modelize: simplify special-case for named constrcutors

[nit.git] / src / modelize / modelize_property.nit

# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Copyright 2012 Jean Privat <jean@pryen.org>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Analysis and verification of property definitions to instantiate model element
module modelize_property

import modelize_class
private import annotation

redef class ToolContext
        var modelize_property_phase: Phase = new ModelizePropertyPhase(self, [modelize_class_phase])
end

private class ModelizePropertyPhase
        super Phase
        redef fun process_nmodule(nmodule)
        do
                for nclassdef in nmodule.n_classdefs do
                        if nclassdef.all_defs == null then continue # skip non principal classdef
                        toolcontext.modelbuilder.build_properties(nclassdef)
                end
        end
end

redef class ModelBuilder
        # Register the npropdef associated to each mpropdef
        # FIXME: why not refine the `MPropDef` class with a nullable attribute?
        var mpropdef2npropdef: HashMap[MPropDef, APropdef] = new HashMap[MPropDef, APropdef]

        # Build the properties of `nclassdef`.
        # REQUIRE: all superclasses are built.
        private fun build_properties(nclassdef: AClassdef)
        do
                # Force building recursively
                if nclassdef.build_properties_is_done then return
                nclassdef.build_properties_is_done = true
                var mclassdef = nclassdef.mclassdef.as(not null)
                if mclassdef.in_hierarchy == null then return # Skip error
                for superclassdef in mclassdef.in_hierarchy.direct_greaters do
                        if not mclassdef2nclassdef.has_key(superclassdef) then continue
                        build_properties(mclassdef2nclassdef[superclassdef])
                end

                for nclassdef2 in nclassdef.all_defs do
                        for npropdef in nclassdef2.n_propdefs do
                                npropdef.build_property(self, mclassdef)
                        end
                        for npropdef in nclassdef2.n_propdefs do
                                npropdef.build_signature(self)
                        end
                        for npropdef in nclassdef2.n_propdefs do
                                npropdef.check_signature(self)
                        end
                end
                process_default_constructors(nclassdef)
        end

        # the root init of the Object class
        # Is usually implicitly defined
        # Then explicit or implicit definitions of root-init are attached to it
        var the_root_init_mmethod: nullable MMethod

        # Introduce or inherit default constructor
        # This is the last part of `build_properties`.
        private fun process_default_constructors(nclassdef: AClassdef)
        do
                var mclassdef = nclassdef.mclassdef.as(not null)

                # Are we a refinement
                if not mclassdef.is_intro then return

                # Look for the init in Object, or create it
                if mclassdef.mclass.name == "Object" and the_root_init_mmethod == null then
                        # Create the implicit root-init method
                        var mprop = new MMethod(mclassdef, "init", mclassdef.mclass.visibility)
                        mprop.is_root_init = true
                        var mpropdef = new MMethodDef(mclassdef, mprop, nclassdef.location)
                        var mparameters = new Array[MParameter]
                        var msignature = new MSignature(mparameters, null)
                        mpropdef.msignature = msignature
                        mpropdef.new_msignature = msignature
                        mprop.is_init = true
                        nclassdef.mfree_init = mpropdef
                        self.toolcontext.info("{mclassdef} gets a free empty constructor {mpropdef}{msignature}", 3)
                        the_root_init_mmethod = mprop
                        return
                end

                # Is the class forbid constructors?
                if not mclassdef.mclass.kind.need_init then return

                # Is there already a constructor defined?
                var defined_init: nullable MMethodDef = null
                for mpropdef in mclassdef.mpropdefs do
                        if not mpropdef isa MMethodDef then continue
                        if not mpropdef.mproperty.is_init then continue
                        if mpropdef.mproperty.is_root_init then
                                assert defined_init == null
                                defined_init = mpropdef
                        else if mpropdef.mproperty.name == "init" then
                                # An explicit old-style init named "init", so return
                                return
                        end
                end

                if not nclassdef isa AStdClassdef then return

                # Collect undefined attributes
                var mparameters = new Array[MParameter]
                var initializers = new Array[MProperty]
                var anode: nullable ANode = null
                for npropdef in nclassdef.n_propdefs do
                        if npropdef isa AAttrPropdef then
                                if npropdef.mpropdef == null then return # Skip broken attribute
                                var at = npropdef.get_single_annotation("noinit", self)
                                if at != null then
                                        npropdef.noinit = true
                                        if npropdef.n_expr != null then
                                                self.error(at, "Error: `noinit` attributes cannot have an initial value")
                                        end
                                        continue # Skip noinit attributes
                                end
                                if npropdef.n_expr != null then continue
                                var paramname = npropdef.mpropdef.mproperty.name.substring_from(1)
                                var ret_type = npropdef.mpropdef.static_mtype
                                if ret_type == null then return
                                var mparameter = new MParameter(paramname, ret_type, false)
                                mparameters.add(mparameter)
                                var msetter = npropdef.mwritepropdef
                                if msetter == null then
                                        # No setter, it is a old-style attribute, so just add it
                                        initializers.add(npropdef.mpropdef.mproperty)
                                else
                                        # Add the setter to the list
                                        initializers.add(msetter.mproperty)
                                end
                                if anode == null then anode = npropdef
                        end
                end
                if anode == null then anode = nclassdef

                if the_root_init_mmethod == null then return

                # Look for most-specific new-stype init definitions
                var spropdefs = the_root_init_mmethod.lookup_super_definitions(mclassdef.mmodule, mclassdef.bound_mtype)
                if spropdefs.is_empty then
                        toolcontext.fatal_error(nclassdef.location, "Fatal error: {mclassdef} does not specialize {the_root_init_mmethod.intro_mclassdef}. Possible duplication of the root class `Object`?")
                end

                # Search the longest-one and checks for conflict
                var longest = spropdefs.first
                if spropdefs.length > 1 then
                        # Check for conflict in the order of initializers
                        # Each initializer list must me a prefix of the longest list
                        # part 1. find the longest list
                        for spd in spropdefs do
                                if spd.initializers.length > longest.initializers.length then longest = spd
                        end
                        # part 2. compare
                        for spd in spropdefs do
                                var i = 0
                                for p in spd.initializers do
                                        if p != longest.initializers[i] then
                                                self.error(nclassdef, "Error: conflict for inherited inits {spd}({spd.initializers.join(", ")}) and {longest}({longest.initializers.join(", ")})")
                                                return
                                        end
                                        i += 1
                                end
                        end
                end

                # Can we just inherit?
                if spropdefs.length == 1 and mparameters.is_empty and defined_init == null then
                        self.toolcontext.info("{mclassdef} inherits the basic constructor {longest}", 3)
                        return
                end

                # Combine the inherited list to what is collected
                if longest.initializers.length > 0 then
                        mparameters.prepend longest.new_msignature.mparameters
                        initializers.prepend longest.initializers
                end

                # If we already have a basic init definition, then setup its initializers
                if defined_init != null then
                        defined_init.initializers.add_all(initializers)
                        var msignature = new MSignature(mparameters, null)
                        defined_init.new_msignature = msignature
                        self.toolcontext.info("{mclassdef} extends its basic constructor signature to {defined_init}{msignature}", 3)
                        return
                end

                # Else create the local implicit basic init definition
                var mprop = the_root_init_mmethod.as(not null)
                var mpropdef = new MMethodDef(mclassdef, mprop, nclassdef.location)
                mpropdef.has_supercall = true
                mpropdef.initializers.add_all(initializers)
                var msignature = new MSignature(mparameters, null)
                mpropdef.new_msignature = msignature
                mpropdef.msignature = new MSignature(new Array[MParameter], null) # always an empty real signature
                nclassdef.mfree_init = mpropdef
                self.toolcontext.info("{mclassdef} gets a free constructor for attributes {mpropdef}{msignature}", 3)
        end

        # Check the visibility of `mtype` as an element of the signature of `mpropdef`.
        fun check_visibility(node: ANode, mtype: MType, mpropdef: MPropDef)
        do
                var mmodule = mpropdef.mclassdef.mmodule
                var mproperty = mpropdef.mproperty

                # Extract visibility information of the main part of `mtype`
                # It is a case-by case
                var vis_type: nullable MVisibility = null # The own visibility of the type
                var mmodule_type: nullable MModule = null # The origial module of the type
                mtype = mtype.as_notnullable
                if mtype isa MClassType then
                        vis_type = mtype.mclass.visibility
                        mmodule_type = mtype.mclass.intro.mmodule
                else if mtype isa MVirtualType then
                        vis_type = mtype.mproperty.visibility
                        mmodule_type = mtype.mproperty.intro_mclassdef.mmodule
                else if mtype isa MParameterType then
                        # nothing, always visible
                else
                        node.debug "Unexpected type {mtype}"
                        abort
                end

                if vis_type != null then
                        assert mmodule_type != null
                        var vis_module_type = mmodule.visibility_for(mmodule_type) # the visibility of the original module
                        if mproperty.visibility > vis_type then
                                error(node, "Error: The {mproperty.visibility} property `{mproperty}` cannot contain the {vis_type} type `{mtype}`")
                                return
                        else if mproperty.visibility > vis_module_type then
                                error(node, "Error: The {mproperty.visibility} property `{mproperty}` cannot contain the type `{mtype}` from the {vis_module_type} module `{mmodule_type}`")
                                return
                        end
                end

                # No error, try to go deeper in generic types
                if node isa AType then
                        for a in node.n_types do
                                var t = a.mtype
                                if t == null then continue # Error, thus skipped
                                check_visibility(a, t, mpropdef)
                        end
                else if mtype isa MGenericType then
                        for t in mtype.arguments do check_visibility(node, t, mpropdef)
                end
        end
end

redef class MPropDef
        # Does the MPropDef contains a call to super or a call of a super-constructor?
        # Subsequent phases of the frontend (esp. typing) set it if required
        var has_supercall: Bool = false is writable
end

redef class AClassdef
        var build_properties_is_done: Bool = false
        # The list of super-constructor to call at the start of the free constructor
        # FIXME: this is needed to implement the crazy constructor thing of the of old compiler. We need to think what to do with since this cannot stay in the modelbuilder
        var super_inits: nullable Collection[MMethod] = null

        # The free init (implicitely constructed by the class if required)
        var mfree_init: nullable MMethodDef = null
end

redef class MClassDef
        # What is the `APropdef` associated to a `MProperty`?
        # Used to check multiple definition of a property.
        var mprop2npropdef: Map[MProperty, APropdef] = new HashMap[MProperty, APropdef]
end

redef class Prod
        # Join the text of all tokens
        # Used to get the 'real name' of method definitions.
        fun collect_text: String
        do
                var v = new TextCollectorVisitor
                v.enter_visit(self)
                assert v.text != ""
                return v.text
        end
end

private class TextCollectorVisitor
        super Visitor
        var text: String = ""
        redef fun visit(n)
        do
                if n isa Token then text += n.text
                n.visit_all(self)
        end
end

redef class APropdef
        # The associated main model entity
        type MPROPDEF: MPropDef

        # The associated propdef once build by a `ModelBuilder`
        var mpropdef: nullable MPROPDEF is writable

        private fun build_property(modelbuilder: ModelBuilder, mclassdef: MClassDef) is abstract
        private fun build_signature(modelbuilder: ModelBuilder) is abstract
        private fun check_signature(modelbuilder: ModelBuilder) is abstract
        private fun new_property_visibility(modelbuilder: ModelBuilder, mclassdef: MClassDef, nvisibility: nullable AVisibility): MVisibility
        do
                var mvisibility = public_visibility
                if nvisibility != null then
                        mvisibility = nvisibility.mvisibility
                        if mvisibility == intrude_visibility then
                                modelbuilder.error(nvisibility, "Error: intrude is not a legal visibility for properties.")
                                mvisibility = public_visibility
                        end
                end
                if mclassdef.mclass.visibility == private_visibility then
                        if mvisibility == protected_visibility then
                                assert nvisibility != null
                                modelbuilder.error(nvisibility, "Error: The only legal visibility for properties in a private class is private.")
                        else if mvisibility == private_visibility then
                                assert nvisibility != null
                                modelbuilder.advice(nvisibility, "useless-visibility", "Warning: private is superfluous since the only legal visibility for properties in a private class is private.")
                        end
                        mvisibility = private_visibility
                end
                return mvisibility
        end

        private fun set_doc(mpropdef: MPropDef, modelbuilder: ModelBuilder)
        do
                var ndoc = self.n_doc
                if ndoc != null then
                        var mdoc = ndoc.to_mdoc
                        mpropdef.mdoc = mdoc
                        mdoc.original_mentity = mpropdef
                else if mpropdef.is_intro and mpropdef.mproperty.visibility >= protected_visibility then
                        modelbuilder.advice(self, "missing-doc", "Documentation warning: Undocumented property `{mpropdef.mproperty}`")
                end

                var at_deprecated = get_single_annotation("deprecated", modelbuilder)
                if at_deprecated != null then
                        if not mpropdef.is_intro then
                                modelbuilder.error(self, "Error: method redefinition cannot be deprecated.")
                        else
                                var info = new MDeprecationInfo
                                ndoc = at_deprecated.n_doc
                                if ndoc != null then info.mdoc = ndoc.to_mdoc
                                mpropdef.mproperty.deprecation = info
                        end
                end
        end

        private fun check_redef_property_visibility(modelbuilder: ModelBuilder, nvisibility: nullable AVisibility, mprop: MProperty)
        do
                if nvisibility == null then return
                var mvisibility = nvisibility.mvisibility
                if mvisibility != mprop.visibility and mvisibility != public_visibility then
                                modelbuilder.error(nvisibility, "Error: redefinition changed the visibility from a {mprop.visibility} to a {mvisibility}")
                end
        end

        private fun check_redef_keyword(modelbuilder: ModelBuilder, mclassdef: MClassDef, kwredef: nullable Token, need_redef: Bool, mprop: MProperty): Bool
        do
                if mclassdef.mprop2npropdef.has_key(mprop) then
                        modelbuilder.error(self, "Error: A property {mprop} is already defined in class {mclassdef.mclass} at line {mclassdef.mprop2npropdef[mprop].location.line_start}.")
                        return false
                end
                if mprop isa MMethod and mprop.is_toplevel != (parent isa ATopClassdef) then
                        if mprop.is_toplevel then
                                modelbuilder.error(self, "Error: {mprop} is a top level method.")
                        else
                                modelbuilder.error(self, "Error: {mprop} is not a top level method.")
                        end
                        return false

                end
                if kwredef == null then
                        if need_redef then
                                modelbuilder.error(self, "Redef error: {mclassdef.mclass}::{mprop.name} is an inherited property. To redefine it, add the redef keyword.")
                                return false
                        end
                else
                        if not need_redef then
                                modelbuilder.error(self, "Error: No property {mclassdef.mclass}::{mprop.name} is inherited. Remove the redef keyword to define a new property.")
                                return false
                        end
                end
                return true
        end

end

redef class ASignature
        # Is the model builder has correctly visited the signature
        var is_visited = false
        # Names of parameters from the AST
        # REQUIRE: is_visited
        var param_names = new Array[String]
        # Types of parameters from the AST
        # REQUIRE: is_visited
        var param_types = new Array[MType]
        # Rank of the vararg (of -1 if none)
        # REQUIRE: is_visited
        var vararg_rank: Int = -1
        # Return type
        var ret_type: nullable MType = null

        # Visit and fill information about a signature
        private fun visit_signature(modelbuilder: ModelBuilder, mclassdef: MClassDef): Bool
        do
                var mmodule = mclassdef.mmodule
                var param_names = self.param_names
                var param_types = self.param_types
                for np in self.n_params do
                        param_names.add(np.n_id.text)
                        var ntype = np.n_type
                        if ntype != null then
                                var mtype = modelbuilder.resolve_mtype(mmodule, mclassdef, ntype)
                                if mtype == null then return false # Skip error
                                for i in [0..param_names.length-param_types.length[ do
                                        param_types.add(mtype)
                                end
                                if np.n_dotdotdot != null then
                                        if self.vararg_rank != -1 then
                                                modelbuilder.error(np, "Error: {param_names[self.vararg_rank]} is already a vararg")
                                                return false
                                        else
                                                self.vararg_rank = param_names.length - 1
                                        end
                                end
                        end
                end
                var ntype = self.n_type
                if ntype != null then
                        self.ret_type = modelbuilder.resolve_mtype(mmodule, mclassdef, ntype)
                        if self.ret_type == null then return false # Skip errir
                end

                self.is_visited = true
                return true
        end

        # Build a visited signature
        fun build_signature(modelbuilder: ModelBuilder): nullable MSignature
        do
                if param_names.length != param_types.length then
                        # Some parameters are typed, other parameters are not typed.
                        modelbuilder.error(self.n_params[param_types.length], "Error: Untyped parameter `{param_names[param_types.length]}'.")
                        return null
                end

                var mparameters = new Array[MParameter]
                for i in [0..param_names.length[ do
                        var mparameter = new MParameter(param_names[i], param_types[i], i == vararg_rank)
                        self.n_params[i].mparameter = mparameter
                        mparameters.add(mparameter)
                end

                var msignature = new MSignature(mparameters, ret_type)
                return msignature
        end
end

redef class AParam
        # The associated mparameter if any
        var mparameter: nullable MParameter = null
end

redef class AMethPropdef
        redef type MPROPDEF: MMethodDef


        # Can self be used as a root init?
        private fun look_like_a_root_init(modelbuilder: ModelBuilder): Bool
        do
                # Need the `init` keyword
                if n_kwinit == null then return false
                # Need to by anonymous
                if self.n_methid != null then return false
                # No parameters
                if self.n_signature.n_params.length > 0 then return false
                # Cannot be private or something
                if not self.n_visibility isa APublicVisibility then return false
                # No annotation on itself
                if get_single_annotation("old_style_init", modelbuilder) != null then return false
                # Nor on its module
                var amod = self.parent.parent.as(AModule)
                var amoddecl = amod.n_moduledecl
                if amoddecl != null then
                        var old = amoddecl.get_single_annotation("old_style_init", modelbuilder)
                        if old != null then return false
                end

                return true
        end

        redef fun build_property(modelbuilder, mclassdef)
        do
                var n_kwinit = n_kwinit
                var n_kwnew = n_kwnew
                var is_init = n_kwinit != null or n_kwnew != null
                var name: String
                var amethodid = self.n_methid
                var name_node: ANode
                if amethodid == null then
                        if not is_init then
                                name = "main"
                                name_node = self
                        else if n_kwinit != null then
                                name = "init"
                                name_node = n_kwinit
                        else if n_kwnew != null then
                                name = "init"
                                name_node = n_kwnew
                        else
                                abort
                        end
                else if amethodid isa AIdMethid then
                        name = amethodid.n_id.text
                        name_node = amethodid
                else
                        # operator, bracket or assign
                        name = amethodid.collect_text
                        name_node = amethodid

                        if name == "-" and self.n_signature.n_params.length == 0 then
                                name = "unary -"
                        end
                end

                var mprop: nullable MMethod = null
                if not is_init or n_kwredef != null then mprop = modelbuilder.try_get_mproperty_by_name(name_node, mclassdef, name).as(nullable MMethod)
                if mprop == null and look_like_a_root_init(modelbuilder) then
                        mprop = modelbuilder.the_root_init_mmethod
                        var nb = n_block
                        if nb isa ABlockExpr and nb.n_expr.is_empty and n_doc == null then
                                modelbuilder.advice(self, "useless-init", "Warning: useless empty init in {mclassdef}")
                        end
                end
                if mprop == null then
                        var mvisibility = new_property_visibility(modelbuilder, mclassdef, self.n_visibility)
                        mprop = new MMethod(mclassdef, name, mvisibility)
                        if look_like_a_root_init(modelbuilder) and modelbuilder.the_root_init_mmethod == null then
                                modelbuilder.the_root_init_mmethod = mprop
                                mprop.is_root_init = true
                        end
                        mprop.is_init = is_init
                        mprop.is_new = n_kwnew != null
                        if parent isa ATopClassdef then mprop.is_toplevel = true
                        if not self.check_redef_keyword(modelbuilder, mclassdef, n_kwredef, false, mprop) then return
                else
                        if not mprop.is_root_init and not self.check_redef_keyword(modelbuilder, mclassdef, n_kwredef, not self isa AMainMethPropdef, mprop) then return
                        check_redef_property_visibility(modelbuilder, self.n_visibility, mprop)
                end
                mclassdef.mprop2npropdef[mprop] = self

                var mpropdef = new MMethodDef(mclassdef, mprop, self.location)

                set_doc(mpropdef, modelbuilder)

                self.mpropdef = mpropdef
                modelbuilder.mpropdef2npropdef[mpropdef] = self
                if mpropdef.is_intro then
                        modelbuilder.toolcontext.info("{mpropdef} introduces new method {mprop.full_name}", 3)
                else
                        modelbuilder.toolcontext.info("{mpropdef} redefines method {mprop.full_name}", 3)
                end
        end

        redef fun build_signature(modelbuilder)
        do
                var mpropdef = self.mpropdef
                if mpropdef == null then return # Error thus skiped
                var mclassdef = mpropdef.mclassdef
                var mmodule = mclassdef.mmodule
                var nsig = self.n_signature

                # Retrieve info from the signature AST
                var param_names = new Array[String] # Names of parameters from the AST
                var param_types = new Array[MType] # Types of parameters from the AST
                var vararg_rank = -1
                var ret_type: nullable MType = null # Return type from the AST
                if nsig != null then
                        if not nsig.visit_signature(modelbuilder, mclassdef) then return
                        param_names = nsig.param_names
                        param_types = nsig.param_types
                        vararg_rank = nsig.vararg_rank
                        ret_type = nsig.ret_type
                end

                # Look for some signature to inherit
                # FIXME: do not inherit from the intro, but from the most specific
                var msignature: nullable MSignature = null
                if not mpropdef.is_intro then
                        msignature = mpropdef.mproperty.intro.msignature
                        if msignature == null then return # Skip error

                        # Check inherited signature arity
                        if param_names.length != msignature.arity then
                                var node: ANode
                                if nsig != null then node = nsig else node = self
                                modelbuilder.error(node, "Redef error: {mpropdef} redefines {mpropdef.mproperty.intro} with {param_names.length} parameter(s), {msignature.arity} expected. Signature is {mpropdef}{msignature}")
                                return
                        end
                else if mpropdef.mproperty.is_init then
                        # FIXME UGLY: inherit signature from a super-constructor
                        for msupertype in mclassdef.supertypes do
                                msupertype = msupertype.anchor_to(mmodule, mclassdef.bound_mtype)
                                var candidate = modelbuilder.try_get_mproperty_by_name2(self, mmodule, msupertype, mpropdef.mproperty.name)
                                if candidate != null then
                                        if msignature == null then
                                                msignature = candidate.intro.as(MMethodDef).msignature
                                        end
                                end
                        end
                end


                # Inherit the signature
                if msignature != null and param_names.length != param_types.length and param_names.length == msignature.arity and param_types.length == 0 then
                        # Parameters are untyped, thus inherit them
                        param_types = new Array[MType]
                        for mparameter in msignature.mparameters do
                                param_types.add(mparameter.mtype)
                        end
                        vararg_rank = msignature.vararg_rank
                end
                if msignature != null and ret_type == null then
                        ret_type = msignature.return_mtype
                end

                if param_names.length != param_types.length then
                        # Some parameters are typed, other parameters are not typed.
                        modelbuilder.error(nsig.n_params[param_types.length], "Error: Untyped parameter `{param_names[param_types.length]}'.")
                        return
                end

                var mparameters = new Array[MParameter]
                for i in [0..param_names.length[ do
                        var mparameter = new MParameter(param_names[i], param_types[i], i == vararg_rank)
                        if nsig != null then nsig.n_params[i].mparameter = mparameter
                        mparameters.add(mparameter)
                end

                msignature = new MSignature(mparameters, ret_type)
                mpropdef.msignature = msignature
                mpropdef.is_abstract = self.get_single_annotation("abstract", modelbuilder) != null
                mpropdef.is_intern = self.get_single_annotation("intern", modelbuilder) != null
                mpropdef.is_extern = self.n_extern_code_block != null or self.get_single_annotation("extern", modelbuilder) != null
        end

        redef fun check_signature(modelbuilder)
        do
                var mpropdef = self.mpropdef
                if mpropdef == null then return # Error thus skiped
                var mclassdef = mpropdef.mclassdef
                var mmodule = mclassdef.mmodule
                var nsig = self.n_signature
                var mysignature = self.mpropdef.msignature
                if mysignature == null then return # Error thus skiped

                # Lookup for signature in the precursor
                # FIXME all precursors should be considered
                if not mpropdef.is_intro then
                        var msignature = mpropdef.mproperty.intro.msignature
                        if msignature == null then return

                        var precursor_ret_type = msignature.return_mtype
                        var ret_type = mysignature.return_mtype
                        if ret_type != null and precursor_ret_type == null then
                                modelbuilder.error(nsig.n_type.as(not null), "Redef Error: {mpropdef.mproperty} is a procedure, not a function.")
                                return
                        end

                        if mysignature.arity > 0 then
                                # Check parameters types
                                for i in [0..mysignature.arity[ do
                                        var myt = mysignature.mparameters[i].mtype
                                        var prt = msignature.mparameters[i].mtype
                                        if not myt.is_subtype(mmodule, mclassdef.bound_mtype, prt) or
                                                        not prt.is_subtype(mmodule, mclassdef.bound_mtype, myt) then
                                                modelbuilder.error(nsig.n_params[i], "Redef Error: Wrong type for parameter `{mysignature.mparameters[i].name}'. found {myt}, expected {prt} as in {mpropdef.mproperty.intro}.")
                                        end
                                end
                        end
                        if precursor_ret_type != null then
                                if ret_type == null then
                                        # Inherit the return type
                                        ret_type = precursor_ret_type
                                else if not ret_type.is_subtype(mmodule, mclassdef.bound_mtype, precursor_ret_type) then
                                        modelbuilder.error(nsig.n_type.as(not null), "Redef Error: Wrong return type. found {ret_type}, expected {precursor_ret_type} as in {mpropdef.mproperty.intro}.")
                                end
                        end
                end

                if mysignature.arity > 0 then
                        # Check parameters visibility
                        for i in [0..mysignature.arity[ do
                                var nt = nsig.n_params[i].n_type
                                if nt != null then modelbuilder.check_visibility(nt, nt.mtype.as(not null), mpropdef)
                        end
                        var nt = nsig.n_type
                        if nt != null then modelbuilder.check_visibility(nt, nt.mtype.as(not null), mpropdef)
                end
        end
end

redef class AAttrPropdef
        redef type MPROPDEF: MAttributeDef

        # Is the node tagged `noinit`?
        var noinit = false

        # Is the node taggeg lazy?
        var is_lazy = false

        # The guard associated to a lasy attribute.
        # Because some engines does not have a working `isset`,
        # this additionnal attribute is used to guard the lazy initialization.
        # TODO: to remove once isset is correctly implemented
        var mlazypropdef: nullable MAttributeDef

        # The associated getter (read accessor) if any
        var mreadpropdef: nullable MMethodDef is writable
        # The associated setter (write accessor) if any
        var mwritepropdef: nullable MMethodDef is writable

        redef fun build_property(modelbuilder, mclassdef)
        do
                var mclass = mclassdef.mclass

                var name: String
                name = self.n_id2.text

                if mclass.kind == interface_kind or mclassdef.mclass.kind == enum_kind then
                        modelbuilder.error(self, "Error: Attempt to define attribute {name} in the interface {mclass}.")
                else if mclass.kind == enum_kind then
                        modelbuilder.error(self, "Error: Attempt to define attribute {name} in the enum class {mclass}.")
                else if mclass.kind == extern_kind then
                        modelbuilder.error(self, "Error: Attempt to define attribute {name} in the extern class {mclass}.")
                end

                # New attribute style
                var nid2 = self.n_id2
                var mprop = new MAttribute(mclassdef, "_" + name, private_visibility)
                var mpropdef = new MAttributeDef(mclassdef, mprop, self.location)
                self.mpropdef = mpropdef
                modelbuilder.mpropdef2npropdef[mpropdef] = self
                set_doc(mpropdef, modelbuilder)

                var readname = name
                var mreadprop = modelbuilder.try_get_mproperty_by_name(nid2, mclassdef, readname).as(nullable MMethod)
                if mreadprop == null then
                        var mvisibility = new_property_visibility(modelbuilder, mclassdef, self.n_visibility)
                        mreadprop = new MMethod(mclassdef, readname, mvisibility)
                        if not self.check_redef_keyword(modelbuilder, mclassdef, n_kwredef, false, mreadprop) then return
                        mreadprop.deprecation = mprop.deprecation
                else
                        if not self.check_redef_keyword(modelbuilder, mclassdef, n_kwredef, true, mreadprop) then return
                        check_redef_property_visibility(modelbuilder, self.n_visibility, mreadprop)
                end
                mclassdef.mprop2npropdef[mreadprop] = self

                var mreadpropdef = new MMethodDef(mclassdef, mreadprop, self.location)
                self.mreadpropdef = mreadpropdef
                modelbuilder.mpropdef2npropdef[mreadpropdef] = self
                mreadpropdef.mdoc = mpropdef.mdoc

                var atlazy = self.get_single_annotation("lazy", modelbuilder)
                if atlazy != null then
                        if n_expr == null then
                                modelbuilder.error(atlazy, "Error: a lazy attribute needs a value")
                        end
                        is_lazy = true
                        var mlazyprop = new MAttribute(mclassdef, "lazy _" + name, none_visibility)
                        var mlazypropdef = new MAttributeDef(mclassdef, mlazyprop, self.location)
                        self.mlazypropdef = mlazypropdef
                end

                var atreadonly = self.get_single_annotation("readonly", modelbuilder)
                if atreadonly != null then
                        if n_expr == null then
                                modelbuilder.error(atreadonly, "Error: a readonly attribute needs a value")
                        end
                        # No setter, so just leave
                        return
                end

                var writename = name + "="
                var atwritable = self.get_single_annotation("writable", modelbuilder)
                if atwritable != null then
                        if not atwritable.n_args.is_empty then
                                writename = atwritable.arg_as_id(modelbuilder) or else writename
                        end
                end
                var mwriteprop = modelbuilder.try_get_mproperty_by_name(nid2, mclassdef, writename).as(nullable MMethod)
                var nwkwredef: nullable Token = null
                if atwritable != null then nwkwredef = atwritable.n_kwredef
                if mwriteprop == null then
                        var mvisibility
                        if atwritable != null then
                                mvisibility = new_property_visibility(modelbuilder, mclassdef, atwritable.n_visibility)
                        else
                                mvisibility = private_visibility
                        end
                        mwriteprop = new MMethod(mclassdef, writename, mvisibility)
                        if not self.check_redef_keyword(modelbuilder, mclassdef, nwkwredef, false, mwriteprop) then return
                        mwriteprop.deprecation = mprop.deprecation
                else
                        if not self.check_redef_keyword(modelbuilder, mclassdef, nwkwredef or else n_kwredef, true, mwriteprop) then return
                        if atwritable != null then
                                check_redef_property_visibility(modelbuilder, atwritable.n_visibility, mwriteprop)
                        end
                end
                mclassdef.mprop2npropdef[mwriteprop] = self

                var mwritepropdef = new MMethodDef(mclassdef, mwriteprop, self.location)
                self.mwritepropdef = mwritepropdef
                modelbuilder.mpropdef2npropdef[mwritepropdef] = self
                mwritepropdef.mdoc = mpropdef.mdoc
        end

        redef fun build_signature(modelbuilder)
        do
                var mpropdef = self.mpropdef
                if mpropdef == null then return # Error thus skiped
                var mclassdef = mpropdef.mclassdef
                var mmodule = mclassdef.mmodule
                var mtype: nullable MType = null

                var mreadpropdef = self.mreadpropdef

                var ntype = self.n_type
                if ntype != null then
                        mtype = modelbuilder.resolve_mtype(mmodule, mclassdef, ntype)
                        if mtype == null then return
                end

                # Inherit the type from the getter (usually an abstact getter)
                if mtype == null and mreadpropdef != null and not mreadpropdef.is_intro then
                        var msignature = mreadpropdef.mproperty.intro.msignature
                        if msignature == null then return # Error, thus skiped
                        mtype = msignature.return_mtype
                end

                var nexpr = self.n_expr
                if mtype == null then
                        if nexpr != null then
                                if nexpr isa ANewExpr then
                                        mtype = modelbuilder.resolve_mtype(mmodule, mclassdef, nexpr.n_type)
                                else if nexpr isa AIntExpr then
                                        var cla = modelbuilder.try_get_mclass_by_name(nexpr, mmodule, "Int")
                                        if cla != null then mtype = cla.mclass_type
                                else if nexpr isa AFloatExpr then
                                        var cla = modelbuilder.try_get_mclass_by_name(nexpr, mmodule, "Float")
                                        if cla != null then mtype = cla.mclass_type
                                else if nexpr isa ACharExpr then
                                        var cla = modelbuilder.try_get_mclass_by_name(nexpr, mmodule, "Char")
                                        if cla != null then mtype = cla.mclass_type
                                else if nexpr isa ABoolExpr then
                                        var cla = modelbuilder.try_get_mclass_by_name(nexpr, mmodule, "Bool")
                                        if cla != null then mtype = cla.mclass_type
                                else if nexpr isa ASuperstringExpr then
                                        var cla = modelbuilder.try_get_mclass_by_name(nexpr, mmodule, "String")
                                        if cla != null then mtype = cla.mclass_type
                                else if nexpr isa AStringFormExpr then
                                        var cla = modelbuilder.try_get_mclass_by_name(nexpr, mmodule, "String")
                                        if cla != null then mtype = cla.mclass_type
                                else
                                        modelbuilder.error(self, "Error: Untyped attribute {mpropdef}. Implicit typing allowed only for literals and new.")
                                end

                                if mtype == null then return
                        end
                else if ntype != null then
                        if nexpr isa ANewExpr then
                                var xmtype = modelbuilder.resolve_mtype(mmodule, mclassdef, nexpr.n_type)
                                if xmtype == mtype then
                                        modelbuilder.advice(ntype, "useless-type", "Warning: useless type definition")
                                end
                        end
                end

                if mtype == null then
                        modelbuilder.error(self, "Error: Untyped attribute {mpropdef}")
                        return
                end

                mpropdef.static_mtype = mtype

                if mreadpropdef != null then
                        var msignature = new MSignature(new Array[MParameter], mtype)
                        mreadpropdef.msignature = msignature
                end

                var mwritepropdef = self.mwritepropdef
                if mwritepropdef != null then
                        var name: String
                        name = n_id2.text
                        var mparameter = new MParameter(name, mtype, false)
                        var msignature = new MSignature([mparameter], null)
                        mwritepropdef.msignature = msignature
                end

                var mlazypropdef = self.mlazypropdef
                if mlazypropdef != null then
                        mlazypropdef.static_mtype = modelbuilder.model.get_mclasses_by_name("Bool").first.mclass_type
                end
        end

        redef fun check_signature(modelbuilder)
        do
                var mpropdef = self.mpropdef
                if mpropdef == null then return # Error thus skiped
                var mclassdef = mpropdef.mclassdef
                var mmodule = mclassdef.mmodule
                var ntype = self.n_type
                var mtype = self.mpropdef.static_mtype
                if mtype == null then return # Error thus skiped

                # Lookup for signature in the precursor
                # FIXME all precursors should be considered
                if not mpropdef.is_intro then
                        var precursor_type = mpropdef.mproperty.intro.static_mtype
                        if precursor_type == null then return

                        if mtype != precursor_type then
                                modelbuilder.error(ntype.as(not null), "Redef Error: Wrong static type. found {mtype}, expected {precursor_type}.")
                                return
                        end
                end

                # Check getter and setter
                var meth = self.mreadpropdef
                if meth != null then
                        self.check_method_signature(modelbuilder, meth)
                        var node: nullable ANode = ntype
                        if node == null then node = self
                        modelbuilder.check_visibility(node, mtype, meth)
                end
                meth = self.mwritepropdef
                if meth != null then
                        self.check_method_signature(modelbuilder, meth)
                        var node: nullable ANode = ntype
                        if node == null then node = self
                        modelbuilder.check_visibility(node, mtype, meth)
                end
        end

        private fun check_method_signature(modelbuilder: ModelBuilder, mpropdef: MMethodDef)
        do
                var mclassdef = mpropdef.mclassdef
                var mmodule = mclassdef.mmodule
                var nsig = self.n_type
                var mysignature = mpropdef.msignature
                if mysignature == null then return # Error thus skiped

                # Lookup for signature in the precursor
                # FIXME all precursors should be considered
                if not mpropdef.is_intro then
                        var msignature = mpropdef.mproperty.intro.msignature
                        if msignature == null then return

                        if mysignature.arity != msignature.arity then
                                var node: ANode
                                if nsig != null then node = nsig else node = self
                                modelbuilder.error(node, "Redef Error: {mysignature.arity} parameters found, {msignature.arity} expected. Signature is {mpropdef}{msignature}")
                                return
                        end
                        var precursor_ret_type = msignature.return_mtype
                        var ret_type = mysignature.return_mtype
                        if ret_type != null and precursor_ret_type == null then
                                var node: ANode
                                if nsig != null then node = nsig else node = self
                                modelbuilder.error(node, "Redef Error: {mpropdef.mproperty} is a procedure, not a function.")
                                return
                        end

                        if mysignature.arity > 0 then
                                # Check parameters types
                                for i in [0..mysignature.arity[ do
                                        var myt = mysignature.mparameters[i].mtype
                                        var prt = msignature.mparameters[i].mtype
                                        if not myt.is_subtype(mmodule, mclassdef.bound_mtype, prt) or
                                                        not prt.is_subtype(mmodule, mclassdef.bound_mtype, myt) then
                                                var node: ANode
                                                if nsig != null then node = nsig else node = self
                                                modelbuilder.error(node, "Redef Error: Wrong type for parameter `{mysignature.mparameters[i].name}'. found {myt}, expected {prt}.")
                                        end
                                end
                        end
                        if precursor_ret_type != null then
                                if ret_type == null then
                                        # Inherit the return type
                                        ret_type = precursor_ret_type
                                else if not ret_type.is_subtype(mmodule, mclassdef.bound_mtype, precursor_ret_type) then
                                        var node: ANode
                                        if nsig != null then node = nsig else node = self
                                        modelbuilder.error(node, "Redef Error: Wrong return type. found {ret_type}, expected {precursor_ret_type}.")
                                end
                        end
                end
        end
end

redef class ATypePropdef
        redef type MPROPDEF: MVirtualTypeDef

        redef fun build_property(modelbuilder, mclassdef)
        do
                var name = self.n_id.text
                var mprop = modelbuilder.try_get_mproperty_by_name(self.n_id, mclassdef, name)
                if mprop == null then
                        var mvisibility = new_property_visibility(modelbuilder, mclassdef, self.n_visibility)
                        mprop = new MVirtualTypeProp(mclassdef, name, mvisibility)
                        for c in name.chars do if c >= 'a' and c<= 'z' then
                                modelbuilder.warning(n_id, "bad-type-name", "Warning: lowercase in the virtual type {name}")
                                break
                        end
                        if not self.check_redef_keyword(modelbuilder, mclassdef, self.n_kwredef, false, mprop) then return
                else
                        if not self.check_redef_keyword(modelbuilder, mclassdef, self.n_kwredef, true, mprop) then return
                        assert mprop isa MVirtualTypeProp
                        check_redef_property_visibility(modelbuilder, self.n_visibility, mprop)
                end
                mclassdef.mprop2npropdef[mprop] = self

                var mpropdef = new MVirtualTypeDef(mclassdef, mprop, self.location)
                self.mpropdef = mpropdef
                modelbuilder.mpropdef2npropdef[mpropdef] = self
                set_doc(mpropdef, modelbuilder)

                var atfixed = get_single_annotation("fixed", modelbuilder)
                if atfixed != null then
                        mpropdef.is_fixed = true
                end
        end

        redef fun build_signature(modelbuilder)
        do
                var mpropdef = self.mpropdef
                if mpropdef == null then return # Error thus skiped
                var mclassdef = mpropdef.mclassdef
                var mmodule = mclassdef.mmodule
                var mtype: nullable MType = null

                var ntype = self.n_type
                mtype = modelbuilder.resolve_mtype(mmodule, mclassdef, ntype)
                if mtype == null then return

                mpropdef.bound = mtype
                # print "{mpropdef}: {mtype}"
        end

        redef fun check_signature(modelbuilder)
        do
                var mpropdef = self.mpropdef
                if mpropdef == null then return # Error thus skiped

                var bound = self.mpropdef.bound
                if bound == null then return # Error thus skiped

                modelbuilder.check_visibility(n_type, bound, mpropdef)

                var mclassdef = mpropdef.mclassdef
                var mmodule = mclassdef.mmodule
                var anchor = mclassdef.bound_mtype

                # Check circularity
                if bound isa MVirtualType then
                        # Slow case: progress on each resolution until: (i) we loop, or (ii) we found a non formal type
                        var seen = [self.mpropdef.mproperty.mvirtualtype]
                        loop
                                if seen.has(bound) then
                                        seen.add(bound)
                                        modelbuilder.error(self, "Error: circularity of virtual type definition: {seen.join(" -> ")}")
                                        return
                                end
                                seen.add(bound)
                                var next = bound.lookup_bound(mmodule, anchor)
                                if not next isa MVirtualType then break
                                bound = next
                        end
                end

                # Check redefinitions
                bound = mpropdef.bound.as(not null)
                for p in mpropdef.mproperty.lookup_super_definitions(mmodule, anchor) do
                        var supbound = p.bound.as(not null)
                        if p.is_fixed then
                                modelbuilder.error(self, "Redef Error: Virtual type {mpropdef.mproperty} is fixed in super-class {p.mclassdef.mclass}")
                                break
                        end
                        if p.mclassdef.mclass == mclassdef.mclass then
                                # Still a warning to pass existing bad code
                                modelbuilder.warning(n_type, "refine-type", "Redef Error: a virtual type cannot be refined.")
                                break
                        end
                        if not bound.is_subtype(mmodule, anchor, supbound) then
                                modelbuilder.error(n_type, "Redef Error: Wrong bound type. Found {bound}, expected a subtype of {supbound}, as in {p}.")
                                break
                        end
                end
        end
end