compiler/error_spec.m:
This new module contains the part of the old error_util.m that defines
the error_spec type, and some functions that can help construct pieces
of error_specs. Most modules of the compiler that deal with errors
will need to import only this part of the old error_util.m.
This change also renames the format_component type to format_piece,
which matches our long-standing naming convention for variables containing
(lists of) values of this type.
compiler/write_error_spec.m:
This new module contains the part of the old error_util.m that
writes out error specs, and converts them to strings.
This diff marks as obsolete the versions of predicates that
write out error specs to the current output stream, without
*explicitly* specifying the intended stream.
compiler/error_sort.m:
This new module contains the part of the old error_util.m that
sorts lists of error specs and error msgs.
compiler/error_type_util.m:
This new module contains the part of the old error_util.m that
convert types to format_pieces that generate readable output.
compiler/parse_tree.m:
compiler/notes/compiler_design.html:
Include and document the new modules.
compiler/error_util.m:
The code remaining in the original error_util.m consists of
general utility predicates and functions that don't fit into
any of the modules above.
Delete an unneeded pair of I/O states from the argument list
of a predicate.
compiler/file_util.m:
Move the unable_to_open_file predicate here from error_util.m,
since it belongs here. Mark another predicate that writes
to the current output stream as obsolete.
compiler/hlds_error_util.m:
Mark two predicates that wrote out error_spec to the current output
stream as obsolete, and add versions that take an explicit output stream.
compiler/Mercury.options:
Compile the modules that call the newly obsoleted predicates
with --no-warn-obsolete, for the time being.
compiler/*.m:
Conform to the changes above, mostly by updating import_module
declarations, and renaming format_component to format_piece.
