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docs: Mention explicitly that bitwise operators do not perform overflow/underflow checks

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Kamil Śliwak 2021-03-25 17:54:43 +01:00
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docs/control-structures.rst
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@ -531,6 +531,12 @@ and will wrap without an error if used inside an unchecked block:
It is not possible to disable the check for division by zero
or modulo by zero using the ``unchecked`` block.
.. note::
Bitwise operators do not perform overflow or underflow checks.
This is particularly visible when using bitwise shifts (``<<``, ``>>``, ``<<=``, ``>>=``) in
place of integer division and multiplication by a power of 2.
For example ``type(uint256).max << 3`` does not revert even though ``type(uint256).max * 8`` would.
.. note::
The second statement in ``int x = type(int).min; -x;`` will result in an overflow
because the negative range can hold one more value than the positive range.