SemverQuery(
id: "union_changed_kind",
human_readable_name: "pub union changed kind",
description: "A public union was replaced by an enum or trait at the same import path.",
required_update: Major,
lint_level: Deny,
reference_link: None,
query: r#"
{
CrateDiff {
baseline {
item {
... on Union {
visibility_limit @filter(op: "=", value: ["$public"])
importable_path {
path @output @tag
public_api @filter(op: "=", value: ["$true"])
}
}
}
}
current {
item {
... on Importable {
visibility_limit @filter(op: "=", value: ["$public"])
name @output
new_kind: __typename @filter(op: "one_of", value: ["$replacement_kinds"]) @output
importable_path {
path @filter(op: "=", value: ["%path"])
public_api @filter(op: "=", value: ["$true"])
}
span_: span @optional {
filename @output
begin_line @output
end_line @output
}
}
}
}
}
}"#,
arguments: {
"public": "public",
"replacement_kinds": ["Enum", "Trait"],
"true": true,
},
error_message: "A public union was replaced by a different kind of item at the same path, which breaks field access and layout assumptions.",
per_result_error_template: Some("union {{join \"::\" path}} became {{lowercase new_kind}} in {{span_filename}}:{{span_begin_line}}"),
// Witness ideas:
// - traits are not a concrete type, so functions with a parameter of the union type would break
// - enums have very sophisticated representation rules, so it'd be very difficult bordering on
// impossible to convert a union to an enum without breaking something
witness: None,
)