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

diff --git a/src/compiling/compiling_methods.nit b/src/compiling/compiling_methods.nit
index 3e20f95..65c05b3 100644
--- a/src/compiling/compiling_methods.nit
+++ b/src/compiling/compiling_methods.nit
@@ -22,9 +22,10 @@ private import syntax
 
 redef class CompilerVisitor
 	# Compile a statment node
-	meth compile_stmt(n: PExpr)
+	meth compile_stmt(n: nullable PExpr)
 	do
-		add_instr("/* Compile stmt {n.locate} */")
+		if n == null then return
+		#add_instr("/* Compile stmt {n.locate} */")
 		n.prepare_compile_stmt(self)
 		var i = cfc._variable_index
 		n.compile_stmt(self)
@@ -34,14 +35,14 @@ redef class CompilerVisitor
 	# Compile is expression node
 	meth compile_expr(n: PExpr): String
 	do
-		add_instr("/* Compile expr {n.locate} */")
+		#add_instr("/* Compile expr {n.locate} */")
 		var i = cfc._variable_index
 		var s = n.compile_expr(self)
 		cfc._variable_index = i
-		if s[0] == ' ' then
+		if s[0] == ' ' or cfc.is_valid_variable(s) then
 			return s
 		end
-		var v = cfc.get_var("Result for expr {n.locate}")
+		var v = cfc.get_var("Result")
 		add_assignment(v, s)
 		return v
 	end
@@ -49,7 +50,8 @@ redef class CompilerVisitor
 	# Ensure that a c expression is a var
 	meth ensure_var(s: String, comment: String): String
 	do
-		if s.substring(0,3) == "variable" then
+		if cfc.is_valid_variable(s) then
+			add_instr("/* Ensure var {s}: {comment}*/")
 			return s
 		end
 		var v = cfc.get_var(null)
@@ -65,9 +67,9 @@ redef class CompilerVisitor
 		end
 	end
 
-	readable writable attr _cfc: CFunctionContext
+	readable writable attr _cfc: nullable CFunctionContext
 
-	readable writable attr _nmc: NitMethodContext
+	readable writable attr _nmc: nullable NitMethodContext
 
 	# C outputs written outside the current C function.
 	readable writable attr _out_contexts: Array[CContext] = new Array[CContext]
@@ -83,12 +85,7 @@ redef class CompilerVisitor
 		return s.to_s
 	end
 
-	redef init(module: MMSrcModule)
-	do
-		super
-	end
-
-	meth invoke_super_init_calls_after(start_prop: MMMethod)
+	meth invoke_super_init_calls_after(start_prop: nullable MMMethod)
 	do
 		var n = nmc.method.node
 		assert n isa AConcreteInitPropdef
@@ -110,7 +107,7 @@ redef class CompilerVisitor
 			end
 			j += 1
 		end
-		var stop_prop: MMMethod = null
+		var stop_prop: nullable MMMethod = null
 		if j < n.explicit_super_init_calls.length then
 			stop_prop = n.explicit_super_init_calls[j]
 		end
@@ -123,12 +120,12 @@ redef class CompilerVisitor
 			if p.signature.arity == 0 then
 				cargs.add(cfc.varname(nmc.method_params[0]))
 			else
-				for va in nmc.method_params do
+				for va in nmc.method_params.as(not null) do
 					cargs.add(cfc.varname(va))
 				end
 			end
 			#s.append(" {p}")
-			p.compile_call(self, cargs)
+			p.compile_stmt_call(self, cargs)
 			i += 1
 		end
 		#s.append(" ]")
@@ -155,7 +152,7 @@ class CFunctionContext
 	attr _varindexes: Map[Variable, Int] = new HashMap[Variable, Int]
 
 	# Are we currenlty in a closure definition?
-	readable writable attr _closure: NitMethodContext = null
+	readable writable attr _closure: nullable NitMethodContext = null
 
 	# Return the cvariable of a Nit variable
 	meth varname(v: Variable): String
@@ -168,7 +165,7 @@ class CFunctionContext
 	end
 
 	# Return the next available variable
-	meth get_var(comment: String): String
+	meth get_var(comment: nullable String): String
 	do
 		var v = variable(_variable_index)
 		_variable_index = _variable_index + 1
@@ -235,6 +232,15 @@ class CFunctionContext
 		end
 	end
 
+	# Is s a valid variable
+	protected meth is_valid_variable(s: String): Bool
+	do
+		for i in [0.._variable_index[ do
+			if s == variable(i) then return true
+		end
+		return false
+	end
+
 	# Mark the variable available
 	meth free_var(v: String)
 	do
@@ -266,30 +272,30 @@ end
 # A Nit method currenlty compiled
 class NitMethodContext
 	# Current method compiled
-	readable attr _method: MMSrcMethod
+	readable attr _method: nullable MMSrcMethod
 
 	# Association between parameters and the corresponding variables
-	readable writable attr _method_params: Array[ParamVariable] 
+	readable writable attr _method_params: nullable Array[ParamVariable]
 
 	# Where a nit return must branch
-	readable writable attr _return_label: String 
-	
+	readable writable attr _return_label: nullable String
+
 	# Where a nit break must branch
-	readable writable attr _break_label: String 
-	
+	readable writable attr _break_label: nullable String
+
 	# Where a nit continue must branch
-	readable writable attr _continue_label: String 
+	readable writable attr _continue_label: nullable String
 
 	# Variable where a functionnal nit return must store its value
-	readable writable attr _return_value: String 
+	readable writable attr _return_value: nullable String
 
 	# Variable where a functionnal nit break must store its value
-	readable writable attr _break_value: String 
+	readable writable attr _break_value: nullable String
 
 	# Variable where a functionnal nit continue must store its value
-	readable writable attr _continue_value: String 
+	readable writable attr _continue_value: nullable String
 
-	init(method: MMSrcMethod)
+	init(method: nullable MMSrcMethod)
 	do
 		_method = method
 	end
@@ -298,15 +304,34 @@ end
 ###############################################################################
 
 redef class ClosureVariable
-	readable writable attr _ctypename: String
+	readable writable attr _ctypename: nullable String
 end
 
 redef class MMMethod
+	# Compile as an expression.
+	# require that signature.return_type != null
+	meth compile_expr_call(v: CompilerVisitor, cargs: Array[String]): String
+	do
+		assert signature.return_type != null
+		var s = intern_compile_call(v, cargs)
+		assert s != null
+		return s
+	end
+
+	# Compile as a statement.
+	# require that signature.return_type == null
+	meth compile_stmt_call(v: CompilerVisitor, cargs: Array[String])
+	do
+		assert signature.return_type == null
+		var s = intern_compile_call(v, cargs)
+		assert s == null
+	end
+
 	# Compile a call on self for given arguments
 	# Most calls are compiled with a table access,
 	# primitive calles are inlined
 	# == and != are guarded and possibly inlined
-	meth compile_call(v: CompilerVisitor, cargs: Array[String]): String
+	private meth intern_compile_call(v: CompilerVisitor, cargs: Array[String]): nullable String
 	do
 		var i = self
 		if i isa MMSrcMethod then
@@ -321,7 +346,7 @@ redef class MMMethod
 		var ne = once "!=".to_symbol
 		if name == ne then
 			var eqp = signature.recv.local_class.select_method(ee)
-			var eqcall = eqp.compile_call(v, cargs)
+			var eqcall = eqp.compile_expr_call(v, cargs)
 			return "TAG_Bool(!UNTAG_Bool({eqcall}))"
 		end
 		if global.is_init then
@@ -348,9 +373,9 @@ redef class MMMethod
 	end
 
 	# Compile a call on self for given arguments and given closures
-	meth compile_call_and_closures(v: CompilerVisitor, cargs: Array[String], clos_defs: Array[PClosureDef]): String
+	meth compile_call_and_closures(v: CompilerVisitor, cargs: Array[String], clos_defs: nullable Array[PClosureDef]): nullable String
 	do
-		var ve: String = null
+		var ve: String
 		var arity = 0
 		if clos_defs != null then arity = clos_defs.length
 
@@ -376,7 +401,7 @@ redef class MMMethod
 		v.nmc.break_value = old_bv
 
 		# Call
-		var e = compile_call(v, realcargs)
+		var e = intern_compile_call(v, realcargs)
 		if e != null then
 			v.add_assignment(ve, e)
 			e = ve
@@ -429,11 +454,27 @@ redef class MMMethod
 end
 
 redef class MMAttribute
-	# Compile an acces on selffor a given reciever.
-	# Result is a valid C left-value for assigment
-	meth compile_access(v: CompilerVisitor, recv: String): String
+	# Compile a read acces on selffor a given reciever.
+	meth compile_isset(v: CompilerVisitor, n: PNode, recv: String): String
+	do
+		return "TAG_Bool({global.attr_access}({recv})!=NIT_NULL) /* isset {local_class}::{name}*/"
+	end
+
+	# Compile a read acces on selffor a given reciever.
+	meth compile_read_access(v: CompilerVisitor, n: PNode, recv: String): String
+	do
+		var res = "{global.attr_access}({recv}) /*{local_class}::{name}*/"
+		if not signature.return_type.is_nullable and v.tc.opt_warn.value > 0 then
+			res = v.ensure_var(res, "{local_class}::{name}")
+			v.add_instr("if ({res} == NIT_NULL) \{ fprintf(stderr, \"Uninitialized attribute %s\", \"{name}\"); {v.printf_locate_error(n)} } /* implicit isset */;")
+		end
+		return res
+	end
+
+	# Compile a write acces on selffor a given reciever.
+	meth compile_write_access(v: CompilerVisitor, n: nullable PNode, recv: String, value: String)
 	do
-		return "{global.attr_access}({recv}) /*{local_class}::{name}*/"
+		v.add_instr("{global.attr_access}({recv}) /*{local_class}::{name}*/ = {value};")
 	end
 end
 
@@ -535,20 +576,20 @@ redef class MMSrcMethod
 	end
 
 	# Compile the method body inline
-	meth do_compile_inside(v: CompilerVisitor, params: Array[String]): String is abstract
+	meth do_compile_inside(v: CompilerVisitor, params: Array[String]): nullable String is abstract
 end
 
 redef class MMReadImplementationMethod
 	redef meth do_compile_inside(v, params)
 	do
-		return node.prop.compile_access(v, params[0])
+		return node.prop.compile_read_access(v, node, params[0])
 	end
 end
 
 redef class MMWriteImplementationMethod
 	redef meth do_compile_inside(v, params)
 	do
-		v.add_assignment(node.prop.compile_access(v, params[0]), params[1])
+		node.prop.compile_write_access(v, node, params[0], params[1])
 		return null
 	end
 end
@@ -574,14 +615,14 @@ redef class MMImplicitInit
 				for i in [1..f[ do
 					args.add(params[i])
 				end
-				sp.compile_call(v, args)
+				sp.compile_stmt_call(v, args)
 			else
-				sp.compile_call(v, args_recv)
+				sp.compile_stmt_call(v, args_recv)
 			end
 		end
 		for i in [f..params.length[ do
 			var attribute = unassigned_attributes[i-f]
-			v.add_assignment(attribute.compile_access(v, recv), params[i])
+			attribute.compile_write_access(v, null, recv, params[i])
 		end
 		return null
 	end
@@ -590,19 +631,49 @@ end
 redef class MMType
 	# Compile a subtype check to self
 	# Return a NIT Bool
-	meth compile_cast(v: CompilerVisitor, recv: String): String
+	meth compile_cast(v: CompilerVisitor, recv: String, fromtype: MMType): String
 	do
 		# Fixme: handle formaltypes
 		var g = local_class.global
-		return "TAG_Bool(({recv}==NIT_NULL) || VAL_ISA({recv}, {g.color_id}, {g.id_id})) /*cast {self}*/"
+		var s = ""
+		if fromtype.is_nullable then
+			if self.is_nullable then
+				s = "({recv}==NIT_NULL) || "
+			else
+				s = "({recv}!=NIT_NULL) && "
+			end
+		else
+			# FIXME This is used to not break code without the nullable KW
+			s = "({recv}==NIT_NULL) || "
+		end
+		return "TAG_Bool({s}VAL_ISA({recv}, {g.color_id}, {g.id_id})) /*cast {self}*/"
 	end
 
 	# Compile a cast assertion
-	meth compile_type_check(v: CompilerVisitor, recv: String, n: PNode)
+	meth compile_type_check(v: CompilerVisitor, recv: String, n: PNode, fromtype: MMType)
 	do
 		# Fixme: handle formaltypes
 		var g = local_class.global
-		v.add_instr("if (({recv}!=NIT_NULL) && !VAL_ISA({recv}, {g.color_id}, {g.id_id})) \{ fprintf(stderr, \"Cast failled\"); {v.printf_locate_error(n)} nit_exit(1); } /*cast {self}*/;")
+		var s = ""
+		if fromtype.is_nullable then
+			if self.is_nullable then
+				s = "({recv}!=NIT_NULL) && "
+			else
+				s = "({recv}==NIT_NULL) || "
+			end
+		else
+			# FIXME This is used to not break code without the nullable KW
+			s = "({recv}!=NIT_NULL) && "
+		end
+		v.add_instr("if ({s}!VAL_ISA({recv}, {g.color_id}, {g.id_id})) \{ fprintf(stderr, \"Cast failled\"); {v.printf_locate_error(n)} nit_exit(1); } /*cast {self}*/;")
+	end
+
+	# Compile a notnull cast assertion
+	meth compile_notnull_check(v: CompilerVisitor, recv: String, n: PNode)
+	do
+		if is_nullable then
+			v.add_instr("if (({recv}==NIT_NULL)) \{ fprintf(stderr, \"Cast failled\"); {v.printf_locate_error(n)} nit_exit(1); } /*cast {self}*/;")
+		end
 	end
 end
 
@@ -610,7 +681,7 @@ end
 
 redef class AMethPropdef
 	# Compile the method body
-	meth do_compile_inside(v: CompilerVisitor, method: MMSrcMethod, params: Array[String]): String is abstract
+	meth do_compile_inside(v: CompilerVisitor, method: MMSrcMethod, params: Array[String]): nullable String is abstract
 end
 
 redef class PSignature
@@ -624,11 +695,11 @@ redef class ASignature
 			var cname = v.cfc.register_variable(ap.variable)
 			v.nmc.method_params.add(ap.variable)
 			var orig_type = orig_sig[ap.position]
-			if not orig_type < ap.variable.stype then
+			if not orig_type < ap.variable.stype.as(not null) then
 				# FIXME: do not test always
 				# FIXME: handle formal types
 				v.add_instr("/* check if p<{ap.variable.stype} with p:{orig_type} */")
-				ap.variable.stype.compile_type_check(v, params[ap.position], ap)
+				ap.variable.stype.compile_type_check(v, params[ap.position], ap, orig_type)
 			end
 			v.add_assignment(cname, params[ap.position])
 		end
@@ -652,13 +723,13 @@ redef class AConcreteMethPropdef
 		params.shift
 		v.nmc.method_params = [self_var]
 
+		var orig_meth: MMLocalProperty = method.global.intro
+		var orig_sig = orig_meth.signature_for(method.signature.recv)
 		if n_signature != null then
-			var orig_meth: MMLocalProperty = method.global.intro
-			var orig_sig = orig_meth.signature_for(method.signature.recv)
 			n_signature.compile_parameters(v, orig_sig, params)
 		end
 
-		var itpos: String = null
+		var itpos: nullable String = null
 		if self isa AConcreteInitPropdef then
 			itpos = "VAL2OBJ({selfcname})->vft[{method.local_class.global.init_table_pos_id}].i"
 			# v.add_instr("printf(\"{method.full_name}: inittable[%d] = %d\\n\", {itpos}, init_table[{itpos}]);")
@@ -670,15 +741,13 @@ redef class AConcreteMethPropdef
 		if self isa AConcreteInitPropdef then
 			v.invoke_super_init_calls_after(null)
 		end
-		if n_block != null then
-			v.compile_stmt(n_block)
-		end
+		v.compile_stmt(n_block)
 		v.add_instr("{v.nmc.return_label}: while(false);")
 		if self isa AConcreteInitPropdef then
 			v.add_instr("init_table[{itpos}] = 1;")
 		end
 
-		var ret: String = null
+		var ret: nullable String = null
 		if method.signature.return_type != null then
 			ret = v.nmc.return_value
 		end
@@ -734,7 +803,7 @@ redef class AInternMethPropdef
 	do
 		var c = method.local_class.name
 		var n = method.name
-		var s: String = null
+		var s: nullable String = null
 		if c == once "Int".to_symbol then
 			if n == once "object_id".to_symbol then
 				s = "{p[0]}"
@@ -940,7 +1009,7 @@ redef class AVardeclExpr
 		if n_expr == null then
 			v.add_instr("/*{cname} is variable {variable.name}*/")
 		else
-			var e = v.compile_expr(n_expr)
+			var e = v.compile_expr(n_expr.as(not null))
 			v.add_assignment(cname, e)
 		end
 	end
@@ -950,8 +1019,8 @@ redef class AReturnExpr
 	redef meth compile_stmt(v)
 	do
 		if n_expr != null then
-			var e = v.compile_expr(n_expr)
-			v.add_assignment(v.nmc.return_value, e)
+			var e = v.compile_expr(n_expr.as(not null))
+			v.add_assignment(v.nmc.return_value.as(not null), e)
 		end
 		if v.cfc.closure == v.nmc then v.add_instr("closctx->has_broke = &({v.nmc.return_value});")
 		v.add_instr("goto {v.nmc.return_label};")
@@ -962,8 +1031,8 @@ redef class ABreakExpr
 	redef meth compile_stmt(v)
 	do
 		if n_expr != null then
-			var e = v.compile_expr(n_expr)
-			v.add_assignment(v.nmc.break_value, e)
+			var e = v.compile_expr(n_expr.as(not null))
+			v.add_assignment(v.nmc.break_value.as(not null), e)
 		end
 		if v.cfc.closure == v.nmc then v.add_instr("closctx->has_broke = &({v.nmc.break_value}); closctx->broke_value = *closctx->has_broke;")
 		v.add_instr("goto {v.nmc.break_label};")
@@ -974,8 +1043,8 @@ redef class AContinueExpr
 	redef meth compile_stmt(v)
 	do
 		if n_expr != null then
-			var e = v.compile_expr(n_expr)
-			v.add_assignment(v.nmc.continue_value, e)
+			var e = v.compile_expr(n_expr.as(not null))
+			v.add_assignment(v.nmc.continue_value.as(not null), e)
 		end
 		v.add_instr("goto {v.nmc.continue_label};")
 	end
@@ -991,9 +1060,7 @@ end
 redef class ADoExpr
 	redef meth compile_stmt(v)
 	do
-		 if n_block != null then
-			 v.compile_stmt(n_block)
-		 end
+		v.compile_stmt(n_block)
 	end
 end
 
@@ -1038,7 +1105,8 @@ redef class AIfexprExpr
 	end
 end
 
-redef class AControlableBlock
+class AControlableBlock
+special PExpr
 	meth compile_inside_block(v: CompilerVisitor) is abstract
 	redef meth compile_stmt(v)
 	do
@@ -1057,6 +1125,7 @@ redef class AControlableBlock
 end
 
 redef class AWhileExpr
+special AControlableBlock
 	redef meth compile_inside_block(v)
 	do
 		v.add_instr("while (true) \{ /*while*/")
@@ -1064,9 +1133,7 @@ redef class AWhileExpr
 		var e = v.compile_expr(n_expr)
 		v.add_instr("if (!UNTAG_Bool({e})) break; /* while*/")
 		v.cfc.free_var(e)
-		if n_block != null then
-			v.compile_stmt(n_block)
-		end
+		v.compile_stmt(n_block)
 		v.add_instr("{v.nmc.continue_label}: while(0);")
 		v.unindent
 		v.add_instr("}")
@@ -1075,30 +1142,27 @@ redef class AWhileExpr
 end
 
 redef class AForExpr
+special AControlableBlock
 	redef meth compile_inside_block(v)
 	do
 		var e = v.compile_expr(n_expr)
 		var ittype = meth_iterator.signature.return_type
 		v.cfc.free_var(e)
 		var iter = v.cfc.get_var("For iterator")
-		v.add_assignment(iter, meth_iterator.compile_call(v, [e]))
+		v.add_assignment(iter, meth_iterator.compile_expr_call(v, [e]))
 		v.add_instr("while (true) \{ /*for*/")
 		v.indent
 		var ok = v.cfc.get_var("For 'is_ok' result")
-		v.add_assignment(ok, meth_is_ok.compile_call(v, [iter]))
+		v.add_assignment(ok, meth_is_ok.compile_expr_call(v, [iter]))
 		v.add_instr("if (!UNTAG_Bool({ok})) break; /*for*/")
 		v.cfc.free_var(ok)
-		var e = meth_item.compile_call(v, [iter])
+		var e = meth_item.compile_expr_call(v, [iter])
 		e = v.ensure_var(e, "For item")
 		var cname = v.cfc.register_variable(variable)
 		v.add_assignment(cname, e)
-		var n_block = n_block
-		if n_block != null then
-			v.compile_stmt(n_block)
-		end
+		v.compile_stmt(n_block)
 		v.add_instr("{v.nmc.continue_label}: while(0);")
-		e = meth_next.compile_call(v, [iter])
-		assert e == null
+		meth_next.compile_stmt_call(v, [iter])
 		v.unindent
 		v.add_instr("}")
 		v.add_instr("{v.nmc.break_label}: while(0);")
@@ -1137,7 +1201,7 @@ redef class AVarReassignExpr
 	do
 		var e1 = v.cfc.varname(variable)
 		var e2 = v.compile_expr(n_value)
-		var e3 = assign_method.compile_call(v, [e1, e2])
+		var e3 = assign_method.compile_expr_call(v, [e1, e2])
 		v.add_assignment(v.cfc.varname(variable), "{e3} /*{variable.name}*/")
 	end
 end
@@ -1199,7 +1263,7 @@ redef class AIsaExpr
 	redef meth compile_expr(v)
 	do
 		var e = v.compile_expr(n_expr)
-		return n_type.stype.compile_cast(v, e)
+		return n_type.stype.compile_cast(v, e, n_expr.stype)
 	end
 end
 
@@ -1207,7 +1271,16 @@ redef class AAsCastExpr
 	redef meth compile_expr(v)
 	do
 		var e = v.compile_expr(n_expr)
-		n_type.stype.compile_type_check(v, e, self)
+		n_type.stype.compile_type_check(v, e, self, n_expr.stype)
+		return e
+	end
+end
+
+redef class AAsNotnullExpr
+	redef meth compile_expr(v)
+	do
+		var e = v.compile_expr(n_expr)
+		n_expr.stype.compile_notnull_check(v, e, self)
 		return e
 	end
 end
@@ -1258,7 +1331,7 @@ redef class AStringFormExpr
 		v.add_instr("else \{")
 		v.indent
 		v.cfc.free_var(cvar)
-		var e = meth_with_native.compile_constructor_call(v, stype , ["BOX_NativeString(\"{_cstring}\")", "TAG_Int({_cstring_length})"])
+		var e = meth_with_native.compile_constructor_call(v, stype, ["BOX_NativeString(\"{_cstring}\")", "TAG_Int({_cstring_length})"])
 		v.add_assignment(cvar, e)
 		v.add_instr("once_value_{i} = {cvar};")
 		v.unindent
@@ -1270,10 +1343,10 @@ redef class AStringFormExpr
 	protected meth string_text: String is abstract
 
 	# The string in a C native format
-	protected attr _cstring: String
+	protected attr _cstring: nullable String
 
 	# The string length in bytes
-	protected attr _cstring_length: Int
+	protected attr _cstring_length: nullable Int
 
 	# Compute _cstring and _cstring_length using string_text
 	protected meth compute_string_info
@@ -1317,20 +1390,20 @@ end
 redef class ASuperstringExpr
 	redef meth compile_expr(v)
 	do
-		var array = meth_with_capacity.compile_constructor_call(v, atype, ["TAG_Int({n_exprs.length})"])
+		var array = meth_with_capacity.compile_constructor_call(v, atype.as(not null), ["TAG_Int({n_exprs.length})"])
 		array = v.ensure_var(array, "Array (for super-string)")
 
 		for ne in n_exprs do
 			var e = v.ensure_var(v.compile_expr(ne), "super-string element")
 			if ne.stype != stype then
 				v.cfc.free_var(e)
-				e = meth_to_s.compile_call(v, [e])
+				e = meth_to_s.compile_expr_call(v, [e])
 			end
 			v.cfc.free_var(e)
-			meth_add.compile_call(v, [array, e])
+			meth_add.compile_stmt_call(v, [array, e])
 		end
 
-		return meth_to_s.compile_call(v, [array])
+		return meth_to_s.compile_expr_call(v, [array])
 	end
 end
 
@@ -1349,7 +1422,7 @@ redef class AArrayExpr
 
 		for ne in n_exprs do
 			var e = v.compile_expr(ne)
-			meth_add.compile_call(v, [recv, e])
+			meth_add.compile_stmt_call(v, [recv, e])
 		end
 		return recv
 	end
@@ -1367,12 +1440,21 @@ end
 redef class ASuperExpr
 	redef meth compile_stmt(v)
 	do
-		var e = compile_expr(v)
-		if e != null then v.add_instr("{e};")
+		var e = intern_compile_call(v)
+		if e != null then
+			v.add_instr(e + ";")
+		end
 	end
 
 	redef meth compile_expr(v)
 	do
+		var e = intern_compile_call(v)
+		assert e != null
+		return e
+	end
+
+	private meth intern_compile_call(v: CompilerVisitor): nullable String
+	do
 		var arity = v.nmc.method_params.length - 1
 		if init_in_superclass != null then
 			arity = init_in_superclass.signature.arity
@@ -1390,7 +1472,7 @@ redef class ASuperExpr
 		end
 		#return "{prop.cname}({args.join(", ")}) /*super {prop.local_class}::{prop.name}*/"
 		if init_in_superclass != null then
-			return init_in_superclass.compile_call(v, args)
+			return init_in_superclass.intern_compile_call(v, args)
 		else
 			if prop.global.is_init then args.add("init_table")
 			return prop.compile_super_call(v, args)
@@ -1402,7 +1484,7 @@ redef class AAttrExpr
 	redef meth compile_expr(v)
 	do
 		var e = v.compile_expr(n_expr)
-		return prop.compile_access(v, e)
+		return prop.compile_read_access(v, n_id, e)
 	end
 end
 
@@ -1411,33 +1493,50 @@ redef class AAttrAssignExpr
 	do
 		var e = v.compile_expr(n_expr)
 		var e2 = v.compile_expr(n_value)
-		v.add_assignment(prop.compile_access(v, e), e2)
+		prop.compile_write_access(v, n_id, e, e2)
 	end
 end
 redef class AAttrReassignExpr
 	redef meth compile_stmt(v)
 	do
 		var e1 = v.compile_expr(n_expr)
-		var e2 = prop.compile_access(v, e1)
+		var e2 = prop.compile_read_access(v, n_id, e1)
 		var e3 = v.compile_expr(n_value)
-		var e4 = assign_method.compile_call(v, [e2, e3])
-		v.add_assignment(e2, e4)
+		var e4 = assign_method.compile_expr_call(v, [e2, e3])
+		prop.compile_write_access(v, n_id, e1, e4)
 	end
 end
 
-redef class ASendExpr
+redef class AIssetAttrExpr
 	redef meth compile_expr(v)
 	do
+		var e = v.compile_expr(n_expr)
+		return prop.compile_isset(v, n_id, e)
+	end
+end
+
+redef class AAbsAbsSendExpr
+	# Compile each argument and add them to the array
+	meth compile_arguments_in(v: CompilerVisitor, cargs: Array[String])
+	do
+		for a in arguments.as(not null) do
+			cargs.add(v.compile_expr(a))
+		end
+	end
+
+end
+
+redef class ASendExpr
+	private meth intern_compile_call(v: CompilerVisitor): nullable String
+	do
 		var recv = v.compile_expr(n_expr)
 		var cargs = new Array[String]
 		cargs.add(recv)
-		for a in arguments do
-			cargs.add(v.compile_expr(a))
-		end
+		compile_arguments_in(v, cargs)
 
-		var e: String
+		var e: nullable String
 		if prop_signature.closures.is_empty then
-			e = prop.compile_call(v, cargs)
+			e = prop.intern_compile_call(v, cargs)
 		else
 			e = prop.compile_call_and_closures(v, cargs, closure_defs)
 		end
@@ -1448,9 +1547,16 @@ redef class ASendExpr
 		return e
 	end
 
+	redef meth compile_expr(v)
+	do
+		var e = intern_compile_call(v)
+		assert e != null
+		return e
+	end
+
 	redef meth compile_stmt(v)
 	do
-		var e = compile_expr(v)
+		var e = intern_compile_call(v)
 		if e != null then
 			v.add_instr(e + ";")
 		end
@@ -1458,20 +1564,20 @@ redef class ASendExpr
 end
 
 redef class ASendReassignExpr
-	redef meth compile_expr(v)
+	redef meth compile_expr(v) do abort
+
+	redef meth compile_stmt(v)
 	do
 		var recv = v.compile_expr(n_expr)
 		var cargs = new Array[String]
 		cargs.add(recv)
-		for a in arguments do
-			cargs.add(v.compile_expr(a))
-		end
+		compile_arguments_in(v, cargs)
 
-		var e2 = read_prop.compile_call(v, cargs)
+		var e2 = read_prop.compile_expr_call(v, cargs)
 		var e3 = v.compile_expr(n_value)
-		var e4 = assign_method.compile_call(v, [e2, e3])
+		var e4 = assign_method.compile_expr_call(v, [e2, e3])
 		cargs.add(e4)
-		return prop.compile_call(v, cargs)
+		prop.compile_stmt_call(v, cargs)
 	end
 end
 
@@ -1479,11 +1585,11 @@ redef class ANewExpr
 	redef meth compile_expr(v)
 	do
 		var cargs = new Array[String]
-		for a in arguments do
-			cargs.add(v.compile_expr(a))
-		end
-		return prop.compile_constructor_call(v, stype, cargs) 
+		compile_arguments_in(v, cargs)
+		return prop.compile_constructor_call(v, stype, cargs)
 	end
+
+	redef meth compile_stmt(v) do abort
 end
 
 redef class PClosureDef
@@ -1492,12 +1598,12 @@ redef class PClosureDef
 	meth compile_closure(v: CompilerVisitor, closcn: String): String is abstract
 
 	# Compile the closure definition inside the current C function.
-	meth do_compile_inside(v: CompilerVisitor, params: Array[String]): String is abstract
+	meth do_compile_inside(v: CompilerVisitor, params: nullable Array[String]): nullable String is abstract
 end
 
 redef class AClosureDef
 	# The cname of the function
-	readable attr _cname: String
+	readable attr _cname: nullable String
 
 	redef meth compile_closure(v, closcn)
 	do
@@ -1605,11 +1711,11 @@ redef class AClosureDef
 		v.nmc.continue_label = "continue_label{v.new_number}"
 		v.nmc.break_label = v.nmc.return_label
 
-		if n_expr != null then v.compile_stmt(n_expr)
+		v.compile_stmt(n_expr)
 
 		v.add_instr("{v.nmc.continue_label}: while(false);")
 
-		var ret: String = null
+		var ret: nullable String = null
 		if closure.signature.return_type != null then ret = v.nmc.continue_value
 
 		v.nmc.continue_value = old_cv
@@ -1621,12 +1727,12 @@ redef class AClosureDef
 end
 
 redef class PClosureDecl
-	meth do_compile_inside(v: CompilerVisitor, params: Array[String]): String is abstract
+	meth do_compile_inside(v: CompilerVisitor, params: Array[String]): nullable String is abstract
 end
 redef class AClosureDecl
 	redef meth do_compile_inside(v, params)
 	do
-		if n_signature != null then n_signature.compile_parameters(v, variable.closure.signature, params)
+		n_signature.compile_parameters(v, variable.closure.signature, params)
 
 		var old_cv = v.nmc.continue_value
 		var old_cl = v.nmc.continue_label
@@ -1636,11 +1742,11 @@ redef class AClosureDecl
 		v.nmc.continue_label = "continue_label{v.new_number}"
 		v.nmc.break_label = v.nmc.return_label
 
-		if n_expr != null then v.compile_stmt(n_expr)
+		v.compile_stmt(n_expr)
 
 		v.add_instr("{v.nmc.continue_label}: while(false);")
 
-		var ret: String = null
+		var ret: nullable String = null
 		if variable.closure.signature.return_type != null then ret = v.nmc.continue_value
 
 		v.nmc.continue_value = old_cv
@@ -1652,11 +1758,11 @@ redef class AClosureDecl
 end
 
 redef class AClosureCallExpr
-	redef meth compile_expr(v)
+	meth intern_compile_call(v: CompilerVisitor): nullable String
 	do
 		var cargs = new Array[String]
-		for a in arguments do cargs.add(v.compile_expr(a))
-		var va: String = null
+		compile_arguments_in(v, cargs)
+		var va: nullable String = null
 		if variable.closure.signature.return_type != null then va = v.cfc.get_var("Closure call result value")
 
 		if variable.closure.is_optional then
@@ -1665,7 +1771,7 @@ redef class AClosureCallExpr
 			var n = variable.decl
 			assert n isa AClosureDecl
 			var s = n.do_compile_inside(v, cargs)
-			if s != null then v.add_assignment(va, s)
+			if s != null then v.add_assignment(va.as(not null), s)
 			v.unindent
 			v.add_instr("} else \{")
 			v.indent
@@ -1682,7 +1788,7 @@ redef class AClosureCallExpr
 		end
 		v.add_instr("if ({ivar}->has_broke) \{")
 		v.indent
-		if n_closure_defs != null and n_closure_defs.length == 1 then do
+		if n_closure_defs.length == 1 then do
 			n_closure_defs.first.do_compile_inside(v, null)
 		end
 		if v.cfc.closure == v.nmc then v.add_instr("if ({ivar}->has_broke) \{ closctx->has_broke = {ivar}->has_broke; closctx->broke_value = {ivar}->broke_value;\}")
@@ -1696,6 +1802,21 @@ redef class AClosureCallExpr
 		end
 		return va
 	end
+
+	redef meth compile_expr(v)
+	do
+		var e = intern_compile_call(v)
+		assert e != null
+		return e
+	end
+
+	redef meth compile_stmt(v)
+	do
+		var e = intern_compile_call(v)
+		if e != null then
+			v.add_instr(e + ";")
+		end
+	end
 end
 
 redef class AProxyExpr