Make postprocessing more robust

This is done by merging extern blocks and sorting items in every module
instead of just in the root module.

The tests were changed to use `cxx` namespaces so they effectively check
that items are manipulated correctly in every single module.

1 files changed, 36 insertions, 22 deletions

diff --git a/bindgen/codegen/postprocessing/sort_semantically.rs b/bindgen/codegen/postprocessing/sort_semantically.rs
index 96596cb0..4f23ab73 100644
--- a/bindgen/codegen/postprocessing/sort_semantically.rs
+++ b/bindgen/codegen/postprocessing/sort_semantically.rs
@@ -1,24 +1,38 @@
-use syn::Item;
+use syn::{
+    visit_mut::{visit_item_mod_mut, VisitMut},
+    Item, ItemMod,
+};
 
-pub(super) fn sort_semantically(items: &mut [Item]) {
-    items.sort_by_key(|item| match item {
-        Item::Type(_) => 0,
-        Item::Struct(_) => 1,
-        Item::Const(_) => 2,
-        Item::Fn(_) => 3,
-        Item::Enum(_) => 4,
-        Item::Union(_) => 5,
-        Item::Static(_) => 6,
-        Item::Trait(_) => 7,
-        Item::TraitAlias(_) => 8,
-        Item::Impl(_) => 9,
-        Item::Mod(_) => 10,
-        Item::Use(_) => 11,
-        Item::Verbatim(_) => 12,
-        Item::ExternCrate(_) => 13,
-        Item::ForeignMod(_) => 14,
-        Item::Macro(_) => 15,
-        Item::Macro2(_) => 16,
-        _ => 18,
-    });
+pub(super) fn sort_semantically(item_mod: &mut ItemMod) {
+    Visitor.visit_item_mod_mut(item_mod)
+}
+
+struct Visitor;
+
+impl VisitMut for Visitor {
+    fn visit_item_mod_mut(&mut self, item_mod: &mut ItemMod) {
+        if let Some((_, ref mut items)) = item_mod.content {
+            items.sort_by_key(|item| match item {
+                Item::Type(_) => 0,
+                Item::Struct(_) => 1,
+                Item::Const(_) => 2,
+                Item::Fn(_) => 3,
+                Item::Enum(_) => 4,
+                Item::Union(_) => 5,
+                Item::Static(_) => 6,
+                Item::Trait(_) => 7,
+                Item::TraitAlias(_) => 8,
+                Item::Impl(_) => 9,
+                Item::Mod(_) => 10,
+                Item::Use(_) => 11,
+                Item::Verbatim(_) => 12,
+                Item::ExternCrate(_) => 13,
+                Item::ForeignMod(_) => 14,
+                Item::Macro(_) => 15,
+                Item::Macro2(_) => 16,
+                _ => 18,
+            });
+        }
+        visit_item_mod_mut(self, item_mod)
+    }
 }