src/lints/trait_method_missing.ron

SemverQuery(
    id: "trait_method_missing",
    human_readable_name: "pub trait method removed or renamed",
    description: "A trait method can no longer be called by its prior path.",
    required_update: Major,
    lint_level: Deny,
    reference_link: Some("https://doc.rust-lang.org/cargo/reference/semver.html#major-any-change-to-trait-item-signatures"),
    query: r#"
    {
        CrateDiff {
            baseline {
                item {
                    ... on Trait {
                        visibility_limit @filter(op: "=", value: ["$public"]) @output
                        name @output

                        importable_path {
                            path @output @tag
                            public_api @filter(op: "=", value: ["$true"])
                        }

                        method {
                            method_name: name @output @tag

                            # TODO: Once we can check whether traits are sealed, split this lint:
                            # - Sealed traits should ignore ineligible (~approx. `#[doc(hidden)]`)
                            #   methods since they are indeed never public API.
                            # - Non-sealed traits should only ignore ineligible methods
                            #   if they have a default implementation; otherwise, implementors
                            #   of the trait have to impl the method regardless of `#[doc(hidden)]`.
                            public_api_eligible @filter(op: "=", value: ["$true"])

                            span_: span @optional {
                                filename @output
                                begin_line @output
                            }
                        }
                    }
                }
            }
            current {
                item {
                    ... on Trait {
                        visibility_limit @filter(op: "=", value: ["$public"])

                        importable_path {
                            path @filter(op: "=", value: ["%path"])
                            public_api @filter(op: "=", value: ["$true"])
                        }

                        method @fold @transform(op: "count") @filter(op: "=", value: ["$zero"]) {
                            name @filter(op: "=", value: ["%method_name"])
                        }
                    }
                }
            }
        }
    }"#,
    arguments: {
        "public": "public",
        "zero": 0,
        "true": true,
    },
    // TODO: This has a false-positive edge case, because it assumes the trait method
    //       was *previously* callable. This might not be the case for partially-sealed traits
    //       which can make some methods uncallable. In that case, the method removal
    //       is not a breaking change, since it could never have been called in the first place.
    error_message: "A trait method is no longer callable, and may have been renamed or removed entirely.",
    per_result_error_template: Some("method {{method_name}} of trait {{name}}, previously in file {{span_filename}}:{{span_begin_line}}"),
)