This patch eliminates the hard-coded limits within rich_location
(up to 3 ranges, up to 2 fixits).  The common case is still
handled by embedding the values inside rich_location - it only
uses dynamic allocation if these limits are exceeded, so
creation of rich_location instances on the stack should still
be fast.  This is implemented via a new container class,
semi_embedded_vec <T, N>.

gcc/ChangeLog:
	* diagnostic-show-locus.c (colorizer::begin_state): Support more
	than 3 ranges per diagnostic by alternating between color 1 and
	color 2.
	(layout::layout): Replace use of rich_location::MAX_RANGES
	with richloc->get_num_locations ().
	(layout::calculate_line_spans): Replace use of
	rich_location::MAX_RANGES with m_layout_ranges.length ().
	(layout::print_annotation_line): Handle arbitrary numbers of
	ranges in caret-printing by defaulting to '^'.
	(selftest::test_one_liner_many_fixits): New function.
	(test_diagnostic_show_locus_one_liner): Call it.
	* diagnostic.c (diagnostic_initialize): Update for renaming
	of rich_location::MAX_RANGES to
	rich_location::STATICALLY_ALLOCATED_RANGES.
	* diagnostic.h (struct diagnostic_context): Likewise.

gcc/testsuite/ChangeLog:
	* gcc.dg/plugin/diagnostic-test-show-locus-bw.c
	(test_many_nested_locations): New function.
	* gcc.dg/plugin/diagnostic_plugin_test_show_locus.c
	(test_show_locus): Handle "test_many_nested_locations".

libcpp/ChangeLog:
	* include/line-map.h (class semi_embedded_vec): New class.
	(semi_embedded_vec<T, NUM_EMBEDDED>::semi_embedded_vec): New ctor.
	(semi_embedded_vec<T, NUM_EMBEDDED>::~semi_embedded_vec): New
	dtor.
	(semi_embedded_vec<T, NUM_EMBEDDED>::operator[]): New methods.
	(semi_embedded_vec<T, NUM_EMBEDDED>::push): New method.
	(semi_embedded_vec<T, NUM_EMBEDDED>::truncate): New method.
	(rich_location::get_num_locations): Reimplement in terms of
	m_ranges.
	(rich_location::get_range): Make non-inline.
	(rich_location::get_num_fixit_hints): Reimplement in terms of
	m_fixit_hints.
	(rich_location::add_fixit): New function.
	(rich_location::MAX_RANGES): Rename to...
	(rich_location::STATICALLY_ALLOCATED_RANGES): ...this.
	(rich_location::MAX_FIXIT_HINTS): Rename to...
	(rich_location::STATICALLY_ALLOCATED_RANGES): ...this, and make
	private.
	(rich_location::m_num_ranges): Eliminate in favor of...
	(rich_location::m_ranges): ...this, converting from a fixed-size
	array to a semi_embedded_vec.
	(rich_location::m_num_fixit_hints): Eliminate in favor of...
	(rich_location::m_fixit_hints): ...this, converting from a
	fixed-size array to a semi_embedded_vec.
	* line-map.c (rich_location::rich_location): Update for above
	changes.
	(rich_location::~rich_location): Likewise.
	(rich_location::get_loc): Likewise.
	(rich_location::get_range): New methods.
	(rich_location::add_range): Update for above changes.
	(rich_location::set_range): Likewise.
	(rich_location::add_fixit_insert): Likewise.
	(rich_location::add_fixit_replace): Likewise.
	(rich_location::get_last_fixit_hint): Likewise.
	(rich_location::reject_impossible_fixit): Likewise.
	(rich_location::add_fixit): New method.

From-SVN: r239879