Add lint for "deprecated" attribute on structs (obi1kenobi#365)

* Add lint for "deprecated" attribute on structs

This was mostly done copying and adjusting code from the "must_use" attribute lint.

* Generalize lint for "deprecated" struct attribute

Now the same query also checks enums and unions.

* Rename struct_deprecated_added lint to its now more general use case

* Reduce comments, use more meaningful strings

* Add tests for deprecated enums

* Add tests for deprecated unions

Unions are not supported yet by the query engine,
so the output file doesn't change.

* Simplify deprecated lint name

* Reorganize deprecated tests

* Apply suggestions from code review

---------

Co-authored-by: Predrag Gruevski <2348618+obi1kenobi@users.noreply.github.com>

src/lints/type_marked_deprecated.ron

@@ -0,0 +1,62 @@
+SemverQuery(
+    id: "type_marked_deprecated",
+    human_readable_name: "#[deprecated] added on type",
+    description: "A type has been newly marked with #[deprecated].",
+    required_update: Minor,
+    reference_link: Some("https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-deprecated-attribute"),
+    query: r#"
+    {
+        CrateDiff {
+            current {
+                item {
+                    ... on ImplOwner {
+                        visibility_limit @filter(op: "=", value: ["$public"])
+                        name @output
+                        owner_type: __typename @tag @output
+
+                        importable_path {
+                            path @tag @output
+                        }
+
+                        attribute {
+                            new_attr: raw_attribute @output
+                            content {
+                                base @filter(op: "=", value: ["$deprecated"])
+                            }
+                        }
+
+                        span_: span @optional {
+                            filename @output
+                            begin_line @output
+                        }
+                    }
+                }
+            }
+            baseline {
+                item {
+                    ... on ImplOwner {
+                        visibility_limit @filter(op: "=", value: ["$public"]) @output
+                        __typename @filter(op: "=", value: ["%owner_type"])
+
+                        importable_path {
+                            path @filter(op: "=", value: ["%path"])
+                        }
+
+                        attribute @fold @transform(op: "count") @filter(op: "=", value: ["$zero"]) {
+                            content {
+                                base @filter(op: "=", value: ["$deprecated"])
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }"#,
+    arguments: {
+        "public": "public",
+        "deprecated": "deprecated",
+        "zero": 0,
+    },
+    error_message: "A type is now #[deprecated]. Downstream crates will get a compiler warning when using this type.",
+    per_result_error_template: Some("{{owner_type}} {{name}} in {{span_filename}}:{{span_begin_line}}"),
+)

src/query.rs

@@ -486,6 +486,7 @@ add_lints!(
     trait_unsafe_added,
     trait_unsafe_removed,
     tuple_struct_to_plain_struct,
+    type_marked_deprecated,
     unit_struct_changed_kind,
     variant_marked_non_exhaustive,
 );

test_crates/type_marked_deprecated/new/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+publish = false
+name = "type_marked_deprecated"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

test_crates/type_marked_deprecated/new/src/enums.rs

@@ -0,0 +1,57 @@
+// These enums did not have the #[deprecated] attribute in the old version.
+// Addition of the attribute should be reported.
+
+#[deprecated]
+pub enum EnumToDeprecatedEnum {
+    First,
+}
+
+#[deprecated = "This attribute was added"]
+pub enum EnumToDeprecatedMessageEnum {
+    First,
+}
+
+// These structs had the #[deprecated] attribute in the old version.
+// They also included the user-defined warning message. Changes of
+// the attribute, including deletion, should NOT be reported by this rule.
+
+pub enum DeprecatedEnumToEnum {
+    First,
+}
+
+#[deprecated = "This message was added"]
+pub enum DeprecatedEnumToDeprecatedMessageEnum {
+    First,
+}
+
+pub enum DeprecatedMessageEnumToEnum {
+    First,
+}
+
+#[deprecated]
+pub enum DeprecatedMessageEnumToDeprecatedEnum {
+    First,
+}
+
+#[deprecated = "This message was changed"]
+pub enum DeprecatedMessageEnumToDeprecatedMessageEnum {
+    First,
+}
+
+// This enum is private and should NOT be reported.
+
+#[deprecated]
+enum DeprecatedPrivateEnum {
+    First,
+}
+
+// This enum was added in the new version of the crate with its attribute.
+// It should NOT be reported by this rule to avoid duplicate lints.
+// It should be reported as a new pub type that is part of the crate's API.
+// This might seem like a nonsensical test but is a valid edge case.
+
+#[deprecated]
+pub enum DeprecatedNewEnum {
+    First,
+}
+

test_crates/type_marked_deprecated/new/src/lib.rs

@@ -0,0 +1,3 @@
+pub mod enums;
+pub mod structs;
+pub mod unions;

test_crates/type_marked_deprecated/new/src/structs.rs

@@ -0,0 +1,59 @@
+// These structs did not have the #[deprecated] attribute in the old version.
+// Addition of the attribute should be reported by this rule.
+
+#[deprecated]
+pub struct StructToDeprecatedStruct {
+    bar: u64,
+}
+
+#[deprecated = "This attribute was added"]
+pub struct StructToDeprecatedMessageStruct {
+    bar: u64,
+}
+
+// These structs had the #[deprecated] attribute in the old version. Changes of
+// the attribute, including deletion, should NOT be reported by this rule.
+
+pub struct DeprecatedStructToStruct {
+    bar: u64,
+}
+
+#[deprecated = "This message was added"]
+pub struct DeprecatedStructToDeprecatedMessageStruct {
+    bar: u64,
+}
+
+// These structs had the #[deprecated] attribute in the old version.
+// They also included the user-defined warning message. Changes of
+// the attribute, including deletion, should NOT be reported by this rule.
+
+pub struct DeprecatedMessageStructToStruct {
+    bar: u64,
+}
+
+#[deprecated]
+pub struct DeprecatedMessageStructToDeprecatedStruct {
+    bar: u64,
+}
+
+#[deprecated = "This message was changed"]
+pub struct DeprecatedMessageStructToDeprecatedMessageStruct {
+    bar: u64,
+}
+
+// This struct is private and should NOT be reported by this rule.
+
+#[deprecated]
+struct DeprecatedPrivateStruct {
+    bar: u64,
+}
+
+// This struct was added in the new version of the crate with its attribute.
+// It should NOT be reported by this rule to avoid duplicate lints.
+// It should be reported as a new pub type that is part of the crate's API.
+// This might seem like a nonsensical test but is a valid edge case.
+
+#[deprecated]
+pub struct DeprecatedNewStruct {
+    bar: u64,
+}

test_crates/type_marked_deprecated/new/src/unions.rs

@@ -0,0 +1,56 @@
+// These unions did not have the #[deprecated] attribute in the old version.
+// Addition of the attribute should be reported.
+
+#[deprecated]
+pub union UnionToDeprecatedUnion {
+    bar: u64,
+}
+
+#[deprecated = "This attribute was added"]
+pub union UnionToDeprecatedMessageUnion {
+    bar: u64,
+}
+
+// These structs had the #[deprecated] attribute in the old version.
+// They also included the user-defined warning message. Changes of
+// the attribute, including deletion, should NOT be reported by this rule.
+
+pub union DeprecatedUnionToUnion {
+    bar: u64,
+}
+
+#[deprecated = "This message was added"]
+pub union DeprecatedUnionToDeprecatedMessageUnion {
+    bar: u64,
+}
+
+pub union DeprecatedMessageUnionToUnion {
+    bar: u64,
+}
+
+#[deprecated]
+pub union DeprecatedMessageUnionToDeprecatedUnion {
+    bar: u64,
+}
+
+#[deprecated = "This message was changed"]
+pub union DeprecatedMessageUnionToDeprecatedMessageUnion {
+    bar: u64,
+}
+
+// This union is private and should NOT be reported.
+
+#[deprecated]
+union DeprecatedPrivateUnion {
+    bar: u64,
+}
+
+// This union was added in the new version of the crate with its attribute.
+// It should NOT be reported by this rule to avoid duplicate lints.
+// It should be reported as a new pub type that is part of the crate's API.
+// This might seem like a nonsensical test but is a valid edge case.
+
+#[deprecated]
+pub union DeprecatedNewUnion {
+    bar: u64,
+}

test_crates/type_marked_deprecated/old/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+publish = false
+name = "type_marked_deprecated"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

test_crates/type_marked_deprecated/old/src/enums.rs

@@ -0,0 +1,43 @@
+// Adding #[deprecated] to these enums should be reported.
+
+pub enum EnumToDeprecatedEnum {
+    First,
+}
+
+pub enum EnumToDeprecatedMessageEnum {
+    First,
+}
+
+// These enums already have the attribute and changes to the attribute should not be reported.
+
+#[deprecated]
+pub enum DeprecatedEnumToEnum {
+    First,
+}
+
+#[deprecated]
+pub enum DeprecatedEnumToDeprecatedMessageEnum {
+    First,
+}
+
+#[deprecated = "This attribute will be deleted"]
+pub enum DeprecatedMessageEnumToEnum {
+    First,
+}
+
+#[deprecated = "This message will be deleted"]
+pub enum DeprecatedMessageEnumToDeprecatedEnum {
+    First,
+}
+
+#[deprecated = "This message will change"]
+pub enum DeprecatedMessageEnumToDeprecatedMessageEnum {
+    First,
+}
+
+// This enum is private and should NOT be reported.
+
+enum DeprecatedPrivateEnum {
+    First,
+}
+

test_crates/type_marked_deprecated/old/src/lib.rs

@@ -0,0 +1,3 @@
+pub mod enums;
+pub mod structs;
+pub mod unions;

test_crates/type_marked_deprecated/old/src/structs.rs

@@ -0,0 +1,43 @@
+// Adding #[deprecated] to these structs should be reported.
+
+pub struct StructToDeprecatedStruct {
+    bar: u64,
+}
+
+pub struct StructToDeprecatedMessageStruct {
+    bar: u64,
+}
+
+// These structs already have the attribute and changes to the attribute should not be reported.
+
+#[deprecated]
+pub struct DeprecatedStructToStruct {
+    bar: u64,
+}
+
+#[deprecated]
+pub struct DeprecatedStructToDeprecatedMessageStruct {
+    bar: u64,
+}
+
+#[deprecated = "This attribute will be deleted"]
+pub struct DeprecatedMessageStructToStruct {
+    bar: u64,
+}
+
+#[deprecated = "This message will be deleted"]
+pub struct DeprecatedMessageStructToDeprecatedStruct {
+    bar: u64,
+}
+
+#[deprecated = "This message will change"]
+pub struct DeprecatedMessageStructToDeprecatedMessageStruct {
+    bar: u64,
+}
+
+// This struct is private and should NOT be reported.
+
+struct DeprecatedPrivateStruct {
+    bar: u64,
+}
+