c2f7c39987
Minor cleanup and consistent formatting of the Markdown-based tests. - Removed lots of unnecessary `a`, `b`, `c`, … variables. - Moved test assertions (`# revealed:` comments) closer to the tested object. - Always separate `# revealed` and `# error` comments from the code by two spaces, according to the discussion [here](https://github.com/astral-sh/ruff/pull/13746/files#r1799385758). This trades readability for consistency in some cases. - Fixed some headings
1.9 KiB
Binary operations on integers
Basic Arithmetic
reveal_type(2 + 1) # revealed: Literal[3]
reveal_type(3 - 4) # revealed: Literal[-1]
reveal_type(3 * -1) # revealed: Literal[-3]
reveal_type(-3 // 3) # revealed: Literal[-1]
reveal_type(-3 / 3) # revealed: float
reveal_type(5 % 3) # revealed: Literal[2]
Division by Zero
This error is really outside the current Python type system, because e.g. int.__truediv__ and
friends are not annotated to indicate that it's an error, and we don't even have a facility to
permit such an annotation. So arguably divide-by-zero should be a lint error rather than a type
checker error. But we choose to go ahead and error in the cases that are very likely to be an error:
dividing something typed as int or float by something known to be Literal[0].
This isn't definitely an error, because the object typed as int or float could be an instance
of a custom subclass which overrides division behavior to handle zero without error. But if this
unusual case occurs, the error can be avoided by explicitly typing the dividend as that safe custom
subclass; we only emit the error if the LHS type is exactly int or float, not if its a subclass.
a = 1 / 0 # error: "Cannot divide object of type `Literal[1]` by zero"
reveal_type(a) # revealed: float
b = 2 // 0 # error: "Cannot floor divide object of type `Literal[2]` by zero"
reveal_type(b) # revealed: int
c = 3 % 0 # error: "Cannot reduce object of type `Literal[3]` modulo zero"
reveal_type(c) # revealed: int
d = int() / 0 # error: "Cannot divide object of type `int` by zero"
# TODO should be int
reveal_type(d) # revealed: @Todo
e = 1.0 / 0 # error: "Cannot divide object of type `float` by zero"
# TODO should be float
reveal_type(e) # revealed: @Todo
class MyInt(int): pass
# No error for a subclass of int
# TODO should be float
reveal_type(MyInt(3) / 0) # revealed: @Todo