Bug: impl block with generics

[Banyc]

pub struct G<T> {
    buf: Vec<T>,
}
#[bon::bon]
impl<T> G<T> {
    #[builder]
    pub fn new() -> Self {
        Self { buf: vec![] }
    }
}

Error msg:

error[E0392]: type parameter `T` is never used
 --> src/lib.rs:5:6
  |
5 | impl<T> G<T> {
  |      ^
  |      |
  |      unused type parameter
  |      `T` is named here, but is likely unused in the containing type
  |
  = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
  = help: if you intended `T` to be a const parameter, use `const T: /* Type */` instead

error[E0392]: type parameter `T` is never used
 --> src/lib.rs:5:6
  |
5 | impl<T> G<T> {
  |      ^ unused type parameter
  |
  = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
  = help: if you intended `T` to be a const parameter, use `const T: /* Type */` instead

error[E0282]: type annotations needed
 --> src/lib.rs:4:1
  |
4 | #[bon::bon]
  | ^^^^^^^^^^^ cannot infer type
  |
  = note: this error originates in the attribute macro `bon::bon` (in Nightly builds, run with -Z macro-backtrace for more info)

Some errors have detailed explanations: E0282, E0392.
For more information about an error, try `rustc --explain E0282`.

[Banyc]

Solution is probably to add the generics T to the phantom; illustrated by the selected part:

[Veetaha]

Thank you for the bug report! The fix was implemented in #17. A new patch version of the crate 1.0.3 with the fix was released.

Feel free to reopen the issue if the problem persists

[Veetaha]

Btw, @Banyc, when looking at your screenshot of generated code I found a bug that the method new() wasn't hidden by default. I'm not sure if this bug affects your code. It doesn't if you don't call the new() method directly.

The method new() was supposed to be renamed to __orig_new() and #[doc(hidden)] should've been added to it. If you'd like to have both new() and builder() methods available, then you should explicitly state that with #[builder(expose_positional_fn)].

I prepared a fix for this other bug in #19 that I'd like to release as a new 1.0.4 patch.