Auto merge of #15649 - zimio:issue-15591-rewrite-ban-type-lint, r=Waf…

…flespeanut

Rewrite the ban-type lint in Python

<!-- Please describe your changes on the following line: -->
Rewrite the ban-type lint in Python.

Question: Should the old ban-type lint written in rust be deleted?

---
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- [x ] `./mach build -d` does not report any errors
- [x ] `./mach test-tidy` does not report any errors
- [x ] These changes fix #15591

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- [ x] There are tests for these changes

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components/script_plugins/lib.rs

@@ -25,15 +25,13 @@ extern crate syntax;
 use rustc_plugin::Registry;
 use syntax::feature_gate::AttributeType::Whitelisted;
 
-mod ban;
 mod unrooted_must_root;
 /// Utilities for writing plugins
 mod utils;
 
 #[plugin_registrar]
 pub fn plugin_registrar(reg: &mut Registry) {
     reg.register_late_lint_pass(box unrooted_must_root::UnrootedPass::new());
-    reg.register_early_lint_pass(box ban::BanPass);
     reg.register_attribute("allow_unrooted_interior".to_string(), Whitelisted);
     reg.register_attribute("must_root".to_string(), Whitelisted);
 }

python/tidy/servo_tidy/tidy.py

@@ -549,6 +549,12 @@ def check_rust(file_name, lines):
             (r": &Vec<", "use &[T] instead of &Vec<T>", no_filter),
             # No benefit over using &str
             (r": &String", "use &str instead of &String", no_filter),
+            # There should be any use of banned types:
+            # Cell<JSVal>, Cell<JS<T>>, DOMRefCell<JS<T>>, DOMRefCell<HEAP<T>>
+            (r"(\s|:)+Cell<JSVal>", "Banned type Cell<JSVal> detected. Use MutJS<JSVal> instead", no_filter),
+            (r"(\s|:)+Cell<JS<.+>>", "Banned type Cell<JS<T>> detected. Use MutJS<JS<T>> instead", no_filter),
+            (r"DOMRefCell<JS<.+>>", "Banned type DOMRefCell<JS<T>> detected. Use MutJS<JS<T>> instead", no_filter),
+            (r"DOMRefCell<Heap<.+>>", "Banned type DOMRefCell<Heap<T>> detected. Use MutJS<JS<T>> instead", no_filter),
             # No benefit to using &Root<T>
             (r": &Root<", "use &T instead of &Root<T>", no_filter),
             (r"^&&", "operators should go at the end of the first line", no_filter),

tests/compiletest/plugin/compile-fail/ban.rs → python/tidy/servo_tidy_tests/ban.rs

@@ -9,10 +9,13 @@ extern crate js;
 
 use js::jsval::JSVal;
 use std::cell::Cell;
+use std::cell::UnsafeCell;
 
 struct Foo {
-    bar: Cell<JSVal>
+    bar: Cell<JSVal>,
     //~^ ERROR Banned type Cell<JSVal> detected. Use MutJS<JSVal> instead
+    foo: UnsafeCell<JSVal>
+    //~^ NOT AN ERROR
 }
 
 fn main() {}

python/tidy/servo_tidy_tests/test_tidy.py

@@ -140,6 +140,14 @@ def test_rust(self):
         self.assertTrue('feature attribute is not in alphabetical order' in feature_errors.next()[2])
         self.assertNoMoreErrors(feature_errors)
 
+        ban_errors = tidy.collect_errors_for_files(iterFile('ban.rs'), [], [tidy.check_rust], print_text=False)
+        self.assertEqual('Banned type Cell<JSVal> detected. Use MutJS<JSVal> instead', ban_errors.next()[2])
+        self.assertNoMoreErrors(ban_errors)
+
+        ban_errors = tidy.collect_errors_for_files(iterFile('ban-domrefcell.rs'), [], [tidy.check_rust], print_text=False)
+        self.assertEqual('Banned type DOMRefCell<JS<T>> detected. Use MutJS<JS<T>> instead', ban_errors.next()[2])
+        self.assertNoMoreErrors(ban_errors)
+
     def test_spec_link(self):
         tidy.SPEC_BASE_PATH = base_path
         errors = tidy.collect_errors_for_files(iterFile('speclink.rs'), [], [tidy.check_spec], print_text=False)