src: introduce new constructors
[nit.git] / src / modelize_property.nit
index 09c13e2..db51cbd 100644 (file)
@@ -18,6 +18,7 @@
 module modelize_property
 
 import modelize_class
+import annotation
 
 redef class ToolContext
        var modelize_property_phase: Phase = new ModelizePropertyPhase(self, [modelize_class_phase])
@@ -28,6 +29,7 @@ private class ModelizePropertyPhase
        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
@@ -48,21 +50,29 @@ redef class ModelBuilder
                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 npropdef in nclassdef.n_propdefs do
-                       npropdef.build_property(self, nclassdef)
-               end
-               for npropdef in nclassdef.n_propdefs do
-                       npropdef.build_signature(self, nclassdef)
-               end
-               for npropdef in nclassdef.n_propdefs do
-                       npropdef.check_signature(self, nclassdef)
+               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)
@@ -72,29 +82,60 @@ redef class ModelBuilder
                # Are we a refinement
                if not mclassdef.is_intro then return
 
+               var mmodule = nclassdef.mclassdef.mmodule
+
+               # 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 mpropdef.mproperty.is_init then return
+                       if not mpropdef.mproperty.is_init then continue
+                       if mpropdef.mproperty.is_root_init then
+                               assert defined_init == null
+                               defined_init = mpropdef
+                       else
+                               # An explicit old-style init, so return
+                               return
+                       end
                end
 
                if not nclassdef isa AStdClassdef then return
 
-               var mmodule = nclassdef.mclassdef.mmodule
-               # Do we inherit for a constructor?
-               var combine = new Array[MMethod]
-               var inhc: nullable MClass = null
-               for st in mclassdef.supertypes do
+               # Do we inherit a old-style constructor?
+               var combine = new Array[MMethod] # old-style constructors without arguments
+               var inhc: nullable MClass = null # single super-class with a constructor with arguments
+               if defined_init == null then for st in mclassdef.supertypes do
                        var c = st.mclass
                        if not c.kind.need_init then continue
-                       st = st.anchor_to(mmodule, nclassdef.mclassdef.bound_mtype)
+                       st = st.anchor_to(mmodule, mclassdef.bound_mtype)
                        var candidate = self.try_get_mproperty_by_name2(nclassdef, mmodule, st, "init").as(nullable MMethod)
-                       if candidate != null and candidate.intro.msignature.arity == 0 then
-                               combine.add(candidate)
-                               continue
+                       if candidate != null then
+                               if candidate.is_root_init then continue
+                               if candidate.intro.msignature != null then
+                                       if candidate.intro.msignature.arity == 0 then
+                                               combine.add(candidate)
+                                               continue
+                                       end
+                               end
                        end
                        var inhc2 = c.inherit_init_from
                        if inhc2 == null then inhc2 = c
@@ -108,15 +149,33 @@ redef class ModelBuilder
 
                # 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 and npropdef.n_expr == null then
+                       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
@@ -130,15 +189,14 @@ redef class ModelBuilder
 
                        # TODO: actively inherit the consturctor
                        self.toolcontext.info("{mclassdef} inherits all constructors from {inhc}", 3)
-                       mclassdef.mclass.inherit_init_from = inhc
-                       return
+                       #mclassdef.mclass.inherit_init_from = inhc
+                       #return
                end
 
                if not combine.is_empty and inhc != null then
                        self.error(nclassdef, "Error: Cannot provide a defaut constructor: conflict for {combine.join(", ")} and {inhc}")
                        return
                end
-
                if not combine.is_empty then
                        if mparameters.is_empty and combine.length == 1 then
                                # No need to create a local init, the inherited one is enough
@@ -148,13 +206,75 @@ redef class ModelBuilder
                                return
                        end
                        nclassdef.super_inits = combine
+                       var mprop = new MMethod(mclassdef, "init", mclassdef.mclass.visibility)
+                       var mpropdef = new MMethodDef(mclassdef, mprop, nclassdef.location)
+                       var msignature = new MSignature(mparameters, null)
+                       mpropdef.msignature = msignature
+                       mprop.is_init = true
+                       nclassdef.mfree_init = mpropdef
+                       self.toolcontext.info("{mclassdef} gets a free empty constructor {mpropdef}{msignature}", 3)
+                       return
+               end
+
+               if the_root_init_mmethod == null then return
+
+               # Look for nost-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
 
-               var mprop = new MMethod(mclassdef, "init", mclassdef.mclass.visibility)
+               # 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.msignature = msignature
-               mprop.is_init = true
+               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
@@ -169,7 +289,7 @@ redef class ModelBuilder
                # 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
-               if mtype isa MNullableType then mtype = mtype.mtype
+               mtype = mtype.as_notnullable
                if mtype isa MClassType then
                        vis_type = mtype.mclass.visibility
                        mmodule_type = mtype.mclass.intro.mmodule
@@ -197,7 +317,11 @@ redef class ModelBuilder
 
                # No error, try to go deeper in generic types
                if node isa AType then
-                       for a in node.n_types do check_visibility(a, a.mtype.as(not null), mpropdef)
+                       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
@@ -210,10 +334,6 @@ redef class MClass
        var inherit_init_from: nullable MClass = null
 end
 
-redef class MClassDef
-       private var propdef_names = new HashSet[String]
-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
@@ -228,7 +348,9 @@ redef class AClassdef
 
        # 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]
@@ -263,10 +385,10 @@ redef class APropdef
        # The associated propdef once build by a `ModelBuilder`
        var mpropdef: nullable MPROPDEF writable
 
-       private fun build_property(modelbuilder: ModelBuilder, nclassdef: AClassdef) is abstract
-       private fun build_signature(modelbuilder: ModelBuilder, nclassdef: AClassdef) is abstract
-       private fun check_signature(modelbuilder: ModelBuilder, nclassdef: AClassdef) is abstract
-       private fun new_property_visibility(modelbuilder: ModelBuilder, nclassdef: AClassdef, nvisibility: nullable AVisibility): MVisibility
+       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
@@ -276,7 +398,7 @@ redef class APropdef
                                mvisibility = public_visibility
                        end
                end
-               if nclassdef.mclassdef.mclass.visibility == private_visibility then
+               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.")
@@ -300,7 +422,7 @@ redef class APropdef
                end
        end
 
-       private fun check_redef_property_visibility(modelbuilder: ModelBuilder, nclassdef: AClassdef, nvisibility: nullable AVisibility, mprop: MProperty)
+       private fun check_redef_property_visibility(modelbuilder: ModelBuilder, nvisibility: nullable AVisibility, mprop: MProperty)
        do
                if nvisibility == null then return
                var mvisibility = nvisibility.mvisibility
@@ -309,20 +431,29 @@ redef class APropdef
                end
        end
 
-       private fun check_redef_keyword(modelbuilder: ModelBuilder, nclassdef: AClassdef, kwredef: nullable Token, need_redef: Bool, mprop: MProperty): Bool
+       private fun check_redef_keyword(modelbuilder: ModelBuilder, mclassdef: MClassDef, kwredef: nullable Token, need_redef: Bool, mprop: MProperty): Bool
        do
-               if nclassdef.mprop2npropdef.has_key(mprop) then
-                       modelbuilder.error(self, "Error: A property {mprop} is already defined in class {nclassdef.mclassdef.mclass}.")
+               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: {nclassdef.mclassdef.mclass}::{mprop.name} is an inherited property. To redefine it, add the redef keyword.")
+                               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 {nclassdef.mclassdef.mclass}::{mprop.name} is inherited. Remove the redef keyword to define a new property.")
+                               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
@@ -347,15 +478,16 @@ redef class ASignature
        var ret_type: nullable MType = null
 
        # Visit and fill information about a signature
-       private fun visit_signature(modelbuilder: ModelBuilder, nclassdef: AClassdef): Bool
+       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(nclassdef, ntype)
+                               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)
@@ -372,7 +504,7 @@ redef class ASignature
                end
                var ntype = self.n_type
                if ntype != null then
-                       self.ret_type = modelbuilder.resolve_mtype(nclassdef, ntype)
+                       self.ret_type = modelbuilder.resolve_mtype(mmodule, mclassdef, ntype)
                        if self.ret_type == null then return false # Skip errir
                end
 
@@ -381,7 +513,7 @@ redef class ASignature
        end
 
        # Build a visited signature
-       fun build_signature(modelbuilder: ModelBuilder, nclassdef: AClassdef): nullable MSignature
+       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.
@@ -409,12 +541,11 @@ end
 redef class AMethPropdef
        redef type MPROPDEF: MMethodDef
 
-       redef fun build_property(modelbuilder, nclassdef)
+       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 mclassdef = nclassdef.mclassdef.as(not null)
                var name: String
                var amethodid = self.n_methid
                var name_node: ANode
@@ -447,39 +578,20 @@ redef class AMethPropdef
                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 then
-                       var mvisibility = new_property_visibility(modelbuilder, nclassdef, self.n_visibility)
+                       var mvisibility = new_property_visibility(modelbuilder, mclassdef, self.n_visibility)
                        mprop = new MMethod(mclassdef, name, mvisibility)
                        mprop.is_init = is_init
                        mprop.is_new = n_kwnew != null
-                       if not self.check_redef_keyword(modelbuilder, nclassdef, n_kwredef, false, mprop) then return
+                       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 n_kwredef == null then
-                               if self isa AMainMethPropdef then
-                                       # no warning
-                               else
-                                       if not self.check_redef_keyword(modelbuilder, nclassdef, n_kwredef, true, mprop) then return
-                               end
-                       end
-                       check_redef_property_visibility(modelbuilder, nclassdef, self.n_visibility, mprop)
+                       if 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
-               nclassdef.mprop2npropdef[mprop] = self
+               mclassdef.mprop2npropdef[mprop] = self
 
                var mpropdef = new MMethodDef(mclassdef, mprop, self.location)
 
-               if mclassdef.propdef_names.has(mprop.name) then
-                       var loc: nullable Location = null
-                       for i in mclassdef.mpropdefs do
-                               if i.mproperty.name == mprop.name then
-                                       loc = i.location
-                                       break
-                               end
-                       end
-                       if loc == null then abort
-                       modelbuilder.error(self, "Error: a property {mprop} is already defined in class {mclassdef.mclass} at {loc}")
-               end
-
-               mclassdef.propdef_names.add(mpropdef.mproperty.name)
-
                set_doc(mpropdef)
 
                self.mpropdef = mpropdef
@@ -491,11 +603,12 @@ redef class AMethPropdef
                end
        end
 
-       redef fun build_signature(modelbuilder, nclassdef)
+       redef fun build_signature(modelbuilder)
        do
                var mpropdef = self.mpropdef
                if mpropdef == null then return # Error thus skiped
-               var mmodule = mpropdef.mclassdef.mmodule
+               var mclassdef = mpropdef.mclassdef
+               var mmodule = mclassdef.mmodule
                var nsig = self.n_signature
 
                # Retrieve info from the signature AST
@@ -504,7 +617,7 @@ redef class AMethPropdef
                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, nclassdef) then return
+                       if not nsig.visit_signature(modelbuilder, mclassdef) then return
                        param_names = nsig.param_names
                        param_types = nsig.param_types
                        vararg_rank = nsig.vararg_rank
@@ -527,8 +640,8 @@ redef class AMethPropdef
                        end
                else if mpropdef.mproperty.is_init then
                        # FIXME UGLY: inherit signature from a super-constructor
-                       for msupertype in nclassdef.mclassdef.supertypes do
-                               msupertype = msupertype.anchor_to(mmodule, nclassdef.mclassdef.bound_mtype)
+                       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
@@ -572,11 +685,12 @@ redef class AMethPropdef
                mpropdef.is_extern = self isa AExternPropdef
        end
 
-       redef fun check_signature(modelbuilder, nclassdef)
+       redef fun check_signature(modelbuilder)
        do
                var mpropdef = self.mpropdef
                if mpropdef == null then return # Error thus skiped
-               var mmodule = mpropdef.mclassdef.mmodule
+               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
@@ -599,8 +713,8 @@ redef class AMethPropdef
                                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, nclassdef.mclassdef.bound_mtype, prt) or
-                                                       not prt.is_subtype(mmodule, nclassdef.mclassdef.bound_mtype, myt) then
+                                       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
@@ -609,7 +723,7 @@ redef class AMethPropdef
                                if ret_type == null then
                                        # Inherit the return type
                                        ret_type = precursor_ret_type
-                               else if not ret_type.is_subtype(mmodule, nclassdef.mclassdef.bound_mtype, precursor_ret_type) then
+                               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
@@ -630,13 +744,25 @@ 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 writable
        # The associated setter (write accessor) if any
        var mwritepropdef: nullable MMethodDef writable
-       redef fun build_property(modelbuilder, nclassdef)
+
+       redef fun build_property(modelbuilder, mclassdef)
        do
-               var mclassdef = nclassdef.mclassdef.as(not null)
                var mclass = mclassdef.mclass
 
                var name: String
@@ -659,15 +785,15 @@ redef class AAttrPropdef
                        # Old attribute style
                        var mprop = modelbuilder.try_get_mproperty_by_name(nid, mclassdef, name)
                        if mprop == null then
-                               var mvisibility = new_property_visibility(modelbuilder, nclassdef, self.n_visibility)
+                               var mvisibility = new_property_visibility(modelbuilder, mclassdef, self.n_visibility)
                                mprop = new MAttribute(mclassdef, name, mvisibility)
-                               if not self.check_redef_keyword(modelbuilder, nclassdef, self.n_kwredef, false, mprop) then return
+                               if not self.check_redef_keyword(modelbuilder, mclassdef, self.n_kwredef, false, mprop) then return
                        else
                                assert mprop isa MAttribute
-                               check_redef_property_visibility(modelbuilder, nclassdef, self.n_visibility, mprop)
-                               if not self.check_redef_keyword(modelbuilder, nclassdef, self.n_kwredef, true, mprop) then return
+                               check_redef_property_visibility(modelbuilder, self.n_visibility, mprop)
+                               if not self.check_redef_keyword(modelbuilder, mclassdef, self.n_kwredef, true, mprop) then return
                        end
-                       nclassdef.mprop2npropdef[mprop] = self
+                       mclassdef.mprop2npropdef[mprop] = self
 
                        var mpropdef = new MAttributeDef(mclassdef, mprop, self.location)
                        self.mpropdef = mpropdef
@@ -675,48 +801,13 @@ redef class AAttrPropdef
                        set_doc(mpropdef)
 
                        var nreadable = self.n_readable
-                       if nreadable != null then
-                               var readname = name.substring_from(1)
-                               var mreadprop = modelbuilder.try_get_mproperty_by_name(nid, mclassdef, readname).as(nullable MMethod)
-                               if mreadprop == null then
-                                       var mvisibility = new_property_visibility(modelbuilder, nclassdef, nreadable.n_visibility)
-                                       mreadprop = new MMethod(mclassdef, readname, mvisibility)
-                                       if not self.check_redef_keyword(modelbuilder, nclassdef, nreadable.n_kwredef, false, mreadprop) then return
-                               else
-                                       if not self.check_redef_keyword(modelbuilder, nclassdef, nreadable.n_kwredef, true, mreadprop) then return
-                                       check_redef_property_visibility(modelbuilder, nclassdef, nreadable.n_visibility, mreadprop)
-                               end
-                               nclassdef.mprop2npropdef[mreadprop] = self
-
-                               var mreadpropdef = new MMethodDef(mclassdef, mreadprop, self.location)
-                               self.mreadpropdef = mreadpropdef
-                               modelbuilder.mpropdef2npropdef[mreadpropdef] = self
-                               mreadpropdef.mdoc = mpropdef.mdoc
-                       end
-
+                       if nreadable != null then modelbuilder.error(nreadable, "Error: old-style getter no more supported")
                        var nwritable = self.n_writable
-                       if nwritable != null then
-                               var writename = name.substring_from(1) + "="
-                               var mwriteprop = modelbuilder.try_get_mproperty_by_name(nid, mclassdef, writename).as(nullable MMethod)
-                               if mwriteprop == null then
-                                       var mvisibility = new_property_visibility(modelbuilder, nclassdef, nwritable.n_visibility)
-                                       mwriteprop = new MMethod(mclassdef, writename, mvisibility)
-                                       if not self.check_redef_keyword(modelbuilder, nclassdef, nwritable.n_kwredef, false, mwriteprop) then return
-                               else
-                                       if not self.check_redef_keyword(modelbuilder, nclassdef, nwritable.n_kwredef, true, mwriteprop) then return
-                                       check_redef_property_visibility(modelbuilder, nclassdef, nwritable.n_visibility, mwriteprop)
-                               end
-                               nclassdef.mprop2npropdef[mwriteprop] = self
-
-                               var mwritepropdef = new MMethodDef(mclassdef, mwriteprop, self.location)
-                               self.mwritepropdef = mwritepropdef
-                               modelbuilder.mpropdef2npropdef[mwritepropdef] = self
-                               mwritepropdef.mdoc = mpropdef.mdoc
-                       end
+                       if nwritable != null then modelbuilder.error(nwritable, "Error: old-style setter no more supported")
                else
                        # New attribute style
                        var nid2 = self.n_id2.as(not null)
-                       var mprop = new MAttribute(mclassdef, "@" + name, none_visibility)
+                       var mprop = new MAttribute(mclassdef, "_" + name, private_visibility)
                        var mpropdef = new MAttributeDef(mclassdef, mprop, self.location)
                        self.mpropdef = mpropdef
                        modelbuilder.mpropdef2npropdef[mpropdef] = self
@@ -725,41 +816,72 @@ redef class AAttrPropdef
                        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, nclassdef, self.n_visibility)
+                               var mvisibility = new_property_visibility(modelbuilder, mclassdef, self.n_visibility)
                                mreadprop = new MMethod(mclassdef, readname, mvisibility)
-                               if not self.check_redef_keyword(modelbuilder, nclassdef, n_kwredef, false, mreadprop) then return
+                               if not self.check_redef_keyword(modelbuilder, mclassdef, n_kwredef, false, mreadprop) then return
                        else
-                               if not self.check_redef_keyword(modelbuilder, nclassdef, n_kwredef, true, mreadprop) then return
-                               check_redef_property_visibility(modelbuilder, nclassdef, self.n_visibility, mreadprop)
+                               if not self.check_redef_keyword(modelbuilder, mclassdef, n_kwredef, true, mreadprop) then return
+                               check_redef_property_visibility(modelbuilder, self.n_visibility, mreadprop)
                        end
-                       nclassdef.mprop2npropdef[mreadprop] = self
+                       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 nwritable = self.n_writable
+                       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 nwritable != null then nwkwredef = nwritable.n_kwredef
+                       if atwritable != null then nwkwredef = atwritable.n_kwredef
                        if mwriteprop == null then
                                var mvisibility
                                if nwritable != null then
-                                       mvisibility = new_property_visibility(modelbuilder, nclassdef, nwritable.n_visibility)
+                                       mvisibility = new_property_visibility(modelbuilder, mclassdef, nwritable.n_visibility)
+                               else 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, nclassdef, nwkwredef, false, mwriteprop) then return
+                               if not self.check_redef_keyword(modelbuilder, mclassdef, nwkwredef, false, mwriteprop) then return
                        else
-                               if not self.check_redef_keyword(modelbuilder, nclassdef, nwkwredef, true, mwriteprop) then return
+                               if not self.check_redef_keyword(modelbuilder, mclassdef, nwkwredef or else n_kwredef, true, mwriteprop) then return
                                if nwritable != null then
-                                       check_redef_property_visibility(modelbuilder, nclassdef, nwritable.n_visibility, mwriteprop)
+                                       check_redef_property_visibility(modelbuilder, nwritable.n_visibility, mwriteprop)
+                               else if atwritable != null then
+                                       check_redef_property_visibility(modelbuilder, atwritable.n_visibility, mwriteprop)
                                end
                        end
-                       nclassdef.mprop2npropdef[mwriteprop] = self
+                       mclassdef.mprop2npropdef[mwriteprop] = self
 
                        var mwritepropdef = new MMethodDef(mclassdef, mwriteprop, self.location)
                        self.mwritepropdef = mwritepropdef
@@ -768,24 +890,34 @@ redef class AAttrPropdef
                end
        end
 
-       redef fun build_signature(modelbuilder, nclassdef)
+       redef fun build_signature(modelbuilder)
        do
                var mpropdef = self.mpropdef
                if mpropdef == null then return # Error thus skiped
-               var mmodule = mpropdef.mclassdef.mmodule
+               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(nclassdef, ntype)
+                       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(nclassdef, nexpr.n_type)
+                                       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
@@ -808,30 +940,30 @@ redef class AAttrPropdef
                                        modelbuilder.error(self, "Error: Untyped attribute {mpropdef}. Implicit typing allowed only for literals and new.")
                                end
 
-                       else
-                               modelbuilder.error(self, "Error: Untyped attribute {mpropdef}")
+                               if mtype == null then return
                        end
-               else
-                       assert ntype != null
+               else if ntype != null then
                        if nexpr isa ANewExpr then
-                               var xmtype = modelbuilder.resolve_mtype(nclassdef, nexpr.n_type)
+                               var xmtype = modelbuilder.resolve_mtype(mmodule, mclassdef, nexpr.n_type)
                                if xmtype == mtype and modelbuilder.toolcontext.opt_warn.value >= 2 then
                                        modelbuilder.warning(ntype, "Warning: useless type definition")
                                end
                        end
                end
 
-               if mtype == null then return
+               if mtype == null then
+                       modelbuilder.error(self, "Error: Untyped attribute {mpropdef}")
+                       return
+               end
 
                mpropdef.static_mtype = mtype
 
-               var mreadpropdef = self.mreadpropdef
                if mreadpropdef != null then
                        var msignature = new MSignature(new Array[MParameter], mtype)
                        mreadpropdef.msignature = msignature
                end
 
-               var msritepropdef = self.mwritepropdef
+               var mwritepropdef = self.mwritepropdef
                if mwritepropdef != null then
                        var name: String
                        if n_id != null then
@@ -843,13 +975,19 @@ redef class AAttrPropdef
                        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, nclassdef)
+       redef fun check_signature(modelbuilder)
        do
                var mpropdef = self.mpropdef
                if mpropdef == null then return # Error thus skiped
-               var mmodule = mpropdef.mclassdef.mmodule
+               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
@@ -869,23 +1007,24 @@ redef class AAttrPropdef
                # Check getter and setter
                var meth = self.mreadpropdef
                if meth != null then
-                       self.check_method_signature(modelbuilder, nclassdef, meth)
+                       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, nclassdef, meth)
+                       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, nclassdef: AClassdef, mpropdef: MMethodDef)
+       private fun check_method_signature(modelbuilder: ModelBuilder, mpropdef: MMethodDef)
        do
-               var mmodule = mpropdef.mclassdef.mmodule
+               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
@@ -916,8 +1055,8 @@ redef class AAttrPropdef
                                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, nclassdef.mclassdef.bound_mtype, prt) and
-                                                       not prt.is_subtype(mmodule, nclassdef.mclassdef.bound_mtype, myt) then
+                                       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}.")
@@ -928,7 +1067,7 @@ redef class AAttrPropdef
                                if ret_type == null then
                                        # Inherit the return type
                                        ret_type = precursor_ret_type
-                               else if not ret_type.is_subtype(mmodule, nclassdef.mclassdef.bound_mtype, precursor_ret_type) then
+                               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}.")
@@ -941,48 +1080,53 @@ end
 redef class ATypePropdef
        redef type MPROPDEF: MVirtualTypeDef
 
-       redef fun build_property(modelbuilder, nclassdef)
+       redef fun build_property(modelbuilder, mclassdef)
        do
-               var mclassdef = nclassdef.mclassdef.as(not null)
                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, nclassdef, self.n_visibility)
+                       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, "Warning: lowercase in the virtual type {name}")
                                break
                        end
-                       if not self.check_redef_keyword(modelbuilder, nclassdef, self.n_kwredef, false, mprop) then return
+                       if not self.check_redef_keyword(modelbuilder, mclassdef, self.n_kwredef, false, mprop) then return
                else
-                       if not self.check_redef_keyword(modelbuilder, nclassdef, self.n_kwredef, true, mprop) then return
+                       if not self.check_redef_keyword(modelbuilder, mclassdef, self.n_kwredef, true, mprop) then return
                        assert mprop isa MVirtualTypeProp
-                       check_redef_property_visibility(modelbuilder, nclassdef, self.n_visibility, mprop)
+                       check_redef_property_visibility(modelbuilder, self.n_visibility, mprop)
                end
-               nclassdef.mprop2npropdef[mprop] = self
+               mclassdef.mprop2npropdef[mprop] = self
 
                var mpropdef = new MVirtualTypeDef(mclassdef, mprop, self.location)
                self.mpropdef = mpropdef
                modelbuilder.mpropdef2npropdef[mpropdef] = self
                set_doc(mpropdef)
+
+               var atfixed = get_single_annotation("fixed", modelbuilder)
+               if atfixed != null then
+                       mpropdef.is_fixed = true
+               end
        end
 
-       redef fun build_signature(modelbuilder, nclassdef)
+       redef fun build_signature(modelbuilder)
        do
                var mpropdef = self.mpropdef
                if mpropdef == null then return # Error thus skiped
-               var mmodule = mpropdef.mclassdef.mmodule
+               var mclassdef = mpropdef.mclassdef
+               var mmodule = mclassdef.mmodule
                var mtype: nullable MType = null
 
                var ntype = self.n_type
-               mtype = modelbuilder.resolve_mtype(nclassdef, ntype)
+               mtype = modelbuilder.resolve_mtype(mmodule, mclassdef, ntype)
                if mtype == null then return
 
                mpropdef.bound = mtype
                # print "{mpropdef}: {mtype}"
        end
 
-       redef fun check_signature(modelbuilder, nclassdef)
+       redef fun check_signature(modelbuilder)
        do
                var mpropdef = self.mpropdef
                if mpropdef == null then return # Error thus skiped
@@ -990,26 +1134,46 @@ redef class ATypePropdef
                var bound = self.mpropdef.bound
                if bound == null then return # Error thus skiped
 
-               modelbuilder.check_visibility(n_type.as(not null), bound, mpropdef)
-
-               # Fast case: the bound is not a formal type
-               if not bound isa MVirtualType then return
-
-               var mmodule = nclassdef.mclassdef.mmodule
-               var anchor = nclassdef.mclassdef.bound_mtype
-
-               # 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
+               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)
-                               modelbuilder.error(self, "Error: circularity of virtual type definition: {seen.join(" -> ")}")
-                               return
+                               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, "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
-                       seen.add(bound)
-                       var next = bound.lookup_bound(mmodule, anchor)
-                       if not next isa MVirtualType then break
-                       bound = next
                end
        end
 end