Explicit operator bound on primitive type shadows built-in operators for that type

[ghost]

I tried this code:

pub fn a<T>(x: T) -> T
where
    i64: std::ops::Mul<T, Output = T>,
    T: Copy
{
    let a = 2 * 2;
    2 * x
}

I expected to see this happen: the variable a is inferred to be i32 (or some other integer type) and the operator 2 * 2 uses the built-in integer multiplication operation.

Instead, this happened: the trait bound i64: std::ops::Mul<T, Output = T> shadows the built-in implementation for Mul<i64, Output=i64> which results in the error:

| pub fn a<T> (x : T) -> T
|          - this type parameter
| where i64: Mul<T, Output=T> {
|     let a = 2*2; 
|               ^ expected type parameter `T`, found integer
|
   = note: expected type parameter `T`
                        found type `{integer}`

It is unclear to me whether this shadowing behavior is intended or unintended, however it works fine if the bound is instead T: Mul<i64, Output=T> which makes me wonder if it is unintended.

Meta

rustc --version --verbose:

rustc 1.65.0 (897e37553 2022-11-02)
binary: rustc
commit-hash: 897e37553bba8b42751c67658967889d11ecd120
commit-date: 2022-11-02
host: aarch64-apple-darwin
release: 1.65.0
LLVM version: 15.0.0