Re: What are the limitations imposed by GNAT without runtime?

[anon@anon.org (anon)]

--  The "Non Ada standard" aka the "GNAT obsolete" pragma statement
--  ( chapter 14.1 from the GNAT_RM.xxx ) 

pragma No_Run_Time ;

--  removes a number of RTL packages at link time but it also direct 
--  the compiler that these packages are no longer available. Such as 
--  "Ada.Text_IO" as well as some attributes/constructs such as 
--  "Image". So, when you use such attributes/constructs or RTL 
--  packages you will receive a compiler error, because you will have 
--  to build these in your RTL or a replacement routine.
--
--  As I suggest before look at those project, because they have had 
--  some of the same problems that you will run into and you can use 
--  their code to see how they solve the problem. 
--
--
--  Before begin this great task you need to know the complete features 
--  of Ada, the compiler and its limitations, the computer system, the 
--  processor assembly language as well as the hardware that is 
--  installed.  Also, with GCC 4.x Adacore altered the GNAT compiler for 
--  its Ada 2005 specification by adding some componts that can cause 
--  problems in creating Stand-Alone code such as a Kernel.
--


procedure Kernel is


  type Wah is ( One, Two ) ;

  -- ------------------------------------------------ --
  -- Simple function replaces the Image attribute for -- 
  -- Wah type                                         --
  -- ------------------------------------------------ --
  function Image_Wah ( V : Wah ) return String is

    begin -- Image_Wah

      if V = One then
        return "One" ;
      else
        return "Two" ;
      end if ;

    end Image_Wah ;


  S : String := Image_Wah ( Wah'First ) ;


begin
  null ;
end Kernel ;


In <1191947316.791605.8420@50g2000hsm.googlegroups.com>,  Lucretia <lucretia9@lycos.co.uk> writes:
>Hi,
>
>I have just tested this again and it seems to work. Basically,
>configure gnat with --target=i386-elf, build, it stops failing cos
>there is no runtime. You can install and it gives you a gnat1 compiler
>in  libexec/gcc/i386-elf/4.2.2/ and gnatbind in bin/.
>
>You have to copy the basic system.ads file from the source archive to
>lib/gcc/i386-elf/4.2.2/adainclude/.
>
>This then allows you can use i386-elf-gcc -c to compile source files.
>You can also use i386-elf-ld to link provided you supply a linker
>script and you'll also need some startup code.
>
>So, as a test I put the following code through the compiler just to
>see if it compiled:
>
>pragma No_Run_Time; -- This isn't in the manual, and I vaguely
>remember something about it being removed, no errors/warnings though.
>
>procedure Kernel is
>
>  type Wah is (One, Two);
>
>  S : String := Wah'Image(Wah'First);
>
>begin
>   null;
>end Kernel;
>
>gives the following error:
>
>kernel.adb:7:20: construct not allowed in configurable run-time mode
>
>What does this mean?
>
>So, apart from tasking and exceptions, what other language constructs
>cannot be used in this mode?
>
>Thanks,
>Luke.
>
>P.S: I'll try not to be sarcastic ;D
>