Fortran: Add range-based diagnostic

GCC's diagnostic engine gained a while ago support for ranges, i.e. instead
of pointing at a single character '^', it can also have a '~~~~^~~~~~' range.

This patch adds support for this and adds 9 users for it, which covers the
most common cases. A single '^' can be still useful. Some location data in
gfortran is rather bad - often the matching pattern includes whitespace such
that the before or after location points to the beginning/end of the
whitespace, which can be far of especially when comments and/or continuation
lines are involed. Otherwise, often a '^' still sufficient, albeit wrong
location data only becomes obvious once starting to use ranges.

The 'locus' is extended to support two ways to store the data; hereby
gfc_current_locus always contains the old format (at least during parsing)
and gfc_current_locus shall not be used in trans*.cc. The latter permits
a nice cleanup to just use input_location. Otherwise, the new format is
only used when switching to ranges.
The only reason to convert from location_t to locus occurs in trans*.cc
for the gfc_error (etc.) diagnostic and for gfc_trans_runtime_check; there
are 5 currently 5 such cases.  For gfc_* diagnostic, we could think of
another letter besides %L or a modifier like '%lL', if deemed useful.

In any case, the new format is just:
  locus->u.location = linemap_position_for_loc_and_offset (line_table,
                         loc->u.lb->location, loc->nextc - loc->u.lb->line);
  locus->nextc = (gfc_char_t *) -1;  /* Marker for new format. */
i.e. using the existing location_t location in in the linebuffer (which
points to column 0) and add as offset the actually used column number.

As location_t handles ranges, we just use it also to store them via:
  location = make_location (caret, begin, end)
There are a few convenience macros/functions but that's all.

Alongside, a few minor fixes were done: linemap_location_before_p replaces
a line-number based comparison, which does not handle multiple statements
in the same line that ';' allows for.

gcc/fortran/ChangeLog:

	* data.cc (gfc_assign_data_value): Use linemap_location_before_p
	and GFC_LOCUS_IS_SET.
	* decl.cc (gfc_verify_c_interop_param): Make better translatable.
	(build_sym, variable_decl, gfc_match_formal_arglist,
	gfc_match_subroutine): Add range-based locations, use it in
	diagnostic and gobble whitespace for better locations.
	* error.cc (gfc_get_location_with_offset): Handle new format.
	(gfc_get_location_range): New.
	* expr.cc (gfc_check_assign): Use GFC_LOCUS_IS_SET.
	* frontend-passes.cc (check_locus_code, check_locus_expr):
	Likewise.
	(runtime_error_ne): Use GFC_LOCUS_IS_SET.
	* gfortran.h (locus): Change lb to union with lb and location.
	(GFC_LOCUS_IS_SET): Define.
	(gfc_get_location_range): New prototype.
	(gfc_new_symbol, gfc_get_symbol, gfc_get_sym_tree,
	gfc_get_ha_symbol, gfc_get_ha_sym_tree): Take optional locus
	argument.
	* io.cc (io_constraint): Use GFC_LOCUS_IS_SET.
	* match.cc (gfc_match_sym_tree): Use range locus.
	* openmp.cc (gfc_match_omp_variable_list,
	gfc_match_omp_doacross_sink): Likewise.
	* parse.cc (next_free): Update for locus struct change.
	* primary.cc (gfc_match_varspec): Likewise.
	(match_variable): Use range locus.
	* resolve.cc (find_array_spec): Use GFC_LOCUS_IS_SET.
	* scanner.cc (gfc_at_eof, gfc_at_bol, gfc_start_source_files,
	gfc_advance_line, gfc_define_undef_line, skip_fixed_comments,
	gfc_gobble_whitespace, include_stmt, gfc_new_file): Update
	for locus struct change.
	* symbol.cc (gfc_new_symbol, gfc_get_sym_tree, gfc_get_symbol,
	gfc_get_ha_sym_tree, gfc_get_ha_symbol): Take optional locus.
	* trans-array.cc (gfc_trans_array_constructor_value): Use %L not %C.
	(gfc_trans_g77_array, gfc_trans_dummy_array_bias,
	gfc_trans_class_array, gfc_trans_deferred_array): Replace
	gfc_{save,set,restore}_backend_locus by directly using
	input_location.
	* trans-common.cc (build_equiv_decl, get_init_field): Likewise.
	* trans-decl.cc (gfc_get_extern_function_decl, build_function_decl,
	build_entry_thunks, gfc_null_and_pass_deferred_len,
	gfc_trans_deferred_vars, gfc_trans_use_stmts, finish_oacc_declare,
	gfc_generate_block_data): Likewise.
	* trans-expr.cc (gfc_copy_class_to_class, gfc_conv_expr): Changes
	to avoid gfc_current_locus.
	* trans-io.cc (set_error_locus): Likewise.
	* trans-openmp.cc (gfc_trans_omp_workshare): Use input_locus directly.
	* trans-stmt.cc (gfc_trans_if_1): Likewise and use GFC_LOCUS_IS_SET.
	* trans-types.cc (gfc_get_union_type, gfc_get_derived_type): Likewise.
	* trans.cc (gfc_locus_from_location): New.
	(trans_runtime_error_vararg, gfc_trans_runtime_check): Use location_t
	for file + line data.
	(gfc_current_backend_file, gfc_save_backend_locus,
	gfc_set_backend_locus, gfc_restore_backend_locus): Remove.
	(trans_code): Use input_location directly, don't set gfc_current_locus.
	* trans.h (gfc_save_backend_locus, gfc_set_backend_locus,
	gfc_restore_backend_locus): Remove prototypes.
	(gfc_locus_from_location): Add prototype.

gcc/testsuite/ChangeLog:

	* gfortran.dg/bounds_check_25.f90: Update expected column
	in the diagnostic.
	* gfortran.dg/goacc/pr92793-1.f90: Likewise.
	* gfortran.dg/gomp/allocate-14.f90: Likewise.
	* gfortran.dg/gomp/polymorphic-mapping.f90: Likewise.
	* gfortran.dg/gomp/reduction5.f90: Likewise.
	* gfortran.dg/gomp/reduction6.f90: Likewise.

1 files changed, 2 insertions, 1 deletions

diff --git a/gcc/fortran/expr.cc b/gcc/fortran/expr.cc
index 36baa9b..65bb9f1 100644
--- a/gcc/fortran/expr.cc
+++ b/gcc/fortran/expr.cc
@@ -3912,7 +3912,8 @@ gfc_check_assign (gfc_expr *lvalue, gfc_expr *rvalue, int conform,
       if (lvalue->ts.type == BT_LOGICAL && rvalue->ts.type == BT_LOGICAL)
 	return true;
 
-      where = lvalue->where.lb ? &lvalue->where : &rvalue->where;
+      where = (GFC_LOCUS_IS_SET (lvalue->where)
+	       ? &lvalue->where : &rvalue->where);
       gfc_error ("Incompatible types in DATA statement at %L; attempted "
 		 "conversion of %s to %s", where,
 		 gfc_typename (rvalue), gfc_typename (lvalue));