Incremental: code is not recompiled when a case of string literal is changed

[matklad]

Originally reported by @redcape at rust-lang/cargo#5320

~/trash
λ rustc --version
rustc 1.26.0-beta.2 (0e350672e 2018-04-05)

λ cat main.rs
fn main() {
    let test_str = "a man a plan a canal panama";
    println!("{}", is_palindrome(test_str));
}

fn is_palindrome(test_str: &str) -> bool {
    use std::iter::FromIterator;

    let non_whitespace = |p : &char| !p.is_whitespace();
    let forward_iter = test_str.chars().filter(non_whitespace);
    let rev_iter = test_str.chars().rev().filter(non_whitespace);
    println!("{:?}", String::from_iter(test_str.chars()));
    println!("{:?}", String::from_iter(test_str.chars().rev()));
    println!("{:?}", String::from_iter(forward_iter.clone()));
    println!("{:?}", String::from_iter(rev_iter.clone()));
    forward_iter.eq(rev_iter)
}

~/trash
λ rustc main.rs -C incremental=inc

~/trash
λ ./main
"a man a plan a canal panama"
"amanap lanac a nalp a nam a"
"amanaplanacanalpanama"
"amanaplanacanalpanama"
true

~/trash
λ vim main.rs # change `"a man` to `"A man`

~/trash
λ cat main.rs
fn main() {
    let test_str = "A man a plan a canal panama";
    println!("{}", is_palindrome(test_str));
}

fn is_palindrome(test_str: &str) -> bool {
    use std::iter::FromIterator;

    let non_whitespace = |p : &char| !p.is_whitespace();
    let forward_iter = test_str.chars().filter(non_whitespace);
    let rev_iter = test_str.chars().rev().filter(non_whitespace);
    println!("{:?}", String::from_iter(test_str.chars()));
    println!("{:?}", String::from_iter(test_str.chars().rev()));
    println!("{:?}", String::from_iter(forward_iter.clone()));
    println!("{:?}", String::from_iter(rev_iter.clone()));
    forward_iter.eq(rev_iter)
}

~/trash
λ ./main
"a man a plan a canal panama" # should be capital A here
"amanap lanac a nalp a nam a"
"amanaplanacanalpanama"
"amanaplanacanalpanama"
true

[sinkuu]

This will be fixed in the next nightly (#49752).

[matklad]

Seems like it, closing then, thanks @sinkuu !