Fix E0023: Non-Exhaustive Pattern Matching in Rust

Mon, 13 Jul 2026 19:56:04 +0800

1. Symptoms

The Rust compiler emits E0023 when a pattern match does not cover all possible values of a type. This error appears in several distinct scenarios, each producing characteristic diagnostic output.

Incomplete Match Expression

When using a `match` statement on an enum without covering all variants, the compiler reports:

error[E0023]: pattern None not covered –> src/main.rs:5:5 | 5 | match opt { | ^ non-exhaustive patterns: None not covered | note: Option<i32> defined here (1 variant) –> /rustc/…/library/core/src/option.rs:… | 1 | enum Option { /* … */ } | ^^^^^^^^^^^^^^ None defined here | help: consider adding a wildcard arm | 5 | match opt { 6 | Some(x) => println!("{}", x), 7 | _ => {} // handle remaining cases 8 | } |

E0023 on ErrorVault — Developer Error Code Dictionary

Fix E0023: Non-Exhaustive Pattern Matching in Rust

1. Symptoms

Incomplete Match Expression

When using a match statement on an enum without covering all variants, the compiler reports:

When using a `match` statement on an enum without covering all variants, the compiler reports: