Variadic check only on last parameter

[0xn4utilus]

I tried this code: https://godbolt.org/z/4r5KGPYeE

// test case 1
fn myfun0(...,_:i32) {}

// test case 2
fn myfun1(a:i32,...,_:i32) {}

// test case 3
struct z {
    x: f64,
    y: f64,
}

impl z {
    fn new(x: f64, ..., y: f64) -> z {
        z { x: x, y: y }
    }
}

I expected to see compilation error as seen when the below code is run.

fn myfun0(_:i32,...) {}

Instead, this happened:

    5 | fn myfun0(...,_:i32) {}
      |    ^~~~~~
<source>:7:4: warning: function is never used: 'myfun1'
    7 | fn myfun1(a:i32,...,_:i32) {}
      |    ^~~~~~
<source>:9:1: warning: struct is never constructed: 'z'
    9 | struct z {
      | ^~~~~~
<source>:15:8: warning: associated function is never used: 'new'
   15 |     fn new(x: f64, ..., y: f64) -> z {
      |        ^~~
<source>:7:11: warning: unused name 'a' [-Wunused-variable]
    7 | fn myfun1(a:i32,...,_:i32) {}
      |           ^
Compiler returned: 0