[COMMITTED] ada: Simplify uses of readdir_gnat with object overlay

[Marc Poulhiès]

From: Piotr Trojanek <troja...@adacore.com>

Code cleanup; behavior is unaffected.

gcc/ada/

        * libgnat/a-direct.adb (Start_Search_Internal): Combine subtype
        and object declaration.
        * libgnat/g-dirope.adb (Read): Replace convoluted unchecked
        conversion with an overlay.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/libgnat/a-direct.adb |  4 +---
 gcc/ada/libgnat/g-dirope.adb | 18 ++++--------------
 2 files changed, 5 insertions(+), 17 deletions(-)

diff --git a/gcc/ada/libgnat/a-direct.adb b/gcc/ada/libgnat/a-direct.adb
index 9e399c1003e..32e020c48c3 100644
--- a/gcc/ada/libgnat/a-direct.adb
+++ b/gcc/ada/libgnat/a-direct.adb
@@ -1367,9 +1367,7 @@ package body Ada.Directories is
          --  the Filter add it to our search vector.
 
          declare
-            subtype File_Name_String is String (1 .. File_Name_Len);
-
-            File_Name : constant File_Name_String
+            File_Name : constant String (1 .. File_Name_Len)
               with Import, Address => File_Name_Addr;
 
          begin
diff --git a/gcc/ada/libgnat/g-dirope.adb b/gcc/ada/libgnat/g-dirope.adb
index 428d27d9e8d..d8ac0ec06f8 100644
--- a/gcc/ada/libgnat/g-dirope.adb
+++ b/gcc/ada/libgnat/g-dirope.adb
@@ -34,7 +34,6 @@ with Ada.Characters.Handling;
 with Ada.Strings.Fixed;
 
 with Ada.Unchecked_Deallocation;
-with Ada.Unchecked_Conversion;
 
 with System;      use System;
 with System.CRTL; use System.CRTL;
@@ -677,24 +676,15 @@ package body GNAT.Directory_Operations is
       end if;
 
       declare
-         subtype Path_String is String (1 .. Filename_Len);
-         type    Path_String_Access is not null access constant Path_String;
-
-         function Address_To_Access is new
-           Ada.Unchecked_Conversion
-             (Source => Address,
-              Target => Path_String_Access);
-
-         Path_Access : constant Path_String_Access :=
-                         Address_To_Access (Filename_Addr);
-
+         Filename : constant String (1 .. Filename_Len)
+           with Import, Address => Filename_Addr;
       begin
          if Str'Length > Filename_Len then
             Last := Str'First + Filename_Len - 1;
-            Str (Str'First .. Last) := Path_Access.all;
+            Str (Str'First .. Last) := Filename;
          else
             Last := Str'Last;
-            Str := Path_Access (1 .. Str'Length);
+            Str := Filename (1 .. Str'Length);
          end if;
       end;
    end Read;
-- 
2.43.2