syntax: better message for signature errors
[nit.git] / src / syntax / mmbuilder.nit
index 436bbe1..0c41698 100644 (file)
@@ -23,7 +23,7 @@ import syntax_base
 
 # Class specialization hierarchy sorter
 private class CSHSorter
-special AbstractSorter[MMLocalClass]
+       super AbstractSorter[MMLocalClass]
        redef fun compare(a, b)
        do
                return a.cshe.rank <=> b.cshe.rank
@@ -59,7 +59,7 @@ redef class MMSrcModule
 
                # Compute specialization relation
                for c in local_classes do
-                       if visibility_for(c.global.intro.module) < c.global.visibility_level then
+                       if visibility_for(c.global.intro.mmmodule) < c.global.visibility_level then
                                continue
                        end
                        c.compute_super_classes
@@ -84,23 +84,20 @@ redef class MMSrcModule
                end
 
                # Check class conformity
-               var mmbv1b = new ClassVerifierVisitor(tc, self)
+               var mmbv1c = new ClassVerifierVisitor(tc, self)
                for c in classes do
-                       c.accept_class_visitor(mmbv1b)
+                       c.accept_class_visitor(mmbv1c)
                end
                tc.check_errors
 
                # Property inhritance and introduction
                var mmbv2 = new PropertyBuilderVisitor(tc, self)
                for c in classes do
-                       # Inherit global properties
-                       c.inherit_global_properties
-
                        # Global property introduction and redefinition 
                        c.accept_class_visitor(mmbv2)
 
                        # Default and inherited constructor if needed
-                       if c isa MMSrcLocalClass and c.global.intro == c and not c.global.is_universal and not c.global.is_interface then
+                       if c isa MMSrcLocalClass and c.global.intro == c and not c.global.is_enum and not c.global.is_interface then
                                c.process_default_constructors(mmbv2)
                        end
 
@@ -114,14 +111,6 @@ redef class MMSrcModule
                        c.accept_properties_visitor(mmbv3)
                end
 
-               # Check inherited local properties
-               for c in classes do
-                       for g in c.global_properties do
-                               if visibility_for(g.intro.module) < g.visibility_level then continue
-                               var p = c[g]
-                       end
-               end
-
                tc.check_errors
        end
 
@@ -158,16 +147,20 @@ end
 redef class MMSrcLocalClass
        redef fun accept_class_visitor(v)
        do
-               for n in nodes do
+               var n = node
+               while n != null do
                        v.enter_visit(n)
+                       n = n.next_node
                end
        end
 
        # Accept a class visitor (on class properties)
        redef fun accept_properties_visitor(v)
        do
-               for n in nodes do
+               var n = node
+               while n != null do
                        v.enter_visit(n)
+                       n = n.next_node
                end
 
                for p in src_local_properties do
@@ -190,7 +183,7 @@ redef class MMSrcLocalClass
                var super_inits = new ArraySet[MMLocalProperty]
                var super_constructors = new ArraySet[MMGlobalProperty]
                for sc in che.direct_greaters do
-                       if sc.global.is_universal or sc.global.is_interface then continue
+                       if sc.global.is_enum or sc.global.is_interface then continue
                        for gp in sc.global_properties do
                                if not gp.is_init then continue
                                super_constructors.add(gp)
@@ -228,7 +221,7 @@ redef class MMSrcLocalClass
                        var superclass: nullable MMLocalClass = null # This most specific non-mixin superclass (if any)
 
                        if supers.length > 1 then
-                               v.error(nodes.first, "Error: Explicit constructor required in {self} since multiple inheritance of constructor is forbiden. Conflicting classes are {supers.join(", ")}. Costructors are {super_constructors.join(", ")}.")
+                               v.error(node, "Error: Explicit constructor required in {self} since multiple inheritance of constructor is forbiden. Conflicting classes are {supers.join(", ")}. Costructors are {super_constructors.join(", ")}.")
                                return
                        else if supers.length == 1 then
                                superclass = supers.first
@@ -318,7 +311,7 @@ end
 
 # Concrete NIT class specialization relation
 class MMSrcAncestor
-special MMAncestor
+       super MMAncestor
        redef readable var _local_class: MMLocalClass
 
        init(c: MMLocalClass)
@@ -333,7 +326,7 @@ end
 # * Build the classes and attach them to global classes
 # * Collect generic formal parameters.
 private class ClassBuilderVisitor
-special AbsSyntaxVisitor
+       super AbsSyntaxVisitor
        # Current class arity
        readable writable var _local_class_arity: Int = 0
 
@@ -347,7 +340,7 @@ end
 # Another pass visitor for syntax analysis.
 # * Build ancertors (with only class informations not the type one)
 private class ClassSpecializationBuilderVisitor
-special AbsSyntaxVisitor
+       super AbsSyntaxVisitor
        redef fun visit(n) do n.accept_class_specialization_builder(self)
        init(tc, m) do super
 end
@@ -355,7 +348,7 @@ end
 # Another pass visitor for syntax analysis.
 # * Compute types in ancestors
 private class ClassAncestorBuilder
-special AbsSyntaxVisitor
+       super AbsSyntaxVisitor
        redef fun visit(n) do n.accept_class_ancestor_builder(self)
        init(tc, m) do super
 end
@@ -363,7 +356,7 @@ end
 # Another pass visitor for syntax analysis.
 # * Checks classes in regard to superclasses
 private class ClassVerifierVisitor
-special AbsSyntaxVisitor
+       super AbsSyntaxVisitor
        redef fun visit(n) do n.accept_class_verifier(self)
        init(tc, m) do super
 end
@@ -374,7 +367,7 @@ end
 # * Build local properties and attache them to global properties
 # * Attach bound to formal types
 private class PropertyBuilderVisitor
-special AbsSyntaxVisitor
+       super AbsSyntaxVisitor
        redef fun visit(n) do n.accept_property_builder(self)
        init(tc, m) do super
 end
@@ -382,7 +375,7 @@ end
 # Another pass pass visitor for syntax analysis.
 # * Check property conformance
 private class PropertyVerifierVisitor
-special AbsSyntaxVisitor
+       super AbsSyntaxVisitor
 
        # The signature currently build
        readable writable var _signature_builder: SignatureBuilder
@@ -399,10 +392,10 @@ end
 # Information about a signature currently build
 private class SignatureBuilder
        # Current visited parameter types
-       readable writable var _params: Array[PParam] = new Array[PParam]
+       readable writable var _params: Array[AParam] = new Array[AParam]
        
        # Visited parameters without type information added
-       readable writable var _untyped_params: Array[PParam] = new Array[PParam]
+       readable writable var _untyped_params: Array[AParam] = new Array[AParam]
 
        # Position of the current star parameter
        readable writable var _vararg_rank: Int = -1
@@ -419,7 +412,7 @@ end
 
 ###############################################################################
 
-redef class PNode
+redef class ANode
        private fun accept_class_builder(v: ClassBuilderVisitor) do accept_abs_syntax_visitor(v)
        private fun accept_class_specialization_builder(v: ClassSpecializationBuilderVisitor) do accept_abs_syntax_visitor(v)
        private fun accept_class_ancestor_builder(v: ClassAncestorBuilder) do accept_abs_syntax_visitor(v)
@@ -435,7 +428,7 @@ redef class AModule
                # Import super-modules
                var module_names_to_import = new Array[Symbol]
                var module_visibility = new HashMap[Symbol, Int]
-               var no_import: nullable PImport = null
+               var no_import: nullable AImport = null
                for i in n_imports do
                        var n = i.module_name
                        if n != null then
@@ -465,23 +458,23 @@ redef class AModule
        end
 end
 
-redef class APackagedecl
+redef class AModuledecl
        redef fun accept_class_builder(v)
        do
-               if n_id.to_symbol != v.module.name then
-                       v.error(n_id, "Error: Package name missmatch between {v.module.name} and {n_id.to_symbol}")
+               if n_id.to_symbol != v.mmmodule.name then
+                       v.error(n_id, "Error: Module name missmatch between {v.mmmodule.name} and {n_id.to_symbol}")
                end
        end
 end
 
-redef class PImport
+redef class AImport
        # Imported module name (or null)
        fun module_name: nullable Symbol is abstract
 
        # Visibility level (intrude/public/private)
        fun visibility_level: Int is abstract
 end
-redef class AImport
+redef class AStdImport
        redef fun module_name
        do
                return n_id.to_symbol
@@ -498,7 +491,7 @@ redef class ANoImport
        end
 end
 
-redef class PVisibility
+redef class AVisibility
        # Visibility level
        fun level: Int is abstract
 end
@@ -516,7 +509,7 @@ redef class AIntrudeVisibility
 end
 
 
-redef class PClassdef
+redef class AClassdef
        redef fun local_class: MMSrcLocalClass do return _local_class.as(not null)
        var _local_class: nullable MMSrcLocalClass
 
@@ -532,27 +525,32 @@ redef class PClassdef
        redef fun accept_class_builder(v)
        do
                var local_class: MMSrcLocalClass
-               var mod = v.module
+               var mod = v.mmmodule
                var local_classes = mod.src_local_classes
                if (local_classes.has_key(name)) then
                        local_class = local_classes[name]
-                       if self isa AClassdef then
+                       _local_class = local_class
+                       if self isa AStdClassdef then
                                # If we are not a special implicit class then rant
-                               v.error(self, "Error: A class {name} is already defined at line {local_class.nodes.first.first_token.location.line_start}.")
+                               v.error(self, "Error: A class {name} is already defined at line {local_class.node.location.line_start}.")
                                return
                        end
-                       local_class.nodes.add(self)
+                       # Add the new node after the last node
+                       var n = local_class.node
+                       while n.next_node != null do n = n.next_node
+                       n.next_node = self
                else
                        local_class = new MMSrcLocalClass(mod, name, self, arity)
+                       _local_class = local_class
                        local_classes[name] = local_class
                        if not mod.has_global_class_named(name) then
-                               local_class.new_global
+                               build_class_introduction(v)
                        else
-                               local_class.set_global(mod.global_class_named(name))
+                               var glob = mod.global_class_named(name)
+                               build_class_refinement(v, glob)
                        end
 
                end
-               _local_class = local_class
                v.local_class_arity = 0
                v.formals = local_class.formal_dict
 
@@ -563,6 +561,70 @@ redef class PClassdef
                v.formals = null
        end
 
+       fun build_class_introduction(v: AbsSyntaxVisitor)
+       do
+               local_class.new_global
+               var glob = local_class.global
+
+               glob.visibility_level = visibility_level
+               if self isa AStdClassdef then
+                       if n_kwredef != null then
+                               v.error(self, "Redef error: No class {name} is imported. Remove the redef keyword to define a new class.")
+                               return
+                       end
+                       glob.is_interface = n_classkind.is_interface
+                       glob.is_abstract = n_classkind.is_abstract
+                       glob.is_enum = n_classkind.is_enum
+               end
+       end
+
+       fun build_class_refinement(v: AbsSyntaxVisitor, glob: MMGlobalClass)
+       do
+               local_class.set_global(glob)
+
+               glob.check_visibility(v, self, v.mmmodule)
+               if self isa AStdClassdef and n_kwredef == null then
+                       v.error(self, "Redef error: {name} is an imported class. Add the redef keyword to refine it.")
+                       return
+               end
+
+               if glob.intro.arity != _local_class.arity then
+                       v.error(self, "Redef error: Formal parameter arity missmatch; got {_local_class.arity}, expected {glob.intro.arity}.")
+               end
+
+               if self isa AStdClassdef and (not glob.is_interface and n_classkind.is_interface or
+                       not glob.is_abstract and n_classkind.is_abstract or
+                       not glob.is_enum and n_classkind.is_enum)
+               then
+                       v.error(self, "Redef error: cannot change kind of class {name}.")
+               end
+       end
+
+       redef fun accept_class_verifier(v)
+       do
+               super
+               var glob = _local_class.global
+               for c in _local_class.cshe.direct_greaters do
+                       var cg = c.global
+                       if glob.is_interface then
+                               if cg.is_enum then
+                                       v.error(self, "Special error: Interface {name} try to specialise enum class {c.name}.")
+                               else if not cg.is_interface then
+                                       v.error(self, "Special error: Interface {name} try to specialise class {c.name}.")
+                               end
+                       else if glob.is_enum then
+                               if not cg.is_interface and not cg.is_enum then
+                                       v.error(self, "Special error: Enum class {name} try to specialise class {c.name}.")
+                               end
+                       else
+                               if cg.is_enum then
+                                       v.error(self, "Special error: Class {name} try to specialise enum class {c.name}.")
+                               end
+                       end
+
+               end
+       end
+
        redef fun accept_abs_syntax_visitor(v)
        do
                v.local_class = _local_class
@@ -571,23 +633,23 @@ redef class PClassdef
        end
 end
 
-redef class PClasskind
+redef class AClasskind
        fun is_interface: Bool do return false
-       fun is_universal: Bool do return false
+       fun is_enum: Bool do return false
        fun is_abstract: Bool do return false
 end
 
 redef class AInterfaceClasskind
        redef fun is_interface do return true
 end
-redef class AUniversalClasskind
-       redef fun is_universal do return true
+redef class AEnumClasskind
+       redef fun is_enum do return true
 end
 redef class AAbstractClasskind
        redef fun is_abstract do return true
 end
 
-redef class AClassdef
+redef class AStdClassdef
        redef fun name
        do
                return n_id.to_symbol
@@ -596,62 +658,6 @@ redef class AClassdef
        do
                return n_formaldefs.length
        end
-       redef fun accept_class_verifier(v)
-       do
-               super
-               var glob = _local_class.global
-               if glob.intro == _local_class then
-                       # Intro
-                       glob.visibility_level = visibility_level
-                       glob.is_interface = n_classkind.is_interface
-                       glob.is_abstract = n_classkind.is_abstract
-                       glob.is_universal = n_classkind.is_universal
-                       if n_kwredef != null then
-                               v.error(self, "Redef error: No class {name} is imported. Remove the redef keyword to define a new class.")
-                       end
-
-                       for c in _local_class.cshe.direct_greaters do
-                               var cg = c.global
-                               if glob.is_interface then
-                                       if cg.is_universal then
-                                               v.error(self, "Special error: Interface {name} try to specialise universal class {c.name}.")
-                                       else if not cg.is_interface then
-                                               v.error(self, "Special error: Interface {name} try to specialise class {c.name}.")
-                                       end
-                               else if glob.is_universal then
-                                       if not cg.is_interface and not cg.is_universal then
-                                               v.error(self, "Special error: Universal class {name} try to specialise class {c.name}.")
-                                       end
-                               else
-                                       if cg.is_universal then
-                                               v.error(self, "Special error: Class {name} try to specialise universal class {c.name}.")
-                                       end
-                               end
-
-                       end
-                       return
-               end
-
-               # Redef
-
-               glob.check_visibility(v, self, v.module)
-               if n_kwredef == null then
-                       v.error(self, "Redef error: {name} is an imported class. Add the redef keyword to refine it.")
-                       return
-               end
-
-               if glob.intro.arity != _local_class.arity then
-                       v.error(self, "Redef error: Formal parameter arity missmatch; got {_local_class.arity}, expected {glob.intro.arity}.")
-               end
-
-               if 
-                       not glob.is_interface and n_classkind.is_interface or
-                       not glob.is_abstract and n_classkind.is_abstract or
-                       not glob.is_universal and n_classkind.is_universal
-               then
-                       v.error(self, "Redef error: cannot change kind of class {name}.")
-               end
-       end
 
        redef fun visibility_level
        do
@@ -695,14 +701,14 @@ redef class AFormaldef
                var o = c.global.intro
                if c == o then
                        if n_type == null then
-                               _formal.bound = v.module.type_any.as_nullable
+                               _formal.bound = v.mmmodule.type_any.as_nullable
                        else
                                var stype = n_type.get_stype(v)
                                if stype == null then return
                                _formal.bound = stype
                        end
                else
-                       var ob = o.get_formal(_formal.position).bound.for_module(v.module)
+                       var ob = o.get_formal(_formal.position).bound.for_module(v.mmmodule)
                        if n_type == null then
                                _formal.bound = ob
                        else
@@ -744,7 +750,7 @@ redef class ASuperclass
        end
 end
 
-redef class PPropdef
+redef class APropdef
        # Process and check properties of the property.
        # * Distinguish inits and methods
        # * Inherit or check visibility.
@@ -776,14 +782,14 @@ redef class PPropdef
                if glob.is_attribute then
                        if gbc.is_interface then
                                v.error(self, "Error: Attempt to define attribute {prop} in the interface {prop.local_class}.")
-                       else if gbc.is_universal then
-                               v.error(self, "Error: Attempt to define attribute {prop} in the universal class {prop.local_class}.")
+                       else if gbc.is_enum then
+                               v.error(self, "Error: Attempt to define attribute {prop} in the enum class {prop.local_class}.")
                        end
                else if glob.is_init then
                        if gbc.is_interface then
                                v.error(self, "Error: Attempt to define a constructor {prop} in the class {prop.local_class}.")
-                       else if gbc.is_universal then
-                               v.error(self, "Error: Attempt to define a constructor {prop} in the universal {prop.local_class}.")
+                       else if gbc.is_enum then
+                               v.error(self, "Error: Attempt to define a constructor {prop} in the enum {prop.local_class}.")
                        end
                end
                if prop.signature == null then
@@ -812,7 +818,6 @@ redef class PPropdef
 
                        if s == null then
                                if v.signature_builder.params.length != isig.arity then
-                                       #prop.node.printl("v.params.length {v.params.length} != isig.arity {isig.arity} ; {prop.full_name} vs {ip.full_name}")
                                        return
                                end
                                for p in v.signature_builder.params do
@@ -847,10 +852,12 @@ redef class PPropdef
                end
 
                var s = prop.signature
-               #print "process {prop.local_class.module}::{prop.local_class}::{prop} from global {prop.global.local_property.local_class.module}::{prop.global.local_property.local_class}::{prop.global.local_property}"
+               #print "process {prop.local_class.mmmodule}::{prop.local_class}::{prop} from global {prop.global.local_property.local_class.mmmodule}::{prop.global.local_property.local_class}::{prop.global.local_property}"
                for i in prop.prhe.direct_greaters do
                        var ip = i.local_class[prop.global]
-                       var isig = i.signature.adaptation_to(v.local_class.get_type)
+                       var isig = i.signature
+                       if isig == null then break # previous signature is invalid
+                       isig = isig.adaptation_to(v.local_class.get_type)
 
                        if s == null then
                                #print "{prop.full_name} inherits signature from {ip.full_name}"
@@ -885,11 +892,22 @@ redef class PPropdef
 
                        if s.arity != isig.arity then
                                v.error(self, "Redef error: {prop.local_class}::{prop} redefines {ip.local_class}::{ip} with {isig.arity} parameter(s).")
-                       else
-                               for i in [0..s.arity[ do
-                                       if s[i] != isig[i] then
-                                               v.error(self, "Redef error: Expected {isig[i]} (as in {ip.local_class}::{ip}), got {s[i]} in {prop.local_class}::{prop}.")
+                       else if s.arity > 0 then
+                               if self isa AMethPropdef then
+                                       # A standard method
+                                       for j in [0..s.arity[ do
+                                               if s[j] != isig[j] then
+                                                       v.error(n_signature.n_params[j], "Redef error: Expected {isig[j]}, as in {ip.local_class}::{ip}.")
+                                               end
                                        end
+                               else if self isa AAttrPropdef then
+                                       # A write accessor
+                                       if s[0] != isig[0] then
+                                               v.error(n_type, "Redef error: Expected {isig[0]}, as in the parameter of {ip.local_class}::{ip}.")
+                                       end
+
+                               else
+                                       abort #
                                end
                        end
 
@@ -900,20 +918,28 @@ redef class PPropdef
                        else if srt != null and isrt == null then
                                v.error(self, "Redef error: The function {prop.local_class}::{prop} redefines the procedure {ip.local_class}::{ip}.")
                        else if srt != null and isrt != null and not srt < isrt then
-                               v.error(self, "Redef error: Expected {isrt} (as in {ip.local_class}::{ip}), got {srt} in {prop.local_class}::{prop}.")
+                               var n: nullable ANode = null
+                               if self isa AMethPropdef then
+                                       n = self.n_signature.n_type
+                               else if self isa AAttrPropdef then
+                                       n = self.n_type
+                               else if self isa ATypePropdef then
+                                       n = self.n_type
+                               end
+                               v.error(n, "Redef error: Expected {isrt}, as in {ip.local_class}::{ip}.")
                        else if not s < isig and nberr == v.tc.error_count then
                                # Systematic fallback for conformance check
                                v.error(self, "Redef error: Incompatible redefinition of {ip.local_class}::{ip} with {prop.local_class}::{prop}")
                        else if srt != null and isrt != null and srt != isrt and prop isa MMAttribute then
                                # FIXME: To remove
-                               v.warning(self, "Redef warning: Expected {isrt} (as in {ip.local_class}::{ip}), got {srt} in {prop.local_class}::{prop}.")
+                               v.warning(self, "Redef warning: Expected {isrt}, as in {ip.local_class}::{ip}.")
                        end
                end
 
                if visibility_level != 1 and glob.visibility_level != visibility_level then
                        v.error(self, "Redef error: {prop.local_class}::{prop} redefinition cannot change visibility.")
                end
-               glob.check_visibility(v, self, v.module, true)
+               glob.check_visibility(v, self, v.mmmodule, true)
        end
 end
 
@@ -926,20 +952,33 @@ redef class AAttrPropdef
        redef fun accept_property_builder(v)
        do
                super
-               var name = n_id.to_symbol
+               var name: Symbol
+               if n_id != null then
+                       name = n_id.to_symbol
+               else
+                       name = ("@" + n_id2.text).to_symbol
+               end
                var lc = v.local_class
                var prop = new MMSrcAttribute(name, lc, self)
                _prop = prop
                v.local_class.add_src_local_property(v, prop)
 
-               if n_readable != null then
-                       name = n_id.text.substring_from(1).to_symbol
+               if n_readable != null or n_id == null then
+                       if n_id != null then
+                               name = n_id.text.substring_from(1).to_symbol
+                       else
+                               name = n_id2.to_symbol
+                       end
                        var readmethod = new MMReadImplementationMethod(name, lc, self)
                        _readmethod = readmethod
                        v.local_class.add_src_local_property(v, readmethod)
                end
-               if n_writable != null then
-                       name = (n_id.text.substring_from(1) + "=").to_symbol
+               if n_writable != null or n_id == null then
+                       if n_id != null then
+                               name = (n_id.text.substring_from(1) + "=").to_symbol
+                       else
+                               name = (n_id2.text + "=").to_symbol
+                       end
                        var writemethod = new MMWriteImplementationMethod(name, lc, self)
                        _writemethod = writemethod
                        v.local_class.add_src_local_property(v, writemethod)
@@ -954,7 +993,7 @@ redef class AAttrPropdef
                        var t0 = n_type.get_stype(v)
                        if t0 != null then t = t0 else return
                else
-                       v.error(self, "Not yet implemented: Attribute definition {_prop.local_class}::{_prop} requires an explicit type.")
+                       v.error(self, "Not yet implemented: Attribute definition {prop.local_class}::{prop} requires an explicit type.")
                        return
                end
 
@@ -962,17 +1001,21 @@ redef class AAttrPropdef
                var signature = new MMSignature(new Array[MMType], t, v.local_class.get_type)
                prop.signature = signature
                var visibility_level = n_visibility.level
-               process_and_check(v, prop, n_kwredef != null, visibility_level)
-               if n_readable != null then
+               process_and_check(v, prop, n_id != null and n_kwredef != null, visibility_level)
+               if n_readable != null or n_id == null then
                        var m = _readmethod.as(not null)
                        m.signature = signature
-                       process_and_check(v, m, n_readable.n_kwredef != null, visibility_level)
+                       process_and_check(v, m, (n_readable != null and n_readable.n_kwredef != null) or (n_id == null and n_kwredef != null), visibility_level)
                        n_type.check_visibility(v, m)
                end
-               if n_writable != null then
+               if n_writable != null or n_id == null then
                        var m = _writemethod.as(not null)
                        m.signature = new MMSignature(new Array[MMType].with_items(t), null, v.local_class.get_type)
-                       process_and_check(v, m, n_writable.n_kwredef != null, visibility_level)
+                       var vl = visibility_level
+                       if n_id == null then
+                               if n_writable == null then vl = 3 else vl = n_writable.n_visibility.level # write accessor has a specific visibility
+                       end
+                       process_and_check(v, m, n_writable != null and n_writable.n_kwredef != null, vl)
                        n_type.check_visibility(v, m)
                end
        end
@@ -1007,7 +1050,7 @@ redef class AMethPropdef
                        # FIXME: Add the 'unary' keyword
                        if n_methid.name == (once "-".to_symbol) then
                                var ns = n_signature
-                               if ns isa ASignature and ns.n_params.length == 0 then
+                               if ns != null and ns.n_params.length == 0 then
                                        name = once "unary -".to_symbol
                                end
                        end
@@ -1055,6 +1098,21 @@ redef class AMainMethPropdef
        end
 end
 
+redef class AExternMethPropdef
+       redef fun accept_property_verifier(v)
+       do
+               super # Compute signature
+               var ename: String
+               if n_extern != null then
+                       ename = n_extern.text
+                       ename = ename.substring(1, ename.length-2)
+               else
+                       ename = "{method.mmmodule.name}_{method.local_class.name}_{method.local_class.name}_{method.name}_{method.signature.arity}"
+               end
+               method.extern_name = ename
+       end
+end
+
 redef class ATypePropdef
        redef fun prop do return _prop.as(not null)
        var _prop: nullable MMSrcTypeProperty
@@ -1087,7 +1145,7 @@ end
 
 # Visitor used to build a full method name from multiple tokens
 private class MethidAccumulator
-special Visitor
+       super Visitor
        readable var _name: Buffer = new Buffer
        redef fun visit(n)
        do
@@ -1099,7 +1157,7 @@ special Visitor
        end
 end
 
-redef class PMethid
+redef class AMethid
        # Method name
        readable var _name: nullable Symbol 
 
@@ -1112,11 +1170,6 @@ redef class PMethid
        end
 end
 
-redef class PSignature
-       # Check that visibilities of types in the signature are compatible with the visibility of the property.
-       fun check_visibility(v: AbsSyntaxVisitor, p: MMLocalProperty) is abstract
-end
-
 redef class ASignature
        redef fun accept_property_verifier(v)
        do
@@ -1151,7 +1204,8 @@ redef class ASignature
                end
        end
 
-       redef fun check_visibility(v, p)
+       # Check that visibilities of types in the signature are compatible with the visibility of the property.
+       fun check_visibility(v: AbsSyntaxVisitor, p: MMLocalProperty)
        do
                if p.global.visibility_level >= 3 then return
                for n in n_params do
@@ -1161,7 +1215,7 @@ redef class ASignature
        end
 end
 
-redef class PParam
+redef class AParam
        redef readable var _position: Int = 0
 
        redef fun variable: ParamVariable do return _variable.as(not null)
@@ -1174,7 +1228,7 @@ redef class PParam
        do
                super
                _position = v.signature_builder.params.length
-               _variable = new ParamVariable(n_id.to_symbol, self)
+               _variable = new ParamVariable(n_id.to_symbol, n_id)
                v.signature_builder.params.add(self)
                v.signature_builder.untyped_params.add(self)
                if n_type != null then
@@ -1199,11 +1253,7 @@ redef class PParam
                end
        end
 
-       fun is_vararg: Bool is abstract
-end
-
-redef class AParam
-       redef fun is_vararg do return n_dotdotdot != null
+       fun is_vararg: Bool do return n_dotdotdot != null
 end
 
 redef class AClosureDecl
@@ -1229,25 +1279,28 @@ redef class AClosureDecl
                end
 
                # Add the finalizer to the closure signature
-               var finalize_sig = new MMSignature(new Array[MMType], null, v.module.type_any) # FIXME should be no receiver
-               var finalizer_clos = new MMClosure(finalize_sig, false, true)
+               var finalize_sig = new MMSignature(new Array[MMType], null, v.mmmodule.type_any) # FIXME should be no receiver
+               var finalizer_clos = new MMClosure(once ("break".to_symbol), finalize_sig, false, true)
                sig.closures.add(finalizer_clos)
 
-               var clos = new MMClosure(sig, n_kwbreak != null, n_expr != null)
+               var name = n_id.to_symbol
+               var clos = new MMClosure(name, sig, n_kwbreak != null, n_expr != null)
+               for c in old_signature_builder.closure_decls do
+                       if c.n_id.to_symbol == name then
+                               v.error(n_id, "A closure '!{name}' already defined at {c.n_id.location.relative_to(n_id.location)}.")
+                               return
+                       end
+               end
                v.signature_builder = old_signature_builder
                _position = old_signature_builder.closure_decls.length
                old_signature_builder.closure_decls.add(self)
-               _variable = new ClosureVariable(n_id.to_symbol, self, clos)
+               _variable = new ClosureVariable(n_id.to_symbol, n_id, clos)
        end
 end
 
-redef class PType
-       # Check that visibilities of types in the signature are compatible with the visibility of the property.
-       private fun check_visibility(v: AbsSyntaxVisitor, p: MMLocalProperty) is abstract
-end
-
 redef class AType
-       redef fun check_visibility(v, p)
+       # Check that visibilities of types in the signature are compatible with the visibility of the property.
+       private fun check_visibility(v: AbsSyntaxVisitor, p: MMLocalProperty)
        do
                if p.global.visibility_level >= 3 then return
                var t = get_stype(v)
@@ -1262,7 +1315,7 @@ redef class AType
        end
 end
 
-redef class PExpr
+redef class AExpr
        redef fun accept_class_builder(v) do end
        redef fun accept_property_builder(v) do end
        redef fun accept_property_verifier(v) do end