new lint: struct_added_without_non_exhaustive

src/lints/struct_added_without_non_exhaustive.ron

@@ -0,0 +1,57 @@
+SemverQuery(
+    id: "struct_added_without_non_exhaustive",
+    human_readable_name: "pub struct added without #[non_exhaustive]",
+    description: "A new public struct was added without #[non_exhaustive], making it harder to evolve in the future.",
+    required_update: Minor,
+    lint_level: Warn,
+    reference_link: Some("https://doc.rust-lang.org/reference/attributes/type_system.html#the-non_exhaustive-attribute"),
+    query: r#"
+    {
+        CrateDiff {
+            current {
+                item {
+                    ... on Struct {
+                        visibility_limit @filter(op: "=", value: ["$public"]) @output
+                        name @output
+                        struct_type @output
+
+                        # Check that it's not marked #[non_exhaustive]
+                        attrs @filter(op: "not_contains", value: ["$non_exhaustive"])
+
+                        importable_path {
+                            path @output @tag
+                            public_api @filter(op: "=", value: ["$true"])
+                        }
+
+                        # Verify all fields are public
+                        field @fold @transform(op: "count") @filter(op: "=", value: ["$zero"]) {
+                            visibility_limit @filter(op: "!=", value: ["$public"])
+                        } 
+
+                        span_: span @optional {
+                            filename @output
+                            begin_line @output
+                        }
+                    }
+                }
+            }
+            baseline @fold @transform(op: "count") @filter(op: "=", value: ["$zero"]) {
+                item {
+                    ... on Struct {
+                        importable_path {
+                            path @filter(op: "=", value: ["%path"])
+                        }
+                    }
+                }
+            }
+        }
+    }"#,
+    arguments: {
+        "public": "public",
+        "zero": 0,
+        "true": true,
+        "non_exhaustive": "non_exhaustive",
+    },
+    error_message: "A new public struct was added without #[non_exhaustive], which may make it difficult to evolve in the future",
+    per_result_error_template: Some("struct {{join \"::\" path}} in file {{span_filename}}:{{span_begin_line}}"),
+)

src/query.rs

@@ -1208,6 +1208,7 @@ add_lints!(
     struct_repr_transparent_removed,
     struct_with_no_pub_fields_changed_type,
     struct_with_pub_fields_changed_type,
+    struct_added_without_non_exhaustive,
     trait_added_supertrait,
     trait_allows_fewer_const_generic_params,
     trait_allows_fewer_generic_type_params,

test_crates/struct_added_without_non_exhaustive/new/Cargo.toml

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

test_crates/struct_added_without_non_exhaustive/new/src/lib.rs

@@ -0,0 +1,50 @@
+// Existing structs shouldn't trigger the lint
+pub struct ExistingStruct {
+    pub field: i32,
+}
+
+// Should NOT trigger the lint - private struct
+struct PrivateStruct {
+    pub field: i32,
+}
+
+// Should trigger the lint - new public struct with all pub fields
+pub struct NewAllPubFields {
+    pub field1: i32,
+    pub field2: String,
+}
+
+// Should NOT trigger the lint - has private field
+pub struct NewWithPrivateField {
+    pub field1: i32,
+    field2: String, // private field
+}
+
+// Should NOT trigger the lint - marked non_exhaustive
+#[non_exhaustive]
+pub struct NewWithNonExhaustive {
+    pub field1: i32,
+    pub field2: String,
+}
+
+// Should NOT trigger the lint - not public
+struct NewPrivateStruct {
+    pub field1: i32,
+    pub field2: String,
+}
+
+// Should trigger the lint - unit struct
+pub struct NewUnitStruct;
+
+// Should NOT trigger the lint - private in public module
+pub mod public_mod {
+    struct PrivateInPublicMod {
+        pub field: i32,
+    }
+}
+
+// Should trigger the lint - tuple struct with all pub fields
+pub struct NewTupleStruct(pub i32, pub String);
+
+// Should NOT trigger the lint - tuple struct with private field
+pub struct NewTupleWithPrivate(pub i32, String);

test_crates/struct_added_without_non_exhaustive/old/Cargo.toml

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

test_crates/struct_added_without_non_exhaustive/old/src/lib.rs

@@ -0,0 +1,8 @@
+// Existing structs shouldn't trigger the lint
+pub struct ExistingStruct {
+    pub field: i32,
+}
+
+struct PrivateStruct {
+    pub field: i32,
+}

test_outputs/query_execution/struct_added_without_non_exhaustive.snap

@@ -0,0 +1,130 @@
+---
+source: src/query.rs
+expression: "&query_execution_results"
+---
+{
+  "./test_crates/inherent_method_must_use_added/": [
+    {
+      "name": String("EnumToStructWithMustUseMethods"),
+      "path": List([
+        String("inherent_method_must_use_added"),
+        String("item_type_changed_inherent_method_must_use_added"),
+        String("EnumToStructWithMustUseMethods"),
+      ]),
+      "span_begin_line": Uint64(8),
+      "span_filename": String("src/item_type_changed_inherent_method_must_use_added.rs"),
+      "struct_type": String("plain"),
+      "visibility_limit": String("public"),
+    },
+    {
+      "name": String("UnionToStructWithMustUseMethods"),
+      "path": List([
+        String("inherent_method_must_use_added"),
+        String("item_type_changed_inherent_method_must_use_added"),
+        String("UnionToStructWithMustUseMethods"),
+      ]),
+      "span_begin_line": Uint64(161),
+      "span_filename": String("src/item_type_changed_inherent_method_must_use_added.rs"),
+      "struct_type": String("plain"),
+      "visibility_limit": String("public"),
+    },
+    {
+      "name": String("NewStructWithMustUseMethods"),
+      "path": List([
+        String("inherent_method_must_use_added"),
+        String("struct_inherent_method_must_use_added"),
+        String("NewStructWithMustUseMethods"),
+      ]),
+      "span_begin_line": Uint64(65),
+      "span_filename": String("src/struct_inherent_method_must_use_added.rs"),
+      "struct_type": String("plain"),
+      "visibility_limit": String("public"),
+    },
+  ],
+  "./test_crates/method_moved_to_trait_must_use_added/": [
+    {
+      "name": String("NewStructWithTraitMustUseMethods"),
+      "path": List([
+        String("method_moved_to_trait_must_use_added"),
+        String("struct_method_moved_to_trait_must_use_added"),
+        String("NewStructWithTraitMustUseMethods"),
+      ]),
+      "span_begin_line": Uint64(147),
+      "span_filename": String("src/struct_method_moved_to_trait_must_use_added.rs"),
+      "struct_type": String("plain"),
+      "visibility_limit": String("public"),
+    },
+  ],
+  "./test_crates/nonbreaking_item_rename/": [
+    {
+      "name": String("NewName"),
+      "path": List([
+        String("nonbreaking_item_rename"),
+        String("NewName"),
+      ]),
+      "span_begin_line": Uint64(2),
+      "span_filename": String("src/lib.rs"),
+      "struct_type": String("unit"),
+      "visibility_limit": String("public"),
+    },
+  ],
+  "./test_crates/struct_added_without_non_exhaustive/": [
+    {
+      "name": String("NewAllPubFields"),
+      "path": List([
+        String("struct_added_without_non_exhaustive"),
+        String("NewAllPubFields"),
+      ]),
+      "span_begin_line": Uint64(12),
+      "span_filename": String("src/lib.rs"),
+      "struct_type": String("plain"),
+      "visibility_limit": String("public"),
+    },
+    {
+      "name": String("NewWithNonExhaustive"),
+      "path": List([
+        String("struct_added_without_non_exhaustive"),
+        String("NewWithNonExhaustive"),
+      ]),
+      "span_begin_line": Uint64(25),
+      "span_filename": String("src/lib.rs"),
+      "struct_type": String("plain"),
+      "visibility_limit": String("public"),
+    },
+    {
+      "name": String("NewUnitStruct"),
+      "path": List([
+        String("struct_added_without_non_exhaustive"),
+        String("NewUnitStruct"),
+      ]),
+      "span_begin_line": Uint64(37),
+      "span_filename": String("src/lib.rs"),
+      "struct_type": String("unit"),
+      "visibility_limit": String("public"),
+    },
+    {
+      "name": String("NewTupleStruct"),
+      "path": List([
+        String("struct_added_without_non_exhaustive"),
+        String("NewTupleStruct"),
+      ]),
+      "span_begin_line": Uint64(47),
+      "span_filename": String("src/lib.rs"),
+      "struct_type": String("tuple"),
+      "visibility_limit": String("public"),
+    },
+  ],
+  "./test_crates/switch_away_from_reexport_as_underscore/": [
+    {
+      "name": String("Struct"),
+      "path": List([
+        String("switch_away_from_reexport_as_underscore"),
+        String("Struct"),
+      ]),
+      "span_begin_line": Uint64(4),
+      "span_filename": String("src/lib.rs"),
+      "struct_type": String("plain"),
+      "visibility_limit": String("public"),
+    },
+  ],
+}