[Bug ada/63725] New: Scalar_Storage_Order is required for nested string types, but cannot be added to those types

[Bug ada/63725] New: Scalar_Storage_Order is required for nested string types, but cannot be added to those types

[daniel.merrill at psware dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63725

            Bug ID: 63725
           Summary: Scalar_Storage_Order is required for nested string
                    types, but cannot be added to those types
           Product: gcc
           Version: 4.9.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ada
          Assignee: unassigned at gcc dot gnu.org
          Reporter: daniel.merrill at psware dot com

Created attachment 33878
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33878&action=edit
demonstrates the problem with nested string types and scalar storage order

Target: i686-pc-linux-gnu
Configured with: ../configure --enable-languages=c,c++,ada --disable-multilib
--
with-gcc --with-gnu-ld --with-gnu-as --target=i686-pc-linux-gnu
--prefix=/c/gcc-
ade -v --with-sysroot=/c/gcc-ade/i686-pc-linux-gnu
--includedir=/c/gcc-ade/i686-
pc-linux-gnu/usr/include
Thread model: posix
gcc version 4.10.0 20140706 (experimental) (GCC)

This is a build of the svn://gcc.gnu.org/svn/gcc/branches/scalar-storage-order
branch.

when the following is defined and compiled with "gnatmake main.adb":

subtype string_type is string (1..15);

   type string_array is array (1..2) of string_type;
   for string_array'Scalar_Storage_Order use System.High_Order_First;

   type BigEndianInt32Array is array (1..10) of int32;


   type bigEndianType is record
      ThirtyTwoBits : int32;
      SixteenBits   : int16;
      TestStrings   : string_array;
   end record;

   for bigEndianType use record
      ThirtyTwoBits at 0 range 0  .. 31;
      SixteenBits   at 0 range 32 .. 47;
      TestStrings   at 0 range 48 .. 79;
   end record;

   for bigEndianType'Bit_Order use System.High_Order_First;
   for bigEndianType'Scalar_Storage_Order use System.High_Order_First;

the following compiler error is produced:

main.adb:17:04: nested composite must have explicit scalar storage order

You are unable to fix this because the nested type is a subtype of string and
you cannot define a scalar_storage_order attribute for a subtype.

[Bug ada/63725] Scalar_Storage_Order and nested string subtypes

[daniel.merrill at psware dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63725

--- Comment #2 from Dan Merrill <daniel.merrill at psware dot com> ---
Is this what you are proposing?

   type string_type is new string (1..15);
   for string_type'Scalar_Storage_Order use System.High_Order_First;

   type string_array is array (1..2) of string_type;
   for string_array'Scalar_Storage_Order use System.High_Order_First;

   type BigEndianInt32Array is array (1..10) of int32;


   type bigEndianType is record
      ThirtyTwoBits : int32;
      SixteenBits   : int16;
      TestStrings   : string_array;
   end record;

   for bigEndianType use record
      ThirtyTwoBits at 0 range 0  .. 31;
      SixteenBits   at 0 range 32 .. 47;
      TestStrings   at 0 range 48 .. 287;
   end record;

   for bigEndianType'Bit_Order use System.High_Order_First;
   for bigEndianType'Scalar_Storage_Order use System.High_Order_First;

?

That seems to work, but in a non trivial case doesn't that make string_type non
inter operable with other string types? In reality I don't care what the scalar
storage order of the string is because they are just bytes and should work the
same across both platforms. It seems like string_type shouldn't even need a
scalar storage order applied to it.