blob: 8c6872d72f11a0f4db270751ef62461e90cde856 [file] [log] [blame]
.. title:: clang-tidy - bugprone-fold-init-type
The check flags type mismatches in
`folds <>`_
like ``std::accumulate`` that might result in loss of precision.
``std::accumulate`` folds an input range into an initial value using the type of
the latter, with ``operator+`` by default. This can cause loss of precision
- Truncation: The following code uses a floating point range and an int
initial value, so truncation will happen at every application of ``operator+``
and the result will be `0`, which might not be what the user expected.
.. code-block:: c++
auto a = {0.5f, 0.5f, 0.5f, 0.5f};
return std::accumulate(std::begin(a), std::end(a), 0);
- Overflow: The following code also returns `0`.
.. code-block:: c++
auto a = {65536LL * 65536 * 65536};
return std::accumulate(std::begin(a), std::end(a), 0);