r-a fails to parse as u8<< expression within macro

[dzamlo]

rust-analyzer version:
rust-analyzer version: 0.3.2237-standalone and rust-analyzer 0.3.2284-standalone

rustc version:
rustc 1.85.0-nightly (7f75bfa1a 2024-12-30)

editor or extension:
Both VSCode and Neovim

repository link (if public, optional):
https://github.com/dzamlo/rust-bitfield/

When calling my macro bitfield, as shown in the code snippet below, I get a "generic arguments are not allowed on builtin types" error from rust-analyzer.

But the code compile without any error or warnings.

If I copy the generated code as outputted by cargo expand in my editor, I don't get the error.

code snippet to reproduce:

use bitfield::bitfield;
bitfield! {
    struct Foo([u8]);
}

If the type in parentheses is a simple type, like u8 and not a slice like type, there is no error. A slice like type in parentheses is handled differently by the macro

You can also check the examples in the "examples" folder of the repo.

[ChayimFriedman2]

From first look, I believe this is #18211. Note there is another syntax error.

Edit: To clarify, the parse error is the problem. rust-analyzer mis-parses the expression (value&1)as u8<<(i%bit_len) (which is indeed unparseable) as a generic argument to u8. I suspect the reason for this parsing error is that we don't handle none groups correctly.