Unset variable control flow

diff --git a/src/syntax/control_flow.nit b/src/syntax/control_flow.nit
index bda14ad..50fcb57 100644 (file)
--- a/src/syntax/control_flow.nit
+++ b/src/syntax/control_flow.nit
@@ -46,6 +46,23 @@ special AbsSyntaxVisitor
        # 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
+                       error(n, "Error: variable '{v}' is possibly unset.")
+                       var cfc = control_flow_ctx
+                       while cfc != null do
+                               print("cfc: " + cfc.set_variables.join(" "))
+                               cfc = cfc.prev
+                       end
+               end
+       end
+
+       meth mark_is_set(v: Variable)
+       do
+               control_flow_ctx.set_variables.add(v)
+       end
+
        init(tc, m) do super
 end
 
@@ -66,6 +83,15 @@ private class ControlFlowContext
        # Current controlable block (for or while)
        readable writable attr _base_block: AControlableBlock
 
+       # Set of variable that are set (assigned)
+       readable attr _set_variables: HashSet[Variable] = new HashSet[Variable]
+
+       # Is a variable set?
+       meth is_set(v: Variable): Bool
+       do
+               return _set_variables.has(v) or (_prev != null and _prev.is_set(v))
+       end
+
        meth sub: ControlFlowContext
        do
                return new ControlFlowContext.with(self)
@@ -112,6 +138,22 @@ redef class AConcreteMethPropdef
        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
+               super
+               if n_expr != null then v.mark_is_set(variable)
+       end
+end
+
 redef class ABlockExpr
        redef meth accept_control_flow(v)
        do
@@ -188,20 +230,28 @@ redef class AIfExpr
                v.visit(n_then)
 
                if n_else == null then
-                       # Restore control flow ctx
+                       # Restore control flow ctx since the 'then" block is optional
                        v.control_flow_ctx = old_control_flow_ctx
                else
                        # Remember what appens in the 'then'
                        var then_control_flow_ctx = v.control_flow_ctx
                        # Reset to execute the 'else'
-                       v.control_flow_ctx = old_control_flow_ctx
+                       v.control_flow_ctx = old_control_flow_ctx.sub
 
                        v.visit(n_else)
 
-                       # Restore and conclude
+                       # 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
+                       if then_control_flow_ctx.unreash then then_control_flow_ctx = v.control_flow_ctx
+                       for variable in v.control_flow_ctx.set_variables do
+                               if then_control_flow_ctx.is_set(variable) then
+                                       old_control_flow_ctx.set_variables.add(variable)
+                               end
+                       end
                        v.control_flow_ctx = old_control_flow_ctx
-                       v.control_flow_ctx.has_return = v.control_flow_ctx.has_return and then_control_flow_ctx.has_return
-                       v.control_flow_ctx.unreash = v.control_flow_ctx.unreash and then_control_flow_ctx.unreash
                end
        end
 end
@@ -219,7 +269,7 @@ special PExpr
 
                super
 
-               # Restore control flow value
+               # Restore control flow value since all controlable blocks are optionnal
                v.control_flow_ctx = old_control_flow_ctx
        end
 end
@@ -232,6 +282,41 @@ 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
+               super
+               v.check_is_set(self, variable)
+       end
+end
+
+redef class AVarAssignExpr
+       redef meth accept_control_flow(v)
+       do
+               super
+               v.mark_is_set(variable)
+       end
+end
+
+redef class AVarReassignExpr
+       redef meth accept_control_flow(v)
+       do
+               super
+               v.check_is_set(self, variable)
+               v.mark_is_set(variable)
+       end
+end
+
+
 redef class AOnceExpr
        redef meth accept_control_flow(v)
        do