Fix a panic in Stylo memory reporting.

`MallocSizeOfOps::enclosing_size_of_op` is an `Option<>` type, and the panic in
question is caused by not providing a value in a case where it's needed for
measuring a HashSet.

HashMaps and HashSets are common enough that it makes sense to make
`enclosing_size_of_op` non-optional, which this patch does.

components/malloc_size_of/lib.rs

@@ -82,9 +82,8 @@ pub struct MallocSizeOfOps {
     /// A function that returns the size of a heap allocation.
     size_of_op: VoidPtrToSizeFn,
 
-    /// Like `size_of_op`, but can take an interior pointer. Optional, because
-    /// many places don't need it.
-    enclosing_size_of_op: Option<VoidPtrToSizeFn>,
+    /// Like `size_of_op`, but can take an interior pointer.
+    enclosing_size_of_op: VoidPtrToSizeFn,
 
     /// Check if a pointer has been seen before, and remember it for next time.
     /// Useful when measuring `Rc`s and `Arc`s. Optional, because many places
@@ -93,8 +92,7 @@ pub struct MallocSizeOfOps {
 }
 
 impl MallocSizeOfOps {
-    pub fn new(size_of: VoidPtrToSizeFn,
-               malloc_enclosing_size_of: Option<VoidPtrToSizeFn>,
+    pub fn new(size_of: VoidPtrToSizeFn, malloc_enclosing_size_of: VoidPtrToSizeFn,
                have_seen_ptr: Option<Box<VoidPtrToBoolFnMut>>) -> Self {
         MallocSizeOfOps {
             size_of_op: size_of,
@@ -129,8 +127,7 @@ impl MallocSizeOfOps {
     /// Call `enclosing_size_of_op` on `ptr`, which must not be empty.
     pub unsafe fn malloc_enclosing_size_of<T>(&self, ptr: *const T) -> usize {
         assert!(!MallocSizeOfOps::is_empty(ptr));
-        let enclosing_size_of_op = self.enclosing_size_of_op.expect("missing enclosing_size_of_op");
-        enclosing_size_of_op(ptr as *const c_void)
+        (self.enclosing_size_of_op)(ptr as *const c_void)
     }
 
     /// Call `have_seen_ptr_op` on `ptr`.

components/style/gecko/generated/bindings.rs

@@ -1898,7 +1898,10 @@ extern "C" {
     pub fn Servo_Element_ClearData(node: RawGeckoElementBorrowed);
 }
 extern "C" {
-    pub fn Servo_Element_SizeOfExcludingThisAndCVs(arg1: MallocSizeOf,
+    pub fn Servo_Element_SizeOfExcludingThisAndCVs(malloc_size_of:
+                                                       MallocSizeOf,
+                                                   malloc_enclosing_size_of:
+                                                       MallocSizeOf,
                                                    seen_ptrs: *mut SeenPtrs,
                                                    node:
                                                        RawGeckoElementBorrowed)
@@ -1964,6 +1967,8 @@ extern "C" {
 }
 extern "C" {
     pub fn Servo_StyleSheet_SizeOfIncludingThis(malloc_size_of: MallocSizeOf,
+                                                malloc_enclosing_size_of:
+                                                    MallocSizeOf,
                                                 sheet:
                                                     RawServoStyleSheetContentsBorrowed)
      -> usize;

ports/geckolib/glue.rs

@@ -783,13 +783,16 @@ pub extern "C" fn Servo_Element_ClearData(element: RawGeckoElementBorrowed) {
 
 #[no_mangle]
 pub extern "C" fn Servo_Element_SizeOfExcludingThisAndCVs(malloc_size_of: GeckoMallocSizeOf,
+                                                          malloc_enclosing_size_of:
+                                                              GeckoMallocSizeOf,
                                                           seen_ptrs: *mut SeenPtrs,
                                                           element: RawGeckoElementBorrowed) -> usize {
     let element = GeckoElement(element);
     let borrow = element.borrow_data();
     if let Some(data) = borrow {
         let have_seen_ptr = move |ptr| { unsafe { Gecko_HaveSeenPtr(seen_ptrs, ptr) } };
-        let mut ops = MallocSizeOfOps::new(malloc_size_of.unwrap(), None,
+        let mut ops = MallocSizeOfOps::new(malloc_size_of.unwrap(),
+                                           malloc_enclosing_size_of.unwrap(),
                                            Some(Box::new(have_seen_ptr)));
         (*data).size_of_excluding_cvs(&mut ops)
     } else {
@@ -1089,11 +1092,14 @@ pub extern "C" fn Servo_StyleSheet_Clone(
 #[no_mangle]
 pub extern "C" fn Servo_StyleSheet_SizeOfIncludingThis(
     malloc_size_of: GeckoMallocSizeOf,
+    malloc_enclosing_size_of: GeckoMallocSizeOf,
     sheet: RawServoStyleSheetContentsBorrowed
 ) -> usize {
     let global_style_data = &*GLOBAL_STYLE_DATA;
     let guard = global_style_data.shared_lock.read();
-    let mut ops = MallocSizeOfOps::new(malloc_size_of.unwrap(), None, None);
+    let mut ops = MallocSizeOfOps::new(malloc_size_of.unwrap(),
+                                       malloc_enclosing_size_of.unwrap(),
+                                       None);
     StylesheetContents::as_arc(&sheet).size_of(&guard, &mut ops)
 }
 
@@ -3753,7 +3759,8 @@ pub extern "C" fn Servo_StyleSet_AddSizeOfExcludingThis(
 ) {
     let data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
     let mut ops = MallocSizeOfOps::new(malloc_size_of.unwrap(),
-                                       malloc_enclosing_size_of, None);
+                                       malloc_enclosing_size_of.unwrap(),
+                                       None);
     let sizes = unsafe { sizes.as_mut() }.unwrap();
     data.add_size_of_children(&mut ops, sizes);
 }