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Restrict unary negation to signed integers.

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chriseth
2020-09-17 15:01:53 +02:00
parent e4231b879b
commit aa7a6922e7
6 changed files with 20 additions and 8 deletions
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docs/types/value-types.rst
+3 -3
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@@ -38,7 +38,7 @@ Operators:
* Comparisons: ``<=``, ``<``, ``==``, ``!=``, ``>=``, ``>`` (evaluate to ``bool``)
* Bit operators: ``&``, ``|``, ``^`` (bitwise exclusive or), ``~`` (bitwise negation)
* Shift operators: ``<<`` (left shift), ``>>`` (right shift)
* Arithmetic operators: ``+``, ``-``, unary ``-``, ``*``, ``/``, ``%`` (modulo), ``**`` (exponentiation)
* Arithmetic operators: ``+``, ``-``, unary ``-`` (only for signed integers), ``*``, ``/``, ``%`` (modulo), ``**`` (exponentiation)
For an integer type ``X``, you can use ``type(X).min`` and ``type(X).max`` to
access the minimum and maximum value representable by the type.
@@ -83,8 +83,8 @@ for example ``uint256(0) - uint256(1) == 2**256 - 1``. You have to take these ov
into account when designing safe smart contracts.
The expression ``-x`` is equivalent to ``(T(0) - x)`` where
``T`` is the type of ``x``. This means that ``-x`` will not be negative
if the type of ``x`` is an unsigned integer type. Also, ``-x`` can be
``T`` is the type of ``x``. It can only be applied to signed types.
The value of ``-x`` can be
positive if ``x`` is negative. There is another caveat also resulting
from two's complement representation::