rust/tests/ui/closures/issue-72408-nested-closures-exponential.rs

60 lines
1.1 KiB
Rust

//@ check-pass
// Closures include captured types twice in a type tree.
//
// Wrapping one closure with another leads to doubling
// the amount of types in the type tree.
//
// This test ensures that rust can handle
// deeply nested type trees with a lot
// of duplicated subtrees.
fn dup(f: impl Fn(i32) -> i32) -> impl Fn(i32) -> i32 {
move |a| f(a * 2)
}
fn main() {
let f = |a| a;
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
// Compiler dies around here if it tries
// to walk the tree exhaustively.
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
let f = dup(f);
println!("Type size was at least {}", f(1));
}