S0023: non-exhaustive match

Generated from rellum-diagnostics/src/db.rs.

Explanation

The compiler proves match exhaustiveness statically so every value has a defined result at runtime. A match that omits some Option, Result, Bool, enum, or record shape could otherwise reach a tick with no selected arm.

Common causes

• matching some(x) without a none arm
• matching ok(x) without an err arm
• matching only some variants of an enum
• omitting else for a guard-based match

Canonical fixes

• add the missing arms

Before:

match value
    some(x) => x

After:

match value
    some(x) => x
    none => 0

• add an else arm when one fallback behavior is correct

Before:

match flag
    true => 1

After:

match flag
    true => 1
    else => 0

Code example

match value
    some(x) => x

Links

• RellC diagnostic overview