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

diff --git a/src/semantize/typing.nit b/src/semantize/typing.nit
index 1e15a05..3f973fd 100644
--- a/src/semantize/typing.nit
+++ b/src/semantize/typing.nit
@@ -36,17 +36,17 @@ private class TypeVisitor
 
 	# The module of the analysis
 	# Used to correctly query the model
-	var mmodule: MModule
+	var mmodule: MModule is noinit
 
 	# The static type of the receiver
 	# Mainly used for type tests and type resolutions
-	var anchor: nullable MClassType = null
+	var anchor: MClassType is noinit
 
 	# The analyzed mclassdef
-	var mclassdef: nullable MClassDef = null
+	var mclassdef: MClassDef is noinit
 
 	# The analyzed property
-	var mpropdef: nullable MPropDef
+	var mpropdef: MPropDef
 
 	var selfvariable = new Variable("self")
 
@@ -59,22 +59,20 @@ private class TypeVisitor
 	init
 	do
 		var mpropdef = self.mpropdef
+		var mclassdef = mpropdef.mclassdef
+		mmodule = mclassdef.mmodule
+		self.mclassdef = mclassdef
+		self.anchor = mclassdef.bound_mtype
 
-		if mpropdef != null then
-			var mclassdef = mpropdef.mclassdef
-			self.mclassdef = mclassdef
-			self.anchor = mclassdef.bound_mtype
-
-			var mclass = mclassdef.mclass
+		var mclass = mclassdef.mclass
 
-			var selfvariable = new Variable("self")
-			self.selfvariable = selfvariable
-			selfvariable.declared_type = mclass.mclass_type
+		var selfvariable = new Variable("self")
+		self.selfvariable = selfvariable
+		selfvariable.declared_type = mclass.mclass_type
 
-			var mprop = mpropdef.mproperty
-			if mprop isa MMethod and mprop.is_new then
-				is_toplevel_context = true
-			end
+		var mprop = mpropdef.mproperty
+		if mprop isa MMethod and mprop.is_new then
+			is_toplevel_context = true
 		end
 	end
 
@@ -277,7 +275,7 @@ private class TypeVisitor
 
 	fun resolve_mtype(node: AType): nullable MType
 	do
-		return self.modelbuilder.resolve_mtype(mmodule, mclassdef, node)
+		return self.modelbuilder.resolve_mtype(mclassdef, node)
 	end
 
 	fun try_get_mclass(node: ANode, name: String): nullable MClass
@@ -863,7 +861,7 @@ redef class AMethPropdef
 		var mpropdef = self.mpropdef
 		if mpropdef == null then return # skip error
 
-		var v = new TypeVisitor(modelbuilder, mpropdef.mclassdef.mmodule, mpropdef)
+		var v = new TypeVisitor(modelbuilder, mpropdef)
 		self.selfvariable = v.selfvariable
 
 		var mmethoddef = self.mpropdef.as(not null)
@@ -930,7 +928,7 @@ redef class AAttrPropdef
 		var mpropdef = self.mreadpropdef
 		if mpropdef == null or mpropdef.msignature == null then return # skip error
 
-		var v = new TypeVisitor(modelbuilder, mpropdef.mclassdef.mmodule, mpropdef)
+		var v = new TypeVisitor(modelbuilder, mpropdef)
 		self.selfvariable = v.selfvariable
 
 		var nexpr = self.n_expr
@@ -1579,9 +1577,7 @@ end
 redef class ACharExpr
 	redef fun accept_typing(v) do
 		var mclass: nullable MClass = null
-		if is_ascii then
-			mclass = v.get_mclass(self, "Byte")
-		else if is_code_point then
+		if is_code_point then
 			mclass = v.get_mclass(self, "Int")
 		else
 			mclass = v.get_mclass(self, "Char")
@@ -1907,6 +1903,11 @@ redef class ASendExpr
 	# The property invoked by the send.
 	var callsite: nullable CallSite
 
+	# Is self a safe call (with `x?.foo`)?
+	# If so and the receiver is null, then the arguments won't be evaluated
+	# and the call skipped (replaced with null).
+	var is_safe: Bool = false
+
 	redef fun bad_expr_message(child)
 	do
 		if child == self.n_expr then
@@ -1919,6 +1920,13 @@ redef class ASendExpr
 	do
 		var nrecv = self.n_expr
 		var recvtype = v.visit_expr(nrecv)
+
+		if nrecv isa ASafeExpr then
+			# Has the receiver the form `x?.foo`?
+			# For parsing "reasons" the `?` is in the receiver node, not the call node.
+			is_safe = true
+		end
+
 		var name = self.property_name
 		var node = self.property_node
 
@@ -1969,6 +1977,10 @@ redef class ASendExpr
 
 		var ret = msignature.return_mtype
 		if ret != null then
+			if is_safe then
+				# A safe receiver makes that the call is not executed and returns null
+				ret = ret.as_nullable
+			end
 			self.mtype = ret
 		else
 			self.is_typed = true
@@ -2019,6 +2031,10 @@ redef class AEqFormExpr
 
 		if mtype == null or mtype2 == null then return
 
+		if mtype == v.type_bool(self) and (n_expr2 isa AFalseExpr or n_expr2 isa ATrueExpr) then
+			v.modelbuilder.warning(self, "useless-truism", "Warning: useless comparison to a Bool literal.")
+		end
+
 		if not mtype2 isa MNullType then return
 
 		v.check_can_be_null(n_expr, mtype)
@@ -2141,7 +2157,6 @@ redef class ASuperExpr
 	redef fun accept_typing(v)
 	do
 		var anchor = v.anchor
-		assert anchor != null
 		var recvtype = v.get_variable(self, v.selfvariable)
 		assert recvtype != null
 		var mproperty = v.mpropdef.mproperty
@@ -2180,7 +2195,6 @@ redef class ASuperExpr
 	private fun process_superinit(v: TypeVisitor)
 	do
 		var anchor = v.anchor
-		assert anchor != null
 		var recvtype = v.get_variable(self, v.selfvariable)
 		assert recvtype != null
 		var mpropdef = v.mpropdef
@@ -2450,6 +2464,28 @@ redef class AIssetAttrExpr
 	end
 end
 
+redef class ASafeExpr
+	redef fun accept_typing(v)
+	do
+		var mtype = v.visit_expr(n_expr)
+		if mtype == null then return # Skip error
+
+		if mtype isa MNullType then
+			# While `null?.foo` is semantically well defined and should not execute `foo` and just return `null`,
+			# currently `null.foo` is forbidden so it seems coherent to also forbid `null?.foo`
+			v.modelbuilder.error(self, "Error: safe operator `?` on `null`.")
+			return
+		end
+
+		self.mtype = mtype.as_notnull
+
+		if not v.can_be_null(mtype) then
+			v.modelbuilder.warning(self, "useless-safe", "Warning: useless safe operator `?` on non-nullable value.")
+			return
+		end
+	end
+end
+
 redef class AVarargExpr
 	redef fun accept_typing(v)
 	do