OpenMP: C/C++ adjust-args numeric ranges

OpenMP: C/C++ adjust-args numeric ranges

This is a backport of the proposed mainline patch posted at
https://gcc.gnu.org/pipermail/gcc-patches/2025-April/681806.html

Add support for OpenMP parameter-lists in an adjust_args clause, more
specifically, numeric ranges and parameter indices.  Many bugs are also
fixed along the way.  Most of the fixes rely on the changes to handling of
clause arguments and can't reasonably be split out, while most of the
changes that fix PR119602 came as a side effect of properly handling numeric
ranges with dependent bounds so it makes sense to include it here.

Variadic arguments with an incorrect type are not currently diagnosed, but
handling for them is otherwise functional.  It is unclear how references to
pointers are supposed to be handled, so for now we sorry for that case.

	PR c++/119659
	PR c++/118859
	PR c++/119601
	PR c++/119602
	PR c++/119775

gcc/c/ChangeLog:

	* c-parser.cc (c_omp_numeric_ranges_always_overlap): New function.
	(c_parser_omp_parm_list): New function.
	(c_finish_omp_declare_variant): Use c_parser_omp_parm_list instead
	of c_parser_omp_variable_list.  Refactor, change format of
	"omp declare variant variant args" attribute.

gcc/cp/ChangeLog:

	PR c++/119659
	PR c++/118859
	PR c++/119601
	PR c++/119602
	PR c++/119775
	* cp-tree.h (finish_omp_parm_list): New declaration.
	(finish_omp_adjust_args): New declaration.
	* decl.cc (omp_declare_variant_finalize_one): Refactor and change
	attribute unpacking, use finish_omp_parm_list and
	finish_omp_adjust_args, refactor append_args diagnostics, add
	nbase_parms to append_args attribute, remove special handling for
	member functions.
	* parser.cc (cp_parser_direct_declarator): Don't pass parms.
	(cp_parser_late_return_type_opt): Remove parms parameter.
	(cp_parser_omp_parm_list): New function.
	(cp_finish_omp_declare_variant): Remove parms parameter.
	Add NULL_TREE instead of nbase_args to append_args_tree.  Refactor,
	use cp_parser_omp_parm_list not cp_parser_omp_var_list_no_open,
	handle "need_device_addr" and remove handling and diagnostics of
	parm list arguments that are done too early.  Change format of
	unnamed variant attribute.
	(cp_parser_late_parsing_omp_declare_simd): Remove parms parameter.
	* pt.cc (tsubst_attribute): Copy "omp declare variant base" nodes,
	substitute parm list numeric range bounds.
	* semantics.cc (finish_omp_parm_list): New function.
	(finish_omp_adjust_args): New function.

gcc/fortran/ChangeLog:

	* trans-openmp.cc (gfc_trans_omp_declare_variant): Change format of
	"omp declare variant variant args" attribute.

gcc/ChangeLog:

	* gimplify.cc (modify_call_for_omp_dispatch): Refactor and change
	attribute unpacking.  For adjust_args variadic functions, expand
	numeric ranges with relative bounds.  Refactor argument adjustment.

libgomp/ChangeLog:

	* libgomp.texi: Set 'adjust args' variadic arguments support to Y.

gcc/testsuite/ChangeLog:

	* c-c++-common/gomp/pr118579.c: Change error text.
	* g++.dg/gomp/adjust-args-1.C: Fix error text, add dg-* directives.
	* g++.dg/gomp/adjust-args-2.C: Add dg-* directives.
	* g++.dg/gomp/append-args-1.C: Add dg-* directives.
	* gcc.dg/gomp/adjust-args-1.c: Fix error text, add dg-* directives.
	* gcc.dg/gomp/append-args-1.c: Fix error text, add dg-* directives.
	* c-c++-common/gomp/adjust-args-7.c: New test.
	* c-c++-common/gomp/adjust-args-8.c: New test.
	* c-c++-common/gomp/adjust-args-9.c: New test.
	* c-c++-common/gomp/adjust-args-10.c: New test.
	* c-c++-common/gomp/adjust-args-11.c: New test.
	* c-c++-common/gomp/adjust-args-12.c: New test.
	* c-c++-common/gomp/adjust-args-13.c: New test.
	* c-c++-common/gomp/adjust-args-14.c: New test.
	* c-c++-common/gomp/adjust-args-15.c: New test.
	* g++.dg/gomp/adjust-args-5.C: New test.
	* g++.dg/gomp/adjust-args-6.C: New test.
	* g++.dg/gomp/adjust-args-7.C: New test.
	* g++.dg/gomp/adjust-args-8.C: New test.
	* g++.dg/gomp/adjust-args-9.C: New test.
	* g++.dg/gomp/adjust-args-10.C: New test.
	* g++.dg/gomp/adjust-args-11.C: New test.
	* g++.dg/gomp/adjust-args-12.C: New test.
	* g++.dg/gomp/adjust-args-13.C: New test.
	* g++.dg/gomp/adjust-args-14.C: New test.
	* g++.dg/gomp/adjust-args-15.C: New test.
	* g++.dg/gomp/adjust-args-16.C: New test.
	* g++.dg/gomp/append-args-9.C: New test.
	* g++.dg/gomp/append-args-10.C: New test.
	* g++.dg/gomp/append-args-11.C: New test.
	* g++.dg/gomp/append-args-omp-interop-t.h: New header.

Signed-off-by: Waffl3x <waffl3x@baylibre.com>