Auto merge of #26792 - servo:static-mut, r=nox

Replace `static mut` with `const`, `static`+`AtomicPtr`, or `static`+`UnsafeCell`

Fixes https://github.com/servo/servo/issues/26550

2 files changed, 21 insertions, 19 deletions

diff --git a/components/script/dom/bindings/codegen/CodegenRust.py b/components/script/dom/bindings/codegen/CodegenRust.py
index 0b1187a07fb..b0361d6ca47 100644
--- a/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/components/script/dom/bindings/codegen/CodegenRust.py
@@ -2750,7 +2750,9 @@ class CGWrapMethod(CGAbstractMethod):
         unforgeable = CopyUnforgeablePropertiesToInstance(self.descriptor)
         if self.descriptor.proxy:
             create = """
-let handler = RegisterBindings::PROXY_HANDLERS[PrototypeList::Proxies::%(concreteType)s as usize];
+let handler: *const libc::c_void =
+    RegisterBindings::proxy_handlers::%(concreteType)s
+    .load(std::sync::atomic::Ordering::Acquire);
 rooted!(in(*cx) let obj = NewProxyObject(
     *cx,
     handler,
@@ -6744,7 +6746,10 @@ class CGRegisterProxyHandlersMethod(CGAbstractMethod):
 
     def definition_body(self):
         return CGList([
-            CGGeneric("PROXY_HANDLERS[Proxies::%s as usize] = Bindings::%s::DefineProxyHandler();"
+            CGGeneric("proxy_handlers::%s.store(\n"
+                      "    Bindings::%s::DefineProxyHandler() as *mut _,\n"
+                      "    std::sync::atomic::Ordering::Release,\n"
+                      ");"
                       % (desc.name, '::'.join([desc.name + 'Binding'] * 2)))
             for desc in self.descriptors
         ], "\n")
@@ -6753,10 +6758,18 @@ class CGRegisterProxyHandlersMethod(CGAbstractMethod):
 class CGRegisterProxyHandlers(CGThing):
     def __init__(self, config):
         descriptors = config.getDescriptors(proxy=True)
-        length = len(descriptors)
         self.root = CGList([
-            CGGeneric("pub static mut PROXY_HANDLERS: [*const libc::c_void; %d] = [0 as *const libc::c_void; %d];"
-                      % (length, length)),
+            CGGeneric(
+                "#[allow(non_upper_case_globals)]\n" +
+                "pub mod proxy_handlers {\n" +
+                "".join(
+                    "    pub static %s: std::sync::atomic::AtomicPtr<libc::c_void> =\n"
+                    "        std::sync::atomic::AtomicPtr::new(std::ptr::null_mut());\n"
+                    % desc.name
+                    for desc in descriptors
+                ) +
+                "}\n"
+            ),
             CGRegisterProxyHandlersMethod(descriptors),
         ], "\n")
 
@@ -7606,8 +7619,6 @@ class GlobalGenRoots():
                                for d in config.getDescriptors(hasInterfaceObject=True)
                                if d.shouldHaveGetConstructorObjectMethod()])
 
-        proxies = [d.name for d in config.getDescriptors(proxy=True)]
-
         return CGList([
             CGGeneric(AUTOGENERATED_WARNING_COMMENT),
             CGGeneric("pub const PROTO_OR_IFACE_LENGTH: usize = %d;\n" % (len(protos) + len(constructors))),
@@ -7624,7 +7635,6 @@ class GlobalGenRoots():
                       "    debug_assert!(proto_id < ID::Last as u16);\n"
                       "    INTERFACES[proto_id as usize]\n"
                       "}\n\n"),
-            CGNonNamespacedEnum('Proxies', proxies, 0, deriving="PartialEq, Copy, Clone"),
         ])
 
     @staticmethod
@@ -7636,8 +7646,6 @@ class GlobalGenRoots():
 
         return CGImports(code, descriptors=[], callbacks=[], dictionaries=[], enums=[], typedefs=[], imports=[
             'crate::dom::bindings::codegen::Bindings',
-            'crate::dom::bindings::codegen::PrototypeList::Proxies',
-            'libc',
         ], config=config, ignored_warnings=[])
 
     @staticmethod
diff --git a/components/script/dom/eventtarget.rs b/components/script/dom/eventtarget.rs
index b39bf977c5b..7018300b107 100644
--- a/components/script/dom/eventtarget.rs
+++ b/components/script/dom/eventtarget.rs
@@ -515,8 +515,8 @@ impl EventTarget {
         let name = CString::new(format!("on{}", &**ty)).unwrap();
 
         // Step 3.9, subsection ParameterList
-        static mut ARG_NAMES: [*const c_char; 1] = [b"event\0" as *const u8 as *const c_char];
-        static mut ERROR_ARG_NAMES: [*const c_char; 5] = [
+        const ARG_NAMES: &[*const c_char] = &[b"event\0" as *const u8 as *const c_char];
+        const ERROR_ARG_NAMES: &[*const c_char] = &[
             b"event\0" as *const u8 as *const c_char,
             b"source\0" as *const u8 as *const c_char,
             b"lineno\0" as *const u8 as *const c_char,
@@ -524,13 +524,7 @@ impl EventTarget {
             b"error\0" as *const u8 as *const c_char,
         ];
         let is_error = ty == &atom!("error") && self.is::<Window>();
-        let args = unsafe {
-            if is_error {
-                &ERROR_ARG_NAMES[..]
-            } else {
-                &ARG_NAMES[..]
-            }
-        };
+        let args = if is_error { ERROR_ARG_NAMES } else { ARG_NAMES };
 
         let cx = window.get_cx();
         let options = unsafe {