refactor: Separate trait parsing & structuring from QObject (#1052)

* refactor: Separate trait parsing from QObject

Move the association between QObject and trait into the structuring
phase.
This should be one of the last things left in the structuring refactor.

Fix #938

* Remove pre-processing of QObjects during parsing.

Now that we've moved everything into the structuring phase, this is no
longer necessary and simplifies parsing a lot.

* Change qobjects to be a Vec instead of BTreeMap, including writing a quick lookup function

---------

Co-authored-by: Ben Ford <ben.ford@kdab.com>

crates/cxx-qt-gen/src/generator/cpp/constructor.rs

@@ -81,7 +81,7 @@ fn expand_arguments(arguments: &[Type], type_names: &TypeNames) -> Result<String
 
 pub fn generate(
     qobject: &GeneratedCppQObject,
-    constructors: &[Constructor],
+    constructors: &[&Constructor],
     base_class: String,
     class_initializers: &[String],
     type_names: &TypeNames,
@@ -287,7 +287,7 @@ mod tests {
     fn constructor_without_base_arguments() {
         let blocks = generate(
             &qobject_for_testing(),
-            &[Constructor {
+            &[&Constructor {
                 arguments: vec![parse_quote! { i32 }, parse_quote! { *mut QObject }],
                 ..mock_constructor()
             }],
@@ -333,7 +333,7 @@ mod tests {
     fn constructor_with_all_arguments() {
         let blocks = generate(
             &qobject_for_testing(),
-            &[Constructor {
+            &[&Constructor {
                 arguments: vec![parse_quote! { i8 }, parse_quote! { i16 }],
                 new_arguments: vec![parse_quote! { i16}, parse_quote! { i32 }],
                 initialize_arguments: vec![parse_quote! { i32 }, parse_quote! { i64 }],
@@ -385,11 +385,11 @@ mod tests {
         let blocks = generate(
             &qobject_for_testing(),
             &[
-                Constructor {
+                &Constructor {
                     arguments: vec![],
                     ..mock_constructor()
                 },
-                Constructor {
+                &Constructor {
                     arguments: vec![parse_quote! { *mut QObject }],
                     base_arguments: vec![parse_quote! { *mut QObject }],
                     ..mock_constructor()

crates/cxx-qt-gen/src/generator/cpp/qobject.rs

@@ -172,23 +172,23 @@ impl GeneratedCppQObject {
         // If this type has threading enabled then add generation
         //
         // Note that threading also includes locking C++ generation
-        if qobject.threading {
+        if structured_qobject.threading {
             // The parser phase should check that this is true
-            debug_assert!(qobject.locking);
+            debug_assert!(structured_qobject.locking);
 
             let (initializer, mut blocks) = threading::generate(&qobject_idents)?;
             generated.blocks.append(&mut blocks);
             class_initializers.push(initializer);
             // If this type has locking enabled then add generation
-        } else if qobject.locking {
+        } else if structured_qobject.locking {
             let (initializer, mut blocks) = locking::generate()?;
             generated.blocks.append(&mut blocks);
             class_initializers.push(initializer);
         }
 
         generated.blocks.append(&mut constructor::generate(
             &generated,
-            &qobject.constructors,
+            &structured_qobject.constructors,
             base_class,
             &class_initializers,
             type_names,

crates/cxx-qt-gen/src/generator/rust/constructor.rs

@@ -179,7 +179,7 @@ fn unsafe_if(condition: bool) -> Option<TokenStream> {
 }
 
 pub fn generate(
-    constructors: &[Constructor],
+    constructors: &[&Constructor],
     qobject_idents: &QObjectNames,
     namespace: &NamespaceName,
     type_names: &TypeNames,
@@ -463,7 +463,7 @@ mod tests {
         NamespaceName::from_namespace_and_ident("qobject", &format_ident!("MyObject"))
     }
 
-    fn generate_mocked(constructors: &[Constructor]) -> GeneratedRustFragment {
+    fn generate_mocked(constructors: &[&Constructor]) -> GeneratedRustFragment {
         let mut type_names = TypeNames::mock();
 
         type_names.mock_insert("QString", None, None, None);
@@ -768,8 +768,8 @@ mod tests {
     #[test]
     fn multiple_constructors() {
         let blocks = generate_mocked(&[
-            mock_constructor(),
-            Constructor {
+            &mock_constructor(),
+            &Constructor {
                 arguments: vec![parse_quote! { *const QObject }],
                 new_arguments: vec![parse_quote! { i16 }],
                 initialize_arguments: vec![
@@ -801,7 +801,7 @@ mod tests {
     #[test]
     fn constructor_impl_with_unused_lifetime() {
         let result = super::generate(
-            &[Constructor {
+            &[&Constructor {
                 lifetime: Some(parse_quote! { 'a }),
                 ..mock_constructor()
             }],

crates/cxx-qt-gen/src/generator/rust/qobject.rs

@@ -81,7 +81,7 @@ impl GeneratedRustFragment {
         }
 
         // If this type has threading enabled then add generation
-        if qobject.threading {
+        if structured_qobject.threading {
             generated.append(&mut threading::generate(
                 &qobject_idents,
                 &namespace_idents,
@@ -94,7 +94,7 @@ impl GeneratedRustFragment {
         //
         // This could be implemented using an auto trait in the future once stable
         // https://doc.rust-lang.org/beta/unstable-book/language-features/auto-traits.html
-        if qobject.locking {
+        if structured_qobject.locking {
             let qualified_impl =
                 type_names.rust_qualified(qobject_idents.name.rust_unqualified())?;
             generated.cxx_qt_mod_contents.push(syn::parse_quote! {
@@ -103,7 +103,7 @@ impl GeneratedRustFragment {
         }
 
         generated.append(&mut constructor::generate(
-            &qobject.constructors,
+            &structured_qobject.constructors,
             &qobject_idents,
             &namespace_idents,
             type_names,