meta.language.classes.override_signature

An overriding method must preserve the inherited method’s operation kind and resolved result type.

Read in specification context · design/meta/language.md

Tests and review

Indexed tests and the implementation-completeness and test-adequacy review; no test run is implied.

Implemented sage_meta::checks_nested_arguments_in_fields_results_and_overrides

crates/sage-meta/tests/language.rs · test:language

#![allow(unused)]
fn main() {
#[test]
#[sage::test(meta.language.classes.override_signature)]
fn checks_nested_arguments_in_fields_results_and_overrides() {
    let errors = check(
        r#"
        class Base { """Base."""
            fn value() -> Vec<Value> { """Get.""" envelope {} }
        }
        class Child extends crate::Base { """Child."""
            input broken: Option<Missing>;
            override fn value() -> Vec<Option<Value>> { """Get.""" envelope {} }
            fn missing() -> Option<Unknown> { """Get.""" envelope {} }
        }
    "#,
    );
    assert!(
        errors
            .iter()
            .any(|e| e.message.contains("unknown type Missing"))
    );
    assert!(
        errors
            .iter()
            .any(|e| e.message.contains("unknown type Unknown"))
    );
    assert!(
        errors
            .iter()
            .any(|e| e.message.contains("preserve method kind and result type"))
    );
    assert!(
        check(
            r#"
        class Base { """Base.""" fn value() -> Vec<Value> { """Get.""" envelope {} } }
        class Child extends crate::Base { """Child."""
            override fn value() -> Vec<crate::Value> { """Get.""" envelope {} }
        }
    "#
        )
        .is_empty()
    );
    let errors = check(
        r#"
        class Base { """Base.""" fn value() -> Value { """Get.""" envelope {} } }
        class Child extends crate::Base { """Child."""
            override query value() -> Value { """Get.""" envelope {} }
        }
    "#,
    );
    assert!(errors.iter().any(|error| {
        error
            .message
            .contains("preserve method kind and result type")
    }));
}
}

See more source ↗

Review: Accepted · Codex /root/anchor_190.

Source review: the complete claim requires preserving both operation kind and resolved result type for an override. The single ordinary implementation association in validate.rs checks the selected inherited method via base/method/ancestors, compares MethodKind and resolve_type results in the respective declaring namespaces, and emits the signature diagnostic on either difference. Recursive canonicalization includes tuple structure and named type arguments, so differing spellings of the same type are accepted while nested differences are rejected; unresolved result types independently produce errors. The single ordinary associated test checks a nested Vec<Value> versus Vec<Option<Value>> mismatch, separately asserts unknown field/result diagnostics, accepts Vec<Value> versus Vec<crate::Value> with no errors, and rejects fn versus query with the same Value result. These visible assertions cover both independent requirements and semantic result equality. Captured check setup parses a valid demo crate with Value declared and invokes validate. All associated inputs were inspected; no TODO/N/A entries or deferred prerequisites exist. Baseline: independently verified exact byte equality of both current source files with the historical snapshots by joining stored lines; the earlier rationale remains supported by current code and assertions. Execution: I ran review start/read and snapshot comparison, and am recording this report; I did not run tests or a workspace build. The coordinator separately reports 321 functional tests and a root cargo build passing, which is not my execution evidence. No edits required.

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meta.language.classes.override_signature

Implementation

Tests and review