Creating a GPR file to use a custom built runtime library

[Jeremiah <jeremiah.breeden@gmail.com>]

I recently took a shot at modding a zero footprint runtime library I found online for a chip that I have.  The runtime appeared to build correctly, so my next step was to setup a null main procedure and see if I could get it to compile.  Using GPRbuild I keep getting error about:

Error: no compiler found for language 'ada', target = arm-eabi, runtime = ../zfp-atsaml21j18

My project GPR file is as follows:
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project Test_ZFP is
   for Languages use ("ada");
   for Source_Dirs use ("src/**");
   for Object_Dir use "obj";
   for Main use ("program.adb");
   for Target use "arm-eabi";

   package Compiler is
      for Default_Switches ("ada") use ("-gnatwa", "-gnatQ", "-gnat12", "-gnatn");
   end Compiler;

   package Builder is
      for Default_Switches ("ada") use ("--RTS=../zfp-atsaml21j18");
   end Builder;

   package Ide is
      for Gnat use "arm-eabi-gnat";
      for Gnatlist use "arm-eabi-gnatls";
   end Ide;

   package Pretty_Printer is
      for Default_Switches ("ada") use ("-cl3");
   end Pretty_Printer;

end Test_ZFP;
*************************************************************

The appropriate tools seem to be available on the path (arm-eabi-gcc, arm-eabi-ld, etc.).

This is the -v output for GPRbuild:
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$ gprbuild -v -p test_zfp.gpr
GPRBUILD GPL 2015 (20150428) (i686-pc-mingw32)
Copyright (C) 2004-2015, Free Software Foundation, Inc.
 26 lines: No errors
gprconfig --batch -o D:\Program_Files\MinGW\msys\1.0\home\Jere\test_zfp\obj\auto.cgpr --target=arm-eabi --config=ada,,../zfp-atsaml21j18
Error: no compiler found for language 'ada', target = arm-eabi, runtime = ../zfp-atsaml21j18
Creating configuration file: D:\Program_Files\MinGW\msys\1.0\home\Jere\test_zfp\obj\auto.cgpr
Checking configuration D:\Program_Files\MinGW\msys\1.0\home\Jere\test_zfp\obj\auto.cgpr

==============Error messages for project file: D:\Program_Files\MinGW\msys\1.0\home\Jere\test_zfp\test_zfp.gpr
     1. project Test_ZFP is
                |
        >>> warning: no compiler specified for language "ada", ignoring all its sources

 26 lines: No errors, 1 warning

     5.    for Main use ("program.adb");
                         |
        >>> "program.adb" is not a source of project "test_zfp"

 26 lines: 1 error
gprbuild: problems with main sources
************************************************************

program.adb is in src/

Any thoughts?  I am sure I am making a simple mistake somewhere.