Merge branch 'ab/fewer-the-index-macros'

Progress on removing 'the_index' convenience wrappers.

* ab/fewer-the-index-macros:
  cocci: apply "pending" index-compatibility to some "builtin/*.c"
  cache.h & test-tool.h: add & use "USE_THE_INDEX_VARIABLE"
  {builtin/*,repository}.c: add & use "USE_THE_INDEX_VARIABLE"
  cocci: apply "pending" index-compatibility to "t/helper/*.c"
  cocci & cache.h: apply variable section of "pending" index-compatibility
  cocci & cache.h: apply a selection of "pending" index-compatibility
  cocci: add a index-compatibility.pending.cocci
  read-cache API & users: make discard_index() return void
  cocci & cache.h: remove rarely used "the_index" compat macros
  builtin/{grep,log}.: don't define "USE_THE_INDEX_COMPATIBILITY_MACROS"
  cache.h: remove unused "the_index" compat macros

contrib/coccinelle/index-compatibility.cocci

@@ -0,0 +1,135 @@
+// the_index.* variables
+@@
+@@
+(
+- active_cache
++ the_index.cache
+|
+- active_cache_changed
++ the_index.cache_changed
+|
+- active_cache_tree
++ the_index.cache_tree
+)
+
+@@
+identifier f != prepare_to_commit;
+@@
+  f(...) {<...
+- active_nr
++ the_index.cache_nr
+  ...>}
+
+// "the_repository" simple cases
+@@
+@@
+(
+- read_cache_unmerged
++ repo_read_index_unmerged
+|
+- hold_locked_index
++ repo_hold_locked_index
+)
+  (
++ the_repository,
+  ...)
+
+// "the_repository" special-cases
+@@
+@@
+(
+- read_cache_preload
++ repo_read_index_preload
+)
+  (
++ the_repository,
+  ...
++ , 0
+  )
+
+// "the_index" simple cases
+@@
+@@
+(
+- is_cache_unborn
++ is_index_unborn
+|
+- unmerged_cache
++ unmerged_index
+|
+- rename_cache_entry_at
++ rename_index_entry_at
+|
+- chmod_cache_entry
++ chmod_index_entry
+|
+- cache_file_exists
++ index_file_exists
+|
+- cache_name_is_other
++ index_name_is_other
+|
+- unmerge_cache_entry_at
++ unmerge_index_entry_at
+|
+- add_to_cache
++ add_to_index
+|
+- add_file_to_cache
++ add_file_to_index
+|
+- add_cache_entry
++ add_index_entry
+|
+- remove_file_from_cache
++ remove_file_from_index
+|
+- ce_match_stat
++ ie_match_stat
+|
+- ce_modified
++ ie_modified
+|
+- resolve_undo_clear
++ resolve_undo_clear_index
+)
+  (
++ &the_index,
+  ...)
+
+@@
+@@
+(
+- refresh_and_write_cache
++ repo_refresh_and_write_index
+)
+  (
++ the_repository,
+  ...
++ , NULL, NULL, NULL
+  )
+
+// "the_index" special-cases
+@@
+@@
+(
+- read_cache_from
++ read_index_from
+)
+  (
++ &the_index,
+  ...
++ , get_git_dir()
+  )
+
+@@
+@@
+(
+- refresh_cache
++ refresh_index
+)
+  (
++ &the_index,
+  ...
++ , NULL, NULL, NULL
+  )

contrib/coccinelle/index-compatibility.pending.cocci

@@ -0,0 +1,24 @@
+// "the_repository" simple cases
+@@
+@@
+(
+- read_cache
++ repo_read_index
+)
+  (
++ the_repository,
+  ...)
+
+// "the_index" simple cases
+@@
+@@
+(
+- discard_cache
++ discard_index
+|
+- cache_name_pos
++ index_name_pos
+)
+  (
++ &the_index,
+  ...)