Bad compile error with fun bar(&foo: Foo) syntax

[ekr]

See the following code fragment:

struct Foo {
}

fn foo(&foo: Foo) {  // illegal syntax
}

fn main() {
    println!("Hello, world!");
}

This generates the following confusing error:

15:29:19|~/tmp/rust_compile_error (master)$ cargo build
   Compiling rust_compile_error v0.1.0 (file:///Users/ekr/tmp/rust_compile_error)
error[E0308]: mismatched types
 --> src/main.rs:4:8
  |
4 | fn foo(&foo: Foo) {
  |        ^^^^ expected struct `Foo`, found reference
  |
  = note: expected type `Foo`
  = note:    found type `&_`

error: aborting due to previous error

error: Could not compile `rust_compile_error`.

[Stebalien]

Well, that code is actually syntactically correct, it just doesn't type-check.

For example, this works:

#[derive(Copy, Clone)]
struct Foo;

fn foo(&foo: &Foo) { // legal syntax
}

fn main() {
    println!("Hello, world!");
}

And is equivalent to:

#[derive(Copy, Clone)]
struct Foo;

fn foo(foo_ref: &Foo) {
    let foo = *foo_ref;
}

fn main() {
    println!("Hello, world!");
}

[ekr]

OK. I was just following @dherman's instructions to file here, so I'll defer to those who know better than me.

[Stebalien]

@ekr yeah, reporting here was the right thing to do. This is confusing and deserves a "did you mean foo: &Foo?".