型引数を返り値やメンバの型に使いまわせない奴

message.txt

$rustc --version
rustc 1.23.0 (766bd11c8 2018-01-01)

$ rustc test.rs
...
error[E0308]: mismatched types
  --> test.rs:12:31
   |
12 |         self.m.insert("hoge", S2);
   |                               ^^ expected type parameter, found struct `S2`
   |
   = note: expected type `T`
              found type `S2`

error[E0308]: mismatched types
  --> test.rs:15:9
   |
14 |     fn s2() -> T {
   |                - expected `T` because of return type
15 |         S2
   |         ^^ expected type parameter, found struct `S2`
   |
   = note: expected type `T`
              found type `S2`

error: aborting due to 2 previous errors

test.rs

use std::collections::HashMap;

trait Trait {
}

struct S1<T: Trait> {
    m: HashMap<&'static str, T>
}

impl<T: Trait> S1<T> {
    fn foo(&mut self) {
        self.m.insert("hoge", S2);
    }
}

struct S2;

impl Trait for S2 {}

fn main() {
    let mut s: S1<S2> = S1 {m: HashMap::new()};
    s.foo();
}

実体を関数(メソッド)内でダイレクトに作って渡そうとすると、型引数を無視した扱いになる模様(解決)