anchor.diff:            drvPath = validate pkg.drvPath;
           };
       };
  +
  +
  +  /* Modify a stdenv so that it produces debug builds; that is,
  +     binaries have debug info, and compiler optimisations are
  +     disabled. */
  +  keepDebugInfo = stdenv: stdenv //
  +    { mkDerivation = args: stdenv.mkDerivation (args // {
  +        dontStrip = true;
  +        NIX_CFLAGS_COMPILE = toString (args.NIX_CFLAGS_COMPILE or "") + " -g -O0";
  +      });
  +    };
  +
   }
  
positive.code:       });
      } // {inherit fetchurl;};
  
      
    # Return a modified stdenv that adds a cross compiler to the
    # builds.
    makeStdenvCross = stdenv: cross: binutilsCross: gccCross: stdenv //
  
negative.code:       inherit cross gccCross binutilsCross;
      };
  
  
    /* Modify a stdenv so that the specified attributes are added to
       every derivation returned by its mkDerivation function.
  
  