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

diff --git a/src/syntax/control_flow.nit b/src/syntax/control_flow.nit
index 50fcb57..f044cd1 100644
--- a/src/syntax/control_flow.nit
+++ b/src/syntax/control_flow.nit
@@ -29,6 +29,17 @@ redef class MMSrcModule
 	end
 end
 
+redef class Variable
+	# Is the variable must be set before being used ?
+	meth must_be_set: Bool do return false
+end
+
+redef class VarVariable
+	redef meth must_be_set do return true
+end
+
+
+
 # Control flow visitor
 # * Check reachability in methods
 # * Associate breaks and continues
@@ -41,14 +52,14 @@ special AbsSyntaxVisitor
 	end
 
 	# Number of nested once
-	readable writable attr _once_count: Int
+	readable writable attr _once_count: Int = 0
 
 	# Current knowledge about variables types
 	readable writable attr _control_flow_ctx: ControlFlowContext
 
 	meth check_is_set(n: PNode, v: Variable)
 	do
-		if not control_flow_ctx.is_set(v) then
+		if v.must_be_set and not control_flow_ctx.is_set(v) then
 			error(n, "Error: variable '{v}' is possibly unset.")
 			var cfc = control_flow_ctx
 			while cfc != null do
@@ -70,15 +81,12 @@ private class ControlFlowContext
 	# Previous control flow context if any
 	readable attr _prev: ControlFlowContext
 
-	# Is a return met?
-	readable writable attr _has_return: Bool 
-
 	# Is a control flow break met? (return, break, continue)
-	readable writable attr _unreash: Bool
+	readable writable attr _unreash: Bool = false
 
 	# Is a control flow already broken?
 	# Used to avoid repeating the same error message
-	readable writable attr _already_unreash: Bool
+	readable writable attr _already_unreash: Bool = false
 
 	# Current controlable block (for or while)
 	readable writable attr _base_block: AControlableBlock
@@ -94,17 +102,16 @@ private class ControlFlowContext
 
 	meth sub: ControlFlowContext
 	do
-		return new ControlFlowContext.with(self)
+		return new ControlFlowContext.with_prev(self)
 	end
 
 	init
 	do 
 	end
 
-	init with(p: ControlFlowContext)
+	init with_prev(p: ControlFlowContext)
 	do
 		_prev = p
-		_has_return = p.has_return
 		_unreash = p.unreash
 		_already_unreash = p.already_unreash
 		_base_block = p.base_block
@@ -132,20 +139,12 @@ redef class AConcreteMethPropdef
 	redef meth accept_control_flow(v)
 	do
 		super
-		if v.control_flow_ctx.has_return == false and method.signature.return_type != null then
-			v.error(self, "Control error: Reached end of function.")
+		if v.control_flow_ctx.unreash == false and method.signature.return_type != null then
+			v.error(self, "Control error: Reached end of function (a 'return' with a value was expected).")
 		end
 	end
 end
 
-redef class PParam
-	redef meth accept_control_flow(v)
-	do
-		super
-		v.mark_is_set(variable)
-	end
-end
-
 redef class AVardeclExpr
 	redef meth accept_control_flow(v)
 	do
@@ -171,7 +170,6 @@ redef class AReturnExpr
 	redef meth accept_control_flow(v)
 	do
 		super
-		v.control_flow_ctx.has_return = true
 		v.control_flow_ctx.unreash = true
 	end
 end
@@ -214,7 +212,6 @@ redef class AAbortExpr
 	redef meth accept_control_flow(v)
 	do
 		super
-		v.control_flow_ctx.has_return = true
 		v.control_flow_ctx.unreash = true
 	end
 end
@@ -241,7 +238,6 @@ redef class AIfExpr
 			v.visit(n_else)
 
 			# Merge then and else in the old control_flow
-			old_control_flow_ctx.has_return = v.control_flow_ctx.has_return and then_control_flow_ctx.has_return
 			old_control_flow_ctx.unreash = v.control_flow_ctx.unreash and then_control_flow_ctx.unreash
 
 			if v.control_flow_ctx.unreash then v.control_flow_ctx = then_control_flow_ctx
@@ -282,15 +278,6 @@ redef class AForExpr
 special AControlableBlock
 end
 
-redef class AForVardeclExpr
-	redef meth accept_control_flow(v)
-	do
-		super
-		v.mark_is_set(variable)
-	end
-end     
-
-
 redef class AVarExpr
 	redef meth accept_control_flow(v)
 	do