E4139#
This expression has type that cannot be implicitly ignored. Use ignore(...)
or
let _ = ...
to explicitly ignore it.
Unit
type can be implicitly ignored.
错误示例#
For example,
fn main {
1 + 1 // This expression has type Int, its value cannot be implicitly ignored.
}
The code here show a deeper problem of the logic of the code: discarding the result makes the computation useless.
建议#
If you do want to discard the result, use ignore(..)
or let _ =
to
explicitly discard the value.
fn main {
ignore(1 + 1)
}