Regression of #63210 param attributes not showing in proc-macro TokenStream

[bbqsrc]

It seems #63210 isn't actually fixed.

Run cargo test -- --nocapture and you'll see the TokenStream does not contain any attributes on a parameter: https://github.com/bbqsrc/params-attribute-example

[Centril]

So I investigated the issue and I don't believe there's a bug here. The macro prints out the following:

$ cargo test -- --nocapture
   Compiling params-attribute-example v0.1.0 (/home/centril/programming/rust/params-attribute-example)
send_help fn hello(#[angery(true)] a: i32, b: i32) { }
error[E0658]: the attribute `angery` is currently unknown to the compiler and may have meaning added to it in the future

If you look closely, you will see that before the line with error[E0658]: ... it says send_help ....

If you slightly change the macro into...

extern crate proc_macro;
use proc_macro::TokenStream;

#[proc_macro_attribute]
pub fn rename_params(args: TokenStream, _: TokenStream) -> TokenStream {
    dbg!(&args);
    TokenStream::new()
}

...you will see it more clearly:

$ cargo test -- --nocapture
   Compiling params-attribute-example v0.1.0 (/home/centril/programming/rust/params-attribute-example)
[src/lib.rs:6] &args = TokenStream [
    Ident {
        ident: "send_help",
        span: #0 bytes(88..97),
    },
]
    Finished dev [unoptimized + debuginfo] target(s) in 0.32s
     Running target/debug/deps/params_attribute_example-cca77142e891e7a2

...

This seems to be in order.

[bbqsrc]

That isn't the problem.

use proc_macro::TokenStream;

#[proc_macro_attribute]
pub fn rename_params(args: TokenStream, input: TokenStream) -> TokenStream {
    dbg!(&input);
    input
}

    Ident {
        ident: "fn",
        span: #0 bytes(0..0),
    },
    Ident {
        ident: "hello",
        span: #0 bytes(0..0),
    },
    Group {
        delimiter: Parenthesis,
        stream: TokenStream [
            Ident {
                ident: "a",
                span: #0 bytes(0..0),
            },
            Punct {
                ch: ':',
                spacing: Alone,
                span: #0 bytes(0..0),
            },
            Ident {
                ident: "i32",
                span: #0 bytes(0..0),
            },
            Punct {
                ch: ',',
                spacing: Alone,
                span: #0 bytes(0..0),
            },
            Ident {
                ident: "b",
                span: #0 bytes(0..0),
            },
            Punct {
                ch: ':',
                spacing: Alone,
                span: #0 bytes(0..0),
            },
            Ident {
                ident: "i32",
                span: #0 bytes(0..0),
            },
        ],
        span: #0 bytes(0..0),
    },
    Group {
        delimiter: Brace,
        stream: TokenStream [],
        span: #0 bytes(0..0),
    },
]
error[E0658]: The attribute `angery` is currently unknown to the compiler and may have meaning added to it in the future
 --> proc-macro-tests/rename_params.rs:5:10
  |
5 | fn hello(#[angery(true)] a: i32, #[a2] b: i32) {}
  |          ^^^^^^^^^^^^^^^
  |
  = note: for more information, see https://github.com/rust-lang/rust/issues/29642
  = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error[E0658]: The attribute `a2` is currently unknown to the compiler and may have meaning added to it in the future
 --> proc-macro-tests/rename_params.rs:5:34
  |
5 | fn hello(#[angery(true)] a: i32, #[a2] b: i32) {}
  |                                  ^^^^^
  |
  = note: for more information, see https://github.com/rust-lang/rust/issues/29642
  = help: add `#![feature(custom_attribute)]` to the crate attributes to enable

error: aborting due to 2 previous errors```

`#[angery(true)]` does not appear in the token stream.

[bbqsrc]

Mm, in the absolutely most recent nightly, it seems to be working now! :D

[Centril]

Odd; I tried this out on nightly-2019-08-05 and it seems to be including angery in the tokenstream output.

[bbqsrc]

Yup, I was doing something wrong somewhere. 🤷‍♂ Just happy it's working now so I can do the cool things :D