Strange non-primitive cast error near erroneous code

[0x7CFE]

tl;dr; If you comment out the let error line, all will compile, obviously.

fn main() {
    let error = error; // Comment me
    for value in (1..10).map(|a| a as f32) {
        
    }
}

However, in presence of it, compiler complains

error[E0605]: non-primitive cast: `{integer}` as `f32`
 --> src/main.rs:3:34
  |
3 |     for value in (1..10).map(|a| a as f32) {
  |                                  ^^^^^^^^
  |
  = note: an `as` expression can only be used to convert between primitive types. Consider using the `From` trait

…which is strange and may mislead user in more complex situation. Looks like broken code affects type inference somehow. By the way, error will also appear, if you put erroneous line after the loop.

rustc 1.21.0-nightly (13d94d5fa 2017-08-10)
binary: rustc
commit-hash: 13d94d5fa8129a34f5c77a1bcd76983f5aed2434
commit-date: 2017-08-10
host: x86_64-unknown-linux-gnu
release: 1.21.0-nightly
LLVM version: 4.0

[Mark-Simulacrum]

#33690 is likely the same/similar.

[chyvonomys]

I also got this error on similar code:

let chars = (0..200).map(|i| {
    let pos = (
        CW * ((i % 50) as f32 + 0.5f32),
        500f32 - CH * ((i / 50) as f32 + 0.5f32),
    )
    //...
}).collect();

Compiler complains about (i % 50) as f32 and (i / 50) as f32.
In my case real error is after this code.

rustc 1.20.0 (f3d6973f4 2017-08-27)
binary: rustc
commit-hash: f3d6973f41a7d1fb83029c9c0ceaf0f5d4fd7208
commit-date: 2017-08-27
host: x86_64-apple-darwin
release: 1.20.0
LLVM version: 4.0