id: string-error
language: rust
severity: error
message: String as an error type
note: |
  Return a #[derive(thiserror::Error)] enum, so a caller can match on what failed and the
  messages live with their variants.
rule:
  any:
    - pattern:
        context: type T = Result<$OK, String>;
        selector: generic_type
    - pattern: Err(format!($$$))
    - pattern: Err($S.to_string())
    - pattern: Err(String::from($$$))
    - all:
        - pattern: Err($S)
        - has:
            kind: arguments
            has:
              kind: string_literal