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Error code E0595

Note: this error code is no longer emitted by the compiler.

Closures cannot mutate immutable captured variables.

Erroneous code example:

#![allow(unused)] fn main() { let x = 3; // error: closure cannot assign to immutable local variable `x` let mut c = || { x += 1 }; }

Make the variable binding mutable:

#![allow(unused)] fn main() { let mut x = 3; // ok! let mut c = || { x += 1 }; }