[Bug ada/70786] New: Missing "not" breaks Ada.Text_IO.Get_Immediate(File, Item, Available)

[ktamp at chem dot uoa.gr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70786

            Bug ID: 70786
           Summary: Missing "not" breaks Ada.Text_IO.Get_Immediate(File,
                    Item, Available)
           Product: gcc
           Version: 5.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ada
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ktamp at chem dot uoa.gr
  Target Milestone: ---

OS: Arch Linux x64
GCC version: 5.3.0

Missing "not" in line #671 of a-textio.adb causes Get_Immediate(File, Item,
Available) to throw an exception when key "[" is pressed. This also affects
processing of keypresses when function keys F5 to F12 are pressed.

Get_Immediate(File, Item) does not have the same issue because "not" is there
(line #611): "(if not Is_Start_Of_Encoding (Character'Val (ch),
File.WC_Method)"

Example code (run and press e.g. key F12):

with Ada.Text_IO; use Ada.Text_IO;
procedure Test is
   C : Character;
   Available : Boolean;
begin
   Get_Immediate (C);
   loop
      Put (Integer'Image (Character'Pos (C)));
      Get_Immediate (C, Available);
      exit when not Available;
   end loop;
end Test;