Resolve fully-qualified associated types

In the parsing stage, the functionality of the syn::Impl parsing is extended to keep track of associated type implementations in trait Impls.

This info is kept in a hash-map, where the key is a combination of (self type, trait name, associated type name) and the value is the concrete type itself.

In the library/transformation stage, this populated hashmap is then referenced to resolve associated types found.

src/bindgen/builder.rs

@@ -394,6 +394,20 @@ impl Builder {
 
         result.source_files.extend_from_slice(self.srcs.as_slice());
 
+        let assoc_types = result
+            .assoc_types
+            .into_iter()
+            .filter_map(
+                |(id, (ty_, count))| {
+                    if count == 0 {
+                        Some((id, ty_))
+                    } else {
+                        None
+                    }
+                },
+            )
+            .collect();
+
         Library::new(
             self.config,
             result.constants,
@@ -405,6 +419,7 @@ impl Builder {
             result.typedefs,
             result.functions,
             result.source_files,
+            assoc_types,
         )
         .generate()
     }

src/bindgen/ir/constant.rs

@@ -13,8 +13,8 @@ use crate::bindgen::config::{Config, Language};
 use crate::bindgen::declarationtyperesolver::DeclarationTypeResolver;
 use crate::bindgen::dependencies::Dependencies;
 use crate::bindgen::ir::{
-    AnnotationSet, Cfg, ConditionWrite, Documentation, GenericParams, Item, ItemContainer, Path,
-    Struct, ToCondition, Type,
+    AnnotationSet, AssocTypeResolver, Cfg, ConditionWrite, Documentation, GenericParams, Item,
+    ItemContainer, Path, Struct, ToCondition, Type,
 };
 use crate::bindgen::library::Library;
 use crate::bindgen::writer::{Source, SourceWriter};
@@ -237,6 +237,31 @@ impl Literal {
         });
         uses_only_primitive_types
     }
+
+    pub fn resolve_assoc_types(&mut self, resolver: &AssocTypeResolver) {
+        match self {
+            Literal::PostfixUnaryOp { value, .. } => {
+                value.resolve_assoc_types(resolver);
+            }
+            Literal::BinOp { left, right, .. } => {
+                left.resolve_assoc_types(resolver);
+                right.resolve_assoc_types(resolver);
+            }
+            Literal::FieldAccess { base, .. } => {
+                base.resolve_assoc_types(resolver);
+            }
+            Literal::Struct { fields, .. } => {
+                for (_, literal) in fields {
+                    literal.resolve_assoc_types(resolver);
+                }
+            }
+            Literal::Cast { ty, value } => {
+                value.resolve_assoc_types(resolver);
+                ty.resolve_assoc_types(resolver);
+            }
+            _ => {}
+        }
+    }
 }
 
 impl Literal {
@@ -689,6 +714,11 @@ impl Item for Constant {
     fn resolve_declaration_types(&mut self, resolver: &DeclarationTypeResolver) {
         self.ty.resolve_declaration_types(resolver);
     }
+
+    fn resolve_assoc_types(&mut self, resolver: &AssocTypeResolver) {
+        self.ty.resolve_assoc_types(resolver);
+        self.value.resolve_assoc_types(resolver);
+    }
 }
 
 impl Constant {

src/bindgen/ir/enumeration.rs

@@ -10,9 +10,9 @@ use crate::bindgen::config::{Config, Language};
 use crate::bindgen::declarationtyperesolver::DeclarationTypeResolver;
 use crate::bindgen::dependencies::Dependencies;
 use crate::bindgen::ir::{
-    AnnotationSet, AnnotationValue, Cfg, ConditionWrite, DeprecatedNoteKind, Documentation, Field,
-    GenericArgument, GenericParams, GenericPath, Item, ItemContainer, Literal, Path, Repr,
-    ReprStyle, Struct, ToCondition, Type,
+    AnnotationSet, AnnotationValue, AssocTypeResolver, Cfg, ConditionWrite, DeprecatedNoteKind,
+    Documentation, Field, GenericArgument, GenericParams, GenericPath, Item, ItemContainer,
+    Literal, Path, Repr, ReprStyle, Struct, ToCondition, Type,
 };
 use crate::bindgen::library::Library;
 use crate::bindgen::mangle;
@@ -652,6 +652,19 @@ impl Item for Enum {
             variant.add_dependencies(library, out);
         }
     }
+
+    fn resolve_assoc_types(&mut self, resolver: &AssocTypeResolver) {
+        for variant in self.variants.iter_mut() {
+            if let Some(literal) = variant.discriminant.as_mut() {
+                literal.resolve_assoc_types(resolver);
+            }
+            if let VariantBody::Body { body, .. } = &mut variant.body {
+                body.resolve_assoc_types(resolver);
+            }
+        }
+
+        self.generic_params.resolve_assoc_types(resolver);
+    }
 }
 
 impl Source for Enum {

src/bindgen/ir/function.rs

@@ -12,8 +12,8 @@ use crate::bindgen::config::{Config, Language, Layout};
 use crate::bindgen::declarationtyperesolver::DeclarationTypeResolver;
 use crate::bindgen::dependencies::Dependencies;
 use crate::bindgen::ir::{
-    AnnotationSet, Cfg, ConditionWrite, DeprecatedNoteKind, Documentation, GenericPath, Path,
-    ToCondition, Type,
+    AnnotationSet, AssocTypeResolver, Cfg, ConditionWrite, DeprecatedNoteKind, Documentation,
+    GenericPath, Path, ToCondition, Type,
 };
 use crate::bindgen::library::Library;
 use crate::bindgen::monomorph::Monomorphs;
@@ -218,6 +218,14 @@ impl Function {
             }
         }
     }
+
+    pub fn resolve_assoc_types(&mut self, resolver: &AssocTypeResolver) {
+        self.ret.resolve_assoc_types(resolver);
+
+        for arg in self.args.iter_mut() {
+            arg.ty.resolve_assoc_types(resolver);
+        }
+    }
 }
 
 impl Source for Function {

src/bindgen/ir/generic_path.rs

@@ -6,10 +6,42 @@ use syn::ext::IdentExt;
 use crate::bindgen::cdecl;
 use crate::bindgen::config::{Config, Language};
 use crate::bindgen::declarationtyperesolver::{DeclarationType, DeclarationTypeResolver};
-use crate::bindgen::ir::{ConstExpr, Path, Type};
+use crate::bindgen::ir::{AssocTypeResolver, ConstExpr, Path, Type};
 use crate::bindgen::utilities::IterHelpers;
 use crate::bindgen::writer::{Source, SourceWriter};
 
+// Struct that serves as key for resolving associated types
+#[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
+pub struct AssocTypeId {
+    pub ty: Box<Type>,
+    pub trait_: Path,
+    pub ident: Path,
+}
+
+impl AssocTypeId {
+    pub fn load(path: &syn::Path, qself: &syn::QSelf) -> Result<Self, String> {
+        let self_type = &qself.ty;
+
+        let ir_type_opt = Type::load(&self_type)?;
+        let ir_type = ir_type_opt.ok_or(String::from("Valid but empty type"))?;
+
+        let path_len = path.segments.len();
+        // Theoretically not possible if qself is present
+        if path_len < 2 {
+            return Err(String::from("Trait not found in type"));
+        }
+
+        let ident = path.segments.last().unwrap().ident.to_string();
+        let trait_ident = path.segments[path_len - 2].ident.to_string();
+
+        Ok(AssocTypeId {
+            ty: Box::new(ir_type),
+            trait_: Path::new(trait_ident),
+            ident: Path::new(ident),
+        })
+    }
+}
+
 #[derive(Debug, Clone)]
 pub enum GenericParamType {
     Type,
@@ -129,6 +161,14 @@ impl GenericParams {
     pub fn write_with_default<F: Write>(&self, config: &Config, out: &mut SourceWriter<F>) {
         self.write_internal(config, out, true);
     }
+
+    pub fn resolve_assoc_types(&mut self, resolver: &AssocTypeResolver) {
+        for generic_param in self.0.iter_mut() {
+            if let GenericParamType::Const(ty_) = &mut generic_param.ty {
+                ty_.resolve_assoc_types(resolver);
+            }
+        }
+    }
 }
 
 impl Deref for GenericParams {
@@ -200,6 +240,7 @@ pub struct GenericPath {
     export_name: String,
     generics: Vec<GenericArgument>,
     ctype: Option<DeclarationType>,
+    assoc: Option<AssocTypeId>,
 }
 
 impl GenericPath {
@@ -210,6 +251,7 @@ impl GenericPath {
             export_name,
             generics,
             ctype: None,
+            assoc: None,
         }
     }
 
@@ -248,6 +290,10 @@ impl GenericPath {
         &self.export_name
     }
 
+    pub fn assoc(&self) -> Option<&AssocTypeId> {
+        self.assoc.as_ref()
+    }
+
     pub fn is_single_identifier(&self) -> bool {
         self.generics.is_empty()
     }
@@ -265,7 +311,7 @@ impl GenericPath {
         self.ctype = resolver.type_for(&self.path);
     }
 
-    pub fn load(path: &syn::Path) -> Result<Self, String> {
+    pub fn load(path: &syn::Path, qself: Option<&syn::QSelf>) -> Result<Self, String> {
         assert!(
             !path.segments.is_empty(),
             "{:?} doesn't have any segments",
@@ -274,6 +320,10 @@ impl GenericPath {
         let last_segment = path.segments.last().unwrap();
         let name = last_segment.ident.unraw().to_string();
 
+        let assoc = qself
+            .map(|qself| AssocTypeId::load(path, qself))
+            .transpose()?;
+
         let path = Path::new(name);
         let phantom_data_path = Path::new("PhantomData");
         if path == phantom_data_path {
@@ -298,6 +348,9 @@ impl GenericPath {
             _ => Vec::new(),
         };
 
-        Ok(Self::new(path, generics))
+        let mut ret = Self::new(path, generics);
+        ret.assoc = assoc;
+
+        Ok(ret)
     }
 }

src/bindgen/ir/global.rs

@@ -8,7 +8,9 @@ use crate::bindgen::cdecl;
 use crate::bindgen::config::Config;
 use crate::bindgen::declarationtyperesolver::DeclarationTypeResolver;
 use crate::bindgen::dependencies::Dependencies;
-use crate::bindgen::ir::{AnnotationSet, Cfg, Documentation, Item, ItemContainer, Path, Type};
+use crate::bindgen::ir::{
+    AnnotationSet, AssocTypeResolver, Cfg, Documentation, Item, ItemContainer, Path, Type,
+};
 use crate::bindgen::library::Library;
 use crate::bindgen::writer::{Source, SourceWriter};
 
@@ -106,6 +108,10 @@ impl Item for Static {
     fn add_dependencies(&self, library: &Library, out: &mut Dependencies) {
         self.ty.add_dependencies(library, out);
     }
+
+    fn resolve_assoc_types(&mut self, resolver: &AssocTypeResolver) {
+        self.ty.resolve_assoc_types(resolver);
+    }
 }
 
 impl Source for Static {

src/bindgen/ir/item.rs

@@ -9,8 +9,8 @@ use crate::bindgen::config::Config;
 use crate::bindgen::declarationtyperesolver::DeclarationTypeResolver;
 use crate::bindgen::dependencies::Dependencies;
 use crate::bindgen::ir::{
-    AnnotationSet, Cfg, Constant, Enum, GenericArgument, OpaqueItem, Path, Static, Struct, Typedef,
-    Union,
+    AnnotationSet, AssocTypeResolver, Cfg, Constant, Enum, GenericArgument, OpaqueItem, Path,
+    Static, Struct, Typedef, Union,
 };
 use crate::bindgen::library::Library;
 use crate::bindgen::monomorph::Monomorphs;
@@ -46,6 +46,7 @@ pub trait Item {
     ) {
         unreachable!("Cannot instantiate {} as a generic.", self.name())
     }
+    fn resolve_assoc_types(&mut self, resolver: &AssocTypeResolver);
 }
 
 #[derive(Debug, Clone)]

src/bindgen/ir/opaque.rs

@@ -8,8 +8,8 @@ use crate::bindgen::config::{Config, Language};
 use crate::bindgen::declarationtyperesolver::DeclarationTypeResolver;
 use crate::bindgen::dependencies::Dependencies;
 use crate::bindgen::ir::{
-    AnnotationSet, Cfg, ConditionWrite, Documentation, GenericArgument, GenericParams, Item,
-    ItemContainer, Path, ToCondition,
+    AnnotationSet, AssocTypeResolver, Cfg, ConditionWrite, Documentation, GenericArgument,
+    GenericParams, Item, ItemContainer, Path, ToCondition,
 };
 use crate::bindgen::library::Library;
 use crate::bindgen::mangle;
@@ -135,6 +135,10 @@ impl Item for OpaqueItem {
 
         out.insert_opaque(self, monomorph, generic_values.to_owned());
     }
+
+    fn resolve_assoc_types(&mut self, resolver: &AssocTypeResolver) {
+        self.generic_params.resolve_assoc_types(resolver);
+    }
 }
 
 impl Source for OpaqueItem {

src/bindgen/ir/structure.rs

@@ -10,9 +10,9 @@ use crate::bindgen::config::{Config, Language, LayoutConfig};
 use crate::bindgen::declarationtyperesolver::DeclarationTypeResolver;
 use crate::bindgen::dependencies::Dependencies;
 use crate::bindgen::ir::{
-    AnnotationSet, Cfg, ConditionWrite, Constant, DeprecatedNoteKind, Documentation, Field,
-    GenericArgument, GenericParams, Item, ItemContainer, Path, Repr, ReprAlign, ReprStyle,
-    ToCondition, Type, Typedef,
+    AnnotationSet, AssocTypeResolver, Cfg, ConditionWrite, Constant, DeprecatedNoteKind,
+    Documentation, Field, GenericArgument, GenericParams, Item, ItemContainer, Path, Repr,
+    ReprAlign, ReprStyle, ToCondition, Type, Typedef,
 };
 use crate::bindgen::library::Library;
 use crate::bindgen::mangle;
@@ -374,6 +374,16 @@ impl Item for Struct {
         let monomorph = self.specialize(generic_values, &mappings, library.get_config());
         out.insert_struct(library, self, monomorph, generic_values.to_owned());
     }
+
+    fn resolve_assoc_types(&mut self, resolver: &AssocTypeResolver) {
+        self.generic_params.resolve_assoc_types(resolver);
+        for field in self.fields.iter_mut() {
+            field.ty.resolve_assoc_types(resolver);
+        }
+        for const_ in self.associated_constants.iter_mut() {
+            const_.resolve_assoc_types(resolver);
+        }
+    }
 }
 
 impl Source for Struct {