Closed
Description
enum Foo {
Bar = (1u & 0xff) << 1,
}
$ rustc -v
rustc 0.11-pre (cee9a83 2014-04-11 15:54:46 -0700)
host: x86_64-unknown-linux-gnu
$ rustc --crate-type lib foo.rs
foo.rs:4:11: 4:27 error: expected constant: bad operands for binary
foo.rs:4 Bar = (1u & 0xff) << 1,
^~~~~~~~~~~~~~~~
error: aborting due to previous error
Dropping the shift gives a more informative error:
foo.rs:4:11: 4:22 error: expected constant: can't do this op on a uint and int
foo.rs:4 Bar = (1u & 0xff), // << 1,
^~~~~~~~~~~
error: aborting due to previous error
The fix is to write 0xffu, but the first error message was no help in finding this within a more complex expression inside a macro.
By contrast, this compiles fine:
static x: uint = (1u & 0xff) << 1;
and this
static x: uint = (1u & 0xffi) << 1;
gives a more conventional type error
foo.rs:1:24: 1:29 error: mismatched types: expected `uint` but found `int` (expected uint but found int)
foo.rs:1 static x: uint = (1u & 0xffi) << 1;