[PATCH] PR fortran/67987 -- character lengths cannot be negative

[Steve Kargl]

On Fri, Oct 16, 2015 at 10:17:34PM +0200, FX wrote:
> > The attach patch enforces the Fortran Standard's requirement
> > that character length must be great than or equal to zero.
> 
> 4.4.3.2. "If the character length parameter value evaluates to
> a negative value, the length of character entities declared is zero."
> 

Thanks.  I missed the above.  The above text goes back to 
at least F90 (see p. 41 on N693.pdf).  New diff attached.

2015-10-16  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/67987
	* decl.c (char_len_param_value): Unwrap unlong line.  If LEN < 0,
	then force it to zero pre Fortran Standards. 
	* resolve.c (gfc_resolve_substring_charlen): Unwrap unlong line.
	If 'start' is larger than 'end', then length of string is negative,
	so explicitly set it to zero.
	(resolve_charlen): Remove -Wsurprising warning.  Update comment to
	text from F2008 standard.

2015-10-16  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/67987
	* gfortran.dg/char_length_2.f90: Add declaration from PR to testcase.

-- 
Steve
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