SARIF output: implement embedded URLs in messages (§3.11.6; PR other/116419)

SARIF output: implement embedded URLs in messages (§3.11.6; PR other/116419)

GCC diagnostic messages can contain URLs, such as to our documentation
when we suggest an option name to correct a misspelling.

SARIF message strings can contain embedded URLs in the plain text
messages (see SARIF v2.1.0 §3.11.6), but previously we were
simply dropping any URLs from the diagnostic messages.

This patch adds support for encoding URLs into messages in our SARIF
output, using the pp_token machinery added in the previous patch.

As well as supporting URLs, the patch also adjusts how we report
event IDs in SARIF message, so that rather than e.g.
  "text": "second 'free' here; first 'free' was at (1)"
we now report:
  "text": "second 'free' here; first 'free' was at [(1)](sarif:/runs/0/results/0/codeFlows/0/threadFlows/0/locations/0)"

i.e. the text "(1)" now has a embedded link referring within the sarif
log to the threadFlowLocation object for the other event, via JSON
pointer (see §3.10.3 "URIs that use the sarif scheme").  Doing so
requires the arious objects to know their index within their containing
array, requiring some reworking of how they are constructed.

gcc/ChangeLog:
	PR other/116419
	* diagnostic-event-id.h (diagnostic_event_id_t::zero_based): New.
	* diagnostic-format-sarif.cc: Include "pretty-print-format-impl.h"
	and "pretty-print-urlifier.h".
	(sarif_result::sarif_result): Add param "idx_within_parent".
	(sarif_result::get_index_within_parent): New accessor.
	(sarif_result::m_idx_within_parent): New field.
	(sarif_code_flow::sarif_code_flow): New ctor.
	(sarif_code_flow::get_parent): New accessor.
	(sarif_code_flow::get_index_within_parent): New accessor.
	(sarif_code_flow::m_parent): New field.
	(sarif_code_flow::m_thread_id_map): New field.
	(sarif_code_flow::m_thread_flows_arr): New field.
	(sarif_code_flow::m_all_tfl_objs): New field.
	(sarif_thread_flow::sarif_thread_flow): Add "parent" and
	"idx_within_parent" params.
	(sarif_thread_flow::get_parent): New accessor.
	(sarif_thread_flow::get_index_within_parent): New accessor.
	(sarif_thread_flow::m_parent): New field.
	(sarif_thread_flow::m_idx_within_parent): New field.
	(sarif_thread_flow_location::sarif_thread_flow_location): New
	ctor.
	(sarif_thread_flow_location::get_parent): New accessor.
	(sarif_thread_flow_location::get_index_within_parent): New
	accessor.
	(sarif_thread_flow_location::m_parent): New field.
	(sarif_thread_flow_location::m_idx_within_parent): New field.
	(sarif_builder::get_code_flow_for_event_ids): New accessor.
	(class sarif_builder::sarif_token_printer): New.
	(sarif_builder::m_token_printer): New member.
	(sarif_builder::m_next_result_idx): New field.
	(sarif_builder::m_current_code_flow): New field.
	(sarif_code_flow::get_or_append_thread_flow): New.
	(sarif_code_flow::get_thread_flow): New.
	(sarif_code_flow::add_location): New.
	(sarif_code_flow::get_thread_flow_loc_obj): New.
	(sarif_thread_flow::add_location): Create the new
	sarif_thread_flow_location internally, rather than passing
	it in as a parm so that we can keep track of its index in
	the array.  Return a reference to it.
	(sarif_builder::sarif_builder): Initialize m_token_printer,
	m_next_result_idx, and m_current_code_flow.
	(sarif_builder::on_report_diagnostic): Pass index to
	make_result_object.
	(sarif_builder::make_result_object): Add "idx_within_parent" param
	and pass to sarif_result ctor.  Pass code flow index to call to
	make_code_flow_object.
	(make_sarif_url_for_event): New.
	(sarif_builder::make_code_flow_object): Add "idx_within_parent"
	param and pass it to sarif_code_flow ctor.  Reimplement walking
	of events so that we first create threadFlow objects for each
	thread, then populate them with threadFlowLocation objects, so
	that the IDs work.  Set m_current_code_flow whilst creating the
	latter, so that we can create correct URIs for "%@".
	(sarif_builder::make_thread_flow_location_object): Replace with...
	(sarif_builder::populate_thread_flow_location_object): ...this.
	(sarif_output_format::get_builder): New accessor.
	(sarif_begin_embedded_link): New.
	(sarif_end_embedded_link): New.
	(sarif_builder::sarif_token_printer::print_tokens): New.
	(diagnostic_output_format_init_sarif): Add "fmt" param; use it to
	set the token printer and output format for the context.
	(diagnostic_output_format_init_sarif_stderr): Move responsibility
	for setting the context's output format to within
	diagnostic_output_format_init_sarif.
	(diagnostic_output_format_init_sarif_file): Likewise.
	(diagnostic_output_format_init_sarif_stream): Likewise.
	(test_sarif_diagnostic_context::test_sarif_diagnostic_context):
	Likewise.
	(selftest::test_make_location_object): Provide an idx for the
	result.
	(selftest::get_result_from_log): New.
	(selftest::get_message_from_log): New.
	(selftest::test_message_with_embedded_link): New test.
	(selftest::diagnostic_format_sarif_cc_tests): Call it.
	* pretty-print-format-impl.h: Include "diagnostic-event-id.h".
	(pp_token::kind): Add "event_id".
	(struct pp_token_event_id): New.
	(is_a_helper <pp_token_event_id *>::test): New.
	(is_a_helper <const pp_token_event_id *>::test): New.
	* pretty-print.cc (pp_token::dump): Handle kind::event_id.
	(pretty_printer::format): Update handling of "%@" in phase 2
	so that we add a pp_token_event_id, rather that the text "(N)".
	(default_token_printer): Handle pp_token::kind::event_id by
	printing the text "(N)".

gcc/testsuite/ChangeLog:
	PR other/116419
	* gcc.dg/sarif-output/bad-pragma.c: New test.
	* gcc.dg/sarif-output/test-bad-pragma.py: New test.
	* gcc.dg/sarif-output/test-include-chain-2.py
	(test_location_relationships): Update expected text of event to
	include an intra-sarif URI to the other event.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>