build: switch to using clang-format instead of GNU indent

GNU indent yields weird output when using the Linux kernel coding
style as in the below examples, which affects code readability.

- Too long lines cause unexpected indentation:
  			if (!
  			    (priv->flags &
  			     GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_DISTRUSTED)
  && (priv->flags & GNUTLS_PKCS11_OBJ_FLAG_OVERWRITE_TRUSTMOD_EXT)
  && data.size > 0) {

- Unary operators (`-` and `+`) after a type cast are not recognized
  properly: `(time_t)-1` becomes `(time-t) - 1`

- Long conditionals are wrapped before binary operators, such as `&&`
  or `||`.  This is not mandatory in the style, but all the occurrences
  are replaced with that style

This switches to using clang-format instead, with the configuration
used in the Linux kernel as of commit
596ff4a09b8981790e15572e8e7bc904df5835e7:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/.clang-format

Signed-off-by: Daiki Ueno <ueno@gnu.org>

4 files changed, 758 insertions, 66 deletions

diff --git a/.clang-format b/.clang-format
new file mode 100644
index 0000000000..cf94406710
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,689 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# clang-format configuration file. Intended for clang-format >= 11.
+#
+# For more information, see:
+#
+#   Documentation/process/clang-format.rst
+#   https://clang.llvm.org/docs/ClangFormat.html
+#   https://clang.llvm.org/docs/ClangFormatStyleOptions.html
+#
+---
+AccessModifierOffset: -4
+AlignAfterOpenBracket: Align
+AlignConsecutiveAssignments: false
+AlignConsecutiveDeclarations: false
+AlignEscapedNewlines: Left
+AlignOperands: true
+AlignTrailingComments: false
+AllowAllParametersOfDeclarationOnNextLine: false
+AllowShortBlocksOnASingleLine: false
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortEnumsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: None
+AllowShortIfStatementsOnASingleLine: false
+AllowShortLoopsOnASingleLine: false
+AlwaysBreakAfterDefinitionReturnType: None
+AlwaysBreakAfterReturnType: None
+AlwaysBreakBeforeMultilineStrings: false
+AlwaysBreakTemplateDeclarations: false
+BinPackArguments: true
+BinPackParameters: true
+BraceWrapping:
+  AfterClass: false
+  AfterControlStatement: false
+  AfterEnum: false
+  AfterFunction: true
+  AfterNamespace: true
+  AfterObjCDeclaration: false
+  AfterStruct: false
+  AfterUnion: false
+  AfterExternBlock: false
+  BeforeCatch: false
+  BeforeElse: false
+  IndentBraces: false
+  SplitEmptyFunction: true
+  SplitEmptyRecord: true
+  SplitEmptyNamespace: true
+BreakBeforeBinaryOperators: None
+BreakBeforeBraces: Custom
+BreakBeforeInheritanceComma: false
+BreakBeforeTernaryOperators: false
+BreakConstructorInitializersBeforeComma: false
+BreakConstructorInitializers: BeforeComma
+BreakAfterJavaFieldAnnotations: false
+BreakStringLiterals: false
+ColumnLimit: 80
+CommentPragmas: '^ IWYU pragma:'
+CompactNamespaces: false
+ConstructorInitializerAllOnOneLineOrOnePerLine: false
+ConstructorInitializerIndentWidth: 8
+ContinuationIndentWidth: 8
+Cpp11BracedListStyle: false
+DerivePointerAlignment: false
+DisableFormat: false
+ExperimentalAutoDetectBinPacking: false
+FixNamespaceComments: false
+
+# Taken from:
+#   git grep -h '^#define [^[:space:]]*for_each[^[:space:]]*(' include/ tools/ \
+#   | sed "s,^#define \([^[:space:]]*for_each[^[:space:]]*\)(.*$,  - '\1'," \
+#   | LC_ALL=C sort -u
+ForEachMacros:
+  - '__ata_qc_for_each'
+  - '__bio_for_each_bvec'
+  - '__bio_for_each_segment'
+  - '__evlist__for_each_entry'
+  - '__evlist__for_each_entry_continue'
+  - '__evlist__for_each_entry_from'
+  - '__evlist__for_each_entry_reverse'
+  - '__evlist__for_each_entry_safe'
+  - '__for_each_mem_range'
+  - '__for_each_mem_range_rev'
+  - '__for_each_thread'
+  - '__hlist_for_each_rcu'
+  - '__map__for_each_symbol_by_name'
+  - '__perf_evlist__for_each_entry'
+  - '__perf_evlist__for_each_entry_reverse'
+  - '__perf_evlist__for_each_entry_safe'
+  - '__rq_for_each_bio'
+  - '__shost_for_each_device'
+  - 'apei_estatus_for_each_section'
+  - 'ata_for_each_dev'
+  - 'ata_for_each_link'
+  - 'ata_qc_for_each'
+  - 'ata_qc_for_each_raw'
+  - 'ata_qc_for_each_with_internal'
+  - 'ax25_for_each'
+  - 'ax25_uid_for_each'
+  - 'bio_for_each_bvec'
+  - 'bio_for_each_bvec_all'
+  - 'bio_for_each_folio_all'
+  - 'bio_for_each_integrity_vec'
+  - 'bio_for_each_segment'
+  - 'bio_for_each_segment_all'
+  - 'bio_list_for_each'
+  - 'bip_for_each_vec'
+  - 'bond_for_each_slave'
+  - 'bond_for_each_slave_rcu'
+  - 'bpf__perf_for_each_map'
+  - 'bpf__perf_for_each_map_named'
+  - 'bpf_for_each_spilled_reg'
+  - 'bpf_object__for_each_map'
+  - 'bpf_object__for_each_program'
+  - 'bpf_object__for_each_safe'
+  - 'bpf_perf_object__for_each'
+  - 'btree_for_each_safe128'
+  - 'btree_for_each_safe32'
+  - 'btree_for_each_safe64'
+  - 'btree_for_each_safel'
+  - 'card_for_each_dev'
+  - 'cgroup_taskset_for_each'
+  - 'cgroup_taskset_for_each_leader'
+  - 'cpufreq_for_each_efficient_entry_idx'
+  - 'cpufreq_for_each_entry'
+  - 'cpufreq_for_each_entry_idx'
+  - 'cpufreq_for_each_valid_entry'
+  - 'cpufreq_for_each_valid_entry_idx'
+  - 'css_for_each_child'
+  - 'css_for_each_descendant_post'
+  - 'css_for_each_descendant_pre'
+  - 'damon_for_each_region'
+  - 'damon_for_each_region_safe'
+  - 'damon_for_each_scheme'
+  - 'damon_for_each_scheme_safe'
+  - 'damon_for_each_target'
+  - 'damon_for_each_target_safe'
+  - 'data__for_each_file'
+  - 'data__for_each_file_new'
+  - 'data__for_each_file_start'
+  - 'device_for_each_child_node'
+  - 'displayid_iter_for_each'
+  - 'dma_fence_array_for_each'
+  - 'dma_fence_chain_for_each'
+  - 'dma_fence_unwrap_for_each'
+  - 'dma_resv_for_each_fence'
+  - 'dma_resv_for_each_fence_unlocked'
+  - 'do_for_each_ftrace_op'
+  - 'drm_atomic_crtc_for_each_plane'
+  - 'drm_atomic_crtc_state_for_each_plane'
+  - 'drm_atomic_crtc_state_for_each_plane_state'
+  - 'drm_atomic_for_each_plane_damage'
+  - 'drm_client_for_each_connector_iter'
+  - 'drm_client_for_each_modeset'
+  - 'drm_connector_for_each_possible_encoder'
+  - 'drm_for_each_bridge_in_chain'
+  - 'drm_for_each_connector_iter'
+  - 'drm_for_each_crtc'
+  - 'drm_for_each_crtc_reverse'
+  - 'drm_for_each_encoder'
+  - 'drm_for_each_encoder_mask'
+  - 'drm_for_each_fb'
+  - 'drm_for_each_legacy_plane'
+  - 'drm_for_each_plane'
+  - 'drm_for_each_plane_mask'
+  - 'drm_for_each_privobj'
+  - 'drm_mm_for_each_hole'
+  - 'drm_mm_for_each_node'
+  - 'drm_mm_for_each_node_in_range'
+  - 'drm_mm_for_each_node_safe'
+  - 'dsa_switch_for_each_available_port'
+  - 'dsa_switch_for_each_cpu_port'
+  - 'dsa_switch_for_each_port'
+  - 'dsa_switch_for_each_port_continue_reverse'
+  - 'dsa_switch_for_each_port_safe'
+  - 'dsa_switch_for_each_user_port'
+  - 'dsa_tree_for_each_user_port'
+  - 'dso__for_each_symbol'
+  - 'dsos__for_each_with_build_id'
+  - 'elf_hash_for_each_possible'
+  - 'elf_section__for_each_rel'
+  - 'elf_section__for_each_rela'
+  - 'elf_symtab__for_each_symbol'
+  - 'evlist__for_each_cpu'
+  - 'evlist__for_each_entry'
+  - 'evlist__for_each_entry_continue'
+  - 'evlist__for_each_entry_from'
+  - 'evlist__for_each_entry_reverse'
+  - 'evlist__for_each_entry_safe'
+  - 'flow_action_for_each'
+  - 'for_each_acpi_dev_match'
+  - 'for_each_active_dev_scope'
+  - 'for_each_active_drhd_unit'
+  - 'for_each_active_iommu'
+  - 'for_each_active_route'
+  - 'for_each_aggr_pgid'
+  - 'for_each_available_child_of_node'
+  - 'for_each_bench'
+  - 'for_each_bio'
+  - 'for_each_board_func_rsrc'
+  - 'for_each_btf_ext_rec'
+  - 'for_each_btf_ext_sec'
+  - 'for_each_bvec'
+  - 'for_each_card_auxs'
+  - 'for_each_card_auxs_safe'
+  - 'for_each_card_components'
+  - 'for_each_card_dapms'
+  - 'for_each_card_pre_auxs'
+  - 'for_each_card_prelinks'
+  - 'for_each_card_rtds'
+  - 'for_each_card_rtds_safe'
+  - 'for_each_card_widgets'
+  - 'for_each_card_widgets_safe'
+  - 'for_each_cgroup_storage_type'
+  - 'for_each_child_of_node'
+  - 'for_each_clear_bit'
+  - 'for_each_clear_bit_from'
+  - 'for_each_clear_bitrange'
+  - 'for_each_clear_bitrange_from'
+  - 'for_each_cmd'
+  - 'for_each_cmsghdr'
+  - 'for_each_collection'
+  - 'for_each_comp_order'
+  - 'for_each_compatible_node'
+  - 'for_each_component_dais'
+  - 'for_each_component_dais_safe'
+  - 'for_each_console'
+  - 'for_each_console_srcu'
+  - 'for_each_cpu'
+  - 'for_each_cpu_and'
+  - 'for_each_cpu_wrap'
+  - 'for_each_dapm_widgets'
+  - 'for_each_dedup_cand'
+  - 'for_each_dev_addr'
+  - 'for_each_dev_scope'
+  - 'for_each_dma_cap_mask'
+  - 'for_each_dpcm_be'
+  - 'for_each_dpcm_be_rollback'
+  - 'for_each_dpcm_be_safe'
+  - 'for_each_dpcm_fe'
+  - 'for_each_drhd_unit'
+  - 'for_each_dss_dev'
+  - 'for_each_efi_memory_desc'
+  - 'for_each_efi_memory_desc_in_map'
+  - 'for_each_element'
+  - 'for_each_element_extid'
+  - 'for_each_element_id'
+  - 'for_each_endpoint_of_node'
+  - 'for_each_event'
+  - 'for_each_event_tps'
+  - 'for_each_evictable_lru'
+  - 'for_each_fib6_node_rt_rcu'
+  - 'for_each_fib6_walker_rt'
+  - 'for_each_free_mem_pfn_range_in_zone'
+  - 'for_each_free_mem_pfn_range_in_zone_from'
+  - 'for_each_free_mem_range'
+  - 'for_each_free_mem_range_reverse'
+  - 'for_each_func_rsrc'
+  - 'for_each_group_evsel'
+  - 'for_each_group_member'
+  - 'for_each_hstate'
+  - 'for_each_if'
+  - 'for_each_inject_fn'
+  - 'for_each_insn'
+  - 'for_each_insn_prefix'
+  - 'for_each_intid'
+  - 'for_each_iommu'
+  - 'for_each_ip_tunnel_rcu'
+  - 'for_each_irq_nr'
+  - 'for_each_lang'
+  - 'for_each_link_codecs'
+  - 'for_each_link_cpus'
+  - 'for_each_link_platforms'
+  - 'for_each_lru'
+  - 'for_each_matching_node'
+  - 'for_each_matching_node_and_match'
+  - 'for_each_mem_pfn_range'
+  - 'for_each_mem_range'
+  - 'for_each_mem_range_rev'
+  - 'for_each_mem_region'
+  - 'for_each_member'
+  - 'for_each_memory'
+  - 'for_each_migratetype_order'
+  - 'for_each_missing_reg'
+  - 'for_each_net'
+  - 'for_each_net_continue_reverse'
+  - 'for_each_net_rcu'
+  - 'for_each_netdev'
+  - 'for_each_netdev_continue'
+  - 'for_each_netdev_continue_rcu'
+  - 'for_each_netdev_continue_reverse'
+  - 'for_each_netdev_feature'
+  - 'for_each_netdev_in_bond_rcu'
+  - 'for_each_netdev_rcu'
+  - 'for_each_netdev_reverse'
+  - 'for_each_netdev_safe'
+  - 'for_each_new_connector_in_state'
+  - 'for_each_new_crtc_in_state'
+  - 'for_each_new_mst_mgr_in_state'
+  - 'for_each_new_plane_in_state'
+  - 'for_each_new_plane_in_state_reverse'
+  - 'for_each_new_private_obj_in_state'
+  - 'for_each_new_reg'
+  - 'for_each_node'
+  - 'for_each_node_by_name'
+  - 'for_each_node_by_type'
+  - 'for_each_node_mask'
+  - 'for_each_node_state'
+  - 'for_each_node_with_cpus'
+  - 'for_each_node_with_property'
+  - 'for_each_nonreserved_multicast_dest_pgid'
+  - 'for_each_of_allnodes'
+  - 'for_each_of_allnodes_from'
+  - 'for_each_of_cpu_node'
+  - 'for_each_of_pci_range'
+  - 'for_each_old_connector_in_state'
+  - 'for_each_old_crtc_in_state'
+  - 'for_each_old_mst_mgr_in_state'
+  - 'for_each_old_plane_in_state'
+  - 'for_each_old_private_obj_in_state'
+  - 'for_each_oldnew_connector_in_state'
+  - 'for_each_oldnew_crtc_in_state'
+  - 'for_each_oldnew_mst_mgr_in_state'
+  - 'for_each_oldnew_plane_in_state'
+  - 'for_each_oldnew_plane_in_state_reverse'
+  - 'for_each_oldnew_private_obj_in_state'
+  - 'for_each_online_cpu'
+  - 'for_each_online_node'
+  - 'for_each_online_pgdat'
+  - 'for_each_path'
+  - 'for_each_pci_bridge'
+  - 'for_each_pci_dev'
+  - 'for_each_pcm_streams'
+  - 'for_each_physmem_range'
+  - 'for_each_populated_zone'
+  - 'for_each_possible_cpu'
+  - 'for_each_present_cpu'
+  - 'for_each_prime_number'
+  - 'for_each_prime_number_from'
+  - 'for_each_probe_cache_entry'
+  - 'for_each_process'
+  - 'for_each_process_thread'
+  - 'for_each_prop_codec_conf'
+  - 'for_each_prop_dai_codec'
+  - 'for_each_prop_dai_cpu'
+  - 'for_each_prop_dlc_codecs'
+  - 'for_each_prop_dlc_cpus'
+  - 'for_each_prop_dlc_platforms'
+  - 'for_each_property_of_node'
+  - 'for_each_reg'
+  - 'for_each_reg_filtered'
+  - 'for_each_registered_fb'
+  - 'for_each_requested_gpio'
+  - 'for_each_requested_gpio_in_range'
+  - 'for_each_reserved_mem_range'
+  - 'for_each_reserved_mem_region'
+  - 'for_each_rtd_codec_dais'
+  - 'for_each_rtd_components'
+  - 'for_each_rtd_cpu_dais'
+  - 'for_each_rtd_dais'
+  - 'for_each_script'
+  - 'for_each_sec'
+  - 'for_each_set_bit'
+  - 'for_each_set_bit_from'
+  - 'for_each_set_bitrange'
+  - 'for_each_set_bitrange_from'
+  - 'for_each_set_clump8'
+  - 'for_each_sg'
+  - 'for_each_sg_dma_page'
+  - 'for_each_sg_page'
+  - 'for_each_sgtable_dma_page'
+  - 'for_each_sgtable_dma_sg'
+  - 'for_each_sgtable_page'
+  - 'for_each_sgtable_sg'
+  - 'for_each_shell_test'
+  - 'for_each_sibling_event'
+  - 'for_each_subelement'
+  - 'for_each_subelement_extid'
+  - 'for_each_subelement_id'
+  - 'for_each_sublist'
+  - 'for_each_subsystem'
+  - 'for_each_supported_activate_fn'
+  - 'for_each_supported_inject_fn'
+  - 'for_each_test'
+  - 'for_each_thread'
+  - 'for_each_token'
+  - 'for_each_unicast_dest_pgid'
+  - 'for_each_vsi'
+  - 'for_each_wakeup_source'
+  - 'for_each_zone'
+  - 'for_each_zone_zonelist'
+  - 'for_each_zone_zonelist_nodemask'
+  - 'func_for_each_insn'
+  - 'fwnode_for_each_available_child_node'
+  - 'fwnode_for_each_child_node'
+  - 'fwnode_graph_for_each_endpoint'
+  - 'gadget_for_each_ep'
+  - 'genradix_for_each'
+  - 'genradix_for_each_from'
+  - 'hash_for_each'
+  - 'hash_for_each_possible'
+  - 'hash_for_each_possible_rcu'
+  - 'hash_for_each_possible_rcu_notrace'
+  - 'hash_for_each_possible_safe'
+  - 'hash_for_each_rcu'
+  - 'hash_for_each_safe'
+  - 'hashmap__for_each_entry'
+  - 'hashmap__for_each_entry_safe'
+  - 'hashmap__for_each_key_entry'
+  - 'hashmap__for_each_key_entry_safe'
+  - 'hctx_for_each_ctx'
+  - 'hists__for_each_format'
+  - 'hists__for_each_sort_list'
+  - 'hlist_bl_for_each_entry'
+  - 'hlist_bl_for_each_entry_rcu'
+  - 'hlist_bl_for_each_entry_safe'
+  - 'hlist_for_each'
+  - 'hlist_for_each_entry'
+  - 'hlist_for_each_entry_continue'
+  - 'hlist_for_each_entry_continue_rcu'
+  - 'hlist_for_each_entry_continue_rcu_bh'
+  - 'hlist_for_each_entry_from'
+  - 'hlist_for_each_entry_from_rcu'
+  - 'hlist_for_each_entry_rcu'
+  - 'hlist_for_each_entry_rcu_bh'
+  - 'hlist_for_each_entry_rcu_notrace'
+  - 'hlist_for_each_entry_safe'
+  - 'hlist_for_each_entry_srcu'
+  - 'hlist_for_each_safe'
+  - 'hlist_nulls_for_each_entry'
+  - 'hlist_nulls_for_each_entry_from'
+  - 'hlist_nulls_for_each_entry_rcu'
+  - 'hlist_nulls_for_each_entry_safe'
+  - 'i3c_bus_for_each_i2cdev'
+  - 'i3c_bus_for_each_i3cdev'
+  - 'idr_for_each_entry'
+  - 'idr_for_each_entry_continue'
+  - 'idr_for_each_entry_continue_ul'
+  - 'idr_for_each_entry_ul'
+  - 'in_dev_for_each_ifa_rcu'
+  - 'in_dev_for_each_ifa_rtnl'
+  - 'inet_bind_bucket_for_each'
+  - 'inet_lhash2_for_each_icsk'
+  - 'inet_lhash2_for_each_icsk_continue'
+  - 'inet_lhash2_for_each_icsk_rcu'
+  - 'interval_tree_for_each_double_span'
+  - 'interval_tree_for_each_span'
+  - 'intlist__for_each_entry'
+  - 'intlist__for_each_entry_safe'
+  - 'iopt_for_each_contig_area'
+  - 'kcore_copy__for_each_phdr'
+  - 'key_for_each'
+  - 'key_for_each_safe'
+  - 'klp_for_each_func'
+  - 'klp_for_each_func_safe'
+  - 'klp_for_each_func_static'
+  - 'klp_for_each_object'
+  - 'klp_for_each_object_safe'
+  - 'klp_for_each_object_static'
+  - 'kunit_suite_for_each_test_case'
+  - 'kvm_for_each_memslot'
+  - 'kvm_for_each_memslot_in_gfn_range'
+  - 'kvm_for_each_vcpu'
+  - 'libbpf_nla_for_each_attr'
+  - 'list_for_each'
+  - 'list_for_each_codec'
+  - 'list_for_each_codec_safe'
+  - 'list_for_each_continue'
+  - 'list_for_each_entry'
+  - 'list_for_each_entry_continue'
+  - 'list_for_each_entry_continue_rcu'
+  - 'list_for_each_entry_continue_reverse'
+  - 'list_for_each_entry_from'
+  - 'list_for_each_entry_from_rcu'
+  - 'list_for_each_entry_from_reverse'
+  - 'list_for_each_entry_lockless'
+  - 'list_for_each_entry_rcu'
+  - 'list_for_each_entry_reverse'
+  - 'list_for_each_entry_safe'
+  - 'list_for_each_entry_safe_continue'
+  - 'list_for_each_entry_safe_from'
+  - 'list_for_each_entry_safe_reverse'
+  - 'list_for_each_entry_srcu'
+  - 'list_for_each_from'
+  - 'list_for_each_prev'
+  - 'list_for_each_prev_safe'
+  - 'list_for_each_safe'
+  - 'llist_for_each'
+  - 'llist_for_each_entry'
+  - 'llist_for_each_entry_safe'
+  - 'llist_for_each_safe'
+  - 'map__for_each_symbol'
+  - 'map__for_each_symbol_by_name'
+  - 'map_for_each_event'
+  - 'map_for_each_metric'
+  - 'maps__for_each_entry'
+  - 'maps__for_each_entry_safe'
+  - 'mci_for_each_dimm'
+  - 'media_device_for_each_entity'
+  - 'media_device_for_each_intf'
+  - 'media_device_for_each_link'
+  - 'media_device_for_each_pad'
+  - 'msi_for_each_desc'
+  - 'nanddev_io_for_each_page'
+  - 'netdev_for_each_lower_dev'
+  - 'netdev_for_each_lower_private'
+  - 'netdev_for_each_lower_private_rcu'
+  - 'netdev_for_each_mc_addr'
+  - 'netdev_for_each_uc_addr'
+  - 'netdev_for_each_upper_dev_rcu'
+  - 'netdev_hw_addr_list_for_each'
+  - 'nft_rule_for_each_expr'
+  - 'nla_for_each_attr'
+  - 'nla_for_each_nested'
+  - 'nlmsg_for_each_attr'
+  - 'nlmsg_for_each_msg'
+  - 'nr_neigh_for_each'
+  - 'nr_neigh_for_each_safe'
+  - 'nr_node_for_each'
+  - 'nr_node_for_each_safe'
+  - 'of_for_each_phandle'
+  - 'of_property_for_each_string'
+  - 'of_property_for_each_u32'
+  - 'pci_bus_for_each_resource'
+  - 'pci_doe_for_each_off'
+  - 'pcl_for_each_chunk'
+  - 'pcl_for_each_segment'
+  - 'pcm_for_each_format'
+  - 'perf_config_items__for_each_entry'
+  - 'perf_config_sections__for_each_entry'
+  - 'perf_config_set__for_each_entry'
+  - 'perf_cpu_map__for_each_cpu'
+  - 'perf_evlist__for_each_entry'
+  - 'perf_evlist__for_each_entry_reverse'
+  - 'perf_evlist__for_each_entry_safe'
+  - 'perf_evlist__for_each_evsel'
+  - 'perf_evlist__for_each_mmap'
+  - 'perf_hpp_list__for_each_format'
+  - 'perf_hpp_list__for_each_format_safe'
+  - 'perf_hpp_list__for_each_sort_list'
+  - 'perf_hpp_list__for_each_sort_list_safe'
+  - 'perf_pmu__for_each_hybrid_pmu'
+  - 'ping_portaddr_for_each_entry'
+  - 'ping_portaddr_for_each_entry_rcu'
+  - 'plist_for_each'
+  - 'plist_for_each_continue'
+  - 'plist_for_each_entry'
+  - 'plist_for_each_entry_continue'
+  - 'plist_for_each_entry_safe'
+  - 'plist_for_each_safe'
+  - 'pnp_for_each_card'
+  - 'pnp_for_each_dev'
+  - 'protocol_for_each_card'
+  - 'protocol_for_each_dev'
+  - 'queue_for_each_hw_ctx'
+  - 'radix_tree_for_each_slot'
+  - 'radix_tree_for_each_tagged'
+  - 'rb_for_each'
+  - 'rbtree_postorder_for_each_entry_safe'
+  - 'rdma_for_each_block'
+  - 'rdma_for_each_port'
+  - 'rdma_umem_for_each_dma_block'
+  - 'resort_rb__for_each_entry'
+  - 'resource_list_for_each_entry'
+  - 'resource_list_for_each_entry_safe'
+  - 'rhl_for_each_entry_rcu'
+  - 'rhl_for_each_rcu'
+  - 'rht_for_each'
+  - 'rht_for_each_entry'
+  - 'rht_for_each_entry_from'
+  - 'rht_for_each_entry_rcu'
+  - 'rht_for_each_entry_rcu_from'
+  - 'rht_for_each_entry_safe'
+  - 'rht_for_each_from'
+  - 'rht_for_each_rcu'
+  - 'rht_for_each_rcu_from'
+  - 'rq_for_each_bvec'
+  - 'rq_for_each_segment'
+  - 'rq_list_for_each'
+  - 'rq_list_for_each_safe'
+  - 'scsi_for_each_prot_sg'
+  - 'scsi_for_each_sg'
+  - 'sctp_for_each_hentry'
+  - 'sctp_skb_for_each'
+  - 'sec_for_each_insn'
+  - 'sec_for_each_insn_continue'
+  - 'sec_for_each_insn_from'
+  - 'shdma_for_each_chan'
+  - 'shost_for_each_device'
+  - 'sk_for_each'
+  - 'sk_for_each_bound'
+  - 'sk_for_each_entry_offset_rcu'
+  - 'sk_for_each_from'
+  - 'sk_for_each_rcu'
+  - 'sk_for_each_safe'
+  - 'sk_nulls_for_each'
+  - 'sk_nulls_for_each_from'
+  - 'sk_nulls_for_each_rcu'
+  - 'snd_array_for_each'
+  - 'snd_pcm_group_for_each_entry'
+  - 'snd_soc_dapm_widget_for_each_path'
+  - 'snd_soc_dapm_widget_for_each_path_safe'
+  - 'snd_soc_dapm_widget_for_each_sink_path'
+  - 'snd_soc_dapm_widget_for_each_source_path'
+  - 'strlist__for_each_entry'
+  - 'strlist__for_each_entry_safe'
+  - 'sym_for_each_insn'
+  - 'sym_for_each_insn_continue_reverse'
+  - 'symbols__for_each_entry'
+  - 'tb_property_for_each'
+  - 'tcf_act_for_each_action'
+  - 'tcf_exts_for_each_action'
+  - 'udp_portaddr_for_each_entry'
+  - 'udp_portaddr_for_each_entry_rcu'
+  - 'usb_hub_for_each_child'
+  - 'v4l2_device_for_each_subdev'
+  - 'v4l2_m2m_for_each_dst_buf'
+  - 'v4l2_m2m_for_each_dst_buf_safe'
+  - 'v4l2_m2m_for_each_src_buf'
+  - 'v4l2_m2m_for_each_src_buf_safe'
+  - 'virtio_device_for_each_vq'
+  - 'while_for_each_ftrace_op'
+  - 'xa_for_each'
+  - 'xa_for_each_marked'
+  - 'xa_for_each_range'
+  - 'xa_for_each_start'
+  - 'xas_for_each'
+  - 'xas_for_each_conflict'
+  - 'xas_for_each_marked'
+  - 'xbc_array_for_each_value'
+  - 'xbc_for_each_key_value'
+  - 'xbc_node_for_each_array_value'
+  - 'xbc_node_for_each_child'
+  - 'xbc_node_for_each_key_value'
+  - 'xbc_node_for_each_subkey'
+  - 'zorro_for_each_dev'
+
+IncludeBlocks: Preserve
+IncludeCategories:
+  - Regex: '.*'
+    Priority: 1
+IncludeIsMainRegex: '(Test)?$'
+IndentCaseLabels: false
+IndentGotoLabels: true
+IndentPPDirectives: None
+IndentWidth: 8
+IndentWrappedFunctionNames: false
+JavaScriptQuotes: Leave
+JavaScriptWrapImports: true
+KeepEmptyLinesAtTheStartOfBlocks: false
+MacroBlockBegin: ''
+MacroBlockEnd: ''
+MaxEmptyLinesToKeep: 1
+NamespaceIndentation: None
+ObjCBinPackProtocolList: Auto
+ObjCBlockIndentWidth: 8
+ObjCSpaceAfterProperty: true
+ObjCSpaceBeforeProtocolList: true
+
+# Taken from git's rules
+PenaltyBreakAssignment: 10
+PenaltyBreakBeforeFirstCallParameter: 30
+PenaltyBreakComment: 10
+PenaltyBreakFirstLessLess: 0
+PenaltyBreakString: 10
+PenaltyExcessCharacter: 100
+PenaltyReturnTypeOnItsOwnLine: 60
+
+PointerAlignment: Right
+ReflowComments: false
+SortIncludes: false
+SortUsingDeclarations: false
+SpaceAfterCStyleCast: false
+SpaceAfterTemplateKeyword: true
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeCtorInitializerColon: true
+SpaceBeforeInheritanceColon: true
+SpaceBeforeParens: ControlStatementsExceptForEachMacros
+SpaceBeforeRangeBasedForLoopColon: true
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 1
+SpacesInAngles: false
+SpacesInContainerLiterals: false
+SpacesInCStyleCastParentheses: false
+SpacesInParentheses: false
+SpacesInSquareBrackets: false
+Standard: Cpp03
+TabWidth: 8
+UseTab: Always
+...
diff --git a/cfg.mk b/cfg.mk
index bde009e4a3..e4ff0ea70c 100644
--- a/cfg.mk
+++ b/cfg.mk
@@ -24,21 +24,21 @@ PACKAGE ?= gnutls
 
 .PHONY: config glimport
 
-INDENT_SOURCES = `find . -name \*.[ch] -o -name gnutls.h.in | grep -v -e ^./build-aux/ -e ^./lib/minitasn1/ -e ^./lib/build-aux/ -e ^./gl/ -e -args.[ch] -e asn1_tab.c -e ^./tests/suite/`
+INDENT_SOURCES = `find . -name \*.[ch] -o -name gnutls.h.in | grep -v -e ^./build-aux/ -e ^./config.h -e ^./devel/ -e ^./gnulib -e ^./lib/minitasn1/ -e ^./lib/includes/gnutls/gnutls.h -e ^./lib/nettle/backport/ -e ^./lib/priority_options.h -e ^./lib/unistring/ -e ^./lib/x509/supported_exts.h -e ^./lib/build-aux/ -e ^./gl/ -e ^./src/gl/ -e ^./src/.*-options.[ch] -e -args.[ch] -e asn1_tab.c -e ^./tests/suite/`
 
 ifeq ($(.DEFAULT_GOAL),abort-due-to-no-makefile)
 .DEFAULT_GOAL := bootstrap
 endif
 
-local-checks-to-skip = sc_GPL_version sc_bindtextdomain			\
-	sc_immutable_NEWS sc_program_name sc_prohibit_atoi_atof		\
-	sc_prohibit_always_true_header_tests                            \
-	sc_prohibit_empty_lines_at_EOF sc_prohibit_hash_without_use	\
-	sc_prohibit_gnu_make_extensions                                 \
-	sc_prohibit_have_config_h sc_prohibit_magic_number_exit		\
-	sc_prohibit_strcmp sc_require_config_h				\
-	sc_require_config_h_first sc_texinfo_acronym sc_trailing_blank	\
-	sc_unmarked_diagnostics sc_useless_cpp_parens			\
+local-checks-to-skip = sc_GPL_version sc_bindtextdomain			  \
+	sc_immutable_NEWS sc_indent sc_program_name sc_prohibit_atoi_atof \
+	sc_prohibit_always_true_header_tests				  \
+	sc_prohibit_empty_lines_at_EOF sc_prohibit_hash_without_use	  \
+	sc_prohibit_gnu_make_extensions					  \
+	sc_prohibit_have_config_h sc_prohibit_magic_number_exit		  \
+	sc_prohibit_strcmp sc_require_config_h				  \
+	sc_require_config_h_first sc_texinfo_acronym sc_trailing_blank	  \
+	sc_unmarked_diagnostics sc_useless_cpp_parens			  \
 	sc_two_space_separator_in_usage
 
 VC_LIST_ALWAYS_EXCLUDE_REGEX = ^maint.mk|gtk-doc.make|m4/pkg|doc/fdl-1.3.texi|src/.*\.bak|src/crywrap/|(devel/perlasm/|lib/accelerated/x86/|build-aux/|gl/|tests/suite/ecore/|doc/protocol/).*$$
@@ -58,6 +58,27 @@ exclude_file_name_regexp--sc_prohibit_strncpy='unistr.in.h'
 exclude_file_name_regexp--sc_prohibit_strncpy='lib/inih/ini.c'
 gl_public_submodule_commit =
 
+# Indentation
+
+exclude_file_name_regexp--clang_format ?= $(exclude_file_name_regexp--sc_clang_format)
+
+.PHONY: clang-format
+clang-format:
+	$(AM_V_GEN)clang-format -i $(INDENT_SOURCES)
+
+sc_clang_format:
+	@if ! clang-format --version 2>&1 >/dev/null; then		     \
+	    echo 1>&2 '$(ME): sc_clang_format: clang-format is missing';     \
+	else								     \
+	  fail=0; files="$(INDENT_SOURCES)";				     \
+	  for f in $$files; do						     \
+	    clang-format --dry-run --Werror "$$f" || fail=1;		     \
+	  done;								     \
+	  test $$fail = 1 &&						     \
+	    { echo 1>&2 '$(ME): code format error, try "make clang-format"'; \
+	      exit 1; } || :;						     \
+	fi
+
 autoreconf:
 	./bootstrap
 
diff --git a/devel/indent-gnutls b/devel/indent-gnutls
index b3eb630b82..01cc144f57 100755
--- a/devel/indent-gnutls
+++ b/devel/indent-gnutls
@@ -1,15 +1,49 @@
 #!/bin/sh
 
 # Copyright (c) 2022 Simon Josefsson
+# Copyright (c) 2023 Daiki Ueno
 # License: GPLv3+ <http://gnu.org/licenses/gpl.html>
 
-if ! indent --version 2> /dev/null | grep 'GNU indent' > /dev/null; then
-    echo 1>&2 "$0: GNU indent is missing"
+: ${CLANG_FORMAT=clang-format}
+
+if ! $CLANG_FORMAT --version 2>&1 >/dev/null; then
+    echo 1>&2 "$0: clang-format is missing"
     exit 77
 fi
 
-INDENT="indent -ppi1 -linux"; export INDENT
+parallel=0
+mode=indent
+
+while test $# -gt 0; do
+    case "$1" in
+	--parallel | -p )
+	    shift
+            parallel=$1
+            shift ;;
+	--check )
+	    mode=check
+	    shift ;;
+	--help )
+	    echo "Usage: indent-gnutls [--parallel=MAX-PROCS] [--check]"
+            exit ;;
+	-* )
+            echo "indent-gnutls: unknown option $1" 1>&2
+            echo "Try 'indent-gnutls --help' for more information." 1>&2
+            exit 1 ;;
+	* )
+            break ;;
+    esac
+done
+
+case $mode in
+    check )
+	CLANG_FORMAT_ARGS="$CLANG_FORMAT_ARGS --dry-run -Werror"
+	;;
+    indent )
+	CLANG_FORMAT_ARGS="$CLANG_FORMAT_ARGS -i"
+	;;
+esac
 
-git ls-files -z | grep -z '\.[ch]\(.in\)\?$' | grep -z -v '^./devel/' | xargs -0 -n1 `dirname "$0"`/indent-maybe
+git ls-files -z | grep -z '\.[ch]\(.in\)\?$' | grep -z -v '^./devel/' | xargs -P "$parallel" -0 -n1 "$CLANG_FORMAT" $CLANG_FORMAT_ARGS
 
 exit $?
diff --git a/devel/indent-maybe b/devel/indent-maybe
deleted file mode 100755
index cdaa58b7e1..0000000000
--- a/devel/indent-maybe
+++ /dev/null
@@ -1,52 +0,0 @@
-#!/bin/sh
-
-# NAME
-#   indent-maybe(3)
-#
-# SYNOPSIS
-#   indent-maybe [options] [single-input-file]
-#
-# DESCRIPTION
-#   Run 'indent' on a file in an idempotent fashion, showing any
-#   modifications performed using diff(3).
-#
-#   There are two concerns with using 'indent' directly that this
-#   script solves:
-#
-#     1) 'indent' modifies files even when no modifications are
-#        necessary, which causes churn to rebuild dependent files, and
-#        it is thus not safe to run 'indent' frequently even for a
-#        file that needs no re-indentation.
-#
-#     2) Running 'indent' on a file once is not guaranteed to return
-#        output that will look the same as running 'indent' on the file
-#        again.  However, running 'indent' twice has this property.
-#
-#   Only GNU indent is supported.
-#
-# ENVIRONMENT
-#   The behaviour of 'indent-maybe' is affected by the INDENT variable which
-#   can be used to override the 'indent' tool that is used.  It may also
-#   include command line parameters, since it is expanded before use.
-#
-# EXAMPLES
-#   indent-maybe lib/kx.h
-#   INDENT="indent -ppi1 -linux" indent-maybe lib/kx.h
-#
-# COPYRIGHT
-#   Copyright (c) 2022 Simon Josefsson
-#   License: GPLv3+ <http://gnu.org/licenses/gpl.html>
-
-: ${INDENT=indent}
-ME="$0"
-
-if ! $INDENT --version 2> /dev/null | grep 'GNU indent' > /dev/null; then
-    echo 1>&2 "$ME: GNU indent is missing, consider INDENT=..."
-    exit 77
-fi
-
-for f in "$@"; do
-    $INDENT -st "$f" | $INDENT -st - | diff -u "$f" - || ($INDENT "$f" && $INDENT "$f")
-done
-
-exit $?