[Bug ada/111945] New: Attribute Image for Unbounded_String raises UTF_ENCODING.ENCODING_ERROR

[Bug ada/111945] New: Attribute Image for Unbounded_String raises UTF_ENCODING.ENCODING_ERROR

[alexandre.dauquier at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111945

            Bug ID: 111945
           Summary: Attribute Image for Unbounded_String raises
                    UTF_ENCODING.ENCODING_ERROR
           Product: gcc
           Version: 12.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ada
          Assignee: unassigned at gcc dot gnu.org
          Reporter: alexandre.dauquier at gmail dot com
                CC: dkm at gcc dot gnu.org
  Target Milestone: ---

Created attachment 56181
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56181&action=edit
Minimum working example

The following code is failing with Gnat 12.2.0. It passes with 13.2.0 though
(so it might already be known ? But I have not found it).

Note, I have picked Characters.Latin_1.Reserved_128 on purpose.

```ada
-- File 'print_non_graphic_character.adb'
with Ada.Characters.Latin_1;
with Ada.Text_IO;
with Ada.Strings.Unbounded;

procedure Print_Non_Graphic_Character is
   Text_String : constant String := "Non Graphic Character: " &
Ada.Characters.Latin_1.Reserved_128;
   Text_Unbounded_String : constant Ada.Strings.Unbounded.Unbounded_String :=
      Ada.Strings.Unbounded.To_Unbounded_String (Text_String);
begin
   Ada.Text_IO.Put_Line (Text_String);
   Ada.Text_IO.Put_Line (Ada.Strings.Unbounded.To_String
(Text_Unbounded_String));
   Ada.Text_IO.Put_Line (Text_Unbounded_String'Image);
end Print_Non_Graphic_Character;
```

Note that it also fails with:

```ada
Ada.Text_IO.Put_Line (Ada.Strings.Unbounded.Unbounded_String'Image
(Text_Unbounded_String));
```

```
-- File 'print_non_graphic_character.gpr'
project Print_Non_Graphic_Character is
   for Main use ("print_non_graphic_character.adb");
   for Object_Dir use ".objs";

   package Compiler is
      -- "-Og" -- Optimize for debug
      -- "-g" -- Generate debug info
      for Default_Switches ("Ada") use ("-g", "-gnat2020", "-Og");
   end Compiler;

   package Binder is
      for Switches ("Ada") use ("-Es"); --  Symbolic traceback
   end Binder;
end Print_Non_Graphic_Character;
```

Cmdline: `gprbuild -p -gnatef print_non_graphic_character.gpr`

Output:
```stdout
Non Graphic Character: �
Non Graphic Character: �

raised ADA.STRINGS.UTF_ENCODING.ENCODING_ERROR : bad input at Item (25)
[./non_graphic_character/.objs/print_non_graphic_character]
0x40e8fb Ada.Strings.Utf_Encoding.Raise_Encoding_Error at a-stuten.adb:126
0x40f38b Ada.Strings.Utf_Encoding.Strings.Decode at a-suenst.adb:163
0x4049a8 Print_Non_Graphic_Character at print_non_graphic_character.adb:13
0x404efa Main at b__print_non_graphic_character.adb:279
[/lib/x86_64-linux-gnu/libc.so.6]
0x7f5e62118d08
[./non_graphic_character/.objs/print_non_graphic_character]
0x404658 _start at ???
0xfffffffffffffffe
```

Output with Gnat 13.2.0 (though I didn't expect the quotation marks):
```stdout
Non Graphic Character: �
Non Graphic Character: �
"Non Graphic Character: �"
"Non Graphic Character: �"
```

Environnement of the bug (with Gnat 12.2.0):

```
> gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/home/dalex78/bin/gnat_native/12.2.1_11f3b811/bin/../libexec/gcc/x86_64-pc-linux-gnu/12.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../src/configure
--prefix=/home/runner/work/GNAT-FSF-builds/GNAT-FSF-builds/sbx/x86_64-linux/gcc/install
--with-build-time-tools=/home/runner/work/GNAT-FSF-builds/GNAT-FSF-builds/sbx/x86_64-linux/binutils/install/bin
--enable-languages=c,ada,c++ --enable-libstdcxx --enable-libstdcxx-threads
--enable-libada --disable-nls --without-libiconv-prefix --disable-libstdcxx-pch
--enable-lto --disable-multilib --enable-threads=posix --with-gnu-ld
--with-gnu-as
--with-mpfr=/home/runner/work/GNAT-FSF-builds/GNAT-FSF-builds/sbx/x86_64-linux/mpfr/install
--with-gmp=/home/runner/work/GNAT-FSF-builds/GNAT-FSF-builds/sbx/x86_64-linux/gmp/install
--with-mpc=/home/runner/work/GNAT-FSF-builds/GNAT-FSF-builds/sbx/x86_64-linux/mpc/install
--with-isl=/home/runner/work/GNAT-FSF-builds/GNAT-FSF-builds/sbx/x86_64-linux/isl/install
--build=x86_64-pc-linux-gnu
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 12.2.0 (GCC)
```

[Bug ada/111945] Attribute Image for Unbounded_String raises UTF_ENCODING.ENCODING_ERROR

[alexandre.dauquier at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111945

--- Comment #1 from Alexandre Dauquier <alexandre.dauquier at gmail dot com> ---
Created attachment 56182
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56182&action=edit
GPR build

[Bug ada/111945] Attribute Image for Unbounded_String raises UTF_ENCODING.ENCODING_ERROR

[ebotcazou at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111945

Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
                 CC|                            |ebotcazou at gcc dot gnu.org
   Target Milestone|---                         |13.0
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #2 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
Indeed fixed in GCC 13 and later, no backport planned.