add function_export_name_changed lint (#728)

* add function_export_name_changed lint

* consolidate export_name_changed and export_name_missing into one lint

* Apply suggestions from code review (pt1)

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

* apply feedback from code review (pt2)

- remove old comments
- add output from new `new_export_name` field

---------

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

src/lints/function_export_name_changed.ron

@@ -0,0 +1,47 @@
+SemverQuery(
+    id: "function_export_name_changed",
+    human_readable_name: "function's export name has changed or been removed",
+    description: "A function's ABI name with #[no_mangle] or #[export_name = \"name\"] has changed or been removed",
+    required_update: Major,
+    reference_link: Some("https://doc.rust-lang.org/reference/abi.html#the-no_mangle-attribute"),
+    query: r#"
+    {
+        CrateDiff {
+            baseline {
+                item {
+                    ... on Function {
+                        importable_path {
+                            path @output @tag
+                        }
+
+                        export_name @output @tag @filter(op: "is_not_null")
+                    }
+                }
+            }
+            
+            current {
+                item {
+                    ... on Function {
+                        name @output
+
+                        new_export_name: export_name @filter(op: "!=", value: ["%export_name"]) @output
+
+                        importable_path {
+                            path @filter(op: "=", value: ["%path"])
+                        }
+
+                        span_: span @optional {
+                            filename @output
+                            begin_line @output
+                        }
+                    }
+                }
+            }
+        }
+    }"#,
+    arguments: {
+    },
+    error_message: "The ABI export name of a function has been changed or removed through the #[no_mangle] or #[export_name] attributes.",
+    per_result_error_template: Some("function {{join \"::\" path}} no longer has ABI name {{export_name}} in {{span_filename}}:{{span_begin_line}}"),
+)
+

src/query.rs

@@ -476,6 +476,7 @@ macro_rules! add_lints {
 }
 
 add_lints!(
+    function_export_name_changed,
     union_field_missing,
     pub_static_now_doc_hidden,
     function_abi_no_longer_unwind,

test_crates/function_export_name_changed/new/Cargo.toml

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

test_crates/function_export_name_changed/new/src/lib.rs

@@ -0,0 +1,43 @@
+/// positive test - a function changes export_name
+#[export_name = "export_name_changed_new"]
+pub fn export_name_changed() {}
+
+/// positive test - a function changes no_mangle to a different export_name
+#[export_name = "no_mangle_changed_to_other_export_name_new"]
+pub fn no_mangle_changed_to_other_export_name() {}
+
+/// positive test - a function changes export_name to a different no_mangle
+#[no_mangle]
+pub fn export_name_changed_to_other_no_mangle() {}
+
+/// negative test - a function changes no_mangle to an equivalent export_name
+#[export_name = "no_mangle_changed_to_same_export_name"]
+pub fn no_mangle_changed_to_same_export_name() {}
+
+/// negative test - a function changes export_name to an equivalent no_mangle
+#[no_mangle]
+pub fn export_name_changed_to_same_no_mangle() {}
+
+/// positive test - a function's no_mangle is removed
+pub fn no_mangle_removed() {}
+
+/// positive test - a function's export_name is removed
+pub fn export_name_removed() {}
+
+/// positive test - a non-public function changes export name
+#[export_name = "private_export_name_changed_new"]
+pub fn private_export_name_changed() {}
+
+/// positive test - export name on one function gets moved to the other
+/// this is still a breaking change because a call to `export_name_moved_1` in the API
+/// is no longer equivalent to a call to `export_name_moved` in the ABI
+pub mod export_name_moved {
+    pub fn export_name_moved_1() {}
+
+    #[export_name = "export_name_moved"]
+    pub fn export_name_moved_2() {}
+}
+
+/// negative test - a function's export name is added
+#[export_name = "export_name_added"]
+pub fn export_name_added() {}

test_crates/function_export_name_changed/old/Cargo.toml

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

test_crates/function_export_name_changed/old/src/lib.rs

@@ -0,0 +1,44 @@
+/// positive test - a function changes export_name
+#[export_name = "export_name_changed_old"]
+pub fn export_name_changed() {}
+
+/// positive test - a function changes no_mangle to a different export_name
+#[no_mangle]
+pub fn no_mangle_changed_to_other_export_name() {}
+
+/// positive test - a function changes export_name to a different no_mangle
+#[export_name = "export_name_changed_to_other_no_mangle_old"]
+pub fn export_name_changed_to_other_no_mangle() {}
+
+/// negative test - a function changes no_mangle to an equivalent export_name
+#[no_mangle]
+pub fn no_mangle_changed_to_same_export_name() {}
+
+/// negative test - a function changes export_name to an equivalent no_mangle
+#[export_name = "export_name_changed_to_same_no_mangle"]
+pub fn export_name_changed_to_same_no_mangle() {}
+
+/// positive test - a function's no_mangle is removed
+#[no_mangle]
+pub fn no_mangle_removed() {}
+
+/// positive test - a function's export_name is removed
+#[export_name = "export_name_removed"]
+pub fn export_name_removed() {}
+
+/// positive test - a non-public function changes export name
+#[export_name = "private_export_name_changed_old"]
+pub fn private_export_name_changed() {}
+
+/// positive test - export name on one function gets moved to the other
+/// this is still a breaking change because a call to `export_name_moved_1` in the API
+/// is no longer equivalent to a call to `export_name_moved` in the ABI
+pub mod export_name_moved {
+    #[export_name = "export_name_moved"]
+    pub fn export_name_moved_1() {}
+
+    pub fn export_name_moved_2() {}
+}
+
+/// negative test - a function's export name is added
+pub fn export_name_added() {}

test_outputs/function_export_name_changed.output.ron

@@ -0,0 +1,82 @@
+{
+    "./test_crates/function_export_name_changed/": [
+        {
+            "export_name": String("export_name_changed_old"),
+            "name": String("export_name_changed"),
+            "new_export_name": String("export_name_changed_new"),
+            "path": List([
+                String("function_export_name_changed"),
+                String("export_name_changed"),
+            ]),
+            "span_begin_line": Uint64(3),
+            "span_filename": String("src/lib.rs"),
+        },
+        {
+            "export_name": String("no_mangle_changed_to_other_export_name"),
+            "name": String("no_mangle_changed_to_other_export_name"),
+            "new_export_name": String("no_mangle_changed_to_other_export_name_new"),
+            "path": List([
+                String("function_export_name_changed"),
+                String("no_mangle_changed_to_other_export_name"),
+            ]),
+            "span_begin_line": Uint64(7),
+            "span_filename": String("src/lib.rs"),
+        },
+        {
+            "export_name": String("export_name_changed_to_other_no_mangle_old"),
+            "name": String("export_name_changed_to_other_no_mangle"),
+            "new_export_name": String("export_name_changed_to_other_no_mangle"),
+            "path": List([
+                String("function_export_name_changed"),
+                String("export_name_changed_to_other_no_mangle"),
+            ]),
+            "span_begin_line": Uint64(11),
+            "span_filename": String("src/lib.rs"),
+        },
+        {
+            "export_name": String("no_mangle_removed"),
+            "name": String("no_mangle_removed"),
+            "new_export_name": Null,
+            "path": List([
+                String("function_export_name_changed"),
+                String("no_mangle_removed"),
+            ]),
+            "span_begin_line": Uint64(22),
+            "span_filename": String("src/lib.rs"),
+        },
+        {
+            "export_name": String("export_name_removed"),
+            "name": String("export_name_removed"),
+            "new_export_name": Null,
+            "path": List([
+                String("function_export_name_changed"),
+                String("export_name_removed"),
+            ]),
+            "span_begin_line": Uint64(25),
+            "span_filename": String("src/lib.rs"),
+        },
+        {
+            "export_name": String("private_export_name_changed_old"),
+            "name": String("private_export_name_changed"),
+            "new_export_name": String("private_export_name_changed_new"),
+            "path": List([
+                String("function_export_name_changed"),
+                String("private_export_name_changed"),
+            ]),
+            "span_begin_line": Uint64(29),
+            "span_filename": String("src/lib.rs"),
+        },
+        {
+            "export_name": String("export_name_moved"),
+            "name": String("export_name_moved_1"),
+            "new_export_name": Null,
+            "path": List([
+                String("function_export_name_changed"),
+                String("export_name_moved"),
+                String("export_name_moved_1"),
+            ]),
+            "span_begin_line": Uint64(35),
+            "span_filename": String("src/lib.rs"),
+        },
+    ]
+}