2007-04-20  Vincent Celier  <celier@adacore.com>
	    Robert Dewar  <dewar@adacore.com>

	* frontend.adb (Frontend): Return immediately if the main source could
	not be parsed, because of preprocessing errors.

	* gnat1drv.adb (gnat1drv): Handle RE_Not_Available gracefully.
	(Gnat1drv): Exit with errors if the main source could not be parsed,
	because of preprocessing errors.
	(Check_Rep_Info): New procedure

From-SVN: r125411