use std::{ borrow::BorrowMut, collections::{HashMap, HashSet}, ops::{Deref, DerefMut}, sync::Arc, }; use super::typecheck::type_inferencer::PrimitiveStore; use super::typecheck::typedef::{FunSignature, FuncArg, SharedUnifier, Type, TypeEnum, Unifier}; use crate::{ symbol_resolver::SymbolResolver, typecheck::{type_inferencer::CodeLocation, typedef::CallId}, }; use itertools::{izip, Itertools}; use parking_lot::RwLock; use rustpython_parser::ast::{self, Stmt}; #[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Copy)] pub struct DefinitionId(pub usize); mod type_annotation; use type_annotation::*; mod helper; #[derive(Clone)] pub struct FunInstance { pub body: Vec>>, pub calls: HashMap, pub subst: HashMap, pub unifier_id: usize, } pub enum TopLevelDef { Class { // name for error messages and symbols name: String, // object ID used for TypeEnum object_id: DefinitionId, /// type variables bounded to the class. /// the first field in the tuple is the var_id of the ///original typevar defined in the top level and returned /// by the symbol resolver type_vars: Vec<(u32, Type)>, // class fields fields: Vec<(String, Type)>, // class methods, pointing to the corresponding function definition. methods: Vec<(String, Type, DefinitionId)>, // ancestor classes, including itself. ancestors: Vec, // symbol resolver of the module defined the class, none if it is built-in type resolver: Option>>, }, Function { // prefix for symbol, should be unique globally, and not ending with numbers name: String, // function signature. signature: Type, // instantiated type variable IDs var_id: Vec, /// Function instance to symbol mapping /// Key: string representation of type variable values, sorted by variable ID in ascending /// order, including type variables associated with the class. /// Value: function symbol name. instance_to_symbol: HashMap, /// Function instances to annotated AST mapping /// Key: string representation of type variable values, sorted by variable ID in ascending /// order, including type variables associated with the class. Excluding rigid type /// variables. /// rigid type variables that would be substituted when the function is instantiated. instance_to_stmt: HashMap, // symbol resolver of the module defined the class resolver: Option>>, }, Initializer { class_id: DefinitionId, }, } pub struct TopLevelContext { pub definitions: Arc>>>>, pub unifiers: Arc>>, } pub struct TopLevelComposer { // list of top level definitions, same as top level context pub definition_ast_list: Vec<(Arc>, Option>)>, // start as a primitive unifier, will add more top_level defs inside pub unifier: Unifier, // primitive store pub primitives_ty: PrimitiveStore, // keyword list to prevent same custom def class name pub keyword_list: Vec, } impl Default for TopLevelComposer { fn default() -> Self { Self::new() } } impl TopLevelComposer { /// return a composer and things to make a "primitive" symbol resolver, so that the symbol /// resolver can later figure out primitive type definitions when passed a primitive type name // TODO: add list and tuples? pub fn new() -> Self { let primitives = Self::make_primitives(); let top_level_def_list = vec![ Arc::new(RwLock::new(Self::make_top_level_class_def(0, None, "int32"))), Arc::new(RwLock::new(Self::make_top_level_class_def(1, None, "int64"))), Arc::new(RwLock::new(Self::make_top_level_class_def(2, None, "float"))), Arc::new(RwLock::new(Self::make_top_level_class_def(3, None, "bool"))), Arc::new(RwLock::new(Self::make_top_level_class_def(4, None, "none"))), ]; let ast_list: Vec>> = vec![None, None, None, None, None]; TopLevelComposer { definition_ast_list: izip!(top_level_def_list, ast_list).collect_vec(), primitives_ty: primitives.0, unifier: primitives.1, // class_method_to_def_id: Default::default(), // to_be_analyzed_class: Default::default(), keyword_list: vec![ "Generic".into(), "virtual".into(), "list".into(), "tuple".into(), "int32".into(), "int64".into(), "float".into(), "bool".into(), "none".into(), "None".into(), ], } } pub fn make_top_level_context(self) -> TopLevelContext { TopLevelContext { definitions: RwLock::new( self.definition_ast_list.into_iter().map(|(x, ..)| x).collect::>(), ) .into(), // FIXME: all the big unifier or? unifiers: Default::default(), } } fn extract_def_list(&self) -> Vec>> { self.definition_ast_list.iter().map(|(def, ..)| def.clone()).collect_vec() } /// step 0, register, just remeber the names of top level classes/function /// and check duplicate class/method/function definition pub fn register_top_level( &mut self, ast: ast::Stmt<()>, resolver: Option>>, ) -> Result<(String, DefinitionId), String> { let mut defined_class_name: HashSet = HashSet::new(); let mut defined_class_method_name: HashSet = HashSet::new(); let mut defined_function_name: HashSet = HashSet::new(); match &ast.node { ast::StmtKind::ClassDef { name, body, .. } => { if self.keyword_list.contains(name) { return Err("cannot use keyword as a class name".into()); } if !defined_class_name.insert(name.clone()) { return Err("duplicate definition of class".into()); } let class_name = name.to_string(); let class_def_id = self.definition_ast_list.len(); // since later when registering class method, ast will still be used, // here push None temporarly, later will move the ast inside let mut class_def_ast = ( Arc::new(RwLock::new(Self::make_top_level_class_def( class_def_id, resolver.clone(), name.as_str(), ))), None, ); // parse class def body and register class methods into the def list. // module's symbol resolver would not know the name of the class methods, // thus cannot return their definition_id let mut class_method_name_def_ids: Vec<( // the simple method name without class name String, // in this top level def, method name is prefixed with the class name Arc>, DefinitionId, Type, )> = Vec::new(); // we do not push anything to the def list, so we keep track of the index // and then push in the correct order after the for loop let mut class_method_index_offset = 0; for b in body { if let ast::StmtKind::FunctionDef { name: method_name, .. } = &b.node { let global_class_method_name = Self::make_class_method_name(class_name.clone(), method_name); if !defined_class_method_name.insert(global_class_method_name.clone()) { return Err("duplicate class method definition".into()); } let method_def_id = self.definition_ast_list.len() + { // plus 1 here since we already have the class def class_method_index_offset += 1; class_method_index_offset }; // dummy method define here let dummy_method_type = self.unifier.get_fresh_var(); class_method_name_def_ids.push(( method_name.clone(), RwLock::new(Self::make_top_level_function_def( global_class_method_name, // later unify with parsed type dummy_method_type.0, resolver.clone(), )) .into(), DefinitionId(method_def_id), dummy_method_type.0, )); } else { // do nothing continue; } } // move the ast to the entry of the class in the ast_list class_def_ast.1 = Some(ast); // get the methods into the class_def for (name, _, id, ty) in &class_method_name_def_ids { let mut class_def = class_def_ast.0.write(); if let TopLevelDef::Class { methods, .. } = class_def.deref_mut() { methods.push((name.clone(), *ty, *id)) } else { unreachable!() } } // now class_def_ast and class_method_def_ast_ids are ok, put them into actual def list in correct order self.definition_ast_list.push(class_def_ast); for (_, def, ..) in class_method_name_def_ids { self.definition_ast_list.push((def, None)); } // put the constructor into the def_list self.definition_ast_list.push(( RwLock::new(TopLevelDef::Initializer { class_id: DefinitionId(class_def_id) }) .into(), None, )); Ok((class_name, DefinitionId(class_def_id))) } ast::StmtKind::FunctionDef { name, .. } => { let fun_name = name.to_string(); if !defined_function_name.insert(name.to_string()) { return Err("duplicate top level function define".into()); } // add to the definition list self.definition_ast_list.push(( RwLock::new(Self::make_top_level_function_def( name.into(), // unify with correct type later self.unifier.get_fresh_var().0, resolver, )) .into(), Some(ast), )); // return Ok((fun_name, DefinitionId(self.definition_ast_list.len() - 1))) } _ => Err("only registrations of top level classes/functions are supprted".into()), } } /// step 1, analyze the type vars associated with top level class /// note that we make a duplicate of the type var returned by symbol resolver /// since one top level type var may be used at multiple places fn analyze_top_level_class_type_var(&mut self) -> Result<(), String> { let def_list = &self.definition_ast_list; let temp_def_list = self.extract_def_list(); let unifier = self.unifier.borrow_mut(); let primitives_store = &self.primitives_ty; for (class_def, class_ast) in def_list { // only deal with class def here let mut class_def = class_def.write(); let (class_bases_ast, class_def_type_vars, class_resolver) = { if let TopLevelDef::Class { type_vars, resolver, .. } = class_def.deref_mut() { if let Some(ast::Located { node: ast::StmtKind::ClassDef { bases, .. }, .. }) = class_ast { (bases, type_vars, resolver) } else { unreachable!("must be both class") } } else { continue; } }; let class_resolver = class_resolver.as_ref().unwrap(); let class_resolver = class_resolver.deref(); let mut is_generic = false; for b in class_bases_ast { match &b.node { // analyze typevars bounded to the class, // only support things like `class A(Generic[T, V])`, // things like `class A(Generic[T, V, ImportedModule.T])` is not supported // i.e. only simple names are allowed in the subscript // should update the TopLevelDef::Class.typevars and the TypeEnum::TObj.params ast::ExprKind::Subscript { value, slice, .. } if { matches!( &value.node, ast::ExprKind::Name { id, .. } if id == "Generic" ) } => { if !is_generic { is_generic = true; } else { return Err("Only single Generic[...] can be in bases".into()); } let mut type_var_list: Vec<&ast::Expr<()>> = vec![]; // if `class A(Generic[T, V, G])` if let ast::ExprKind::Tuple { elts, .. } = &slice.node { type_var_list.extend(elts.iter()); // `class A(Generic[T])` } else { type_var_list.push(slice.deref()); } // parse the type vars let type_vars = type_var_list .into_iter() .map(|e| { class_resolver.parse_type_annotation( &temp_def_list, unifier, primitives_store, e, ) }) .collect::, _>>()?; // check if all are unique type vars let all_unique_type_var = { let mut occured_type_var_id: HashSet = HashSet::new(); type_vars.iter().all(|x| { let ty = unifier.get_ty(*x); if let TypeEnum::TVar { id, .. } = ty.as_ref() { occured_type_var_id.insert(*id) } else { false } }) }; if !all_unique_type_var { return Err("expect unique type variables".into()); } // NOTE: create a copy of all type vars for the type vars associated with class let type_vars = type_vars .into_iter() .map(|x| { // must be type var here after previous check let dup = duplicate_type_var(unifier, x); (dup.2, dup.0) }) .collect_vec(); // add to TopLevelDef class_def_type_vars.extend(type_vars); } // if others, do nothing in this function _ => continue, } } } Ok(()) } /// step 2, base classes. /// now that the type vars of all classes are done, handle base classes and /// put Self class into the ancestors list. We only allow single inheritance fn analyze_top_level_class_bases(&mut self) -> Result<(), String> { let temp_def_list = self.extract_def_list(); for (class_def, class_ast) in self.definition_ast_list.iter_mut() { let mut class_def = class_def.write(); let (class_bases, class_ancestors, class_resolver, class_id, class_type_vars) = { if let TopLevelDef::Class { ancestors, resolver, object_id, type_vars, .. } = class_def.deref_mut() { if let Some(ast::Located { node: ast::StmtKind::ClassDef { bases, .. }, .. }) = class_ast { (bases, ancestors, resolver, *object_id, type_vars) } else { unreachable!("must be both class") } } else { continue; } }; let class_resolver = class_resolver.as_ref().unwrap(); let class_resolver = class_resolver.deref(); // only allow single inheritance let mut has_base = false; for b in class_bases { // type vars have already been handled, so skip on `Generic[...]` if matches!( &b.node, ast::ExprKind::Subscript { value, .. } if matches!( &value.node, ast::ExprKind::Name { id, .. } if id == "Generic" ) ) { continue; } if has_base { return Err("a class def can only have at most one base class \ declaration and one generic declaration" .into()); } has_base = true; let base_ty = parse_ast_to_type_annotation_kinds( class_resolver, &temp_def_list, self.unifier.borrow_mut(), &self.primitives_ty, b, )?; if let TypeAnnotation::CustomClassKind { id, .. } = &base_ty { // check to prevent cyclic base class let all_base = Self::get_all_base(*id, &temp_def_list); if all_base.contains(&class_id) { return Err("cyclic base detected".into()); } // find the intersection of type vars occured // in the base class type parameter // and the type vars occured in the class generic declaration let type_var_occured_in_base = get_type_var_contained_in_type_annotation(&base_ty); for type_ann in type_var_occured_in_base { if let TypeAnnotation::TypeVarKind(id, ty) = type_ann { for (ty_id, class_typvar_ty) in class_type_vars.iter() { // if they refer to the same top level defined // type var, we unify them together if id == *ty_id { // assert to make sure assert!(matches!( self.unifier.get_ty(ty).as_ref(), TypeEnum::TVar { .. } )); self.unifier.unify(ty, *class_typvar_ty)?; } } } else { unreachable!("must be type var annotation") } } class_ancestors.push(base_ty); } else { return Err("class base declaration can only be custom class".into()); } } // push self to the ancestors class_ancestors.push(make_self_type_annotation( &temp_def_list, class_id, self.unifier.borrow_mut(), )?) } Ok(()) } /// step 3, class fields and methods fn analyze_top_level_class_fields_methods(&mut self) -> Result<(), String> { let temp_def_list = self.extract_def_list(); let unifier = self.unifier.borrow_mut(); let primitives = &self.primitives_ty; let def_ast_list = &self.definition_ast_list; let mut type_var_to_concrete_def: HashMap = HashMap::new(); for (class_def, class_ast) in def_ast_list { Self::analyze_single_class( class_def.clone(), &class_ast.as_ref().unwrap().node, &temp_def_list, unifier, primitives, &mut type_var_to_concrete_def, )? } // base class methods add and check // TODO: // unification of previously assigned typevar for (ty, def) in type_var_to_concrete_def { let target_ty = get_type_from_type_annotation_kinds(&temp_def_list, unifier, primitives, &def)?; unifier.unify(ty, target_ty)?; } Ok(()) } /// step 4, after class methods are done fn analyze_top_level_function(&mut self) -> Result<(), String> { let def_list = &self.definition_ast_list; let temp_def_list = self.extract_def_list(); let unifier = self.unifier.borrow_mut(); let primitives_store = &self.primitives_ty; for (function_def, function_ast) in def_list { let function_def = function_def.read(); let function_def = function_def.deref(); let function_ast = if let Some(function_ast) = function_ast { function_ast } else { // no ast, class method, continue continue; }; if let TopLevelDef::Function { signature: dummy_ty, resolver, .. } = function_def { if let ast::StmtKind::FunctionDef { args, returns, .. } = &function_ast.node { let resolver = resolver.as_ref(); let resolver = resolver.unwrap(); let resolver = resolver.deref(); // occured type vars should not be handled separately let mut occured_type_var: HashMap = HashMap::new(); let mut function_var_map: HashMap = HashMap::new(); let arg_types = { // make sure no duplicate parameter let mut defined_paramter_name: HashSet = HashSet::new(); let have_unique_fuction_parameter_name = args .args .iter() .all(|x| defined_paramter_name.insert(x.node.arg.clone())); if !have_unique_fuction_parameter_name { return Err("top level function have duplicate parameter name".into()); } args.args .iter() .map(|x| -> Result { let annotation = x .node .annotation .as_ref() .ok_or_else(|| { "function parameter type annotation needed".to_string() })? .as_ref(); let type_annotation = parse_ast_to_type_annotation_kinds( resolver, temp_def_list.as_slice(), unifier, primitives_store, annotation, )?; // if there are same type variables appears, we only need to copy them once let type_vars_within = get_type_var_contained_in_type_annotation(&type_annotation) .into_iter() .map(|x| { if let TypeAnnotation::TypeVarKind(id, ty) = x { // assert here to make sure the ty is TypeEnum::TVar assert!(matches!( unifier.get_ty(ty).as_ref(), TypeEnum::TVar { .. } )); (id, ty) } else { unreachable!("must be type var annotation kind") } }) .collect_vec(); for (top_level_var_id, ty) in type_vars_within { if let Some(occured_ty) = occured_type_var.get(&top_level_var_id) { // if already occured, we unify this two duplicated // type var of the same top level type var unifier.unify(ty, *occured_ty)?; } else { // if not, put it into the occured type var hashmap, // since parse_ast_to_type_var already duplicated it // we do not need to duplicate it again occured_type_var.insert(top_level_var_id, ty); // the type var map to it self if let TypeEnum::TVar { id: self_id, .. } = unifier.get_ty(ty).as_ref() { function_var_map.insert(*self_id, ty); } else { unreachable!("must be type var"); } } } // NOTE: get the actual ty after handling the type vars, really? why? let ty = get_type_from_type_annotation_kinds( temp_def_list.as_ref(), unifier, primitives_store, &type_annotation, )?; // TODO: default value? Ok(FuncArg { name: x.node.arg.clone(), ty, default_value: Default::default(), }) }) .collect::, _>>()? }; let return_ty_annotation = { let return_annotation = returns .as_ref() .ok_or_else(|| "function return type needed".to_string())? .as_ref(); parse_ast_to_type_annotation_kinds( resolver, &temp_def_list, unifier, primitives_store, return_annotation, )? }; let type_vars_within = get_type_var_contained_in_type_annotation(&return_ty_annotation) .into_iter() .map(|x| { if let TypeAnnotation::TypeVarKind(id, ty) = x { (id, ty) } else { unreachable!("must be type var here") } }) .collect_vec(); for (top_level_var_id, ty) in type_vars_within { if let Some(existing_ty) = occured_type_var.get(&top_level_var_id) { // should not return err here unifier.unify(ty, *existing_ty)?; } else { occured_type_var.insert(top_level_var_id, ty); } } // NOTE: get the actual ty after handling the type vars, really? why? let return_ty = get_type_from_type_annotation_kinds( &temp_def_list, unifier, primitives_store, &return_ty_annotation, )?; let function_ty = unifier.add_ty(TypeEnum::TFunc( FunSignature { args: arg_types, ret: return_ty, vars: function_var_map } .into(), )); unifier.unify(*dummy_ty, function_ty)?; } else { unreachable!("must be both function"); } } else { continue; } } Ok(()) } /// step 5, field instantiation? fn analyze_top_level_field_instantiation(&mut self) -> Result<(), String> { // TODO: unimplemented!() } fn analyze_single_class( class_def: Arc>, class_ast: &ast::StmtKind<()>, temp_def_list: &[Arc>], unifier: &mut Unifier, primitives: &PrimitiveStore, type_var_to_concrete_def: &mut HashMap, ) -> Result<(), String> { let mut class_def = class_def.write(); let ( class_id, _class_name, _class_bases_ast, class_body_ast, _class_ancestor_def, class_fields_def, class_methods_def, class_type_vars_def, class_resolver, ) = if let TopLevelDef::Class { object_id, ancestors, fields, methods, resolver, type_vars, .. } = class_def.deref_mut() { if let ast::StmtKind::ClassDef { name, bases, body, .. } = &class_ast { ( object_id, name.clone(), bases, body, ancestors, fields, methods, type_vars, resolver, ) } else { unreachable!("here must be class def ast"); } } else { unreachable!("here must be class def ast"); }; let class_resolver = class_resolver.as_ref().unwrap(); let class_resolver = class_resolver.as_ref(); for b in class_body_ast { if let ast::StmtKind::FunctionDef { args, returns, name, body, .. } = &b.node { let (method_dummy_ty, ..) = Self::get_class_method_def_info(class_methods_def, name)?; // handle var map, to create a new copy of type var // while tracking the type var associated with class // from the duplicated type var's var_id to themselves // include the class type vars like the type var context of the method let mut method_var_map: HashMap = class_type_vars_def .iter() .map(|(_, ty)| { if let TypeEnum::TVar { id, .. } = unifier.get_ty(*ty).as_ref() { (*id, *ty) } else { unreachable!("must be type var here") } }) .collect(); // from the def_id of top level type vars to duplicated type vars // also include the class type var like the type var context of the method let mut occured_type_vars: HashMap = class_type_vars_def.iter().map(|(id, ty)| (*id, *ty)).collect(); let arg_types: Vec = { // check method parameters cannot have same name let mut defined_paramter_name: HashSet = HashSet::new(); let have_unique_fuction_parameter_name = args.args.iter().all(|x| defined_paramter_name.insert(x.node.arg.clone())); if !have_unique_fuction_parameter_name { return Err("class method have duplicate parameter name".into()); } let mut result = Vec::new(); for x in &args.args { let name = x.node.arg.clone(); if name != "self" { let type_ann = { let annotation_expr = x .node .annotation .as_ref() .ok_or_else(|| "type annotation needed".to_string())? .as_ref(); parse_ast_to_type_annotation_kinds( class_resolver, temp_def_list, unifier, primitives, annotation_expr, )? }; // find type vars within this method parameter type annotation let type_vars_within = get_type_var_contained_in_type_annotation(&type_ann); // handle the class type var and the method type var for type_var_within in type_vars_within { if let TypeAnnotation::TypeVarKind(top_level_id, ty) = type_var_within { if let Some(duped_ty) = occured_type_vars.get(&top_level_id) { // if already occured, not matter if it is class typevar or method typevar, just unify unifier.unify(ty, *duped_ty)?; } else { // if not insert them to the occured_type_vars and the method_varmap // note that the content to insert is different occured_type_vars.insert(top_level_id, ty); method_var_map.insert( if let TypeEnum::TVar { id, .. } = unifier.get_ty(ty).as_ref() { *id } else { unreachable!("must be type var") }, ty, ); } } else { unreachable!("must be type var annotation"); } } // finish handling type vars let dummy_func_arg = FuncArg { name, ty: unifier.get_fresh_var().0, // TODO: symbol default value? default_value: None, }; // push the dummy type and the type annotation // into the list for later unification type_var_to_concrete_def.insert(dummy_func_arg.ty, type_ann.clone()); result.push(dummy_func_arg) } else { // if the parameter name is self // python does not seem to enforce the name // representing the self class object to be // `self`??, but we do it here let dummy_func_arg = FuncArg { name: "self".into(), ty: unifier.get_fresh_var().0, default_value: None, }; type_var_to_concrete_def.insert( dummy_func_arg.ty, make_self_type_annotation(temp_def_list, *class_id, unifier)?, ); result.push(dummy_func_arg); } } result }; let ret_type = { if name != "__init__" { let result = returns .as_ref() .ok_or_else(|| "method return type annotation needed".to_string())? .as_ref(); let annotation = parse_ast_to_type_annotation_kinds( class_resolver, temp_def_list, unifier, primitives, result, )?; // find type vars within this return type annotation let type_vars_within = get_type_var_contained_in_type_annotation(&annotation); // handle the class type var and the method type var for type_var_within in type_vars_within { if let TypeAnnotation::TypeVarKind(top_id, ty) = type_var_within { if let Some(duped_ty) = occured_type_vars.get(&top_id) { // if already occured, not matter if it is class typevar or method typevar, just unify unifier.unify(ty, *duped_ty)?; } else { // if not insert them to the occured_type_vars and the method_varmap // note that the content to insert is different occured_type_vars.insert(top_id, ty); method_var_map.insert( if let TypeEnum::TVar { id, .. } = unifier.get_ty(ty).as_ref() { *id } else { unreachable!("must be type var") }, ty, ); } } else { unreachable!("must be type var annotation"); } } let dummy_return_type = unifier.get_fresh_var().0; type_var_to_concrete_def.insert(dummy_return_type, annotation.clone()); dummy_return_type } else { // if is the "__init__" function, the return type is self let dummy_return_type = unifier.get_fresh_var().0; type_var_to_concrete_def.insert( dummy_return_type, make_self_type_annotation(temp_def_list, *class_id, unifier)?, ); dummy_return_type } }; let method_type = unifier.add_ty(TypeEnum::TFunc( FunSignature { args: arg_types, ret: ret_type, vars: method_var_map }.into(), )); // NOTE: unify now since function type is not in type annotation define // which is fine since type within method_type will be subst later unifier.unify(method_dummy_ty, method_type)?; // class fields if name == "__init__" { for b in body { let mut defined_fields: HashSet = HashSet::new(); // TODO: check the type of value, field instantiation check? if let ast::StmtKind::AnnAssign { annotation, target, value: _, .. } = &b.node { if let ast::ExprKind::Attribute { value, attr, .. } = &target.node { if matches!(&value.node, ast::ExprKind::Name { id, .. } if id == "self") { if defined_fields.insert(attr.to_string()) { let dummy_field_type = unifier.get_fresh_var().0; class_fields_def.push((attr.to_string(), dummy_field_type)); let annotation = parse_ast_to_type_annotation_kinds( class_resolver, &temp_def_list, unifier, primitives, annotation.as_ref(), )?; // find type vars within this return type annotation let type_vars_within = get_type_var_contained_in_type_annotation(&annotation); // handle the class type var and the method type var for type_var_within in type_vars_within { if let TypeAnnotation::TypeVarKind(top_level_id, ty) = type_var_within { if let Some(duped_ty) = occured_type_vars.get(&top_level_id) { // if already occured, not matter if it is class typevar or method typevar, just unify unifier.unify(ty, *duped_ty)?; } else { return Err("this type var is not available inside this function".into()); } } else { unreachable!("must be type var annotation"); } } type_var_to_concrete_def .insert(dummy_field_type, annotation); } else { return Err("same class fields defined twice".into()); } } } } } } } else { continue; } } Ok(()) } }