[PATCH 2/5] fortran: [PR49802] Allow VALUE attribute on assumed-length CHARACTER and array dummies

[Jerry D]

See attached 2 of 5 patch

Regression tested on x86_64

Regards,

Jerry

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fortran: [PR49802]-2 Allow VALUE on assumed-length
  CHARACTER dummies

Fortran 2003 C528 prohibited the VALUE attribute on a CHARACTER dummy
whose length is not one.  Fortran 2008 relaxed this with C557, and
F2023 Annex C.2 lists it as a Fortran 2008 feature that the Fortran
2008 Introduction did not mention.  gfortran was still rejecting both
an assumed length and a specified but non-constant length, such as
another dummy argument used as the length.

resolve.cc relaxes the constant-length requirement, gated by
gfc_notify_std so that -std=f2003 still rejects it, and consolidates
the C-interop length checks into a single "must have length one"
condition ordered ahead of the Fortran 2008 allowance.

trans-types.cc keeps such a dummy passed by reference, since VALUE now
means copy-in-only semantics rather than pass-by-value of the raw data,
and conv_dummy_value makes the caller-side copy.  The copy size is
scaled by the size of the character kind, so that a kind wider than one
byte copies the whole string rather than its first bytes.

	PR fortran/49802

gcc/fortran/ChangeLog:

	* resolve.cc (resolve_symbol): Allow character(len=*) VALUE and a
	specified but non-constant length under Fortran 2008; consolidate
	the C-interop length checks into a single "must have length one"
	check ordered ahead of the Fortran 2008 allowance.
	* trans-expr.cc (conv_dummy_value): For assumed-length or
	non-constant-length CHARACTER VALUE dummies, make a caller-side
	copy and pass its address; scale the copy size by the size of the
	character kind.
	* trans-types.cc (gfc_sym_type): Use byref=1 for assumed-length or
	non-constant-length VALUE character dummies, so the ABI still
	passes by reference.

gcc/testsuite/ChangeLog:

	* gfortran.dg/value_5.f90: Compile under -std=f2003 so the Fortran
	2008 assumed-length VALUE relaxation is exercised as a rejection,
	and update the C-interop error expectation to match the
	consolidated diagnostic.
	* gfortran.dg/value_6.f90: New test.
	* gfortran.dg/value_7.f90: New test.
	* gfortran.dg/value_11.f90: New test.
	* gfortran.dg/value_14.f90: New test.
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