2008-08-22  Robert Dewar  <dewar@adacore.com>

	* checks.adb (Determine_Range): Deal with values that might be invalid

	* opt.adb, opt.ads (Assume_No_Invalid_Values[_Config]): New configuration
	switches.

	* par-prag.adb: Dummy entry for pragma Assume_No_Invalid_Values

	* sem_prag.adb: Implement pragma Assume_No_Default_Values

	* snames.adb, snames.ads, snames.h:
	Add entries for pragma Assume_No_Invalid_Values

	* switch-c.adb: Add processing for -gnatB switch

	* usage.adb: Add entry for flag -gnatB (no bad invalid values)

From-SVN: r139484