Support No_Secondary_Stack restriction

[senier]

The No_Secondary_Stack restriction is not fulfilled by the generated code at the moment:

package Test is
   type M is
      message
         F : Opaque;
      end message;
end Test;

Compile
   [Ada]          rflx-test-m.adb
rflx-test-m.adb:55:18: error: violation of restriction "NO_SECONDARY_STACK" at /home/senier/tmp/RecordFlux/no_secondary_stack/pragmas.adc:1
rflx-test-m.adb:192:07: error: violation of restriction "NO_SECONDARY_STACK" at /home/senier/tmp/RecordFlux/no_secondary_stack/pragmas.adc:1
rflx-test-m.ads:545:18: error: violation of restriction "NO_SECONDARY_STACK" at /home/senier/tmp/RecordFlux/no_secondary_stack/pragmas.adc:1
gprbuild: *** compilation phase failed
make: *** [Makefile:2: build/obj/libtest.a] Error 4

The problem is the Read function that return the unconstrained Bytes type:

   function Read (Ctx : Context) return RFLX_Types.Bytes is
     (Ctx.Buffer.all (RFLX_Types.To_Index (Ctx.First) .. RFLX_Types.To_Index (Ctx.Verified_Last)));

We should replace those with procedures and and add pragma Restrictions (No_Secondary_Stack); to our compile tests.

[treiher]

GNAT Community 2019 complains about violations of the No_Secondary_Stack restriction, even for functions with Ghost aspect. I don't see a simple workaround, so I would propose to drop support for this version.

While all other compilers ignore the with aunit; in the project file, if AUnit is not used, the FSF GNAT builds the AUnit sources anyway. That leads to a failing compilation if the restriction "No_Secondary_Stack" is enabled. Does anyone see a better workaround than disabling building the AUnit test suite with restrictions for FSF GNAT?