[Ada] Missing predicate function body for derived type in nested package

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

This patch fixes a bug in the construction of predicate functions.  For a
derived type, we must ensure that the parent type is already frozen so that its
predicate function has been constructed already. This is necessary if the
parent is declared in a nested package and its own freeze point has not been
reached when the derived type is frozen by a local object declaration.

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

2018-06-11  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* sem_ch13.adb (Build_Predicate_Functions): For a derived type, ensure
	that its parent is already frozen so that its predicate function, if
	any, has already been constructed.

gcc/testsuite/

	* gnat.dg/predicate1.adb: New testcase.

--- gcc/ada/sem_ch13.adb
+++ gcc/ada/sem_ch13.adb
@@ -11114,13 +11114,27 @@ package body Sem_Ch13 is
 
       --  If we have a type with predicates, build predicate function. This is
       --  not needed in the generic case, nor within TSS subprograms and other
-      --  predefined primitives.
+      --  predefined primitives. For a derived type, ensure that the parent
+      --  type is already frozen so that its predicate function has been
+      --  constructed already. This is necessary if the parent is declared
+      --  in a nested package and its own freeze point has not been reached.
 
       if Is_Type (E)
         and then Nongeneric_Case
         and then not Within_Internal_Subprogram
         and then Has_Predicates (E)
       then
+         declare
+            Atyp : constant Entity_Id := Nearest_Ancestor (E);
+         begin
+            if Present (Atyp)
+              and then Has_Predicates (Atyp)
+              and then not Is_Frozen (Atyp)
+            then
+               Freeze_Before (N, Atyp);
+            end if;
+         end;
+
          Build_Predicate_Functions (E, N);
       end if;
 

--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/predicate1.adb
@@ -0,0 +1,40 @@
+--  { dg-do run }
+--  { dg-options "-gnata" }
+
+procedure Predicate1 with SPARK_Mode is
+    type R is record
+       F : Integer;
+    end record;
+
+    package Nested is
+       subtype S is R with Predicate => S.F = 42;
+       procedure P (X : in out S) is null;
+
+       type T is private;
+       procedure P (X : in out T) is null;
+    private
+       type T is new S;
+    end Nested;
+
+    X : Nested.T;
+    Y : Nested.S;
+
+    X_Uninitialized : Boolean := False;
+    Y_Uninitialized : Boolean := False;
+begin
+   begin
+      Nested.P (X);
+   exception
+      when others => X_Uninitialized := True;
+   end;
+
+   begin
+      Nested.P (Y);
+   exception
+      when others => Y_Uninitialized := True;
+   end;
+
+   if not X_Uninitialized or else not Y_Uninitialized then
+      raise Program_Error;
+   end if;
+end Predicate1;