diff --git a/Makefile b/Makefile
index e1024009a3..cbcc7f5eae 100644
--- a/Makefile
+++ b/Makefile
@@ -173,11 +173,7 @@ iwyu: build/.ran-cmake
 	|src/nvim/event/stream.h\
 	|src/nvim/event/time.h\
 	|src/nvim/event/wstream.h\
-	|src/nvim/ex_cmds.h\
-	|src/nvim/ex_docmd.h\
 	|src/nvim/extmark.h\
-	|src/nvim/file_search.h\
-	|src/nvim/fileio.h\
 	|src/nvim/fold.h\
 	|src/nvim/garray.h\
 	|src/nvim/getchar.h\
@@ -186,14 +182,11 @@ iwyu: build/.ran-cmake
 	|src/nvim/highlight.h\
 	|src/nvim/highlight_group.h\
 	|src/nvim/input.h\
-	|src/nvim/insexpand.h\
 	|src/nvim/keycodes.h\
 	|src/nvim/log.h\
 	|src/nvim/lua/executor.h\
 	|src/nvim/main.h\
 	|src/nvim/mark.h\
-	|src/nvim/mouse.h\
-	|src/nvim/move.h\
 	|src/nvim/msgpack_rpc/channel.h\
 	|src/nvim/msgpack_rpc/channel_defs.h\
 	|src/nvim/msgpack_rpc/helpers.h\
@@ -207,10 +200,6 @@ iwyu: build/.ran-cmake
 	|src/nvim/path.h\
 	|src/nvim/plines.h\
 	|src/nvim/popupmenu.h\
-	|src/nvim/search.h\
-	|src/nvim/spell.h\
-	|src/nvim/syntax.h\
-	|src/nvim/textobject.h\
 	|src/nvim/tui/input.h\
 	|src/nvim/ui.h\
 	|src/nvim/viml/parser/expressions.h\
diff --git a/src/clint.py b/src/clint.py
index a45969af31..9b946998c9 100755
--- a/src/clint.py
+++ b/src/clint.py
@@ -931,11 +931,7 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/event/stream.h",
             "src/nvim/event/time.h",
             "src/nvim/event/wstream.h",
-            "src/nvim/ex_cmds.h",
-            "src/nvim/ex_docmd.h",
             "src/nvim/extmark.h",
-            "src/nvim/file_search.h",
-            "src/nvim/fileio.h",
             "src/nvim/fold.h",
             "src/nvim/garray.h",
             "src/nvim/getchar.h",
@@ -944,14 +940,11 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/highlight.h",
             "src/nvim/highlight_group.h",
             "src/nvim/input.h",
-            "src/nvim/insexpand.h",
             "src/nvim/keycodes.h",
             "src/nvim/log.h",
             "src/nvim/lua/executor.h",
             "src/nvim/main.h",
             "src/nvim/mark.h",
-            "src/nvim/mouse.h",
-            "src/nvim/move.h",
             "src/nvim/msgpack_rpc/channel.h",
             "src/nvim/msgpack_rpc/channel_defs.h",
             "src/nvim/msgpack_rpc/helpers.h",
@@ -965,10 +958,6 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/path.h",
             "src/nvim/plines.h",
             "src/nvim/popupmenu.h",
-            "src/nvim/search.h",
-            "src/nvim/spell.h",
-            "src/nvim/syntax.h",
-            "src/nvim/textobject.h",
             "src/nvim/tui/input.h",
             "src/nvim/ui.h",
             "src/nvim/viml/parser/expressions.h",
diff --git a/src/nvim/autocmd.h b/src/nvim/autocmd.h
index 259a56cf5c..8ff4d75ddf 100644
--- a/src/nvim/autocmd.h
+++ b/src/nvim/autocmd.h
@@ -27,18 +27,57 @@ EXTERN win_T *last_cursormoved_win INIT( = NULL);
 /// For CursorMoved event, only used when last_cursormoved_win == curwin
 EXTERN pos_T last_cursormoved INIT( = { 0, 0, 0 });
 
-#ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "autocmd.h.generated.h"
-#endif
+EXTERN bool autocmd_busy INIT( = false);     ///< Is apply_autocmds() busy?
+EXTERN int autocmd_no_enter INIT( = false);  ///< *Enter autocmds disabled
+EXTERN int autocmd_no_leave INIT( = false);  ///< *Leave autocmds disabled
+EXTERN bool did_filetype INIT( = false);     ///< FileType event found
+/// value for did_filetype when starting to execute autocommands
+EXTERN bool keep_filetype INIT( = false);
 
-#define AUGROUP_DEFAULT    (-1)      // default autocmd group
-#define AUGROUP_ERROR      (-2)      // erroneous autocmd group
-#define AUGROUP_ALL        (-3)      // all autocmd groups
-#define AUGROUP_DELETED    (-4)      // all autocmd groups
-// #define AUGROUP_NS       -5      // TODO(tjdevries): Support namespaced based augroups
+/// When deleting the current buffer, another one must be loaded.
+/// If we know which one is preferred, au_new_curbuf is set to it.
+EXTERN bufref_T au_new_curbuf INIT( = { NULL, 0, 0 });
 
-#define BUFLOCAL_PAT_LEN 25
+// When deleting a buffer/window and autocmd_busy is true, do not free the
+// buffer/window. but link it in the list starting with
+// au_pending_free_buf/ap_pending_free_win, using b_next/w_next.
+// Free the buffer/window when autocmd_busy is being set to false.
+EXTERN buf_T *au_pending_free_buf INIT( = NULL);
+EXTERN win_T *au_pending_free_win INIT( = NULL);
+
+EXTERN char *autocmd_fname INIT( = NULL);       ///< fname for <afile> on cmdline
+EXTERN bool autocmd_fname_full INIT( = false);  ///< autocmd_fname is full path
+EXTERN int autocmd_bufnr INIT( = 0);            ///< fnum for <abuf> on cmdline
+EXTERN char *autocmd_match INIT( = NULL);       ///< name for <amatch> on cmdline
+EXTERN bool did_cursorhold INIT( = false);      ///< set when CursorHold t'gerd
+
+typedef struct {
+  win_T *auc_win;     ///< Window used in aucmd_prepbuf().  When not NULL the
+                      ///< window has been allocated.
+  bool auc_win_used;  ///< This auc_win is being used.
+} aucmdwin_T;
+
+/// When executing autocommands for a buffer that is not in any window, a
+/// special window is created to handle the side effects.  When autocommands
+/// nest we may need more than one.
+EXTERN kvec_t(aucmdwin_T) aucmd_win_vec INIT( = KV_INITIAL_VALUE);
+#define aucmd_win (aucmd_win_vec.items)
+#define AUCMD_WIN_COUNT ((int)aucmd_win_vec.size)
+
+enum {
+  AUGROUP_DEFAULT = -1,  ///< default autocmd group
+  AUGROUP_ERROR   = -2,  ///< erroneous autocmd group
+  AUGROUP_ALL     = -3,  ///< all autocmd groups
+  AUGROUP_DELETED = -4,  ///< all autocmd groups
+  // AUGROUP_NS      = -5,  // TODO(tjdevries): Support namespaced based augroups
+};
+
+enum { BUFLOCAL_PAT_LEN = 25, };
 
 /// Iterates over all the events for auto commands
 #define FOR_ALL_AUEVENTS(event) \
   for (event_T event = (event_T)0; (int)event < (int)NUM_EVENTS; event = (event_T)((int)event + 1))  // NOLINT
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "autocmd.h.generated.h"
+#endif
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index a43ca3d78a..de36bf016f 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -14,6 +14,7 @@
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
 #include "nvim/ascii_defs.h"
+#include "nvim/autocmd.h"
 #include "nvim/buffer.h"
 #include "nvim/buffer_defs.h"
 #include "nvim/channel.h"
diff --git a/src/nvim/eval.h b/src/nvim/eval.h
index 1fc2891917..7306645cc3 100644
--- a/src/nvim/eval.h
+++ b/src/nvim/eval.h
@@ -4,17 +4,18 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#include "nvim/buffer_defs.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/channel.h"
-#include "nvim/cmdexpand_defs.h"
+#include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"
 #include "nvim/event/time.h"
 #include "nvim/ex_cmds_defs.h"
-#include "nvim/globals.h"
 #include "nvim/hashtab_defs.h"
 #include "nvim/macros_defs.h"
+#include "nvim/mbyte_defs.h"  // IWYU pragma: keep
 #include "nvim/os/fileio.h"
 #include "nvim/os/stdpaths_defs.h"
+#include "nvim/vim_defs.h"  // IWYU pragma: keep
 
 #define COPYID_INC 2
 #define COPYID_MASK (~0x1)
diff --git a/src/nvim/eval/encode.c b/src/nvim/eval/encode.c
index 8505c30fad..38be10dbaf 100644
--- a/src/nvim/eval/encode.c
+++ b/src/nvim/eval/encode.c
@@ -21,6 +21,7 @@
 #include "nvim/eval/typval_encode.h"
 #include "nvim/garray.h"
 #include "nvim/gettext.h"
+#include "nvim/globals.h"
 #include "nvim/hashtab.h"
 #include "nvim/macros_defs.h"
 #include "nvim/math.h"
diff --git a/src/nvim/eval/typval_defs.h b/src/nvim/eval/typval_defs.h
index c6bd11ccdb..a6a0282fad 100644
--- a/src/nvim/eval/typval_defs.h
+++ b/src/nvim/eval/typval_defs.h
@@ -13,8 +13,10 @@
 typedef int64_t varnumber_T;
 typedef uint64_t uvarnumber_T;
 
-/// Refcount for dict or list that should not be freed
-enum { DO_NOT_FREE_CNT = (INT_MAX / 2), };
+enum {
+  /// Refcount for dict or list that should not be freed
+  DO_NOT_FREE_CNT = (INT_MAX / 2),
+};
 
 /// Additional values for tv_list_alloc() len argument
 enum ListLenSpecials {
@@ -291,12 +293,9 @@ typedef struct {
   uint64_t channel_id;     /// Only used when script_id is SID_API_CLIENT.
 } LastSet;
 
-/// Maximum number of function arguments
-enum { MAX_FUNC_ARGS = 20, };
-/// Short variable name length
-enum { VAR_SHORT_LEN = 20, };
-/// Number of fixed variables used for arguments
-enum { FIXVAR_CNT = 12, };
+enum { MAX_FUNC_ARGS = 20, };  ///< Maximum number of function arguments
+enum { VAR_SHORT_LEN = 20, };  ///< Short variable name length
+enum { FIXVAR_CNT = 12, };     ///< Number of fixed variables used for arguments
 
 /// Structure to hold info for a function that is currently being executed.
 typedef struct funccall_S funccall_T;
diff --git a/src/nvim/ex_cmds.h b/src/nvim/ex_cmds.h
index de13f03197..011d42c6d9 100644
--- a/src/nvim/ex_cmds.h
+++ b/src/nvim/ex_cmds.h
@@ -1,27 +1,28 @@
 #pragma once
 
-#include <stdbool.h>
-
 #include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: export
-#include "nvim/os/time.h"
+#include "nvim/os/time_defs.h"
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
 
-// flags for do_ecmd()
-#define ECMD_HIDE            0x01    // don't free the current buffer
-#define ECMD_SET_HELP        0x02    // set b_help flag of (new) buffer before
-                                     // opening file
-#define ECMD_OLDBUF          0x04    // use existing buffer if it exists
-#define ECMD_FORCEIT         0x08    // ! used in Ex command
-#define ECMD_ADDBUF          0x10    // don't edit, just add to buffer list
-#define ECMD_ALTBUF          0x20    // like ECMD_ADDBUF and set the alternate file
-#define ECMD_NOWINENTER      0x40    // do not trigger BufWinEnter
+/// flags for do_ecmd()
+enum {
+  ECMD_HIDE       = 0x01,  ///< don't free the current buffer
+  ECMD_SET_HELP   = 0x02,  ///< set b_help flag of (new) buffer before opening file
+  ECMD_OLDBUF     = 0x04,  ///< use existing buffer if it exists
+  ECMD_FORCEIT    = 0x08,  ///< ! used in Ex command
+  ECMD_ADDBUF     = 0x10,  ///< don't edit, just add to buffer list
+  ECMD_ALTBUF     = 0x20,  ///< like ECMD_ADDBUF and set the alternate file
+  ECMD_NOWINENTER = 0x40,  ///< do not trigger BufWinEnter
+};
 
-// for lnum argument in do_ecmd()
-#define ECMD_LASTL      0       // use last position in loaded file
-#define ECMD_LAST       (-1)    // use last position in all files
-#define ECMD_ONE        1       // use first line
+/// for lnum argument in do_ecmd()
+enum {
+  ECMD_LASTL = 0,   ///< use last position in loaded file
+  ECMD_LAST  = -1,  ///< use last position in all files
+  ECMD_ONE   = 1,   ///< use first line
+};
 
 /// Previous :substitute replacement string definition
 typedef struct {
diff --git a/src/nvim/ex_docmd.h b/src/nvim/ex_docmd.h
index 698153e8df..ce23b9f464 100644
--- a/src/nvim/ex_docmd.h
+++ b/src/nvim/ex_docmd.h
@@ -6,8 +6,8 @@
 #include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/getchar_defs.h"
-#include "nvim/globals.h"
 #include "nvim/types_defs.h"  // IWYU pragma: keep
+#include "nvim/vim_defs.h"  // IWYU pragma: keep
 
 /// flags for do_cmdline()
 enum {
diff --git a/src/nvim/ex_eval_defs.h b/src/nvim/ex_eval_defs.h
index c7231bb315..3f5e510a20 100644
--- a/src/nvim/ex_eval_defs.h
+++ b/src/nvim/ex_eval_defs.h
@@ -13,9 +13,11 @@ struct eslist_elem {
   eslist_T *next;         ///< next element on the list
 };
 
-/// For conditional commands a stack is kept of nested conditionals.
-/// When cs_idx < 0, there is no conditional command.
-enum { CSTACK_LEN = 50, };
+enum {
+  /// For conditional commands a stack is kept of nested conditionals.
+  /// When cs_idx < 0, there is no conditional command.
+  CSTACK_LEN = 50,
+};
 
 typedef struct {
   int cs_flags[CSTACK_LEN];       ///< CSF_ flags
diff --git a/src/nvim/file_search.h b/src/nvim/file_search.h
index d4b5c5d352..a2d578a668 100644
--- a/src/nvim/file_search.h
+++ b/src/nvim/file_search.h
@@ -1,14 +1,14 @@
 #pragma once
 
-#include <stdlib.h>
-
-#include "nvim/globals.h"
 #include "nvim/types_defs.h"  // IWYU pragma: keep
+#include "nvim/vim_defs.h"  // IWYU pragma: keep
 
-// Flags for find_file_*() functions.
-#define FINDFILE_FILE   0       // only files
-#define FINDFILE_DIR    1       // only directories
-#define FINDFILE_BOTH   2       // files and directories
+/// Flags for find_file_*() functions.
+enum {
+  FINDFILE_FILE = 0,  ///< only files
+  FINDFILE_DIR  = 1,  ///< only directories
+  FINDFILE_BOTH = 2,  ///< files and directories
+};
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "file_search.h.generated.h"
diff --git a/src/nvim/fileio.h b/src/nvim/fileio.h
index d1f6561507..32a5ec3002 100644
--- a/src/nvim/fileio.h
+++ b/src/nvim/fileio.h
@@ -8,44 +8,49 @@
 #include "nvim/eval/typval_defs.h"
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/garray_defs.h"  // IWYU pragma: keep
-#include "nvim/globals.h"
 #include "nvim/os/fs_defs.h"  // IWYU pragma: keep
-#include "nvim/pos_defs.h"
+#include "nvim/pos_defs.h"  // IWYU pragma: keep
 
-// Values for readfile() flags
-#define READ_NEW        0x01    // read a file into a new buffer
-#define READ_FILTER     0x02    // read filter output
-#define READ_STDIN      0x04    // read from stdin
-#define READ_BUFFER     0x08    // read from curbuf (converting stdin)
-#define READ_DUMMY      0x10    // reading into a dummy buffer
-#define READ_KEEP_UNDO  0x20    // keep undo info
-#define READ_FIFO       0x40    // read from fifo or socket
-#define READ_NOWINENTER 0x80    // do not trigger BufWinEnter
-#define READ_NOFILE     0x100   // do not read a file, do trigger BufReadCmd
+/// Values for readfile() flags
+enum {
+  READ_NEW        = 0x01,   ///< read a file into a new buffer
+  READ_FILTER     = 0x02,   ///< read filter output
+  READ_STDIN      = 0x04,   ///< read from stdin
+  READ_BUFFER     = 0x08,   ///< read from curbuf (converting stdin)
+  READ_DUMMY      = 0x10,   ///< reading into a dummy buffer
+  READ_KEEP_UNDO  = 0x20,   ///< keep undo info
+  READ_FIFO       = 0x40,   ///< read from fifo or socket
+  READ_NOWINENTER = 0x80,   ///< do not trigger BufWinEnter
+  READ_NOFILE     = 0x100,  ///< do not read a file, do trigger BufReadCmd
+};
 
 typedef varnumber_T (*CheckItem)(void *expr, const char *name);
 
 enum {
-  FIO_LATIN1 = 0x01,       // convert Latin1
-  FIO_UTF8 = 0x02,         // convert UTF-8
-  FIO_UCS2 = 0x04,         // convert UCS-2
-  FIO_UCS4 = 0x08,         // convert UCS-4
-  FIO_UTF16 = 0x10,        // convert UTF-16
-  FIO_ENDIAN_L = 0x80,     // little endian
-  FIO_NOCONVERT = 0x2000,  // skip encoding conversion
-  FIO_UCSBOM = 0x4000,     // check for BOM at start of file
-  FIO_ALL = -1,            // allow all formats
+  FIO_LATIN1 = 0x01,       ///< convert Latin1
+  FIO_UTF8 = 0x02,         ///< convert UTF-8
+  FIO_UCS2 = 0x04,         ///< convert UCS-2
+  FIO_UCS4 = 0x08,         ///< convert UCS-4
+  FIO_UTF16 = 0x10,        ///< convert UTF-16
+  FIO_ENDIAN_L = 0x80,     ///< little endian
+  FIO_NOCONVERT = 0x2000,  ///< skip encoding conversion
+  FIO_UCSBOM = 0x4000,     ///< check for BOM at start of file
+  FIO_ALL = -1,            ///< allow all formats
 };
 
-// When converting, a read() or write() may leave some bytes to be converted
-// for the next call.  The value is guessed...
-#define CONV_RESTLEN 30
+enum {
+  /// When converting, a read() or write() may leave some bytes to be converted
+  /// for the next call.  The value is guessed...
+  CONV_RESTLEN = 30,
+};
 
-#define WRITEBUFSIZE         8192    // size of normal write buffer
+enum { WRITEBUFSIZE = 8192, };  ///< size of normal write buffer
 
-// We have to guess how much a sequence of bytes may expand when converting
-// with iconv() to be able to allocate a buffer.
-#define ICONV_MULT 8
+enum {
+  /// We have to guess how much a sequence of bytes may expand when converting
+  /// with iconv() to be able to allocate a buffer.
+  ICONV_MULT = 8,
+};
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "fileio.h.generated.h"
diff --git a/src/nvim/getchar.h b/src/nvim/getchar.h
index 177a021706..e1bc64bfee 100644
--- a/src/nvim/getchar.h
+++ b/src/nvim/getchar.h
@@ -15,8 +15,7 @@ typedef enum {
   FLUSH_INPUT,      ///< flush typebuf and inchar() input
 } flush_buffers_T;
 
-/// Maximum number of streams to read script from
-enum { NSCRIPT = 15, };
+enum { NSCRIPT = 15, };  ///< Maximum number of streams to read script from
 
 /// Streams to read script from
 extern FileDescriptor *scriptin[NSCRIPT];
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 270ffe4fa0..1299aa12e5 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -103,34 +103,6 @@ EXTERN struct nvim_stats_s {
 EXTERN int Rows INIT( = DFLT_ROWS);     // nr of rows in the screen
 EXTERN int Columns INIT( = DFLT_COLS);  // nr of columns in the screen
 
-// We use 64-bit file functions here, if available.  E.g. ftello() returns
-// off_t instead of long, which helps if long is 32 bit and off_t is 64 bit.
-// We assume that when fseeko() is available then ftello() is too.
-// Note that Windows has different function names.
-#if (defined(_MSC_VER) && (_MSC_VER >= 1300)) || defined(__MINGW32__)
-typedef __int64 off_T;
-# ifdef __MINGW32__
-#  define vim_lseek lseek64
-#  define vim_fseek fseeko64
-#  define vim_ftell ftello64
-# else
-#  define vim_lseek _lseeki64
-#  define vim_fseek _fseeki64
-#  define vim_ftell _ftelli64
-# endif
-#else
-typedef off_t off_T;
-# ifdef HAVE_FSEEKO
-#  define vim_lseek lseek
-#  define vim_ftell ftello
-#  define vim_fseek fseeko
-# else
-#  define vim_lseek lseek
-#  define vim_ftell ftell
-#  define vim_fseek(a, b, c) fseek(a, (long)b, c)
-# endif
-#endif
-
 // When vgetc() is called, it sets mod_mask to the set of modifiers that are
 // held down based on the MOD_MASK_* symbols that are read first.
 EXTERN int mod_mask INIT( = 0);  // current key modifiers
@@ -370,24 +342,7 @@ EXTERN bool did_check_timestamps INIT( = false);   // did check timestamps
                                                    // recently
 EXTERN int no_check_timestamps INIT( = 0);         // Don't check timestamps
 
-EXTERN bool autocmd_busy INIT( = false);          // Is apply_autocmds() busy?
-EXTERN int autocmd_no_enter INIT( = false);       // *Enter autocmds disabled
-EXTERN int autocmd_no_leave INIT( = false);       // *Leave autocmds disabled
 EXTERN int modified_was_set;                     // did ":set modified"
-EXTERN bool did_filetype INIT( = false);          // FileType event found
-// value for did_filetype when starting to execute autocommands
-EXTERN bool keep_filetype INIT( = false);
-
-// When deleting the current buffer, another one must be loaded.
-// If we know which one is preferred, au_new_curbuf is set to it.
-EXTERN bufref_T au_new_curbuf INIT( = { NULL, 0, 0 });
-
-// When deleting a buffer/window and autocmd_busy is true, do not free the
-// buffer/window. but link it in the list starting with
-// au_pending_free_buf/ap_pending_free_win, using b_next/w_next.
-// Free the buffer/window when autocmd_busy is being set to false.
-EXTERN buf_T *au_pending_free_buf INIT( = NULL);
-EXTERN win_T *au_pending_free_win INIT( = NULL);
 
 // Mouse coordinates, set by handle_mouse_event()
 EXTERN int mouse_grid;
@@ -426,19 +381,6 @@ EXTERN win_T *prevwin INIT( = NULL);  // previous window
 
 EXTERN win_T *curwin;        // currently active window
 
-typedef struct {
-  win_T *auc_win;     ///< Window used in aucmd_prepbuf().  When not NULL the
-                      ///< window has been allocated.
-  bool auc_win_used;  ///< This auc_win is being used.
-} aucmdwin_T;
-
-/// When executing autocommands for a buffer that is not in any window, a
-/// special window is created to handle the side effects.  When autocommands
-/// nest we may need more than one.
-EXTERN kvec_t(aucmdwin_T) aucmd_win_vec INIT( = KV_INITIAL_VALUE);
-#define aucmd_win (aucmd_win_vec.items)
-#define AUCMD_WIN_COUNT ((int)aucmd_win_vec.size)
-
 // The window layout is kept in a tree of frames.  topframe points to the top
 // of the tree.
 EXTERN frame_T *topframe;      // top of the window frame tree
@@ -758,11 +700,6 @@ EXTERN char last_mode[MODE_MAX_LENGTH] INIT( = "n");
 EXTERN char *last_cmdline INIT( = NULL);        // last command line (for ":)
 EXTERN char *repeat_cmdline INIT( = NULL);      // command line for "."
 EXTERN char *new_last_cmdline INIT( = NULL);    // new value for last_cmdline
-EXTERN char *autocmd_fname INIT( = NULL);       // fname for <afile> on cmdline
-EXTERN bool autocmd_fname_full INIT( = false);  // autocmd_fname is full path
-EXTERN int autocmd_bufnr INIT( = 0);            // fnum for <abuf> on cmdline
-EXTERN char *autocmd_match INIT( = NULL);       // name for <amatch> on cmdline
-EXTERN bool did_cursorhold INIT( = false);      // set when CursorHold t'gerd
 
 EXTERN int postponed_split INIT( = 0);        // for CTRL-W CTRL-] command
 EXTERN int postponed_split_flags INIT( = 0);  // args for win_split()
@@ -1051,39 +988,7 @@ EXTERN bool headless_mode INIT(= false);
 
 // uncrustify:on
 
-/// Used to track the status of external functions.
-/// Currently only used for iconv().
-typedef enum {
-  kUnknown,
-  kWorking,
-  kBroken,
-} WorkingStatus;
-
-/// The scope of a working-directory command like `:cd`.
-///
-/// Scopes are enumerated from lowest to highest. When adding a scope make sure
-/// to update all functions using scopes as well, such as the implementation of
-/// `getcwd()`. When using scopes as limits (e.g. in loops) don't use the scopes
-/// directly, use `MIN_CD_SCOPE` and `MAX_CD_SCOPE` instead.
-typedef enum {
-  kCdScopeInvalid = -1,
-  kCdScopeWindow,   ///< Affects one window.
-  kCdScopeTabpage,  ///< Affects one tab page.
-  kCdScopeGlobal,   ///< Affects the entire Nvim instance.
-} CdScope;
-
-#define MIN_CD_SCOPE  kCdScopeWindow
-#define MAX_CD_SCOPE  kCdScopeGlobal
-
-/// What caused the current directory to change.
-typedef enum {
-  kCdCauseOther = -1,
-  kCdCauseManual,  ///< Using `:cd`, `:tcd`, `:lcd` or `chdir()`.
-  kCdCauseWindow,  ///< Switching to another window.
-  kCdCauseAuto,    ///< On 'autochdir'.
-} CdCause;
-
-// Only filled for Win32.
+/// Only filled for Win32.
 EXTERN char windowsVersion[20] INIT( = { 0 });
 
 /// While executing a regexp and set to OPTION_MAGIC_ON or OPTION_MAGIC_OFF this
diff --git a/src/nvim/hashtab_defs.h b/src/nvim/hashtab_defs.h
index 089838fcae..8888eab972 100644
--- a/src/nvim/hashtab_defs.h
+++ b/src/nvim/hashtab_defs.h
@@ -34,11 +34,13 @@ typedef struct hashitem_S {
   char *hi_key;
 } hashitem_T;
 
-/// Initial size for a hashtable.
-/// Our items are relatively small and growing is expensive, thus start with 16.
-/// Must be a power of 2.
-/// This allows for storing 10 items (2/3 of 16) before a resize is needed.
-enum { HT_INIT_SIZE = 16, };
+enum {
+  /// Initial size for a hashtable.
+  /// Our items are relatively small and growing is expensive, thus start with 16.
+  /// Must be a power of 2.
+  /// This allows for storing 10 items (2/3 of 16) before a resize is needed.
+  HT_INIT_SIZE = 16,
+};
 
 /// An array-based hashtable.
 ///
diff --git a/src/nvim/insexpand.h b/src/nvim/insexpand.h
index 121d5568ff..b880e64ea4 100644
--- a/src/nvim/insexpand.h
+++ b/src/nvim/insexpand.h
@@ -1,10 +1,9 @@
 #pragma once
 
-#include "nvim/macros_defs.h"
 #include "nvim/option_defs.h"  // IWYU pragma: keep
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
 #include "nvim/types_defs.h"  // IWYU pragma: keep
-#include "nvim/vim_defs.h"
+#include "nvim/vim_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "insexpand.h.generated.h"
diff --git a/src/nvim/mapping_defs.h b/src/nvim/mapping_defs.h
index 6691c5ac3b..4f0334c226 100644
--- a/src/nvim/mapping_defs.h
+++ b/src/nvim/mapping_defs.h
@@ -5,8 +5,7 @@
 #include "nvim/eval/typval_defs.h"
 #include "nvim/types_defs.h"
 
-/// Maximum length of key sequence to be mapped.
-enum { MAXMAPLEN = 50, };
+enum { MAXMAPLEN = 50, };  ///< Maximum length of key sequence to be mapped.
 
 /// Structure used for mappings and abbreviations.
 typedef struct mapblock mapblock_T;
diff --git a/src/nvim/mbyte_defs.h b/src/nvim/mbyte_defs.h
index 2904047223..efb4f558a6 100644
--- a/src/nvim/mbyte_defs.h
+++ b/src/nvim/mbyte_defs.h
@@ -4,13 +4,14 @@
 
 #include "nvim/iconv_defs.h"
 
-/// Maximum number of bytes in a multi-byte character.  It can be one 32-bit
-/// character of up to 6 bytes, or one 16-bit character of up to three bytes
-/// plus six following composing characters of three bytes each.
-enum { MB_MAXBYTES = 21, };
-
-/// max length of an unicode char
-enum { MB_MAXCHAR = 6, };
+enum {
+  /// Maximum number of bytes in a multi-byte character.  It can be one 32-bit
+  /// character of up to 6 bytes, or one 16-bit character of up to three bytes
+  /// plus six following composing characters of three bytes each.
+  MB_MAXBYTES = 21,
+  /// max length of an unicode char
+  MB_MAXCHAR = 6,
+};
 
 /// properties used in enc_canon_table[] (first three mutually exclusive)
 enum {
diff --git a/src/nvim/message.h b/src/nvim/message.h
index adbb40277b..904fb2d3ad 100644
--- a/src/nvim/message.h
+++ b/src/nvim/message.h
@@ -30,8 +30,7 @@ enum {
   VIM_DISCARDALL = 6,
 };
 
-/// special attribute addition: Put message in history
-enum { MSG_HIST = 0x1000, };
+enum { MSG_HIST = 0x1000, };  ///< special attribute addition: Put message in history
 
 typedef struct {
   String text;
diff --git a/src/nvim/mouse.h b/src/nvim/mouse.h
index 928b3e360b..d787b8ff57 100644
--- a/src/nvim/mouse.h
+++ b/src/nvim/mouse.h
@@ -4,7 +4,7 @@
 #include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/normal_defs.h"  // IWYU pragma: keep
 #include "nvim/types_defs.h"  // IWYU pragma: keep
-#include "nvim/vim_defs.h"
+#include "nvim/vim_defs.h"  // IWYU pragma: keep
 
 /// jump_to_mouse() returns one of first five these values, possibly with
 /// some of the other five added.
diff --git a/src/nvim/move.h b/src/nvim/move.h
index ab8fb2b386..f48de6987b 100644
--- a/src/nvim/move.h
+++ b/src/nvim/move.h
@@ -1,11 +1,9 @@
 #pragma once
 
-#include <stdbool.h>
-
 #include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/types_defs.h"  // IWYU pragma: keep
-#include "nvim/vim_defs.h"
+#include "nvim/vim_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "move.h.generated.h"
diff --git a/src/nvim/normal_defs.h b/src/nvim/normal_defs.h
index 060c1057f9..6ea6660a8b 100644
--- a/src/nvim/normal_defs.h
+++ b/src/nvim/normal_defs.h
@@ -70,6 +70,5 @@ enum {
   REPLACE_NL_NCHAR  = -2,
 };
 
-/// columns needed by shown command
-enum { SHOWCMD_COLS = 10, };
+enum { SHOWCMD_COLS = 10, };  ///< columns needed by shown command
 enum { SHOWCMD_BUFLEN = SHOWCMD_COLS + 1 + 30, };
diff --git a/src/nvim/os/os_defs.h b/src/nvim/os/os_defs.h
index 12de55a227..db575e005a 100644
--- a/src/nvim/os/os_defs.h
+++ b/src/nvim/os/os_defs.h
@@ -113,3 +113,31 @@
   && (defined(S_ISCHR) || defined(S_IFCHR))
 # define OPEN_CHR_FILES
 #endif
+
+// We use 64-bit file functions here, if available.  E.g. ftello() returns
+// off_t instead of long, which helps if long is 32 bit and off_t is 64 bit.
+// We assume that when fseeko() is available then ftello() is too.
+// Note that Windows has different function names.
+#if (defined(_MSC_VER) && (_MSC_VER >= 1300)) || defined(__MINGW32__)
+typedef __int64 off_T;
+# ifdef __MINGW32__
+#  define vim_lseek lseek64
+#  define vim_fseek fseeko64
+#  define vim_ftell ftello64
+# else
+#  define vim_lseek _lseeki64
+#  define vim_fseek _fseeki64
+#  define vim_ftell _ftelli64
+# endif
+#else
+typedef off_t off_T;
+# ifdef HAVE_FSEEKO
+#  define vim_lseek lseek
+#  define vim_ftell ftello
+#  define vim_fseek fseeko
+# else
+#  define vim_lseek lseek
+#  define vim_ftell ftell
+#  define vim_fseek(a, b, c) fseek(a, (long)b, c)
+# endif
+#endif
diff --git a/src/nvim/pos_defs.h b/src/nvim/pos_defs.h
index 98a1762a5c..a9816c6a66 100644
--- a/src/nvim/pos_defs.h
+++ b/src/nvim/pos_defs.h
@@ -12,19 +12,15 @@ typedef int colnr_T;
 /// Format used to print values which have colnr_T type
 #define PRIdCOLNR "d"
 
-/// Maximal (invalid) line number
-enum { MAXLNUM = 0x7fffffff, };
+enum { MAXLNUM = 0x7fffffff, };  ///< Maximal (invalid) line number
 
-/// Maximal column number
-/// MAXCOL used to be INT_MAX, but with 64 bit ints that results in running
-/// out of memory when trying to allocate a very long line.
-enum { MAXCOL = 0x7fffffff, };
+// MAXCOL used to be INT_MAX, but with 64 bit ints that results in running
+// out of memory when trying to allocate a very long line.
+enum { MAXCOL = 0x7fffffff, };   ///< Maximal column number
 
-/// Minimum line number
-enum { MINLNUM = 1, };
+enum { MINLNUM = 1, };           ///< Minimum line number
 
-/// Minimum column number
-enum { MINCOL = 1, };
+enum { MINCOL = 1, };            ///< Minimum column number
 
 /// position in file or buffer
 typedef struct {
diff --git a/src/nvim/regexp_defs.h b/src/nvim/regexp_defs.h
index 079f3b6929..31bc0e86e8 100644
--- a/src/nvim/regexp_defs.h
+++ b/src/nvim/regexp_defs.h
@@ -33,18 +33,22 @@ typedef enum {
   MAGIC_ALL = 4,   ///< "\v" very magic
 } magic_T;
 
-/// The number of sub-matches is limited to 10.
-/// The first one (index 0) is the whole match, referenced with "\0".
-/// The second one (index 1) is the first sub-match, referenced with "\1".
-/// This goes up to the tenth (index 9), referenced with "\9".
-enum { NSUBEXP = 10, };
-
-/// In the NFA engine: how many braces are allowed.
-/// TODO(RE): Use dynamic memory allocation instead of static, like here
-enum { NFA_MAX_BRACES = 20, };
-
-/// In the NFA engine: how many states are allowed.
 enum {
+  /// The number of sub-matches is limited to 10.
+  /// The first one (index 0) is the whole match, referenced with "\0".
+  /// The second one (index 1) is the first sub-match, referenced with "\1".
+  /// This goes up to the tenth (index 9), referenced with "\9".
+  NSUBEXP = 10,
+};
+
+enum {
+  /// In the NFA engine: how many braces are allowed.
+  /// TODO(RE): Use dynamic memory allocation instead of static, like here
+  NFA_MAX_BRACES = 20,
+};
+
+enum {
+  /// In the NFA engine: how many states are allowed.
   NFA_MAX_STATES = 100000,
   NFA_TOO_EXPENSIVE = -1,
 };
diff --git a/src/nvim/search.h b/src/nvim/search.h
index 48ca555e7f..12553c8e74 100644
--- a/src/nvim/search.h
+++ b/src/nvim/search.h
@@ -3,61 +3,73 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include "nvim/buffer_defs.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"
 #include "nvim/normal_defs.h"  // IWYU pragma: keep
 #include "nvim/os/time_defs.h"
 #include "nvim/pos_defs.h"
 #include "nvim/regexp_defs.h"  // IWYU pragma: keep
 #include "nvim/types_defs.h"
-#include "nvim/vim_defs.h"
+#include "nvim/vim_defs.h"  // IWYU pragma: keep
 
-// Values for the find_pattern_in_path() function args 'type' and 'action':
-#define FIND_ANY        1
-#define FIND_DEFINE     2
-#define CHECK_PATH      3
+/// Values for the find_pattern_in_path() function args 'type' and 'action':
+enum {
+  FIND_ANY    = 1,
+  FIND_DEFINE = 2,
+  CHECK_PATH  = 3,
+};
 
-#define ACTION_SHOW     1
-#define ACTION_GOTO     2
-#define ACTION_SPLIT    3
-#define ACTION_SHOW_ALL 4
-#define ACTION_EXPAND   5
+enum {
+  ACTION_SHOW     = 1,
+  ACTION_GOTO     = 2,
+  ACTION_SPLIT    = 3,
+  ACTION_SHOW_ALL = 4,
+  ACTION_EXPAND   = 5,
+};
 
-// Values for 'options' argument in do_search() and searchit()
-#define SEARCH_REV    0x01  ///< go in reverse of previous dir.
-#define SEARCH_ECHO   0x02  ///< echo the search command and handle options
-#define SEARCH_MSG    0x0c  ///< give messages (yes, it's not 0x04)
-#define SEARCH_NFMSG  0x08  ///< give all messages except not found
-#define SEARCH_OPT    0x10  ///< interpret optional flags
-#define SEARCH_HIS    0x20  ///< put search pattern in history
-#define SEARCH_END    0x40  ///< put cursor at end of match
-#define SEARCH_NOOF   0x80  ///< don't add offset to position
-#define SEARCH_START 0x100  ///< start search without col offset
-#define SEARCH_MARK  0x200  ///< set previous context mark
-#define SEARCH_KEEP  0x400  ///< keep previous search pattern
-#define SEARCH_PEEK  0x800  ///< peek for typed char, cancel search
-#define SEARCH_COL  0x1000  ///< start at specified column instead of zero
+/// Values for "options" argument in do_search() and searchit()
+enum {
+  SEARCH_REV   = 0x01,    ///< go in reverse of previous dir.
+  SEARCH_ECHO  = 0x02,    ///< echo the search command and handle options
+  SEARCH_MSG   = 0x0c,    ///< give messages (yes, it's not 0x04)
+  SEARCH_NFMSG = 0x08,    ///< give all messages except not found
+  SEARCH_OPT   = 0x10,    ///< interpret optional flags
+  SEARCH_HIS   = 0x20,    ///< put search pattern in history
+  SEARCH_END   = 0x40,    ///< put cursor at end of match
+  SEARCH_NOOF  = 0x80,    ///< don't add offset to position
+  SEARCH_START = 0x100,   ///< start search without col offset
+  SEARCH_MARK  = 0x200,   ///< set previous context mark
+  SEARCH_KEEP  = 0x400,   ///< keep previous search pattern
+  SEARCH_PEEK  = 0x800,   ///< peek for typed char, cancel search
+  SEARCH_COL   = 0x1000,  ///< start at specified column instead of zero
+};
 
-// Values for flags argument for findmatchlimit()
-#define FM_BACKWARD     0x01    // search backwards
-#define FM_FORWARD      0x02    // search forwards
-#define FM_BLOCKSTOP    0x04    // stop at start/end of block
-#define FM_SKIPCOMM     0x08    // skip comments
+/// Values for flags argument for findmatchlimit()
+enum {
+  FM_BACKWARD  = 0x01,  ///< search backwards
+  FM_FORWARD   = 0x02,  ///< search forwards
+  FM_BLOCKSTOP = 0x04,  ///< stop at start/end of block
+  FM_SKIPCOMM  = 0x08,  ///< skip comments
+};
 
-// Values for sub_cmd and which_pat argument for search_regcomp()
-// Also used for which_pat argument for searchit()
-#define RE_SEARCH       0       // save/use pat in/from search_pattern
-#define RE_SUBST        1       // save/use pat in/from subst_pattern
-#define RE_BOTH         2       // save pat in both patterns
-#define RE_LAST         2       // use last used pattern if "pat" is NULL
+/// Values for sub_cmd and which_pat argument for search_regcomp()
+/// Also used for which_pat argument for searchit()
+enum {
+  RE_SEARCH = 0,  ///< save/use pat in/from search_pattern
+  RE_SUBST  = 1,  ///< save/use pat in/from subst_pattern
+  RE_BOTH   = 2,  ///< save pat in both patterns
+  RE_LAST   = 2,  ///< use last used pattern if "pat" is NULL
+};
 
 // Values for searchcount()
-#define SEARCH_STAT_DEF_TIMEOUT 40
-#define SEARCH_STAT_DEF_MAX_COUNT 99
-#define SEARCH_STAT_BUF_LEN 12
+enum { SEARCH_STAT_DEF_TIMEOUT = 40, };
+enum { SEARCH_STAT_DEF_MAX_COUNT = 99, };
+enum { SEARCH_STAT_BUF_LEN = 12, };
 
-/// Maximum number of characters that can be fuzzy matched
-#define MAX_FUZZY_MATCHES 256
+enum {
+  /// Maximum number of characters that can be fuzzy matched
+  MAX_FUZZY_MATCHES = 256,
+};
 
 /// Structure containing offset definition for the last search pattern
 ///
diff --git a/src/nvim/spell.h b/src/nvim/spell.h
index f3977fdaf2..43ba00e901 100644
--- a/src/nvim/spell.h
+++ b/src/nvim/spell.h
@@ -1,11 +1,8 @@
 #pragma once
 
-#include <stdbool.h>
-
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
-#include "nvim/globals.h"
 #include "nvim/spell_defs.h"  // IWYU pragma: export
-#include "nvim/vim_defs.h"
+#include "nvim/vim_defs.h"  // IWYU pragma: keep
 
 /// First language that is loaded, start of the linked list of loaded languages.
 extern slang_T *first_lang;
diff --git a/src/nvim/spell_defs.h b/src/nvim/spell_defs.h
index dfa399750f..6293bc314b 100644
--- a/src/nvim/spell_defs.h
+++ b/src/nvim/spell_defs.h
@@ -8,12 +8,13 @@
 #include "nvim/hashtab_defs.h"
 #include "nvim/regexp_defs.h"
 
-/// Assume max. word len is this many bytes.
-/// Some places assume a word length fits in a byte, thus it can't be above 255.
-enum { MAXWLEN = 254, };
+enum {
+  /// Assume max. word len is this many bytes.
+  /// Some places assume a word length fits in a byte, thus it can't be above 255.
+  MAXWLEN = 254,
+};
 
-/// Number of regions supported.
-enum { MAXREGIONS = 8, };
+enum { MAXREGIONS = 8, };  ///< Number of regions supported.
 
 /// Type used for indexes in the word tree need to be at least 4 bytes.  If int
 /// is 8 bytes we could use something smaller, but what?
diff --git a/src/nvim/syntax.h b/src/nvim/syntax.h
index 4e9c7a27dc..b9065acf7d 100644
--- a/src/nvim/syntax.h
+++ b/src/nvim/syntax.h
@@ -1,33 +1,32 @@
 #pragma once
 
-#include <stdbool.h>
-
 #include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
-#include "nvim/globals.h"
 #include "nvim/macros_defs.h"
 #include "nvim/syntax_defs.h"  // IWYU pragma: export
 
-#define HL_CONTAINED   0x01    // not used on toplevel
-#define HL_TRANSP      0x02    // has no highlighting
-#define HL_ONELINE     0x04    // match within one line only
-#define HL_HAS_EOL     0x08    // end pattern that matches with $
-#define HL_SYNC_HERE   0x10    // sync point after this item (syncing only)
-#define HL_SYNC_THERE  0x20    // sync point at current line (syncing only)
-#define HL_MATCH       0x40    // use match ID instead of item ID
-#define HL_SKIPNL      0x80    // nextgroup can skip newlines
-#define HL_SKIPWHITE   0x100   // nextgroup can skip white space
-#define HL_SKIPEMPTY   0x200   // nextgroup can skip empty lines
-#define HL_KEEPEND     0x400   // end match always kept
-#define HL_EXCLUDENL   0x800   // exclude NL from match
-#define HL_DISPLAY     0x1000  // only used for displaying, not syncing
-#define HL_FOLD        0x2000  // define fold
-#define HL_EXTEND      0x4000  // ignore a keepend
-#define HL_MATCHCONT   0x8000  // match continued from previous line
-#define HL_TRANS_CONT  0x10000  // transparent item without contains arg
-#define HL_CONCEAL     0x20000  // can be concealed
-#define HL_CONCEALENDS 0x40000  // can be concealed
+enum {
+  HL_CONTAINED   = 0x01,     ///< not used on toplevel
+  HL_TRANSP      = 0x02,     ///< has no highlighting
+  HL_ONELINE     = 0x04,     ///< match within one line only
+  HL_HAS_EOL     = 0x08,     ///< end pattern that matches with $
+  HL_SYNC_HERE   = 0x10,     ///< sync point after this item (syncing only)
+  HL_SYNC_THERE  = 0x20,     ///< sync point at current line (syncing only)
+  HL_MATCH       = 0x40,     ///< use match ID instead of item ID
+  HL_SKIPNL      = 0x80,     ///< nextgroup can skip newlines
+  HL_SKIPWHITE   = 0x100,    ///< nextgroup can skip white space
+  HL_SKIPEMPTY   = 0x200,    ///< nextgroup can skip empty lines
+  HL_KEEPEND     = 0x400,    ///< end match always kept
+  HL_EXCLUDENL   = 0x800,    ///< exclude NL from match
+  HL_DISPLAY     = 0x1000,   ///< only used for displaying, not syncing
+  HL_FOLD        = 0x2000,   ///< define fold
+  HL_EXTEND      = 0x4000,   ///< ignore a keepend
+  HL_MATCHCONT   = 0x8000,   ///< match continued from previous line
+  HL_TRANS_CONT  = 0x10000,  ///< transparent item without contains arg
+  HL_CONCEAL     = 0x20000,  ///< can be concealed
+  HL_CONCEALENDS = 0x40000,  ///< can be concealed
+};
 
 #define SYN_GROUP_STATIC(s) syn_check_group(S_LEN(s))
 
diff --git a/src/nvim/textobject.h b/src/nvim/textobject.h
index a540c7c98f..735a2fec3d 100644
--- a/src/nvim/textobject.h
+++ b/src/nvim/textobject.h
@@ -2,7 +2,7 @@
 
 #include "nvim/normal_defs.h"  // IWYU pragma: keep
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
-#include "nvim/vim_defs.h"
+#include "nvim/vim_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "textobject.h.generated.h"
diff --git a/src/nvim/undo_defs.h b/src/nvim/undo_defs.h
index 0b78ea543f..09a9689f67 100644
--- a/src/nvim/undo_defs.h
+++ b/src/nvim/undo_defs.h
@@ -6,8 +6,7 @@
 #include "nvim/mark_defs.h"
 #include "nvim/pos_defs.h"
 
-/// Size in bytes of the hash used in the undo file.
-enum { UNDO_HASH_SIZE = 32, };
+enum { UNDO_HASH_SIZE = 32, };  ///< Size in bytes of the hash used in the undo file.
 
 typedef struct u_header u_header_T;
 
diff --git a/src/nvim/vim_defs.h b/src/nvim/vim_defs.h
index faf79b1c79..155265ac42 100644
--- a/src/nvim/vim_defs.h
+++ b/src/nvim/vim_defs.h
@@ -15,11 +15,10 @@
 # error Configure did not run properly.
 #endif
 
-// bring lots of system header files
-#include "nvim/os/os_defs.h"  // IWYU pragma: keep
-
-/// length of a buffer to store a number in ASCII (64 bits binary + NUL)
-enum { NUMBUFLEN = 65, };
+enum {
+  /// length of a buffer to store a number in ASCII (64 bits binary + NUL)
+  NUMBUFLEN = 65,
+};
 
 #define MAX_TYPENR 65535
 
@@ -32,6 +31,41 @@ typedef enum {
   BACKWARD_FILE = -3,
 } Direction;
 
+/// Used to track the status of external functions.
+/// Currently only used for iconv().
+typedef enum {
+  kUnknown,
+  kWorking,
+  kBroken,
+} WorkingStatus;
+
+/// The scope of a working-directory command like `:cd`.
+///
+/// Scopes are enumerated from lowest to highest. When adding a scope make sure
+/// to update all functions using scopes as well, such as the implementation of
+/// `getcwd()`. When using scopes as limits (e.g. in loops) don't use the scopes
+/// directly, use `MIN_CD_SCOPE` and `MAX_CD_SCOPE` instead.
+typedef enum {
+  kCdScopeInvalid = -1,
+  kCdScopeWindow,   ///< Affects one window.
+  kCdScopeTabpage,  ///< Affects one tab page.
+  kCdScopeGlobal,   ///< Affects the entire Nvim instance.
+} CdScope;
+
+#define MIN_CD_SCOPE  kCdScopeWindow
+#define MAX_CD_SCOPE  kCdScopeGlobal
+
+/// What caused the current directory to change.
+typedef enum {
+  kCdCauseOther = -1,
+  kCdCauseManual,  ///< Using `:cd`, `:tcd`, `:lcd` or `chdir()`.
+  kCdCauseWindow,  ///< Switching to another window.
+  kCdCauseAuto,    ///< On 'autochdir'.
+} CdCause;
+
+// bring lots of system header files
+#include "nvim/os/os_defs.h"  // IWYU pragma: keep
+
 // return values for functions
 #if !(defined(OK) && (OK == 1))
 // OK already defined to 1 in MacOS X curses, skip this
diff --git a/src/nvim/window.h b/src/nvim/window.h
index 3650fef46e..d70292508a 100644
--- a/src/nvim/window.h
+++ b/src/nvim/window.h
@@ -38,8 +38,10 @@ enum {
   STATUS_HEIGHT = 1,  ///< height of a status line under a window
 };
 
-/// Lowest number used for window ID. Cannot have this many windows per tab.
-enum { LOWEST_WIN_ID = 1000, };
+enum {
+  /// Lowest number used for window ID. Cannot have this many windows per tab.
+  LOWEST_WIN_ID = 1000,
+};
 
 /// Set to true if 'cmdheight' was explicitly set to 0.
 EXTERN bool p_ch_was_zero INIT( = false);