gcc/ChangeLog:
* diagnostic-format-json.cc (on_begin_diagnostic): Convert param
to const reference.
(on_end_diagnostic): Likewise.
(json_output_format::on_end_diagnostic): Likewise.
* diagnostic-format-sarif.cc
(sarif_invocation::add_notification_for_ice): Likewise.
(sarif_result::on_nested_diagnostic): Likewise.
(sarif_ice_notification::sarif_ice_notification): Likewise.
(sarif_builder::end_diagnostic): Likewise.
(sarif_builder::make_result_object): Likewise.
(make_reporting_descriptor_object_for_warning): Likewise.
(sarif_builder::make_locations_arr): Likewise.
(sarif_output_format::on_begin_diagnostic): Likewise.
(sarif_output_format::on_end_diagnostic): Likewise.
* diagnostic.cc (default_diagnostic_starter): Make diagnostic_info
param const.
(default_diagnostic_finalizer): Likewise.
(diagnostic_context::report_diagnostic): Pass diagnostic by
reference to on_{begin,end}_diagnostic.
(diagnostic_text_output_format::on_begin_diagnostic): Convert
param to const reference.
(diagnostic_text_output_format::on_end_diagnostic): Likewise.
* diagnostic.h (diagnostic_starter_fn): Make diagnostic_info param
const.
(diagnostic_finalizer_fn): Likeewise.
(diagnostic_output_format::on_begin_diagnostic): Convert param to
const reference.
(diagnostic_output_format::on_end_diagnostic): Likewise.
(diagnostic_text_output_format::on_begin_diagnostic): Likewise.
(diagnostic_text_output_format::on_end_diagnostic): Likewise.
(default_diagnostic_starter): Make diagnostic_info param const.
(default_diagnostic_finalizer): Likewise.
* langhooks-def.h (lhd_print_error_function): Make diagnostic_info
param const.
* langhooks.cc (lhd_print_error_function): Likewise.
* langhooks.h (lang_hooks::print_error_function): Likewise.
* tree-diagnostic.cc (diagnostic_report_current_function):
Likewise.
(default_tree_diagnostic_starter): Likewise.
(virt_loc_aware_diagnostic_finalizer): Likewise.
* tree-diagnostic.h (diagnostic_report_current_function):
Likewise.
(virt_loc_aware_diagnostic_finalizer): Likewise.
gcc/fortran/ChangeLog:
* error.cc (gfc_diagnostic_starter): Make diagnostic_info param
const.
(gfc_diagnostic_finalizer): Likewise.
gcc/jit/ChangeLog:
* dummy-frontend.cc (jit_begin_diagnostic): Make diagnostic_info
param const.
(jit_end_diagnostic): Likewise. Pass to add_diagnostic by
reference.
* jit-playback.cc (jit::playback::context::add_diagnostic):
Convert diagnostic_info to const reference.
* jit-playback.h (jit::playback::context::add_diagnostic):
Likewise.