What are the limitations imposed by GNAT without runtime?

[Lucretia <lucretia9@lycos.co.uk>]

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