typing: ensure monotony on literal arrays

[nit.git] / src / semantize / typing.nit

diff --git a/src/semantize/typing.nit b/src/semantize/typing.nit
index 8ca8c6e..ba08e4d 100644 (file)
--- a/src/semantize/typing.nit
+++ b/src/semantize/typing.nit
@@ -252,11 +252,11 @@ private class TypeVisitor
 
                # One is null (mtype2 see above) the other is not null
                if anode isa AEqExpr then
-                       anode.after_flow_context.when_true.set_var(variable, mtype2)
-                       anode.after_flow_context.when_false.set_var(variable, mtype)
+                       anode.after_flow_context.when_true.set_var(self, variable, mtype2)
+                       anode.after_flow_context.when_false.set_var(self, variable, mtype)
                else if anode isa ANeExpr then
-                       anode.after_flow_context.when_false.set_var(variable, mtype2)
-                       anode.after_flow_context.when_true.set_var(variable, mtype)
+                       anode.after_flow_context.when_false.set_var(self, variable, mtype2)
+                       anode.after_flow_context.when_true.set_var(self, variable, mtype)
                else
                        abort
                end
@@ -468,12 +468,18 @@ private class TypeVisitor
                end
        end
 
+       # Some variables where type-adapted during the visit
+       var dirty = false
+
+       # Some loops had been visited during the visit
+       var has_loop = false
+
        fun set_variable(node: AExpr, variable: Variable, mtype: nullable MType)
        do
                var flow = node.after_flow_context
                assert flow != null
 
-               flow.set_var(variable, mtype)
+               flow.set_var(self, variable, mtype)
        end
 
        fun merge_types(node: ANode, col: Array[nullable MType]): nullable MType
@@ -549,9 +555,12 @@ redef class FlowContext
        # Adapt the variable to a static type
        # Warning1: do not modify vars directly.
        # Warning2: sub-flow may have cached a unadapted variable
-       private fun set_var(variable: Variable, mtype: nullable MType)
+       private fun set_var(v: TypeVisitor, variable: Variable, mtype: nullable MType)
        do
+               if vars.has_key(variable) and vars[variable] == mtype then return
                self.vars[variable] = mtype
+               v.dirty = true
+               #node.debug "set {variable} to {mtype or else "X"}"
        end
 
        # Look in the flow and previous flow and collect all first reachable type adaptation of a local variable
@@ -623,7 +632,12 @@ redef class AMethPropdef
                        assert variable != null
                        variable.declared_type = mtype
                end
-               v.visit_stmt(nblock)
+
+               loop
+                       v.dirty = false
+                       v.visit_stmt(nblock)
+                       if not v.has_loop or not v.dirty then break
+               end
 
                if not nblock.after_flow_context.is_unreachable and msignature.return_mtype != null then
                        # We reach the end of the function without having a return, it is bad
@@ -952,8 +966,8 @@ end
 redef class AWhileExpr
        redef fun accept_typing(v)
        do
+               v.has_loop = true
                v.visit_expr_bool(n_expr)
-
                v.visit_stmt(n_block)
                self.is_typed = true
        end
@@ -962,6 +976,7 @@ end
 redef class ALoopExpr
        redef fun accept_typing(v)
        do
+               v.has_loop = true
                v.visit_stmt(n_block)
                self.is_typed = true
        end
@@ -1097,12 +1112,14 @@ redef class AForExpr
 
        redef fun accept_typing(v)
        do
+               v.has_loop = true
                var mtype = v.visit_expr(n_expr)
                if mtype == null then return
 
                self.do_type_iterator(v, mtype)
 
                v.visit_stmt(n_block)
+
                self.mtype = n_block.mtype
                self.is_typed = true
        end
@@ -1317,6 +1334,8 @@ redef class AArrayExpr
                        end
                end
                if mtype == null then
+                       # Ensure monotony for type adaptation on loops
+                       if self.element_mtype != null then mtypes.add self.element_mtype
                        mtype = v.merge_types(self, mtypes)
                end
                if mtype == null or mtype isa MNullType then
@@ -1401,7 +1420,7 @@ redef class AIsaExpr
                        #var from = if orig != null then orig.to_s else "invalid"
                        #var to = if mtype != null then mtype.to_s else "invalid"
                        #debug("adapt {variable}: {from} -> {to}")
-                       self.after_flow_context.when_true.set_var(variable, mtype)
+                       self.after_flow_context.when_true.set_var(v, variable, mtype)
                end
 
                self.mtype = v.type_bool(self)