Initial implementation of a --leaf-changes-only option to abidiff

Initial implementation of a --leaf-changes-only option to abidiff

This patch allows abidiff to take the --leaf-changes-only option and
then to display only the changes that are local to any given type.
That means the reporting agent won't follow pointers when displaying
changes.  That gives less context to the ABI change reports but then
they are less cluttered.

To do this, the patch introduces a new reporting agent to libabigail:
abigail::comparison::leaf_reporter.  When given a graph of diff nodes,
this agent only reports about the leaf (local) changes.  That is, it
will *NOT* follow pointers, references, underlying types of qualified
and typedef types and things like that. It will just report about
changes that are local to a given type.

This reporting agent is then used (in lieu of the default
abigail::comparison::default_reporter agent) when the
--leaf-changes-only option is provided by the user on the command line
of abidiff.

Note that abidiff also takes the --impacted-interfaces option to so
that the leaf reporter shows the set of interfaces impacted
by each leaf change.

	* doc/manuals/abidiff.rst: Add documentation the new
	--leaf-changes-only and --impacted-interfaces options.
	* src/abg-leaf-reporter.cc: New file.
	* src/Makefile.am: Add the new src/abg-leaf-reporter.cc file to
	source distribution.
	* include/abg-fwd.h (get_var_size_in_bits)
	(function_decl_is_less_than): Declare new functions.
	(get_name): Add new overload for type_or_decl_base*.
	* include/abg-ir.h (struct type_or_decl_hash, type_or_decl_equal)
	(type_or_decl_base_comp): Define new types.
	(artifact_sptr_set_type, artifact_ptr_set_type): Define new
	typedefs.
	* include/abg-comp-filter.h: Update copyright year.
	(has_basic_type_name_change): Add new function declaration.
	* src/abg-comp-filter.cc (decl_name_changed): Take a
	type_or_decl_base rather than just a decl.  Add an overload for
	diff*.
	(has_basic_type_name_change): Define new function.
	* include/abg-comparison.h: Update copyright year.
	(string_diff_ptr_map): Define this new typedef.
	(class diff_maps): Define this new class.
	(diff_context::{set_corpora}): Remove this member function.
	(diff_context::{set_corpus_diff, get_corpus_diff,
	show_leaf_changes_only, show_impacted_interfaces,
	forbid_visiting_a_node_twice_per_interface}): Declare these new
	member functions.
	(diff_node_visitor::priv_): Add a new pimpl data member.
	(diff_node_visitor::{diff_node_visitor, get_visiting_kind,
	set_visiting_kind}): Turn these into out-of-line member functions.
	(diff_node_visitor::{set,get}_current_topmost_iface_diff): Add new
	member functions.
	(class {scope_diff, function_type_diff, corpus_diff}): Add class
	leaf_reporter as a friend.
	(corpus_diff::mark_leaf_diff_nodes, get_leaf_diffs): Declare new
	member functions.
	(diff::{visiting_a_node_twice_is_forbidden_per_interface,
	parent_interface_node}): Define new member functions.
	(is_diff_of_basic_type): Return a type_decl_diff* rather than just
	a bool.
	(is_enum_diff, is_array_diff, is_function_type, is_typedef_diff)
	(is_corpus_diff): Declare new functions.
	(corpus_diff::diff_stats::{num_leaf_changes,
	num_leaf_changes_filtered_out, net_num_leaf_changes}): Add new
	member functions.
	(is_distinct_diff): Declare new function.
	* include/abg-reporter.h: Forward-declare "class diff_maps".
	(reporter_base::diff_to_be_reported): Declare a new virtual member
	function.
	(reporter_base::{report_local_typedef_changes,
	report_local_reference_type_changes,
	report_local_function_type_changes}): Declare new member
	functions.
	(class leaf_reporter): Define new type.
	* src/abg-comparison-priv.h (struct diff_hash, diff_equal): Define
	new types.
	(diff_artifact_set_map_type): Define new typedef.
	(diff_context::priv::{first_corpus_, second_corpus_}): Remove
	these data members.
	(diff_context::priv::{corpus_diff_, leaf_changes_only_,
	reset_visited_diffs_for_each_interface_,
	show_impacted_interfaces_}): Add new data members.
	(diff_context::priv::priv): Adjust.
	(corpus_diff::priv::{leaf_diffs_, parent_interface_}): Add new
	data member.
	(corpus_diff::diff_stats::priv::{num_leaf_changes,
	num_leaf_changes_filtered_out}): Add new data members.
	(corpus_diff::priv::count_leaf_changes): Define new member
	function.
	(sort_artifacts_set, get_fn_decl_or_var_decl_diff_ancestor)
	(is_diff_of_global_decls): Declare new functions.
	(function_comp::operator()): Factorize this out into the new
	function abigail::ir::function_decl_is_less_than.
	* src/abg-ir.cc (get_var_size_in_bits)
	(function_decl_is_less_than): Define new functions.
	(get_name): Define new overload for type_or_decl_base*.
	* src/abg-comparison.cc (is_enum_diff, is_typedef_diff)
	(is_array_diff, is_function_type_diff, is_corpus_diff)
	(is_distinct_diff, sort_artifacts_set, is_diff_of_global_decls):
	Define new functions.
	(is_union_diff): Fix comment.
	(diff_context::forbid_visiting_a_node_twice_per_interface): Define
	new member functions.
	(diff_context::set_corpus_diff, get_corpus_diff)
	(diff_context::show_leaf_changes_only)
	(diff_context::visiting_a_node_twice_is_forbidden_per_interface)
	(diff_context::show_impacted_interfaces): Define new member
	functions.
	(diff_context::get_reporter): Create the reporter that matches
	what diff_context::show_leaf_changes_only says.
	(diff_node_visitor::priv): Define a new type.
	(diff_node_visitor::{diff_node_visitor, get_visiting_kind,
	set_visiting_kind, or_visiting_kind,
	set_current_topmost_iface_diff, get_current_topmost_iface_diff}):
	Define new out-of-line member functions.
	(struct diff_maps::priv): Define new type.
	(diff_maps::{diff_maps, get_type_decl_diff_map,
	get_type_decl_diff_map, get_enum_diff_map, get_class_diff_map,
	get_union_diff_map, get_typedef_diff_map, get_array_diff_map,
	get_function_type_diff_map, get_function_decl_diff_map,
	get_var_decl_diff_map, get_reference_diff_map,
	get_fn_parm_diff_map, get_distinct_diff_map, insert_diff_node,
	lookup_impacted_interfaces}): Define member functions.
	(corpus_diff::{mark_leaf_diff_nodes, get_leaf_diffs}): Define new
	member functions.
	(struct leaf_diff_node_marker_visitor): Define new type.
	(corpus_diff::apply_filters_and_suppressions_before_reporting):
	Mark diff nodes in here.
	(corpus_diff::traverse): Appropriately set the current topmost
	interface into the visitor before visiting a diff node.
	(compute_diff): In the overload for corpus_sptr, adjust to reflect
	that we are now storing the corpus_diff in the diff context.
	(is_diff_of_basic_type): Return a type_decl_diff*, not just a
	bool.
	(corpus_diff::priv::count_leaf_changes): Define a new member
	function.
	(corpus_diff::diff_stats::{num_leaf_changes,
	num_leaf_changes_filtered_out, net_num_leaf_changes}): Define new
	member functions.
	(corpus_diff::priv::apply_filters_and_compute_diff_stats): Use the
	new corpus_diff::priv::count_leaf_changes to compute the number of
	leaf changes.
	(corpus_diff::priv::emit_diff_stats): Emit the report about leaf
	type changes when necessary.
	* src/abg-reporter-priv.h (report_mem_header): Declare new
	overload.
	(maybe_show_relative_offset_change,): Pass the var_diff_sptr
	parameter by const reference.
	(represent): Pass the var_diff_sptr parameter by const reference
	and take a new "local-only" flag.
	(maybe_show_relative_size_change)
	(maybe_report_interfaces_impacted_by_diff): Declare new functions.
	* src/abg-default-reporter.cc: Adjust copyright year.
	(default_reporter::{report_local_typedef_changes,
	report_local_qualified_type_changes,
	report_local_reference_type_changes,
	report_local_function_type_changes}): Define new member functions.
	(default_reporter::report): Adjust.  Add an overload for
	function_type_diff&. In the overload for qualified_type_diff, if
	the name of the underlying type changed, do not detail the changes
	any further.  In the overload for function_decl_diff, Adjust to
	use the new diff_context::get_{first, second}_corpus member
	function.  In the overload for enum_diff, call the new
	maybe_report_interfaces_impacted_by_diff that is advertised below.
	* src/abg-reporter-priv.cc (represent): Adjust the overload for
	var_diff_sptr.
	(report_mem_header): Define new overload.
	(maybe_show_relative_size_change)
	(maybe_report_interfaces_impacted_by_diff): Define new functions.
	(reporter_base::diff_to_be_reported): Define new member function.
	(maybe_show_relative_offset_change): Pass the var_diff_sptr
	parameter by const reference.
	(represent): In the overload for var_diff_sptr, pass the
	var_diff_sptr parameter by reference.  Take a 'local_only' flag.
	Iisplay type changes only if we are not displaying "local changes
	only".  Display size changes of data members too, when in
	"local-only" mode.
	* src/abg-suppression.cc (sonames_of_binaries_match)
	(names_of_binaries_match): Adjust.
	* tools/abidiff.cc (options::{leaf_changes_only,
	show_impacted_interfaces}): Add new data members.
	(display_usage): Emit usage string for the new --leaf-changes-only
	and --impacted-interfaces options.
	(parse_command_line): Parse the new --leaf-changes-only and the
	--impacted-interfaces options.
	(set_diff_context_from_opts): Set the 'show-leaf-changes' and the
	'show-impacted-interfaces' flags.
	* tests/data/test-diff-filter/libtest42-leaf-report-v{0,1}.so: New
	test input.
	* tests/data/test-diff-filter/test42-leaf-report-output-0.txt: New
	test reference output.
	* tests/data/test-diff-filter/test42-leaf-report-v{0,1}.cc: Source
	code of the new test inputs.
	* tests/test-diff-filter.cc (in_out_specs): Use the new test
	inputs above in this harness.
	* tests/data/test-diff-suppr/libtest35-leaf-v0.so: New test input.
	* tests/data/test-diff-suppr/test35-leaf-report-0.txt: New test
	reference output.
	* tests/data/test-diff-suppr/test35-leaf-v{0,1}.cc: Source code of
	the new test inputs.
	* tests/data/test-diff-suppr/test35-leaf.suppr: Suppression
	specification to use for the test35 test.
	* tests/data/test-diff-suppr/libtest36-leaf-v0.so: New test input.
	* tests/data/test-diff-suppr/libtest36-leaf-v1.so: Likewise.
	* tests/data/test-diff-suppr/test36-leaf-report-0.txt: New
	reference test output.
	* tests/data/test-diff-suppr/test36-leaf-v0.cc: Source code of
	test input above.
	* tests/data/test-diff-suppr/test36-leaf-v1.cc: Likewise.
	* tests/test-diff-suppr.cc (in_out_specs): Use the new test inputs
	above in this harness.
	* tests/data/Makefile.am: Add the new test inputs above to source
	distribution.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>