DEC comparisons - allow Hollerith constants in comparisons.

DEC comparisons - allow Hollerith constants in comparisons.

The -fdec option enables the use of Hollerith comparisons in comparisons
with INTEGER, COMPLEX, REAL and CHARACTER expressions.

	Mark Eggleston  <mark.eggleston@codethink.com>
	Jim MacArthur  <jim.macarthur@codethink.co.uk>

	* gfortran.texi: Update Hollerith constants support for character types
	and use in comparisons.
	* invoke.texi: Tidy up list of options. Update description of
	-fdec-char-conversions.
	* resolve.c (is_character_based): New.
	(Convert_hollerith_to_character): New.  (convert_to_numeric): New.
	(resolve_operator): If both sides are character based and -fdec is
	enabled convert Hollerith to character. If an operand is Hollerith, the
	other is numeric and -fdec is enabled convert to numeric.
	(resolve_ordinary_assign): Add check for -fdec-char-conversions for
	assignment of character literals.

	Mark Eggleston <mark.eggleston@codethink.com>
	Jim MacArthur <jim.macarthur@codethink.co.uk>

	* gfortran.dg/dec-comparison-character_1.f90: New test.
	* gfortran.dg/dec-comparison-character_2.f90: New test.
	* gfortran.dg/dec-comparison-character_3.f90: New test.
	* gfortran.dg/dec-comparison-complex_1.f90: New test.
	* gfortran.dg/dec-comparison-complex_2.f90: New test.
	* gfortran.dg/dec-comparison-complex_3.f90: New test.
	* gfortran.dg/dec-comparison-int_1.f90: New test.
	* gfortran.dg/dec-comparison-int_2.f90: New test.
	* gfortran.dg/dec-comparison-int_3.f90: New test.
	* gfortran.dg/dec-comparison-real_1.f90: New test.
	* gfortran.dg/dec-comparison-real_2.f90: New test.
	* gfortran.dg/dec-comparison-real_3.f90: New test.
	* gfortran.dg/dec-comparison.f90: New test.

Co-Authored-By: Jim MacArthur <jim.macarthur@codethink.co.uk>
From-SVN: r278674