[Ada] Missing error on illegal categorization dependency

[Pierre-Marie de Rodat <derodat at adacore dot com>]

This patch modifies the analysis of subprogram declarations to ensure that an
aspect which is converted into a categorization pragma is properly taken into
account when verifying the dependencies of a subprogram unit.

------------
-- Source --
------------

--  pack.ads

package Pack is end Pack;

--  proc1.ads

with Pack;

procedure Proc1 with Pure;

--  proc2.ads

with Pack;

procedure Proc2;
pragma Pure (Proc2);

----------------------------
-- Compilation and output --
----------------------------

$ gcc -c proc1.ads
$ gcc -c proc2.ads
proc1.ads:1:06: cannot depend on "Pack" (wrong categorization)
proc1.ads:1:06: pure unit cannot depend on non-pure unit
proc2.ads:1:06: cannot depend on "Pack" (wrong categorization)
proc2.ads:1:06: pure unit cannot depend on non-pure unit

Tested on x86_64-pc-linux-gnu, committed on trunk

2018-05-22  Hristian Kirtchev  <kirtchev@adacore.com>

gcc/ada/

	* sem_ch6.adb (Analyze_Subprogram_Declaration): Set the proper
	categorization of the unit after processing the aspects in case one of
	its aspects is converted into a categorization pragma.

--- gcc/ada/sem_ch6.adb
+++ gcc/ada/sem_ch6.adb
@@ -4844,18 +4844,6 @@ package body Sem_Ch6 is
          Set_Kill_Elaboration_Checks (Designator);
       end if;
 
-      if Scop /= Standard_Standard and then not Is_Child_Unit (Designator) then
-         Set_Categorization_From_Scope (Designator, Scop);
-
-      else
-         --  For a compilation unit, check for library-unit pragmas
-
-         Push_Scope (Designator);
-         Set_Categorization_From_Pragmas (N);
-         Validate_Categorization_Dependency (N, Designator);
-         Pop_Scope;
-      end if;
-
       --  For a compilation unit, set body required. This flag will only be
       --  reset if a valid Import or Interface pragma is processed later on.
 
@@ -4883,19 +4871,35 @@ package body Sem_Ch6 is
          Write_Eol;
       end if;
 
-      if Is_Protected_Type (Current_Scope) then
-
-         --  Indicate that this is a protected operation, because it may be
-         --  used in subsequent declarations within the protected type.
+      --  Indicate that this is a protected operation, because it may be used
+      --  in subsequent declarations within the protected type.
 
+      if Is_Protected_Type (Current_Scope) then
          Set_Convention (Designator, Convention_Protected);
       end if;
 
       List_Inherited_Pre_Post_Aspects (Designator);
 
+      --  Process the aspects before establishing the proper categorization in
+      --  case the subprogram is a compilation unit and one of its aspects is
+      --  converted into a categorization pragma.
+
       if Has_Aspects (N) then
          Analyze_Aspect_Specifications (N, Designator);
       end if;
+
+      if Scop /= Standard_Standard and then not Is_Child_Unit (Designator) then
+         Set_Categorization_From_Scope (Designator, Scop);
+
+      --  Otherwise the unit is a compilation unit and/or a child unit. Set the
+      --  proper categorization of the unit based on its pragmas.
+
+      else
+         Push_Scope (Designator);
+         Set_Categorization_From_Pragmas (N);
+         Validate_Categorization_Dependency (N, Designator);
+         Pop_Scope;
+      end if;
    end Analyze_Subprogram_Declaration;
 
    --------------------------------------