refactor: move some constants out of vim_defs.h (#26298)

89 files changed, 339 insertions, 352 deletions

diff --git a/Makefile b/Makefile
index b1c39d5816..c6a0c053ea 100644
--- a/Makefile
+++ b/Makefile
@@ -143,7 +143,6 @@ iwyu: build/.ran-cmake
 	cmake --build build > build/iwyu.log
 	iwyu-fix-includes --only_re="src/nvim" --ignore_re="(src/nvim/eval/encode.c|src/nvim/auto/|src/nvim/os/lang.c|src/nvim/map.c\
 	|src/nvim/api/extmark.h\
-	|src/nvim/api/private/defs.h\
 	|src/nvim/api/private/dispatch.h\
 	|src/nvim/api/private/helpers.h\
 	|src/nvim/api/private/validate.h\
@@ -154,14 +153,11 @@ iwyu: build/.ran-cmake
 	|src/nvim/autocmd_defs.h\
 	|src/nvim/buffer.h\
 	|src/nvim/buffer_defs.h\
-	|src/nvim/buffer_updates.h\
 	|src/nvim/channel.h\
 	|src/nvim/charset.h\
 	|src/nvim/cmdexpand.h\
 	|src/nvim/cmdhist.h\
-	|src/nvim/context.h\
 	|src/nvim/decoration.h\
-	|src/nvim/decoration_provider.h\
 	|src/nvim/diff.h\
 	|src/nvim/drawline.h\
 	|src/nvim/drawscreen.h\
@@ -169,7 +165,6 @@ iwyu: build/.ran-cmake
 	|src/nvim/eval/encode.h\
 	|src/nvim/eval/typval.h\
 	|src/nvim/eval/typval_defs.h\
-	|src/nvim/eval/typval_encode.h\
 	|src/nvim/eval/userfunc.h\
 	|src/nvim/eval/window.h\
 	|src/nvim/event/libuv_process.h\
@@ -185,7 +180,6 @@ iwyu: build/.ran-cmake
 	|src/nvim/ex_cmds.h\
 	|src/nvim/ex_cmds_defs.h\
 	|src/nvim/ex_docmd.h\
-	|src/nvim/ex_getln.h\
 	|src/nvim/extmark.h\
 	|src/nvim/file_search.h\
 	|src/nvim/fileio.h\
@@ -203,15 +197,12 @@ iwyu: build/.ran-cmake
 	|src/nvim/lua/executor.h\
 	|src/nvim/main.h\
 	|src/nvim/mark.h\
-	|src/nvim/marktree.h\
-	|src/nvim/message.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\
 	|src/nvim/msgpack_rpc/unpacker.h\
-	|src/nvim/ops.h\
 	|src/nvim/option.h\
 	|src/nvim/os/fileio.h\
 	|src/nvim/os/input.h\
diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index 349bb93133..6ffb514487 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -4189,8 +4189,8 @@ maparg({name} [, {mode} [, {abbr} [, {dict}]]])                       *maparg()*
 		  "mode_bits" Nvim's internal binary representation of "mode".
 			     |mapset()| ignores this; only "mode" is used.
 			     See |maplist()| for usage examples. The values
-			     are from src/nvim/vim.h and may change in the
-			     future.
+			     are from src/nvim/state_defs.h and may change in
+			     the future.
 
 		The dictionary can be used to restore a mapping with
 		|mapset()|.
@@ -4257,8 +4257,8 @@ maplist([{abbr}])                                                    *maplist()*
 			endfor
 			echo saved_maps->mapnew({_, m -> m.lhs})
 <		The values of the mode_bits are defined in Nvim's
-		src/nvim/vim.h file and they can be discovered at runtime
-		using |:map-commands| and "maplist()". Example: >vim
+		src/nvim/state_defs.h file and they can be discovered at
+		runtime using |:map-commands| and "maplist()". Example: >vim
 			omap xyzzy <Nop>
 			let op_bit = maplist()->filter(
 			    \ {_, m -> m.lhs == 'xyzzy'})[0].mode_bits
diff --git a/runtime/lua/vim/_meta/vimfn.lua b/runtime/lua/vim/_meta/vimfn.lua
index 947424c4ad..05e5b2b871 100644
--- a/runtime/lua/vim/_meta/vimfn.lua
+++ b/runtime/lua/vim/_meta/vimfn.lua
@@ -5050,8 +5050,8 @@ function vim.fn.map(expr1, expr2) end
 ---   "mode_bits" Nvim's internal binary representation of "mode".
 ---        |mapset()| ignores this; only "mode" is used.
 ---        See |maplist()| for usage examples. The values
----        are from src/nvim/vim.h and may change in the
----        future.
+---        are from src/nvim/state_defs.h and may change in
+---        the future.
 ---
 --- The dictionary can be used to restore a mapping with
 --- |mapset()|.
@@ -5129,8 +5129,8 @@ function vim.fn.mapcheck(name, mode, abbr) end
 ---   endfor
 ---   echo saved_maps->mapnew({_, m -> m.lhs})
 --- <The values of the mode_bits are defined in Nvim's
---- src/nvim/vim.h file and they can be discovered at runtime
---- using |:map-commands| and "maplist()". Example: >vim
+--- src/nvim/state_defs.h file and they can be discovered at
+--- runtime using |:map-commands| and "maplist()". Example: >vim
 ---   omap xyzzy <Nop>
 ---   let op_bit = maplist()->filter(
 ---       \ {_, m -> m.lhs == 'xyzzy'})[0].mode_bits
diff --git a/src/clint.py b/src/clint.py
index ef2ac57a87..e730b9276b 100755
--- a/src/clint.py
+++ b/src/clint.py
@@ -898,7 +898,6 @@ def CheckIncludes(filename, lines, error):
     # the Makefile.
     check_includes_ignore = [
             "src/nvim/api/extmark.h",
-            "src/nvim/api/private/defs.h",
             "src/nvim/api/private/dispatch.h",
             "src/nvim/api/private/helpers.h",
             "src/nvim/api/private/validate.h",
@@ -909,14 +908,11 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/autocmd_defs.h",
             "src/nvim/buffer.h",
             "src/nvim/buffer_defs.h",
-            "src/nvim/buffer_updates.h",
             "src/nvim/channel.h",
             "src/nvim/charset.h",
             "src/nvim/cmdexpand.h",
             "src/nvim/cmdhist.h",
-            "src/nvim/context.h",
             "src/nvim/decoration.h",
-            "src/nvim/decoration_provider.h",
             "src/nvim/diff.h",
             "src/nvim/drawline.h",
             "src/nvim/drawscreen.h",
@@ -924,7 +920,6 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/eval/encode.h",
             "src/nvim/eval/typval.h",
             "src/nvim/eval/typval_defs.h",
-            "src/nvim/eval/typval_encode.h",
             "src/nvim/eval/userfunc.h",
             "src/nvim/eval/window.h",
             "src/nvim/event/libuv_process.h",
@@ -940,7 +935,6 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/ex_cmds.h",
             "src/nvim/ex_cmds_defs.h",
             "src/nvim/ex_docmd.h",
-            "src/nvim/ex_getln.h",
             "src/nvim/extmark.h",
             "src/nvim/file_search.h",
             "src/nvim/fileio.h",
@@ -958,15 +952,12 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/lua/executor.h",
             "src/nvim/main.h",
             "src/nvim/mark.h",
-            "src/nvim/marktree.h",
-            "src/nvim/message.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",
             "src/nvim/msgpack_rpc/unpacker.h",
-            "src/nvim/ops.h",
             "src/nvim/option.h",
             "src/nvim/os/fileio.h",
             "src/nvim/os/input.h",
diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index 96e0e240f2..0df231868d 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -34,6 +34,7 @@
 #include "nvim/move.h"
 #include "nvim/ops.h"
 #include "nvim/pos_defs.h"
+#include "nvim/state_defs.h"
 #include "nvim/types_defs.h"
 #include "nvim/undo.h"
 #include "nvim/vim_defs.h"
diff --git a/src/nvim/autocmd.c b/src/nvim/autocmd.c
index 585fac1228..74a1dbdbc3 100644
--- a/src/nvim/autocmd.c
+++ b/src/nvim/autocmd.c
@@ -29,7 +29,7 @@
 #include "nvim/globals.h"
 #include "nvim/grid.h"
 #include "nvim/hashtab.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/insexpand.h"
 #include "nvim/lua/executor.h"
 #include "nvim/main.h"
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index e6bedca232..8a594dea92 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -89,8 +89,8 @@
 #include "nvim/regexp.h"
 #include "nvim/runtime.h"
 #include "nvim/search.h"
-#include "nvim/sign.h"
 #include "nvim/spell.h"
+#include "nvim/state_defs.h"
 #include "nvim/statusline.h"
 #include "nvim/strings.h"
 #include "nvim/syntax.h"
diff --git a/src/nvim/buffer_updates.c b/src/nvim/buffer_updates.c
index 6a96f715af..01bcb9d7be 100644
--- a/src/nvim/buffer_updates.c
+++ b/src/nvim/buffer_updates.c
@@ -11,7 +11,6 @@
 #include "nvim/buffer.h"
 #include "nvim/buffer_defs.h"
 #include "nvim/buffer_updates.h"
-#include "nvim/extmark.h"
 #include "nvim/func_attr.h"
 #include "nvim/globals.h"
 #include "nvim/log.h"
diff --git a/src/nvim/buffer_updates.h b/src/nvim/buffer_updates.h
index ca5246c571..e844f3b2a8 100644
--- a/src/nvim/buffer_updates.h
+++ b/src/nvim/buffer_updates.h
@@ -3,8 +3,8 @@
 #include <stdint.h>  // IWYU pragma: keep
 
 #include "nvim/buffer_defs.h"  // IWYU pragma: keep
-#include "nvim/extmark.h"
-#include "nvim/pos_defs.h"
+#include "nvim/extmark_defs.h"  // IWYU pragma: keep
+#include "nvim/pos_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "buffer_updates.h.generated.h"
diff --git a/src/nvim/bufwrite.c b/src/nvim/bufwrite.c
index 178218729a..f774fcb057 100644
--- a/src/nvim/bufwrite.c
+++ b/src/nvim/bufwrite.c
@@ -26,7 +26,7 @@
 #include "nvim/func_attr.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/iconv_defs.h"
 #include "nvim/input.h"
 #include "nvim/macros_defs.h"
diff --git a/src/nvim/change.c b/src/nvim/change.c
index 20cc034638..81a55b92ee 100644
--- a/src/nvim/change.c
+++ b/src/nvim/change.c
@@ -24,7 +24,7 @@
 #include "nvim/func_attr.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/indent.h"
 #include "nvim/indent_c.h"
 #include "nvim/insexpand.h"
diff --git a/src/nvim/cmdexpand.c b/src/nvim/cmdexpand.c
index 275b284392..367b86ec55 100644
--- a/src/nvim/cmdexpand.c
+++ b/src/nvim/cmdexpand.c
@@ -35,7 +35,7 @@
 #include "nvim/grid.h"
 #include "nvim/hashtab.h"
 #include "nvim/help.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/highlight_group.h"
 #include "nvim/keycodes.h"
 #include "nvim/log.h"
diff --git a/src/nvim/context.h b/src/nvim/context.h
index f39399e806..1c18a1af7c 100644
--- a/src/nvim/context.h
+++ b/src/nvim/context.h
@@ -1,6 +1,5 @@
 #pragma once
 
-#include <msgpack.h>
 #include <msgpack/sbuffer.h>
 #include <stddef.h>
 
diff --git a/src/nvim/cursor_shape.c b/src/nvim/cursor_shape.c
index 82068ce9c5..745c0cc6ed 100644
--- a/src/nvim/cursor_shape.c
+++ b/src/nvim/cursor_shape.c
@@ -15,6 +15,7 @@
 #include "nvim/log.h"
 #include "nvim/macros_defs.h"
 #include "nvim/option_vars.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/ui.h"
 #include "nvim/vim_defs.h"
diff --git a/src/nvim/debugger.c b/src/nvim/debugger.c
index dd248ca58e..a343c1ad6b 100644
--- a/src/nvim/debugger.c
+++ b/src/nvim/debugger.c
@@ -32,6 +32,7 @@
 #include "nvim/pos_defs.h"
 #include "nvim/regexp.h"
 #include "nvim/runtime.h"
+#include "nvim/state_defs.h"
 #include "nvim/vim_defs.h"
 
 /// batch mode debugging: don't save and restore typeahead.
diff --git a/src/nvim/decoration.h b/src/nvim/decoration.h
index 829046f1b9..f5448c051b 100644
--- a/src/nvim/decoration.h
+++ b/src/nvim/decoration.h
@@ -1,16 +1,15 @@
 #pragma once
 
 #include <stdbool.h>
-#include <stddef.h>
+#include <stddef.h>  // IWYU pragma: keep
 #include <stdint.h>
 
 #include "klib/kvec.h"
 #include "nvim/buffer_defs.h"
 #include "nvim/decoration_defs.h"  // IWYU pragma: export
-#include "nvim/extmark_defs.h"
 #include "nvim/macros_defs.h"
 #include "nvim/marktree.h"
-#include "nvim/pos_defs.h"
+#include "nvim/pos_defs.h"  // IWYU pragma: keep
 #include "nvim/types_defs.h"
 
 // actual Decor* data is in decoration_defs.h
diff --git a/src/nvim/decoration_provider.h b/src/nvim/decoration_provider.h
index 90bd9e6a41..e0dd67a6f7 100644
--- a/src/nvim/decoration_provider.h
+++ b/src/nvim/decoration_provider.h
@@ -4,7 +4,7 @@
 #include <stdint.h>
 
 #include "klib/kvec.h"
-#include "nvim/buffer_defs.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/macros_defs.h"
 #include "nvim/types_defs.h"
 
diff --git a/src/nvim/digraph.c b/src/nvim/digraph.c
index 647ab26441..99d5cf1035 100644
--- a/src/nvim/digraph.c
+++ b/src/nvim/digraph.c
@@ -22,7 +22,7 @@
 #include "nvim/getchar.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/keycodes.h"
 #include "nvim/mapping.h"
 #include "nvim/mbyte.h"
@@ -32,6 +32,7 @@
 #include "nvim/option_vars.h"
 #include "nvim/os/input.h"
 #include "nvim/runtime.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/types_defs.h"
 #include "nvim/vim_defs.h"
diff --git a/src/nvim/drawline.c b/src/nvim/drawline.c
index 5b90231a62..e0887ed1d0 100644
--- a/src/nvim/drawline.c
+++ b/src/nvim/drawline.c
@@ -21,6 +21,7 @@
 #include "nvim/drawscreen.h"
 #include "nvim/eval.h"
 #include "nvim/fold.h"
+#include "nvim/fold_defs.h"
 #include "nvim/globals.h"
 #include "nvim/grid.h"
 #include "nvim/highlight.h"
@@ -48,8 +49,7 @@
 #include "nvim/ui.h"
 #include "nvim/vim_defs.h"
 
-#define MB_FILLER_CHAR '<'  // character used when a double-width character
-                            // doesn't fit.
+#define MB_FILLER_CHAR '<'  // character used when a double-width character doesn't fit.
 
 /// possible draw states in win_line(), drawn in sequence.
 typedef enum {
diff --git a/src/nvim/drawline.h b/src/nvim/drawline.h
index 6a9c6d5597..5a7f220a13 100644
--- a/src/nvim/drawline.h
+++ b/src/nvim/drawline.h
@@ -5,7 +5,7 @@
 
 #include "klib/kvec.h"
 #include "nvim/decoration_provider.h"
-#include "nvim/fold.h"
+#include "nvim/fold_defs.h"
 #include "nvim/macros_defs.h"
 #include "nvim/pos_defs.h"
 #include "nvim/types_defs.h"
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 77065f95e9..71a12ea1b0 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -29,7 +29,7 @@
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
 #include "nvim/grid.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/highlight_group.h"
 #include "nvim/indent.h"
 #include "nvim/indent_c.h"
diff --git a/src/nvim/eval.h b/src/nvim/eval.h
index b8104cf82a..1fc2891917 100644
--- a/src/nvim/eval.h
+++ b/src/nvim/eval.h
@@ -277,6 +277,9 @@ enum {
   EVAL_EVALUATE = 1,  ///< when missing don't actually evaluate
 };
 
+// Character used as separated in autoload function/variable names.
+#define AUTOLOAD_CHAR '#'
+
 /// Passed to an eval() function to enable evaluation.
 EXTERN evalarg_T EVALARG_EVALUATE INIT( = { EVAL_EVALUATE, NULL, NULL, NULL });
 
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index 6355dd6b93..55f4721c3a 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -6198,8 +6198,8 @@ M.funcs = {
         "mode_bits" Nvim's internal binary representation of "mode".
       	     |mapset()| ignores this; only "mode" is used.
       	     See |maplist()| for usage examples. The values
-      	     are from src/nvim/vim.h and may change in the
-      	     future.
+      	     are from src/nvim/state_defs.h and may change in
+      	     the future.
 
       The dictionary can be used to restore a mapping with
       |mapset()|.
@@ -6287,8 +6287,8 @@ M.funcs = {
       	endfor
       	echo saved_maps->mapnew({_, m -> m.lhs})
       <The values of the mode_bits are defined in Nvim's
-      src/nvim/vim.h file and they can be discovered at runtime
-      using |:map-commands| and "maplist()". Example: >vim
+      src/nvim/state_defs.h file and they can be discovered at
+      runtime using |:map-commands| and "maplist()". Example: >vim
       	omap xyzzy <Nop>
       	let op_bit = maplist()->filter(
       	    \ {_, m -> m.lhs == 'xyzzy'})[0].mode_bits
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 974631d61f..e369397047 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -48,7 +48,7 @@
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
 #include "nvim/help.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/highlight_group.h"
 #include "nvim/indent.h"
 #include "nvim/input.h"
@@ -79,6 +79,7 @@
 #include "nvim/regexp.h"
 #include "nvim/search.h"
 #include "nvim/spell.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/terminal.h"
 #include "nvim/types_defs.h"
diff --git a/src/nvim/ex_cmds2.c b/src/nvim/ex_cmds2.c
index a00124ea30..1722b7902b 100644
--- a/src/nvim/ex_cmds2.c
+++ b/src/nvim/ex_cmds2.c
@@ -26,7 +26,7 @@
 #include "nvim/fileio.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/macros_defs.h"
 #include "nvim/mark.h"
 #include "nvim/memory.h"
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 381e23b27d..0b466bbe4e 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -44,7 +44,7 @@
 #include "nvim/getchar.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/highlight_group.h"
 #include "nvim/input.h"
 #include "nvim/keycodes.h"
diff --git a/src/nvim/ex_docmd.h b/src/nvim/ex_docmd.h
index 3781ba1a34..698153e8df 100644
--- a/src/nvim/ex_docmd.h
+++ b/src/nvim/ex_docmd.h
@@ -28,6 +28,8 @@ enum {
 // Whether a command index indicates a user command.
 #define IS_USER_CMDIDX(idx) ((int)(idx) < 0)
 
+enum { DIALOG_MSG_SIZE = 1000, };  ///< buffer size for dialog_msg()
+
 /// Structure used to save the current state.  Used when executing Normal mode
 /// commands while in any other mode.
 typedef struct {
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index b078f77b98..64ef17b157 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -39,7 +39,7 @@
 #include "nvim/getchar.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/highlight_group.h"
 #include "nvim/keycodes.h"
 #include "nvim/macros_defs.h"
diff --git a/src/nvim/ex_getln.h b/src/nvim/ex_getln.h
index 967aab6138..93bdd2299f 100644
--- a/src/nvim/ex_getln.h
+++ b/src/nvim/ex_getln.h
@@ -9,8 +9,6 @@
 #include "nvim/option_defs.h"  // IWYU pragma: keep
 #include "nvim/types_defs.h"  // IWYU pragma: keep
 
-struct cmdline_info;
-
 /// Command-line colors: one chunk
 ///
 /// Defines a region which has the same highlighting.
diff --git a/src/nvim/extmark.c b/src/nvim/extmark.c
index 794a76907c..d9c1993f32 100644
--- a/src/nvim/extmark.c
+++ b/src/nvim/extmark.c
@@ -26,6 +26,7 @@
 // code for redrawing the line with the deleted decoration.
 
 #include <assert.h>
+#include <stddef.h>
 
 #include "nvim/api/private/defs.h"
 #include "nvim/buffer_defs.h"
diff --git a/src/nvim/extmark.h b/src/nvim/extmark.h
index 53a8215882..061cd0ed5f 100644
--- a/src/nvim/extmark.h
+++ b/src/nvim/extmark.h
@@ -17,9 +17,6 @@ EXTERN int extmark_splice_pending INIT( = 0);
 
 typedef kvec_t(MTPair) ExtmarkInfoArray;
 
-// TODO(bfredl): good enough name for now.
-typedef ptrdiff_t bcount_t;
-
 // delete the columns between mincol and endcol
 typedef struct {
   int start_row;
diff --git a/src/nvim/extmark_defs.h b/src/nvim/extmark_defs.h
index 458c80b16b..c5a8684545 100644
--- a/src/nvim/extmark_defs.h
+++ b/src/nvim/extmark_defs.h
@@ -3,6 +3,9 @@
 #include "klib/kvec.h"
 #include "nvim/types_defs.h"
 
+// TODO(bfredl): good enough name for now.
+typedef ptrdiff_t bcount_t;
+
 typedef struct undo_object ExtmarkUndoObject;
 typedef kvec_t(ExtmarkUndoObject) extmark_undo_vec_t;
 
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 303776b2eb..0bb664bcf5 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -37,7 +37,7 @@
 #include "nvim/getchar.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/iconv_defs.h"
 #include "nvim/log.h"
 #include "nvim/macros_defs.h"
@@ -60,6 +60,7 @@
 #include "nvim/regexp.h"
 #include "nvim/sha256.h"
 #include "nvim/shada.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/types_defs.h"
 #include "nvim/ui.h"
diff --git a/src/nvim/fold.c b/src/nvim/fold.c
index 69857d2628..c905b2d3ed 100644
--- a/src/nvim/fold.c
+++ b/src/nvim/fold.c
@@ -45,6 +45,7 @@
 #include "nvim/plines.h"
 #include "nvim/pos_defs.h"
 #include "nvim/search.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/syntax.h"
 #include "nvim/types_defs.h"
diff --git a/src/nvim/fold_defs.h b/src/nvim/fold_defs.h
index 20a5805769..68ecd9cc7e 100644
--- a/src/nvim/fold_defs.h
+++ b/src/nvim/fold_defs.h
@@ -2,13 +2,14 @@
 
 #include "nvim/pos_defs.h"
 
-// Info used to pass info about a fold from the fold-detection code to the
-// code that displays the foldcolumn.
+/// Info used to pass info about a fold from the fold-detection code to the
+/// code that displays the foldcolumn.
 typedef struct foldinfo {
-  linenr_T fi_lnum;             // line number where fold starts
-  int fi_level;                 // level of the fold; when this is zero the
-                                // other fields are invalid
-  int fi_low_level;             // lowest fold level that starts in the same
-                                // line
+  linenr_T fi_lnum;  ///< line number where fold starts
+  int fi_level;      ///< level of the fold; when this is zero the
+                     ///< other fields are invalid
+  int fi_low_level;  ///< lowest fold level that starts in the same line
   linenr_T fi_lines;
 } foldinfo_T;
+
+enum { FOLD_TEXT_LEN = 51, };  ///< buffer size for get_foldtext()
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 080be8a1d4..270ffe4fa0 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -15,6 +15,7 @@
 #include "nvim/menu_defs.h"
 #include "nvim/os/os_defs.h"
 #include "nvim/runtime.h"
+#include "nvim/state_defs.h"
 #include "nvim/syntax_defs.h"
 #include "nvim/types_defs.h"
 
diff --git a/src/nvim/grid.c b/src/nvim/grid.c
index e5b870e6b0..2ef89b778e 100644
--- a/src/nvim/grid.c
+++ b/src/nvim/grid.c
@@ -29,7 +29,6 @@
 #include "nvim/option_vars.h"
 #include "nvim/types_defs.h"
 #include "nvim/ui.h"
-#include "nvim/vim_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "grid.c.generated.h"
diff --git a/src/nvim/highlight.h b/src/nvim/highlight.h
index 8c8657ae77..e5d3f3d1ca 100644
--- a/src/nvim/highlight.h
+++ b/src/nvim/highlight.h
@@ -29,3 +29,6 @@ static inline int win_hl_attr(win_T *wp, int hlf)
     rgb_bg = rgb_bg != -1 ? rgb_bg : (dark_ ? 0x000000 : 0xFFFFFF); \
     rgb_sp = rgb_sp != -1 ? rgb_sp : 0xFF0000; \
   } while (0);
+
+// Enums need a typecast to be used as array index.
+#define HL_ATTR(n)      hl_attr_active[(int)(n)]
diff --git a/src/nvim/indent.c b/src/nvim/indent.c
index e3ba395164..348f3a6528 100644
--- a/src/nvim/indent.c
+++ b/src/nvim/indent.c
@@ -36,6 +36,7 @@
 #include "nvim/pos_defs.h"
 #include "nvim/regexp.h"
 #include "nvim/search.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/textformat.h"
 #include "nvim/types_defs.h"
@@ -1369,11 +1370,11 @@ int get_lisp_indent(void)
 
 static int lisp_match(char *p)
 {
-  char buf[LSIZE];
+  char buf[512];
   char *word = *curbuf->b_p_lw != NUL ? curbuf->b_p_lw : p_lispwords;
 
   while (*word != NUL) {
-    (void)copy_option_part(&word, buf, LSIZE, ",");
+    (void)copy_option_part(&word, buf, sizeof(buf), ",");
     int len = (int)strlen(buf);
 
     if ((strncmp(buf, p, (size_t)len) == 0) && ascii_iswhite_or_nul(p[len])) {
diff --git a/src/nvim/indent_c.c b/src/nvim/indent_c.c
index 77851bfaac..c140d468d8 100644
--- a/src/nvim/indent_c.c
+++ b/src/nvim/indent_c.c
@@ -22,6 +22,7 @@
 #include "nvim/plines.h"
 #include "nvim/pos_defs.h"
 #include "nvim/search.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/vim_defs.h"
 
diff --git a/src/nvim/input.c b/src/nvim/input.c
index e3fe17fcf9..fb25968071 100644
--- a/src/nvim/input.c
+++ b/src/nvim/input.c
@@ -11,7 +11,7 @@
 #include "nvim/getchar.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/input.h"
 #include "nvim/keycodes.h"
 #include "nvim/mbyte.h"
@@ -19,8 +19,8 @@
 #include "nvim/message.h"
 #include "nvim/mouse.h"
 #include "nvim/os/input.h"
+#include "nvim/state_defs.h"
 #include "nvim/ui.h"
-#include "nvim/vim_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "input.c.generated.h"  // IWYU pragma: export
diff --git a/src/nvim/insexpand.c b/src/nvim/insexpand.c
index e1a6b1fbf3..12543a2d42 100644
--- a/src/nvim/insexpand.c
+++ b/src/nvim/insexpand.c
@@ -29,7 +29,7 @@
 #include "nvim/getchar.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/indent.h"
 #include "nvim/indent_c.h"
 #include "nvim/insexpand.h"
diff --git a/src/nvim/lua/converter.c b/src/nvim/lua/converter.c
index 4c6e38ca57..4598d48c4a 100644
--- a/src/nvim/lua/converter.c
+++ b/src/nvim/lua/converter.c
@@ -7,12 +7,9 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include "klib/kvec.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
-#include "nvim/memory.h"
-// FIXME: vim.h is not actually needed, but otherwise it states MAXPATHL is
-//        redefined
-#include "klib/kvec.h"
 #include "nvim/ascii_defs.h"
 #include "nvim/eval/decode.h"
 #include "nvim/eval/typval.h"
@@ -24,6 +21,7 @@
 #include "nvim/lua/converter.h"
 #include "nvim/lua/executor.h"
 #include "nvim/macros_defs.h"
+#include "nvim/memory.h"
 #include "nvim/message.h"
 #include "nvim/types_defs.h"
 #include "nvim/vim_defs.h"
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 3d8f33628f..6585bd1df7 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -17,10 +17,6 @@
 # include <sanitizer/ubsan_interface.h>
 #endif
 
-// uncrustify:off
-#include "nvim/vim_defs.h"
-// uncrustify:on
-
 #include "auto/config.h"  // IWYU pragma: keep
 #include "nvim/api/extmark.h"
 #include "nvim/api/private/defs.h"
@@ -99,6 +95,7 @@
 #include "nvim/ui_client.h"
 #include "nvim/ui_compositor.h"
 #include "nvim/version.h"
+#include "nvim/vim_defs.h"
 #include "nvim/window.h"
 #ifdef MSWIN
 # include "nvim/os/os_win_console.h"
diff --git a/src/nvim/mapping.c b/src/nvim/mapping.c
index 6fc9c04194..17593a9121 100644
--- a/src/nvim/mapping.c
+++ b/src/nvim/mapping.c
@@ -29,7 +29,7 @@
 #include "nvim/getchar.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/keycodes.h"
 #include "nvim/lua/executor.h"
 #include "nvim/macros_defs.h"
@@ -44,6 +44,7 @@
 #include "nvim/regexp_defs.h"
 #include "nvim/runtime.h"
 #include "nvim/search.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/types_defs.h"
 #include "nvim/ui.h"
diff --git a/src/nvim/mapping_defs.h b/src/nvim/mapping_defs.h
index 8056273a09..6691c5ac3b 100644
--- a/src/nvim/mapping_defs.h
+++ b/src/nvim/mapping_defs.h
@@ -5,6 +5,9 @@
 #include "nvim/eval/typval_defs.h"
 #include "nvim/types_defs.h"
 
+/// Maximum length of key sequence to be mapped.
+enum { MAXMAPLEN = 50, };
+
 /// Structure used for mappings and abbreviations.
 typedef struct mapblock mapblock_T;
 struct mapblock {
diff --git a/src/nvim/mark.c b/src/nvim/mark.c
index 8bc9965b50..5839cf7a2e 100644
--- a/src/nvim/mark.c
+++ b/src/nvim/mark.c
@@ -20,7 +20,7 @@
 #include "nvim/fold.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/mark.h"
 #include "nvim/mbyte.h"
 #include "nvim/memline.h"
diff --git a/src/nvim/marktree.h b/src/nvim/marktree.h
index 37119048ae..c76359d3f9 100644
--- a/src/nvim/marktree.h
+++ b/src/nvim/marktree.h
@@ -1,21 +1,16 @@
 #pragma once
 
-#include <assert.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
 
 #include "klib/kvec.h"
-#include "nvim/assert_defs.h"
 #include "nvim/decoration_defs.h"
-#include "nvim/garray_defs.h"
+#include "nvim/garray_defs.h"  // IWYU pragma: keep
 #include "nvim/map_defs.h"
-#include "nvim/pos_defs.h"
-#include "nvim/types_defs.h"
+#include "nvim/pos_defs.h"  // IWYU pragma: keep
 // only for debug functions:
-#include "nvim/api/private/defs.h"
-
-struct mtnode_s;
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 
 #define MT_MAX_DEPTH 20
 #define MT_BRANCH_FACTOR 10
diff --git a/src/nvim/mbyte_defs.h b/src/nvim/mbyte_defs.h
index c5c973c71a..2904047223 100644
--- a/src/nvim/mbyte_defs.h
+++ b/src/nvim/mbyte_defs.h
@@ -4,6 +4,11 @@
 
 #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, };
 
diff --git a/src/nvim/memfile.h b/src/nvim/memfile.h
index 2d1930e95c..687ac042a4 100644
--- a/src/nvim/memfile.h
+++ b/src/nvim/memfile.h
@@ -11,6 +11,15 @@ enum {
   MFS_ZERO  = 8,  ///< only write block 0
 };
 
+enum {
+  /// Minimal size for block 0 of a swap file.
+  /// NOTE: This depends on size of struct block0! It's not done with a sizeof(),
+  /// because struct block0 is defined in memline.c (Sorry).
+  /// The maximal block size is arbitrary.
+  MIN_SWAP_PAGE_SIZE = 1048,
+  MAX_SWAP_PAGE_SIZE = 50000,
+};
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "memfile.h.generated.h"
 #endif
diff --git a/src/nvim/memline.c b/src/nvim/memline.c
index 3ecbcaad1e..3c671121b7 100644
--- a/src/nvim/memline.c
+++ b/src/nvim/memline.c
@@ -60,7 +60,7 @@
 #include "nvim/getchar.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/input.h"
 #include "nvim/macros_defs.h"
 #include "nvim/main.h"
@@ -167,29 +167,29 @@ enum {
   B0_MAGIC_CHAR = 0x55,
 };
 
-// Block zero holds all info about the swapfile. This is the first block in the file.
-//
-// NOTE: DEFINITION OF BLOCK 0 SHOULD NOT CHANGE! It would make all existing swapfiles unusable!
-//
-// If size of block0 changes anyway, adjust MIN_SWAP_PAGE_SIZE in vim.h!!
-//
-// This block is built up of single bytes, to make it portable across
-// different machines. b0_magic_* is used to check the byte order and size of
-// variables, because the rest of the swapfile is not portable.
+/// Block zero holds all info about the swapfile. This is the first block in the file.
+///
+/// NOTE: DEFINITION OF BLOCK 0 SHOULD NOT CHANGE! It would make all existing swapfiles unusable!
+///
+/// If size of block0 changes anyway, adjust MIN_SWAP_PAGE_SIZE in memfile.h!!
+///
+/// This block is built up of single bytes, to make it portable across
+/// different machines. b0_magic_* is used to check the byte order and size of
+/// variables, because the rest of the swapfile is not portable.
 typedef struct {
   char b0_id[2];                     ///< ID for block 0: BLOCK0_ID0 and BLOCK0_ID1.
-  char b0_version[10];               // Vim version string
-  char b0_page_size[4];              // number of bytes per page
-  char b0_mtime[4];                  // last modification time of file
-  char b0_ino[4];                    // inode of b0_fname
-  char b0_pid[4];                    // process id of creator (or 0)
-  char b0_uname[B0_UNAME_SIZE];      // name of user (uid if no name)
-  char b0_hname[B0_HNAME_SIZE];      // host name (if it has a name)
-  char b0_fname[B0_FNAME_SIZE_ORG];  // name of file being edited
-  long b0_magic_long;                // check for byte order of long
-  int b0_magic_int;                  // check for byte order of int
-  int16_t b0_magic_short;            // check for byte order of short
-  char b0_magic_char;                // check for last char
+  char b0_version[10];               ///< Vim version string
+  char b0_page_size[4];              ///< number of bytes per page
+  char b0_mtime[4];                  ///< last modification time of file
+  char b0_ino[4];                    ///< inode of b0_fname
+  char b0_pid[4];                    ///< process id of creator (or 0)
+  char b0_uname[B0_UNAME_SIZE];      ///< name of user (uid if no name)
+  char b0_hname[B0_HNAME_SIZE];      ///< host name (if it has a name)
+  char b0_fname[B0_FNAME_SIZE_ORG];  ///< name of file being edited
+  long b0_magic_long;                ///< check for byte order of long
+  int b0_magic_int;                  ///< check for byte order of int
+  int16_t b0_magic_short;            ///< check for byte order of short
+  char b0_magic_char;                ///< check for last char
 } ZeroBlock;
 
 // Note: b0_dirty and b0_flags are put at the end of the file name.  For very
diff --git a/src/nvim/memory.c b/src/nvim/memory.c
index 5eb4a548fb..a13091793c 100644
--- a/src/nvim/memory.c
+++ b/src/nvim/memory.c
@@ -30,6 +30,7 @@
 #include "nvim/message.h"
 #include "nvim/option_vars.h"
 #include "nvim/sign.h"
+#include "nvim/state_defs.h"
 #include "nvim/ui.h"
 #include "nvim/usercmd.h"
 #include "nvim/vim_defs.h"
diff --git a/src/nvim/menu.c b/src/nvim/menu.c
index fb42913bfe..3252a73970 100644
--- a/src/nvim/menu.c
+++ b/src/nvim/menu.c
@@ -20,7 +20,7 @@
 #include "nvim/getchar.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/keycodes.h"
 #include "nvim/macros_defs.h"
 #include "nvim/mbyte.h"
diff --git a/src/nvim/message.c b/src/nvim/message.c
index 4bf099d1fa..3268ff389a 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -50,6 +50,7 @@
 #include "nvim/pos_defs.h"
 #include "nvim/regexp.h"
 #include "nvim/runtime.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/types_defs.h"
 #include "nvim/ui.h"
diff --git a/src/nvim/message.h b/src/nvim/message.h
index 04ea1a76ff..adbb40277b 100644
--- a/src/nvim/message.h
+++ b/src/nvim/message.h
@@ -1,15 +1,15 @@
 #pragma once
 
-#include <stdarg.h>
+#include <errno.h>
 #include <stdbool.h>
-#include <stddef.h>
+#include <stddef.h>  // IWYU pragma: keep
+#include <stdio.h>
 
 #include "klib/kvec.h"
 #include "nvim/api/private/defs.h"
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/grid_defs.h"
 #include "nvim/macros_defs.h"
-#include "nvim/types_defs.h"
 
 /// Types of dialogs passed to do_dialog().
 enum {
@@ -30,6 +30,9 @@ enum {
   VIM_DISCARDALL = 6,
 };
 
+/// special attribute addition: Put message in history
+enum { MSG_HIST = 0x1000, };
+
 typedef struct {
   String text;
   int attr;
@@ -77,3 +80,14 @@ EXTERN int msg_listdo_overwrite INIT( = 0);
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "message.h.generated.h"
 #endif
+
+// Prefer using semsg(), because perror() may send the output to the wrong
+// destination and mess up the screen.
+#define PERROR(msg) (void)semsg("%s: %s", (msg), strerror(errno))
+
+#ifndef MSWIN
+/// Headless (no UI) error message handler.
+# define os_errmsg(str)        fprintf(stderr, "%s", (str))
+/// Headless (no UI) message handler.
+# define os_msg(str)           printf("%s", (str))
+#endif
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index 503b3671fa..1f789dc153 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -40,7 +40,7 @@
 #include "nvim/globals.h"
 #include "nvim/grid.h"
 #include "nvim/help.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/keycodes.h"
 #include "nvim/macros_defs.h"
 #include "nvim/mapping.h"
diff --git a/src/nvim/normal_defs.h b/src/nvim/normal_defs.h
index dcb7aa6186..060c1057f9 100644
--- a/src/nvim/normal_defs.h
+++ b/src/nvim/normal_defs.h
@@ -64,6 +64,12 @@ enum {
   CA_NO_ADJ_OP_END = 2,  ///< don't adjust operator end
 };
 
+/// Replacement for nchar used by nv_replace().
+enum {
+  REPLACE_CR_NCHAR  = -1,
+  REPLACE_NL_NCHAR  = -2,
+};
+
 /// columns needed by shown command
 enum { SHOWCMD_COLS = 10, };
 enum { SHOWCMD_BUFLEN = SHOWCMD_COLS + 1 + 30, };
diff --git a/src/nvim/ops.c b/src/nvim/ops.c
index e66f46945e..3a4e87edf7 100644
--- a/src/nvim/ops.c
+++ b/src/nvim/ops.c
@@ -32,7 +32,7 @@
 #include "nvim/getchar.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/indent.h"
 #include "nvim/indent_c.h"
 #include "nvim/keycodes.h"
@@ -103,9 +103,9 @@ static const char e_search_pattern_and_expression_register_may_not_contain_two_o
 #define OPF_LINES  1  // operator always works on lines
 #define OPF_CHANGE 2  // operator changes text
 
-// The names of operators.
-// IMPORTANT: Index must correspond with defines in vim.h!!!
-// The third field indicates whether the operator always works on lines.
+/// The names of operators.
+/// IMPORTANT: Index must correspond with defines in ops.h!!!
+/// The third field indicates whether the operator always works on lines.
 static char opchars[][3] = {
   { NUL, NUL, 0 },                       // OP_NOP
   { 'd', NUL, OPF_CHANGE },              // OP_DELETE
diff --git a/src/nvim/ops.h b/src/nvim/ops.h
index 106e59f383..67a613cbca 100644
--- a/src/nvim/ops.h
+++ b/src/nvim/ops.h
@@ -1,78 +1,82 @@
 #pragma once
 
-#include <lauxlib.h>
 #include <stdbool.h>
 #include <stddef.h>
 
 #include "nvim/ascii_defs.h"
 #include "nvim/eval/typval_defs.h"
-#include "nvim/ex_cmds_defs.h"
-#include "nvim/extmark.h"
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
+#include "nvim/extmark_defs.h"  // IWYU pragma: keep
+#include "nvim/func_attr.h"
 #include "nvim/macros_defs.h"
-#include "nvim/normal.h"
-#include "nvim/option_defs.h"
-#include "nvim/os/time.h"
+#include "nvim/normal_defs.h"
+#include "nvim/option_defs.h"  // IWYU pragma: keep
+#include "nvim/os/time_defs.h"
 #include "nvim/pos_defs.h"
 #include "nvim/types_defs.h"
 
 typedef int (*Indenter)(void);
 
-// flags for do_put()
-#define PUT_FIXINDENT    1      // make indent look nice
-#define PUT_CURSEND      2      // leave cursor after end of new text
-#define PUT_CURSLINE     4      // leave cursor on last line of new text
-#define PUT_LINE         8      // put register as lines
-#define PUT_LINE_SPLIT   16     // split line for linewise register
-#define PUT_LINE_FORWARD 32     // put linewise register below Visual sel.
-#define PUT_BLOCK_INNER  64     // in block mode, do not add trailing spaces
+/// flags for do_put()
+enum {
+  PUT_FIXINDENT    = 1,   ///< make indent look nice
+  PUT_CURSEND      = 2,   ///< leave cursor after end of new text
+  PUT_CURSLINE     = 4,   ///< leave cursor on last line of new text
+  PUT_LINE         = 8,   ///< put register as lines
+  PUT_LINE_SPLIT   = 16,  ///< split line for linewise register
+  PUT_LINE_FORWARD = 32,  ///< put linewise register below Visual sel.
+  PUT_BLOCK_INNER  = 64,  ///< in block mode, do not add trailing spaces
+};
 
-// Registers:
-//      0 = register for latest (unnamed) yank
-//   1..9 = registers '1' to '9', for deletes
-// 10..35 = registers 'a' to 'z'
-//     36 = delete register '-'
-//     37 = selection register '*'
-//     38 = clipboard register '+'
-#define DELETION_REGISTER 36
-#define NUM_SAVED_REGISTERS 37
-// The following registers should not be saved in ShaDa file:
-#define STAR_REGISTER 37
-#define PLUS_REGISTER 38
-#define NUM_REGISTERS 39
+/// Registers:
+///      0 = register for latest (unnamed) yank
+///   1..9 = registers '1' to '9', for deletes
+/// 10..35 = registers 'a' to 'z'
+///     36 = delete register '-'
+///     37 = selection register '*'
+///     38 = clipboard register '+'
+enum {
+  DELETION_REGISTER   = 36,
+  NUM_SAVED_REGISTERS = 37,
+  // The following registers should not be saved in ShaDa file:
+  STAR_REGISTER       = 37,
+  PLUS_REGISTER       = 38,
+  NUM_REGISTERS       = 39,
+};
 
-// Operator IDs; The order must correspond to opchars[] in ops.c!
-#define OP_NOP          0       // no pending operation
-#define OP_DELETE       1       // "d"  delete operator
-#define OP_YANK         2       // "y"  yank operator
-#define OP_CHANGE       3       // "c"  change operator
-#define OP_LSHIFT       4       // "<"  left shift operator
-#define OP_RSHIFT       5       // ">"  right shift operator
-#define OP_FILTER       6       // "!"  filter operator
-#define OP_TILDE        7       // "g~" switch case operator
-#define OP_INDENT       8       // "="  indent operator
-#define OP_FORMAT       9       // "gq" format operator
-#define OP_COLON        10      // ":"  colon operator
-#define OP_UPPER        11      // "gU" make upper case operator
-#define OP_LOWER        12      // "gu" make lower case operator
-#define OP_JOIN         13      // "J"  join operator, only for Visual mode
-#define OP_JOIN_NS      14      // "gJ"  join operator, only for Visual mode
-#define OP_ROT13        15      // "g?" rot-13 encoding
-#define OP_REPLACE      16      // "r"  replace chars, only for Visual mode
-#define OP_INSERT       17      // "I"  Insert column, only for Visual mode
-#define OP_APPEND       18      // "A"  Append column, only for Visual mode
-#define OP_FOLD         19      // "zf" define a fold
-#define OP_FOLDOPEN     20      // "zo" open folds
-#define OP_FOLDOPENREC  21      // "zO" open folds recursively
-#define OP_FOLDCLOSE    22      // "zc" close folds
-#define OP_FOLDCLOSEREC 23      // "zC" close folds recursively
-#define OP_FOLDDEL      24      // "zd" delete folds
-#define OP_FOLDDELREC   25      // "zD" delete folds recursively
-#define OP_FORMAT2      26      // "gw" format operator, keeps cursor pos
-#define OP_FUNCTION     27      // "g@" call 'operatorfunc'
-#define OP_NR_ADD       28      // "<C-A>" Add to the number or alphabetic
-                                // character (OP_ADD conflicts with Perl)
-#define OP_NR_SUB       29      // "<C-X>" Subtract from the number or
-                                // alphabetic character
+/// Operator IDs; The order must correspond to opchars[] in ops.c!
+enum {
+  OP_NOP          = 0,   ///< no pending operation
+  OP_DELETE       = 1,   ///< "d"  delete operator
+  OP_YANK         = 2,   ///< "y"  yank operator
+  OP_CHANGE       = 3,   ///< "c"  change operator
+  OP_LSHIFT       = 4,   ///< "<"  left shift operator
+  OP_RSHIFT       = 5,   ///< ">"  right shift operator
+  OP_FILTER       = 6,   ///< "!"  filter operator
+  OP_TILDE        = 7,   ///< "g~" switch case operator
+  OP_INDENT       = 8,   ///< "="  indent operator
+  OP_FORMAT       = 9,   ///< "gq" format operator
+  OP_COLON        = 10,  ///< ":"  colon operator
+  OP_UPPER        = 11,  ///< "gU" make upper case operator
+  OP_LOWER        = 12,  ///< "gu" make lower case operator
+  OP_JOIN         = 13,  ///< "J"  join operator, only for Visual mode
+  OP_JOIN_NS      = 14,  ///< "gJ"  join operator, only for Visual mode
+  OP_ROT13        = 15,  ///< "g?" rot-13 encoding
+  OP_REPLACE      = 16,  ///< "r"  replace chars, only for Visual mode
+  OP_INSERT       = 17,  ///< "I"  Insert column, only for Visual mode
+  OP_APPEND       = 18,  ///< "A"  Append column, only for Visual mode
+  OP_FOLD         = 19,  ///< "zf" define a fold
+  OP_FOLDOPEN     = 20,  ///< "zo" open folds
+  OP_FOLDOPENREC  = 21,  ///< "zO" open folds recursively
+  OP_FOLDCLOSE    = 22,  ///< "zc" close folds
+  OP_FOLDCLOSEREC = 23,  ///< "zC" close folds recursively
+  OP_FOLDDEL      = 24,  ///< "zd" delete folds
+  OP_FOLDDELREC   = 25,  ///< "zD" delete folds recursively
+  OP_FORMAT2      = 26,  ///< "gw" format operator, keeps cursor pos
+  OP_FUNCTION     = 27,  ///< "g@" call 'operatorfunc'
+  OP_NR_ADD       = 28,  ///< "<C-A>" Add to the number or alphabetic character
+  OP_NR_SUB       = 29,  ///< "<C-X>" Subtract from the number or alphabetic character
+};
 
 /// Flags for get_reg_contents().
 enum GRegFlags {
diff --git a/src/nvim/option.c b/src/nvim/option.c
index ec974aaa7a..96d6d8e01e 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -89,6 +89,7 @@
 #include "nvim/spell.h"
 #include "nvim/spellfile.h"
 #include "nvim/spellsuggest.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/tag.h"
 #include "nvim/terminal.h"
diff --git a/src/nvim/os/input.c b/src/nvim/os/input.c
index 5ae24c89ab..f3bd1c7ed9 100644
--- a/src/nvim/os/input.c
+++ b/src/nvim/os/input.c
@@ -28,7 +28,6 @@
 #include "nvim/profile.h"
 #include "nvim/rbuffer.h"
 #include "nvim/state.h"
-#include "nvim/vim_defs.h"
 
 #define READ_BUFFER_SIZE 0xfff
 #define INPUT_BUFFER_SIZE (READ_BUFFER_SIZE * 4)
diff --git a/src/nvim/os/os_defs.h b/src/nvim/os/os_defs.h
index e5060a5e6a..9db559e7a5 100644
--- a/src/nvim/os/os_defs.h
+++ b/src/nvim/os/os_defs.h
@@ -41,6 +41,8 @@
 // Command-processing buffer. Use large buffers for all platforms.
 #define CMDBUFFSIZE 1024
 
+#define ROOT_UID 0
+
 /// Converts libuv error (negative int) to error description string.
 #define os_strerror uv_strerror
 
diff --git a/src/nvim/os/os_win_console.c b/src/nvim/os/os_win_console.c
index 1a5ecefaa9..816e81e997 100644
--- a/src/nvim/os/os_win_console.c
+++ b/src/nvim/os/os_win_console.c
@@ -1,8 +1,10 @@
+#include <string.h>
+
+#include "nvim/globals.h"
 #include "nvim/os/fs.h"
 #include "nvim/os/input.h"
 #include "nvim/os/os.h"
 #include "nvim/os/os_win_console.h"
-#include "nvim/vim_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "os/os_win_console.c.generated.h"
diff --git a/src/nvim/os/shell.c b/src/nvim/os/shell.c
index 994c67ae4c..191be784e8 100644
--- a/src/nvim/os/shell.c
+++ b/src/nvim/os/shell.c
@@ -38,6 +38,7 @@
 #include "nvim/pos_defs.h"
 #include "nvim/profile.h"
 #include "nvim/rbuffer.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/tag.h"
 #include "nvim/types_defs.h"
diff --git a/src/nvim/os/users.c b/src/nvim/os/users.c
index 5f77b5a6ee..ae0994a73f 100644
--- a/src/nvim/os/users.c
+++ b/src/nvim/os/users.c
@@ -17,6 +17,9 @@
 #endif
 #ifdef MSWIN
 # include <lm.h>
+
+# include "nvim/mbyte.h"
+# include "nvim/message.h"
 #endif
 
 // All user names (for ~user completion as done by shell).
diff --git a/src/nvim/plines.c b/src/nvim/plines.c
index 5ad453043b..6e9f92c193 100644
--- a/src/nvim/plines.c
+++ b/src/nvim/plines.c
@@ -24,7 +24,6 @@
 #include "nvim/pos_defs.h"
 #include "nvim/state.h"
 #include "nvim/types_defs.h"
-#include "nvim/vim_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "plines.c.generated.h"
diff --git a/src/nvim/popupmenu.c b/src/nvim/popupmenu.c
index 5f2faf01b7..f009722357 100644
--- a/src/nvim/popupmenu.c
+++ b/src/nvim/popupmenu.c
@@ -31,6 +31,7 @@
 #include "nvim/option_vars.h"
 #include "nvim/popupmenu.h"
 #include "nvim/pos_defs.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/ui.h"
 #include "nvim/ui_compositor.h"
diff --git a/src/nvim/quickfix.c b/src/nvim/quickfix.c
index eee0296ad6..4e20eb8925 100644
--- a/src/nvim/quickfix.c
+++ b/src/nvim/quickfix.c
@@ -34,7 +34,7 @@
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
 #include "nvim/help.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/highlight_group.h"
 #include "nvim/macros_defs.h"
 #include "nvim/mark.h"
@@ -252,6 +252,8 @@ static const char *e_current_quickfix_list_was_changed =
 static const char *e_current_location_list_was_changed =
   N_("E926: Current location list was changed");
 
+enum { QF_WINHEIGHT = 10, };  ///< default height for quickfix window
+
 // Quickfix window check helper macro
 #define IS_QF_WINDOW(wp) (bt_quickfix((wp)->w_buffer) && (wp)->w_llist_ref == NULL)
 // Location list window check helper macro
diff --git a/src/nvim/runtime.c b/src/nvim/runtime.c
index a0926865e6..38d3942126 100644
--- a/src/nvim/runtime.c
+++ b/src/nvim/runtime.c
@@ -55,6 +55,9 @@
 #include "nvim/types_defs.h"
 #include "nvim/usercmd.h"
 #include "nvim/vim_defs.h"
+#ifdef USE_CRNL
+# include "nvim/highlight.h"
+#endif
 
 /// Structure used to store info for each sourced file.
 /// It is shared between do_source() and getsourceline().
@@ -65,7 +68,7 @@ struct source_cookie {
   char *nextline;               ///< if not NULL: line that was read ahead
   linenr_T sourcing_lnum;       ///< line number of the source file
   int finished;                 ///< ":finish" used
-#if defined(USE_CRNL)
+#ifdef USE_CRNL
   int fileformat;               ///< EOL_UNKNOWN, EOL_UNIX or EOL_DOS
   bool error;                   ///< true if LF found after CR-LF
 #endif
diff --git a/src/nvim/search.c b/src/nvim/search.c
index 4c790a50a1..642219c1e0 100644
--- a/src/nvim/search.c
+++ b/src/nvim/search.c
@@ -28,7 +28,7 @@
 #include "nvim/getchar.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/indent_c.h"
 #include "nvim/insexpand.h"
 #include "nvim/macros_defs.h"
@@ -50,7 +50,9 @@
 #include "nvim/profile.h"
 #include "nvim/regexp.h"
 #include "nvim/search.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
+#include "nvim/tag.h"
 #include "nvim/ui.h"
 #include "nvim/vim_defs.h"
 #include "nvim/window.h"
diff --git a/src/nvim/sign.c b/src/nvim/sign.c
index 62dc450ff5..d05c708d2c 100644
--- a/src/nvim/sign.c
+++ b/src/nvim/sign.c
@@ -29,7 +29,7 @@
 #include "nvim/func_attr.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/highlight_group.h"
 #include "nvim/macros_defs.h"
 #include "nvim/map_defs.h"
diff --git a/src/nvim/state.h b/src/nvim/state.h
index 6617b77fa0..8c5957bf9a 100644
--- a/src/nvim/state.h
+++ b/src/nvim/state.h
@@ -1,14 +1,6 @@
 #pragma once
 
-typedef struct vim_state VimState;
-
-typedef int (*state_check_callback)(VimState *state);
-typedef int (*state_execute_callback)(VimState *state, int key);
-
-struct vim_state {
-  state_check_callback check;
-  state_execute_callback execute;
-};
+#include "nvim/state_defs.h"  // IWYU pragma: export
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "state.h.generated.h"
diff --git a/src/nvim/state_defs.h b/src/nvim/state_defs.h
new file mode 100644
index 0000000000..0b32412f5a
--- /dev/null
+++ b/src/nvim/state_defs.h
@@ -0,0 +1,45 @@
+#pragma once
+
+typedef struct vim_state VimState;
+
+typedef int (*state_check_callback)(VimState *state);
+typedef int (*state_execute_callback)(VimState *state, int key);
+
+struct vim_state {
+  state_check_callback check;
+  state_execute_callback execute;
+};
+
+/// Values for State
+///
+/// The lower bits up to 0x80 are used to distinguish normal/visual/op_pending
+/// /cmdline/insert/replace/terminal mode.  This is used for mapping.  If none
+/// of these bits are set, no mapping is done.  See the comment above do_map().
+/// The upper bits are used to distinguish between other states and variants of
+/// the base modes.
+enum {
+  MODE_NORMAL      = 0x01,  ///< Normal mode, command expected
+  MODE_VISUAL      = 0x02,  ///< Visual mode - use get_real_state()
+  MODE_OP_PENDING  = 0x04,  ///< Normal mode, operator is pending - use get_real_state()
+  MODE_CMDLINE     = 0x08,  ///< Editing the command line
+  MODE_INSERT      = 0x10,  ///< Insert mode, also for Replace mode
+  MODE_LANGMAP     = 0x20,  ///< Language mapping, can be combined with MODE_INSERT and MODE_CMDLINE
+  MODE_SELECT      = 0x40,  ///< Select mode, use get_real_state()
+  MODE_TERMINAL    = 0x80,  ///< Terminal mode
+
+  MAP_ALL_MODES    = 0xff,  ///< all mode bits used for mapping
+
+  REPLACE_FLAG     = 0x100,  ///< Replace mode flag
+  MODE_REPLACE     = REPLACE_FLAG | MODE_INSERT,
+  VREPLACE_FLAG    = 0x200,  ///< Virtual-replace mode flag
+  MODE_VREPLACE    = REPLACE_FLAG | VREPLACE_FLAG | MODE_INSERT,
+  MODE_LREPLACE    = REPLACE_FLAG | MODE_LANGMAP,
+
+  MODE_NORMAL_BUSY = 0x1000 | MODE_NORMAL,  ///< Normal mode, busy with a command
+  MODE_HITRETURN   = 0x2000 | MODE_NORMAL,  ///< waiting for return or command
+  MODE_ASKMORE     = 0x3000,  ///< Asking if you want --more--
+  MODE_SETWSIZE    = 0x4000,  ///< window size has changed
+  MODE_EXTERNCMD   = 0x5000,  ///< executing an external command
+  MODE_SHOWMATCH   = 0x6000 | MODE_INSERT,  ///< show matching paren
+  MODE_CONFIRM     = 0x7000,  ///< ":confirm" prompt
+};
diff --git a/src/nvim/statusline.c b/src/nvim/statusline.c
index d42a180948..604ec3dfae 100644
--- a/src/nvim/statusline.c
+++ b/src/nvim/statusline.c
@@ -37,6 +37,7 @@
 #include "nvim/plines.h"
 #include "nvim/pos_defs.h"
 #include "nvim/sign.h"
+#include "nvim/state_defs.h"
 #include "nvim/statusline.h"
 #include "nvim/strings.h"
 #include "nvim/ui.h"
diff --git a/src/nvim/syntax.c b/src/nvim/syntax.c
index 33d0d46d94..11282ea170 100644
--- a/src/nvim/syntax.c
+++ b/src/nvim/syntax.c
@@ -25,7 +25,7 @@
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
 #include "nvim/hashtab.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/highlight_group.h"
 #include "nvim/indent_c.h"
 #include "nvim/macros_defs.h"
diff --git a/src/nvim/tag.c b/src/nvim/tag.c
index f99f0dc612..c6a1a13606 100644
--- a/src/nvim/tag.c
+++ b/src/nvim/tag.c
@@ -29,7 +29,7 @@
 #include "nvim/globals.h"
 #include "nvim/hashtab.h"
 #include "nvim/help.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/input.h"
 #include "nvim/insexpand.h"
 #include "nvim/macros_defs.h"
@@ -51,6 +51,7 @@
 #include "nvim/regexp.h"
 #include "nvim/runtime.h"
 #include "nvim/search.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/tag.h"
 #include "nvim/ui.h"
diff --git a/src/nvim/tag.h b/src/nvim/tag.h
index f628d23fbe..87e71c8bef 100644
--- a/src/nvim/tag.h
+++ b/src/nvim/tag.h
@@ -5,6 +5,8 @@
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/option_defs.h"  // IWYU pragma: keep
 
+enum { LSIZE = 512, };  ///< max. size of a line in the tags file
+
 /// Values for do_tag().
 enum {
   DT_TAG    = 1,   ///< jump to newer position or same tag again
diff --git a/src/nvim/textformat.c b/src/nvim/textformat.c
index 64c698f48f..b69d438a59 100644
--- a/src/nvim/textformat.c
+++ b/src/nvim/textformat.c
@@ -32,6 +32,7 @@
 #include "nvim/os/input.h"
 #include "nvim/pos_defs.h"
 #include "nvim/search.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/textformat.h"
 #include "nvim/textobject.h"
diff --git a/src/nvim/ui.c b/src/nvim/ui.c
index 3cc07b835e..36f34bc75a 100644
--- a/src/nvim/ui.c
+++ b/src/nvim/ui.c
@@ -29,11 +29,11 @@
 #include "nvim/option.h"
 #include "nvim/option_vars.h"
 #include "nvim/os/time.h"
+#include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/ui.h"
 #include "nvim/ui_client.h"
 #include "nvim/ui_compositor.h"
-#include "nvim/vim_defs.h"
 #include "nvim/window.h"
 #include "nvim/winfloat.h"
 
diff --git a/src/nvim/ui_compositor.c b/src/nvim/ui_compositor.c
index 9b6dafae98..b698e017dc 100644
--- a/src/nvim/ui_compositor.c
+++ b/src/nvim/ui_compositor.c
@@ -27,7 +27,6 @@
 #include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/ui_compositor.h"
-#include "nvim/vim_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "ui_compositor.c.generated.h"
diff --git a/src/nvim/undo.c b/src/nvim/undo.c
index b60211941f..93a973c33d 100644
--- a/src/nvim/undo.c
+++ b/src/nvim/undo.c
@@ -104,7 +104,7 @@
 #include "nvim/getchar.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/macros_defs.h"
 #include "nvim/mark.h"
 #include "nvim/memline.h"
diff --git a/src/nvim/undo_defs.h b/src/nvim/undo_defs.h
index 3e745ab4dc..0b78ea543f 100644
--- a/src/nvim/undo_defs.h
+++ b/src/nvim/undo_defs.h
@@ -6,28 +6,31 @@
 #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, };
+
 typedef struct u_header u_header_T;
 
-// Structure to store info about the Visual area.
+/// Structure to store info about the Visual area.
 typedef struct {
-  pos_T vi_start;               // start pos of last VIsual
-  pos_T vi_end;                 // end position of last VIsual
-  int vi_mode;                  // VIsual_mode of last VIsual
-  colnr_T vi_curswant;          // MAXCOL from w_curswant
+  pos_T vi_start;       ///< start pos of last VIsual
+  pos_T vi_end;         ///< end position of last VIsual
+  int vi_mode;          ///< VIsual_mode of last VIsual
+  colnr_T vi_curswant;  ///< MAXCOL from w_curswant
 } visualinfo_T;
 
 #include "nvim/buffer_defs.h"
 
 typedef struct u_entry u_entry_T;
 struct u_entry {
-  u_entry_T *ue_next;           // pointer to next entry in list
-  linenr_T ue_top;              // number of line above undo block
-  linenr_T ue_bot;              // number of line below undo block
-  linenr_T ue_lcount;           // linecount when u_save called
-  char **ue_array;              // array of lines in undo block
-  linenr_T ue_size;             // number of lines in ue_array
+  u_entry_T *ue_next;  ///< pointer to next entry in list
+  linenr_T ue_top;     ///< number of line above undo block
+  linenr_T ue_bot;     ///< number of line below undo block
+  linenr_T ue_lcount;  ///< linecount when u_save called
+  char **ue_array;     ///< array of lines in undo block
+  linenr_T ue_size;    ///< number of lines in ue_array
 #ifdef U_DEBUG
-  int ue_magic;                 // magic number to check allocation
+  int ue_magic;        ///< magic number to check allocation
 #endif
 };
 
@@ -35,40 +38,42 @@ struct u_header {
   // The following have a pointer and a number. The number is used when reading
   // the undo file in u_read_undo()
   union {
-    u_header_T *ptr;            // pointer to next undo header in list
+    u_header_T *ptr;              ///< pointer to next undo header in list
     int seq;
   } uh_next;
   union {
-    u_header_T *ptr;            // pointer to previous header in list
+    u_header_T *ptr;              ///< pointer to previous header in list
     int seq;
   } uh_prev;
   union {
-    u_header_T *ptr;            // pointer to next header for alt. redo
+    u_header_T *ptr;              ///< pointer to next header for alt. redo
     int seq;
   } uh_alt_next;
   union {
-    u_header_T *ptr;            // pointer to previous header for alt. redo
+    u_header_T *ptr;              ///< pointer to previous header for alt. redo
     int seq;
   } uh_alt_prev;
-  int uh_seq;                   // sequence number, higher == newer undo
-  int uh_walk;                  // used by undo_time()
-  u_entry_T *uh_entry;          // pointer to first entry
-  u_entry_T *uh_getbot_entry;   // pointer to where ue_bot must be set
-  pos_T uh_cursor;              // cursor position before saving
+  int uh_seq;                     ///< sequence number, higher == newer undo
+  int uh_walk;                    ///< used by undo_time()
+  u_entry_T *uh_entry;            ///< pointer to first entry
+  u_entry_T *uh_getbot_entry;     ///< pointer to where ue_bot must be set
+  pos_T uh_cursor;                ///< cursor position before saving
   colnr_T uh_cursor_vcol;
-  int uh_flags;                   // see below
-  fmark_T uh_namedm[NMARKS];      // marks before undo/after redo
-  extmark_undo_vec_t uh_extmark;  // info to move extmarks
-  visualinfo_T uh_visual;         // Visual areas before undo/after redo
-  time_t uh_time;                 // timestamp when the change was made
-  int uh_save_nr;                 // set when the file was saved after the
-                                  // changes in this block
+  int uh_flags;                   ///< see below
+  fmark_T uh_namedm[NMARKS];      ///< marks before undo/after redo
+  extmark_undo_vec_t uh_extmark;  ///< info to move extmarks
+  visualinfo_T uh_visual;         ///< Visual areas before undo/after redo
+  time_t uh_time;                 ///< timestamp when the change was made
+  int uh_save_nr;                 ///< set when the file was saved after the
+                                  ///< changes in this block
 #ifdef U_DEBUG
-  int uh_magic;                 // magic number to check allocation
+  int uh_magic;                   ///< magic number to check allocation
 #endif
 };
 
-// values for uh_flags
-#define UH_CHANGED  0x01        // b_changed flag before undo/after redo
-#define UH_EMPTYBUF 0x02        // buffer was empty
-#define UH_RELOAD   0x04        // buffer was reloaded
+/// values for uh_flags
+enum {
+  UH_CHANGED  = 0x01,  ///< b_changed flag before undo/after redo
+  UH_EMPTYBUF = 0x02,  ///< buffer was empty
+  UH_RELOAD   = 0x04,  ///< buffer was reloaded
+};
diff --git a/src/nvim/usercmd.c b/src/nvim/usercmd.c
index e277bfb829..7c65af5138 100644
--- a/src/nvim/usercmd.c
+++ b/src/nvim/usercmd.c
@@ -20,7 +20,7 @@
 #include "nvim/garray.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/keycodes.h"
 #include "nvim/lua/executor.h"
 #include "nvim/macros_defs.h"
diff --git a/src/nvim/version.c b/src/nvim/version.c
index d6fcfaaf1f..227ecf7b3c 100644
--- a/src/nvim/version.c
+++ b/src/nvim/version.c
@@ -24,7 +24,7 @@
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
 #include "nvim/grid.h"
-#include "nvim/highlight_defs.h"
+#include "nvim/highlight.h"
 #include "nvim/lua/executor.h"
 #include "nvim/mbyte.h"
 #include "nvim/memory.h"
diff --git a/src/nvim/vim_defs.h b/src/nvim/vim_defs.h
index 42358fe4cb..84c81e0960 100644
--- a/src/nvim/vim_defs.h
+++ b/src/nvim/vim_defs.h
@@ -34,57 +34,17 @@ enum { NUMBUFLEN = 65, };
 
 #define MAX_TYPENR 65535
 
-#define ROOT_UID 0
-
 #include "nvim/gettext.h"
 #include "nvim/keycodes.h"
 #include "nvim/macros_defs.h"
 
-// special attribute addition: Put message in history
-#define MSG_HIST                0x1000
-
-// Values for State
-//
-// The lower bits up to 0x80 are used to distinguish normal/visual/op_pending
-// /cmdline/insert/replace/terminal mode.  This is used for mapping.  If none
-// of these bits are set, no mapping is done.  See the comment above do_map().
-// The upper bits are used to distinguish between other states and variants of
-// the base modes.
-
-#define MODE_NORMAL          0x01    // Normal mode, command expected
-#define MODE_VISUAL          0x02    // Visual mode - use get_real_state()
-#define MODE_OP_PENDING      0x04    // Normal mode, operator is pending - use
-                                     // get_real_state()
-#define MODE_CMDLINE         0x08    // Editing the command line
-#define MODE_INSERT          0x10    // Insert mode, also for Replace mode
-#define MODE_LANGMAP         0x20    // Language mapping, can be combined with
-                                     // MODE_INSERT and MODE_CMDLINE
-#define MODE_SELECT          0x40    // Select mode, use get_real_state()
-#define MODE_TERMINAL        0x80    // Terminal mode
-
-#define MAP_ALL_MODES        0xff    // all mode bits used for mapping
-
-#define REPLACE_FLAG         0x100   // Replace mode flag
-#define MODE_REPLACE         (REPLACE_FLAG | MODE_INSERT)
-#define VREPLACE_FLAG        0x200   // Virtual-replace mode flag
-#define MODE_VREPLACE        (REPLACE_FLAG | VREPLACE_FLAG | MODE_INSERT)
-#define MODE_LREPLACE        (REPLACE_FLAG | MODE_LANGMAP)
-
-#define MODE_NORMAL_BUSY     (0x1000 | MODE_NORMAL)  // Normal mode, busy with a command
-#define MODE_HITRETURN       (0x2000 | MODE_NORMAL)  // waiting for return or command
-#define MODE_ASKMORE         0x3000  // Asking if you want --more--
-#define MODE_SETWSIZE        0x4000  // window size has changed
-#define MODE_EXTERNCMD       0x5000  // executing an external command
-#define MODE_SHOWMATCH       (0x6000 | MODE_INSERT)  // show matching paren
-#define MODE_CONFIRM         0x7000  // ":confirm" prompt
-
 /// Directions.
 typedef enum {
   kDirectionNotSet = 0,
   FORWARD = 1,
-  BACKWARD = (-1),
+  BACKWARD = -1,
   FORWARD_FILE = 3,
-  BACKWARD_FILE = (-3),
+  BACKWARD_FILE = -3,
 } Direction;
 
 // return values for functions
@@ -95,36 +55,6 @@ typedef enum {
 #define FAIL                    0
 #define NOTDONE                 2   // not OK or FAIL but skipped
 
-// Minimal size for block 0 of a swap file.
-// NOTE: This depends on size of struct block0! It's not done with a sizeof(),
-// because struct block0 is defined in memline.c (Sorry).
-// The maximal block size is arbitrary.
-#define MIN_SWAP_PAGE_SIZE 1048
-#define MAX_SWAP_PAGE_SIZE 50000
-
-#define STATUS_HEIGHT   1       // height of a status line under a window
-#define QF_WINHEIGHT    10      // default height for quickfix window
-
-// Buffer sizes
-
-#ifndef CMDBUFFSIZE
-# define CMDBUFFSIZE    256     // size of the command processing buffer
-#endif
-
-#define LSIZE       512         // max. size of a line in the tags file
-
-#define DIALOG_MSG_SIZE 1000    // buffer size for dialog_msg()
-
-enum { FOLD_TEXT_LEN = 51, };  //!< buffer size for get_foldtext()
-
-// Maximum length of key sequence to be mapped.
-// Must be able to hold an Amiga resize report.
-
-#define MAXMAPLEN   50
-
-// Size in bytes of the hash used in the undo file.
-#define UNDO_HASH_SIZE 32
-
 #define CLEAR_FIELD(field)  memset(&(field), 0, sizeof(field))
 #define CLEAR_POINTER(ptr)  memset((ptr), 0, sizeof(*(ptr)))
 
@@ -160,45 +90,8 @@ enum { FOLD_TEXT_LEN = 51, };  //!< buffer size for get_foldtext()
 
 #define STRCAT(d, s)        strcat((char *)(d), (char *)(s))  // NOLINT(runtime/printf)
 
-// Character used as separated in autoload function/variable names.
-#define AUTOLOAD_CHAR '#'
-
-#include "nvim/message.h"
-
-// Prefer using semsg(), because perror() may send the output to the wrong
-// destination and mess up the screen.
-#define PERROR(msg) (void)semsg("%s: %s", (msg), strerror(errno))
-
-#include "nvim/path.h"
-
-// Enums need a typecast to be used as array index.
-#define HL_ATTR(n)      hl_attr_active[(int)(n)]
-
-/// 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.
-#define MB_MAXBYTES    21
-
-#ifndef MSWIN
-/// Headless (no UI) error message handler.
-# define os_errmsg(str)        fprintf(stderr, "%s", (str))
-/// Headless (no UI) message handler.
-# define os_msg(str)           printf("%s", (str))
-#endif
-
-#include "nvim/buffer_defs.h"    // buffer and windows
-#include "nvim/ex_cmds_defs.h"   // Ex command defines
-#include "nvim/globals.h"        // global variables and messages
-
-// Lowest number used for window ID. Cannot have this many windows per tab.
-#define LOWEST_WIN_ID 1000
-
 // BSD is supposed to cover FreeBSD and similar systems.
 #if (defined(BSD) || defined(__FreeBSD_kernel__)) \
   && (defined(S_ISCHR) || defined(S_IFCHR))
 # define OPEN_CHR_FILES
 #endif
-
-// Replacement for nchar used by nv_replace().
-#define REPLACE_CR_NCHAR    (-1)
-#define REPLACE_NL_NCHAR    (-2)
diff --git a/src/nvim/viml/parser/expressions.c b/src/nvim/viml/parser/expressions.c
index 914f9ef445..8b637fbb9b 100644
--- a/src/nvim/viml/parser/expressions.c
+++ b/src/nvim/viml/parser/expressions.c
@@ -58,6 +58,7 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/assert_defs.h"
 #include "nvim/charset.h"
+#include "nvim/eval.h"
 #include "nvim/func_attr.h"
 #include "nvim/gettext.h"
 #include "nvim/keycodes.h"
@@ -65,7 +66,6 @@
 #include "nvim/mbyte.h"
 #include "nvim/memory.h"
 #include "nvim/types_defs.h"
-#include "nvim/vim_defs.h"
 #include "nvim/viml/parser/expressions.h"
 #include "nvim/viml/parser/parser.h"
 
diff --git a/src/nvim/window.h b/src/nvim/window.h
index 39dd7f8766..3650fef46e 100644
--- a/src/nvim/window.h
+++ b/src/nvim/window.h
@@ -32,12 +32,15 @@ enum {
   WSP_NEWLOC = 0x100,  ///< don't copy location list
 };
 
-/// Minimum screen size
 enum {
-  MIN_COLUMNS = 12,  ///< minimal columns for screen
-  MIN_LINES   = 2,   ///< minimal lines for screen
+  MIN_COLUMNS = 12,   ///< minimal columns for screen
+  MIN_LINES   = 2,    ///< minimal lines for screen
+  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, };
+
 /// Set to true if 'cmdheight' was explicitly set to 0.
 EXTERN bool p_ch_was_zero INIT( = false);
 
diff --git a/test/functional/api/keymap_spec.lua b/test/functional/api/keymap_spec.lua
index 3af1faaece..434f117956 100644
--- a/test/functional/api/keymap_spec.lua
+++ b/test/functional/api/keymap_spec.lua
@@ -487,7 +487,7 @@ describe('nvim_set_keymap, nvim_del_keymap', function()
   end)
 
   it('error if LHS longer than MAXMAPLEN', function()
-    -- assume MAXMAPLEN of 50 chars, as declared in vim.h
+    -- assume MAXMAPLEN of 50 chars, as declared in mapping_defs.h
     local MAXMAPLEN = 50
     local lhs = ''
     for i=1,MAXMAPLEN do
diff --git a/test/functional/api/server_requests_spec.lua b/test/functional/api/server_requests_spec.lua
index cb273aedba..1ad4ad3a02 100644
--- a/test/functional/api/server_requests_spec.lua
+++ b/test/functional/api/server_requests_spec.lua
@@ -199,7 +199,7 @@ describe('server -> client', function()
 
     it('can communicate buffers, tabpages, and windows', function()
       eq({1}, eval("rpcrequest(vim, 'nvim_list_tabpages')"))
-      -- Window IDs start at 1000 (LOWEST_WIN_ID in vim.h)
+      -- Window IDs start at 1000 (LOWEST_WIN_ID in window.h)
       eq({1000}, eval("rpcrequest(vim, 'nvim_list_wins')"))
 
       local buf = eval("rpcrequest(vim, 'nvim_list_bufs')")[1]