re PR ada/22255 (Reset on shared file causes Use_Error.)

    gcc/ada/
	PR ada/22255
	* s-fileio.adb (Reset): Do not raise Use_Error if mode isn't changed.

    gcc/testsuite/
	PR ada/22255
	* gnat.dg/test_direct_io.adb: New file.

From-SVN: r132708

1 files changed, 9 insertions, 7 deletions

diff --git a/gcc/ada/s-fileio.adb b/gcc/ada/s-fileio.adb
index a56877e..4a8393c 100644
--- a/gcc/ada/s-fileio.adb
+++ b/gcc/ada/s-fileio.adb
@@ -1074,13 +1074,15 @@ package body System.File_IO is
    begin
       Check_File_Open (File);
 
-      --  Change of mode not allowed for shared file or file with no name
-      --  or file that is not a regular file, or for a system file.
-
-      if File.Shared_Status = Yes
-        or else File.Name'Length <= 1
-        or else File.Is_System_File
-        or else not File.Is_Regular_File
+      --  Change of mode not allowed for shared file or file with no name or
+      --  file that is not a regular file, or for a system file. Note that we
+      --  allow the "change" of mode if it is not in fact doing a change.
+
+      if Mode /= File.Mode
+        and then (File.Shared_Status = Yes
+                    or else File.Name'Length <= 1
+                    or else File.Is_System_File
+                    or else not File.Is_Regular_File)
       then
          raise Use_Error;