performed by C++:
+ short result = static_cast<short>(static_cast<int>(argument1) +
static_cast<int>(argument2));
+ }
+
+ void recommended_with_gsl(short argument1, short argument2) {
----------------
PiotrZSL wrote:
I'm not sure if this example with gsl is needed.
Thing that should be here is:
- if this is detected by this check
- ways to handle this in explicit way (gsl::narrow, gsl::narrow_cast,
static_cast, ...)
Also documentation should mention `-Wconversion`
https://github.com/llvm/llvm-project/pull/118209
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