sem_prag.adb (Check_Missing_Part_Of): List all values of State_Space_Kind for readability reasons.

2014-01-29  Hristian Kirtchev  <kirtchev@adacore.com>

	* sem_prag.adb (Check_Missing_Part_Of): List all values of
	State_Space_Kind for readability reasons. Do not emit an error on
	a private item when the enclosing package lacks aspect/pragma
	Abstract_State. Do not emit an error on a private package
	instantiation when the corresponding generic template lacks
	visible state.
	(Has_Visible_State): New routine.
	* sem_util.adb (Find_Placement_In_State_Space): The visible
	declarations of any kind of child units in general act as proper
	placement location.

From-SVN: r207261

3 files changed, 118 insertions, 20 deletions

diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index 35eea8d..0f31179 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,3 +1,16 @@
+2014-01-29  Hristian Kirtchev  <kirtchev@adacore.com>
+
+	* sem_prag.adb (Check_Missing_Part_Of): List all values of
+	State_Space_Kind for readability reasons. Do not emit an error on
+	a private item when the enclosing package lacks aspect/pragma
+	Abstract_State. Do not emit an error on a private package
+	instantiation when the corresponding generic template lacks
+	visible state.
+	(Has_Visible_State): New routine.
+	* sem_util.adb (Find_Placement_In_State_Space): The visible
+	declarations of any kind of child units in general act as proper
+	placement location.
+
 2014-01-29  Robert Dewar  <dewar@adacore.com>
 
 	* a-except-2005.adb, a-except.adb, a-excpol-abort.adb, a-exstat.adb,
diff --git a/gcc/ada/sem_prag.adb b/gcc/ada/sem_prag.adb
index 3837275..fbd955b 100644
--- a/gcc/ada/sem_prag.adb
+++ b/gcc/ada/sem_prag.adb
@@ -23732,9 +23732,57 @@ package body Sem_Prag is
    ---------------------------
 
    procedure Check_Missing_Part_Of (Item_Id : Entity_Id) is
+      function Has_Visible_State (Pack_Id : Entity_Id) return Boolean;
+      --  Determine whether a package denoted by Pack_Id declares at least one
+      --  visible state.
+
+      -----------------------
+      -- Has_Visible_State --
+      -----------------------
+
+      function Has_Visible_State (Pack_Id : Entity_Id) return Boolean is
+         Item_Id : Entity_Id;
+
+      begin
+         --  Traverse the entity chain of the package trying to find at least
+         --  one visible abstract state, variable or a package [instantiation]
+         --  that declares a visible state.
+
+         Item_Id := First_Entity (Pack_Id);
+         while Present (Item_Id)
+           and then not In_Private_Part (Item_Id)
+         loop
+            --  Do not consider internally generated items
+
+            if not Comes_From_Source (Item_Id) then
+               null;
+
+            --  A visible state has been found
+
+            elsif Ekind_In (Item_Id, E_Abstract_State, E_Variable) then
+               return True;
+
+            --  Recursively peek into nested packages and instantiations
+
+            elsif Ekind (Item_Id) = E_Package
+              and then Has_Visible_State (Item_Id)
+            then
+               return True;
+            end if;
+
+            Next_Entity (Item_Id);
+         end loop;
+
+         return False;
+      end Has_Visible_State;
+
+      --  Local variables
+
       Pack_Id   : Entity_Id;
       Placement : State_Space_Kind;
 
+   --  Start of processing for Check_Missing_Part_Of
+
    begin
       --  Do not consider internally generated entities as these can never
       --  have a Part_Of indicator.
@@ -23761,37 +23809,76 @@ package body Sem_Prag is
       --  do not require a Part_Of indicator because they can never act as a
       --  hidden state.
 
+      if Placement = Not_In_Package then
+         null;
+
       --  An item declared in the body state space of a package always act as a
       --  constituent and does not need explicit Part_Of indicator.
 
+      elsif Placement = Body_State_Space then
+         null;
+
       --  In general an item declared in the visible state space of a package
       --  does not require a Part_Of indicator. The only exception is when the
       --  related package is a private child unit in which case Part_Of must
       --  denote a state in the parent unit or in one of its descendants.
 
-      if Placement = Visible_State_Space then
+      elsif Placement = Visible_State_Space then
          if Is_Child_Unit (Pack_Id)
            and then Is_Private_Descendant (Pack_Id)
          then
-            Error_Msg_N
-              ("indicator Part_Of is required in this context (SPARK RM "
-               & "7.2.6(3))", Item_Id);
-            Error_Msg_Name_1 := Chars (Pack_Id);
-            Error_Msg_N
-              ("\& is declared in the visible part of private child unit %",
-               Item_Id);
+            --  A package instantiation does not need a Part_Of indicator when
+            --  the related generic template has no visible state.
+
+            if Ekind (Item_Id) = E_Package
+              and then Is_Generic_Instance (Item_Id)
+              and then not Has_Visible_State (Item_Id)
+            then
+               null;
+
+            --  All other cases require Part_Of
+
+            else
+               Error_Msg_N
+                 ("indicator Part_Of is required in this context (SPARK RM "
+                  & "7.2.6(3))", Item_Id);
+               Error_Msg_Name_1 := Chars (Pack_Id);
+               Error_Msg_N
+                 ("\& is declared in the visible part of private child unit %",
+                  Item_Id);
+            end if;
          end if;
 
       --  When the item appears in the private state space of a packge, it must
       --  be a part of some state declared by the said package.
 
-      elsif Placement = Private_State_Space then
-         Error_Msg_N
-           ("indicator Part_Of is required in this context (SPARK RM "
-            & "7.2.6(2))", Item_Id);
-         Error_Msg_Name_1 := Chars (Pack_Id);
-         Error_Msg_N
-           ("\& is declared in the private part of package %", Item_Id);
+      else pragma Assert (Placement = Private_State_Space);
+
+         --  The related package does not declare a state, the item cannot act
+         --  as a Part_Of constituent.
+
+         if No (Get_Pragma (Pack_Id, Pragma_Abstract_State)) then
+            null;
+
+         --  A package instantiation does not need a Part_Of indicator when the
+         --  related generic template has no visible state.
+
+         elsif Ekind (Pack_Id) = E_Package
+           and then Is_Generic_Instance (Pack_Id)
+           and then not Has_Visible_State (Pack_Id)
+         then
+            null;
+
+         --  All other cases require Part_Of
+
+         else
+            Error_Msg_N
+              ("indicator Part_Of is required in this context (SPARK RM "
+               & "7.2.6(2))", Item_Id);
+            Error_Msg_Name_1 := Chars (Pack_Id);
+            Error_Msg_N
+              ("\& is declared in the private part of package %", Item_Id);
+         end if;
       end if;
    end Check_Missing_Part_Of;
 
diff --git a/gcc/ada/sem_util.adb b/gcc/ada/sem_util.adb
index f5a13cd..e6b3233 100644
--- a/gcc/ada/sem_util.adb
+++ b/gcc/ada/sem_util.adb
@@ -5884,12 +5884,10 @@ package body Sem_Util is
             else
                Placement := Visible_State_Space;
 
-               --  The visible state space of a private child unit acts as the
-               --  proper placement of an item.
+               --  The visible state space of a child unit acts as the proper
+               --  placement of an item.
 
-               if Is_Child_Unit (Context)
-                 and then Is_Private_Descendant (Context)
-               then
+               if Is_Child_Unit (Context) then
                   return;
                end if;
             end if;