https://github.com/JonasToth created
https://github.com/llvm/llvm-project/pull/118209
This PR improves the docs for this check to include an example of hidden
narrowing conversions from the integer promotion rules in arithmetic.
>From c662917b248335c85714e791f55e12e834baa87d Mon Sep 17 00:00:00 2001
From: Jonas Toth <developm...@jonas-toth.eu>
Date: Sun, 1 Dec 2024 12:02:13 +0100
Subject: [PATCH] [clang-tidy][docs] improve documentation on
cppcoreguidelines-narrowing-conversions (#111510)
---
.../cppcoreguidelines/narrowing-conversions.rst | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git
a/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/narrowing-conversions.rst
b/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/narrowing-conversions.rst
index 04260e75aa558f..f4d1976ad4c688 100644
---
a/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/narrowing-conversions.rst
+++
b/clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/narrowing-conversions.rst
@@ -27,6 +27,21 @@ 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));
+ }
+
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