X-Git-Url: http://nitlanguage.org

diff --git a/src/model/model.nit b/src/model/model.nit
index 19cd205..3733566 100644
--- a/src/model/model.nit
+++ b/src/model/model.nit
@@ -75,7 +75,7 @@ redef class Model
 	# Collections of classes grouped by their short name
 	private var mclasses_by_name = new MultiHashMap[String, MClass]
 
-	# Return all class named `name`.
+	# Return all classes named `name`.
 	#
 	# If such a class does not exist, null is returned
 	# (instead of an empty array)
@@ -159,7 +159,7 @@ redef class MModule
 		return self.in_importation <= mclass.intro_mmodule
 	end
 
-	# Full hierarchy of introduced ans imported classes.
+	# Full hierarchy of introduced and imported classes.
 	#
 	# Create a new hierarchy got by flattening the classes for the module
 	# and its imported modules.
@@ -603,7 +603,7 @@ class MClassDef
 	# ENSURE: `bound_mtype.mclass == self.mclass`
 	var bound_mtype: MClassType
 
-	redef var location: Location
+	redef var location
 
 	redef fun visibility do return mclass.visibility
 
@@ -720,8 +720,11 @@ class MClassDef
 	# All properties introduced by the classdef
 	var intro_mproperties = new Array[MProperty]
 
-	# All property definitions in the class (introductions and redefinitions)
+	# All property introductions and redefinitions in `self` (not inheritance).
 	var mpropdefs = new Array[MPropDef]
+
+	# All property introductions and redefinitions (not inheritance) in `self` by its associated property.
+	var mpropdefs_by_property = new HashMap[MProperty, MPropDef]
 end
 
 # A global static type
@@ -832,14 +835,14 @@ abstract class MType
 		end
 		#print "4.is {sub} a {sup}? <- no more resolution"
 
-		if sub isa MBottomType then
+		if sub isa MBottomType or sub isa MErrorType then
 			return true
 		end
 
 		assert sub isa MClassType else print_error "{sub} <? {sup}" # It is the only remaining type
 
 		# Handle sup-type when the sub-type is class-based (other cases must have be identified before).
-		if sup isa MFormalType or sup isa MNullType or sup isa MBottomType then
+		if sup isa MFormalType or sup isa MNullType or sup isa MBottomType or sup isa MErrorType then
 			# These types are not super-types of Class-based types.
 			return false
 		end
@@ -1033,7 +1036,7 @@ abstract class MType
 	# The result is returned exactly as declared in the "type" property (verbatim).
 	# So it could be another formal type.
 	#
-	# In case of conflicts or inconsistencies in the model, the method returns a `MBottomType`.
+	# In case of conflicts or inconsistencies in the model, the method returns a `MErrorType`.
 	fun lookup_bound(mmodule: MModule, resolved_receiver: MType): MType do return self
 
 	# Resolve the formal type to its simplest equivalent form.
@@ -1048,9 +1051,24 @@ abstract class MType
 	# By default, return self.
 	# See the redefinitions for specific behavior in each kind of type.
 	#
-	# In case of conflicts or inconsistencies in the model, the method returns a `MBottomType`.
+	# In case of conflicts or inconsistencies in the model, the method returns a `MErrorType`.
 	fun lookup_fixed(mmodule: MModule, resolved_receiver: MType): MType do return self
 
+	# Is the type a `MErrorType` or contains an `MErrorType`?
+	#
+	# `MErrorType` are used in result with conflict or inconsistencies.
+	#
+	# See `is_legal_in` to check conformity with generic bounds.
+	fun is_ok: Bool do return true
+
+	# Is the type legal in a given `mmodule` (with an optional `anchor`)?
+	#
+	# A type is valid if:
+	#
+	# * it does not contain a `MErrorType` (see `is_ok`).
+	# * its generic formal arguments are within their bounds.
+	fun is_legal_in(mmodule: MModule, anchor: nullable MClassType): Bool do return is_ok
+
 	# Can the type be resolved?
 	#
 	# In order to resolve open types, the formal types must make sence.
@@ -1349,6 +1367,24 @@ class MGenericType
 		return true
 	end
 
+	redef fun is_ok
+	do
+		for t in arguments do if not t.is_ok then return false
+		return super
+	end
+
+	redef fun is_legal_in(mmodule, anchor)
+	do
+		var mtype
+		if need_anchor then
+			assert anchor != null
+			mtype = anchor_to(mmodule, anchor)
+		else
+			mtype = self
+		end
+		if not mtype.is_ok then return false
+		return mtype.is_subtype(mmodule, null, mtype.mclass.intro.bound_mtype)
+	end
 
 	redef fun depth
 	do
@@ -1392,9 +1428,11 @@ class MVirtualType
 
 	redef fun model do return self.mproperty.intro_mclassdef.mmodule.model
 
-	redef fun lookup_bound(mmodule: MModule, resolved_receiver: MType): MType
+	redef fun lookup_bound(mmodule, resolved_receiver)
 	do
-		return lookup_single_definition(mmodule, resolved_receiver).bound or else new MBottomType(model)
+		# There is two possible invalid cases: the vt does not exists in resolved_receiver or the bound is broken
+		if not resolved_receiver.has_mproperty(mmodule, mproperty) then return new MErrorType(model)
+		return lookup_single_definition(mmodule, resolved_receiver).bound or else new MErrorType(model)
 	end
 
 	private fun lookup_single_definition(mmodule: MModule, resolved_receiver: MType): MVirtualTypeDef
@@ -1430,7 +1468,7 @@ class MVirtualType
 
 		var prop = lookup_single_definition(mmodule, resolved_receiver)
 		var res = prop.bound
-		if res == null then return new MBottomType(model)
+		if res == null then return new MErrorType(model)
 
 		# Recursively lookup the fixed result
 		res = res.lookup_fixed(mmodule, resolved_receiver)
@@ -1451,6 +1489,9 @@ class MVirtualType
 	do
 		if not cleanup_virtual then return self
 		assert can_resolve_for(mtype, anchor, mmodule)
+
+		if mproperty.is_selftype then return mtype
+
 		# self is a virtual type declared (or inherited) in mtype
 		# The point of the function it to get the bound of the virtual type that make sense for mtype
 		# But because mtype is maybe a virtual/formal type, we need to get a real receiver first
@@ -1552,7 +1593,8 @@ class MParameterType
 				return res
 			end
 		end
-		abort
+		# Cannot found `self` in `resolved_receiver`
+		return new MErrorType(model)
 	end
 
 	# A PT is fixed when:
@@ -1665,6 +1707,10 @@ abstract class MProxyType
 		return self.mtype.can_resolve_for(mtype, anchor, mmodule)
 	end
 
+	redef fun is_ok do return mtype.is_ok
+
+	redef fun is_legal_in(mmodule, anchor) do return mtype.is_legal_in(mmodule, anchor)
+
 	redef fun lookup_fixed(mmodule, resolved_receiver)
 	do
 		var t = mtype.lookup_fixed(mmodule, resolved_receiver)
@@ -1778,9 +1824,10 @@ end
 # The special universal most specific type.
 #
 # This type is intended to be only used internally for type computation or analysis and should not be exposed to the user.
-# The bottom type can de used to denote things that are absurd, dead, or the absence of knowledge.
+# The bottom type can de used to denote things that are dead (no instance).
 #
 # Semantically it is the singleton `null.as_notnull`.
+# Is also means that `self.as_nullable == null`.
 class MBottomType
 	super MType
 	redef var model
@@ -1800,6 +1847,31 @@ class MBottomType
 	redef fun collect_mtypes(mmodule) do return new HashSet[MClassType]
 end
 
+# A special type used as a silent error marker when building types.
+#
+# This type is intended to be only used internally for type operation and should not be exposed to the user.
+# The error type can de used to denote things that are conflicting or inconsistent.
+#
+# Some methods on types can return a `MErrorType` to denote a broken or a conflicting result.
+# Use `is_ok` to check if a type is (or contains) a `MErrorType` .
+class MErrorType
+	super MType
+	redef var model
+	redef fun to_s do return "error"
+	redef fun full_name do return "error"
+	redef fun c_name do return "error"
+	redef fun need_anchor do return false
+	redef fun resolve_for(mtype, anchor, mmodule, cleanup_virtual) do return self
+	redef fun can_resolve_for(mtype, anchor, mmodule) do return true
+	redef fun is_ok do return false
+
+	redef fun collect_mclassdefs(mmodule) do return new HashSet[MClassDef]
+
+	redef fun collect_mclasses(mmodule) do return new HashSet[MClass]
+
+	redef fun collect_mtypes(mmodule) do return new HashSet[MClassType]
+end
+
 # A signature of a method
 class MSignature
 	super MType
@@ -2053,14 +2125,27 @@ abstract class MProperty
 		#print "select prop {mproperty} for {mtype} in {self}"
 		# First, select all candidates
 		var candidates = new Array[MPROPDEF]
-		for mpropdef in self.mpropdefs do
-			# If the definition is not imported by the module, then skip
-			if not mmodule.in_importation <= mpropdef.mclassdef.mmodule then continue
-			# If the definition is not inherited by the type, then skip
-			if not mtype.is_subtype(mmodule, null, mpropdef.mclassdef.bound_mtype) then continue
-			# Else, we keep it
-			candidates.add(mpropdef)
+
+		# Here we have two strategies: iterate propdefs or iterate classdefs.
+		var mpropdefs = self.mpropdefs
+		if mpropdefs.length <= 1 or mpropdefs.length < mtype.collect_mclassdefs(mmodule).length then
+			# Iterate on all definitions of `self`, keep only those inherited by `mtype` in `mmodule`
+			for mpropdef in mpropdefs do
+				# If the definition is not imported by the module, then skip
+				if not mmodule.in_importation <= mpropdef.mclassdef.mmodule then continue
+				# If the definition is not inherited by the type, then skip
+				if not mtype.is_subtype(mmodule, null, mpropdef.mclassdef.bound_mtype) then continue
+				# Else, we keep it
+				candidates.add(mpropdef)
+			end
+		else
+			# Iterate on all super-classdefs of `mtype`, keep only the definitions of `self`, if any.
+			for mclassdef in mtype.collect_mclassdefs(mmodule) do
+				var p = mclassdef.mpropdefs_by_property.get_or_null(self)
+				if p != null then candidates.add p
+			end
 		end
+
 		# Fast track for only one candidate
 		if candidates.length <= 1 then
 			self.lookup_definitions_cache[mmodule, mtype] = candidates
@@ -2247,6 +2332,9 @@ class MVirtualTypeProp
 
 	# The formal type associated to the virtual type property
 	var mvirtualtype = new MVirtualType(self)
+
+	# Is `self` the special virtual type `SELF`?
+	var is_selftype: Bool is lazy do return name == "SELF"
 end
 
 # A definition of a property (local property)
@@ -2277,6 +2365,7 @@ abstract class MPropDef
 	do
 		mclassdef.mpropdefs.add(self)
 		mproperty.mpropdefs.add(self)
+		mclassdef.mpropdefs_by_property[mproperty] = self
 		if mproperty.intro_mclassdef == mclassdef then
 			assert not isset mproperty._intro
 			mproperty.intro = self