refactor: move Arena and ArenaMem to memory_defs.h (#26240)

109 files changed, 274 insertions, 309 deletions

diff --git a/Makefile b/Makefile
index a229237268..8d6acd94f0 100644
--- a/Makefile
+++ b/Makefile
@@ -161,7 +161,6 @@ iwyu: build/.ran-cmake
 	|src/nvim/assert.h\
 	|src/nvim/autocmd.h\
 	|src/nvim/autocmd_defs.h\
-	|src/nvim/base64.h\
 	|src/nvim/buffer.h\
 	|src/nvim/buffer_defs.h\
 	|src/nvim/buffer_updates.h\
@@ -174,8 +173,6 @@ iwyu: build/.ran-cmake
 	|src/nvim/cmdhist.h\
 	|src/nvim/context.h\
 	|src/nvim/cursor.h\
-	|src/nvim/cursor_shape.h\
-	|src/nvim/debugger.h\
 	|src/nvim/decoration.h\
 	|src/nvim/decoration_defs.h\
 	|src/nvim/decoration_provider.h\
@@ -188,9 +185,7 @@ iwyu: build/.ran-cmake
 	|src/nvim/eval/buffer.h\
 	|src/nvim/eval/decode.h\
 	|src/nvim/eval/encode.h\
-	|src/nvim/eval/executor.h\
 	|src/nvim/eval/funcs.h\
-	|src/nvim/eval/gc.h\
 	|src/nvim/eval/typval.h\
 	|src/nvim/eval/typval_defs.h\
 	|src/nvim/eval/typval_encode.h\
@@ -208,13 +203,10 @@ iwyu: build/.ran-cmake
 	|src/nvim/event/time.h\
 	|src/nvim/event/wstream.h\
 	|src/nvim/ex_cmds.h\
-	|src/nvim/ex_cmds2.h\
 	|src/nvim/ex_cmds_defs.h\
 	|src/nvim/ex_docmd.h\
-	|src/nvim/ex_eval.h\
 	|src/nvim/ex_eval_defs.h\
 	|src/nvim/ex_getln.h\
-	|src/nvim/ex_session.h\
 	|src/nvim/extmark.h\
 	|src/nvim/extmark_defs.h\
 	|src/nvim/file_search.h\
@@ -227,7 +219,6 @@ iwyu: build/.ran-cmake
 	|src/nvim/grid.h\
 	|src/nvim/grid_defs.h\
 	|src/nvim/hashtab.h\
-	|src/nvim/help.h\
 	|src/nvim/highlight.h\
 	|src/nvim/highlight_defs.h\
 	|src/nvim/highlight_group.h\
@@ -239,13 +230,7 @@ iwyu: build/.ran-cmake
 	|src/nvim/keycodes.h\
 	|src/nvim/linematch.h\
 	|src/nvim/log.h\
-	|src/nvim/lua/base64.h\
 	|src/nvim/lua/executor.h\
-	|src/nvim/lua/secure.h\
-	|src/nvim/lua/spell.h\
-	|src/nvim/lua/stdlib.h\
-	|src/nvim/lua/treesitter.h\
-	|src/nvim/lua/xdiff.h\
 	|src/nvim/macros.h\
 	|src/nvim/main.h\
 	|src/nvim/map.h\
@@ -257,7 +242,6 @@ iwyu: build/.ran-cmake
 	|src/nvim/match.h\
 	|src/nvim/mbyte.h\
 	|src/nvim/mbyte_defs.h\
-	|src/nvim/memfile.h\
 	|src/nvim/memfile_defs.h\
 	|src/nvim/memline.h\
 	|src/nvim/memory.h\
@@ -268,16 +252,12 @@ iwyu: build/.ran-cmake
 	|src/nvim/msgpack_rpc/channel.h\
 	|src/nvim/msgpack_rpc/channel_defs.h\
 	|src/nvim/msgpack_rpc/helpers.h\
-	|src/nvim/msgpack_rpc/server.h\
 	|src/nvim/msgpack_rpc/unpacker.h\
 	|src/nvim/normal.h\
-	|src/nvim/nvim/extmark.h\
 	|src/nvim/ops.h\
 	|src/nvim/option.h\
 	|src/nvim/option_defs.h\
 	|src/nvim/option_vars.h\
-	|src/nvim/optionstr.h\
-	|src/nvim/os/dl.h\
 	|src/nvim/os/fileio.h\
 	|src/nvim/os/fs.h\
 	|src/nvim/os/input.h\
@@ -286,9 +266,6 @@ iwyu: build/.ran-cmake
 	|src/nvim/os/pty_conpty_win.h\
 	|src/nvim/os/pty_process_unix.h\
 	|src/nvim/os/pty_process_win.h\
-	|src/nvim/os/shell.h\
-	|src/nvim/os/time.h\
-	|src/nvim/os/tty.h\
 	|src/nvim/path.h\
 	|src/nvim/plines.h\
 	|src/nvim/popupmenu.h\
@@ -298,20 +275,13 @@ iwyu: build/.ran-cmake
 	|src/nvim/regexp_defs.h\
 	|src/nvim/runtime.h\
 	|src/nvim/search.h\
-	|src/nvim/sha256.h\
-	|src/nvim/shada.h\
 	|src/nvim/sign.h\
-	|src/nvim/sign_defs.h\
 	|src/nvim/spell.h\
 	|src/nvim/spell_defs.h\
-	|src/nvim/spellfile.h\
-	|src/nvim/state.h\
 	|src/nvim/statusline.h\
 	|src/nvim/statusline_defs.h\
 	|src/nvim/strings.h\
 	|src/nvim/syntax.h\
-	|src/nvim/tag.h\
-	|src/nvim/terminal.h\
 	|src/nvim/testing.h\
 	|src/nvim/textformat.h\
 	|src/nvim/textobject.h\
diff --git a/src/clint.py b/src/clint.py
index 293545199b..d853428cd0 100755
--- a/src/clint.py
+++ b/src/clint.py
@@ -916,7 +916,6 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/assert.h",
             "src/nvim/autocmd.h",
             "src/nvim/autocmd_defs.h",
-            "src/nvim/base64.h",
             "src/nvim/buffer.h",
             "src/nvim/buffer_defs.h",
             "src/nvim/buffer_updates.h",
@@ -929,8 +928,6 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/cmdhist.h",
             "src/nvim/context.h",
             "src/nvim/cursor.h",
-            "src/nvim/cursor_shape.h",
-            "src/nvim/debugger.h",
             "src/nvim/decoration.h",
             "src/nvim/decoration_defs.h",
             "src/nvim/decoration_provider.h",
@@ -943,9 +940,7 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/eval/buffer.h",
             "src/nvim/eval/decode.h",
             "src/nvim/eval/encode.h",
-            "src/nvim/eval/executor.h",
             "src/nvim/eval/funcs.h",
-            "src/nvim/eval/gc.h",
             "src/nvim/eval/typval.h",
             "src/nvim/eval/typval_defs.h",
             "src/nvim/eval/typval_encode.h",
@@ -963,13 +958,10 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/event/time.h",
             "src/nvim/event/wstream.h",
             "src/nvim/ex_cmds.h",
-            "src/nvim/ex_cmds2.h",
             "src/nvim/ex_cmds_defs.h",
             "src/nvim/ex_docmd.h",
-            "src/nvim/ex_eval.h",
             "src/nvim/ex_eval_defs.h",
             "src/nvim/ex_getln.h",
-            "src/nvim/ex_session.h",
             "src/nvim/extmark.h",
             "src/nvim/extmark_defs.h",
             "src/nvim/file_search.h",
@@ -982,7 +974,6 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/grid.h",
             "src/nvim/grid_defs.h",
             "src/nvim/hashtab.h",
-            "src/nvim/help.h",
             "src/nvim/highlight.h",
             "src/nvim/highlight_defs.h",
             "src/nvim/highlight_group.h",
@@ -994,13 +985,7 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/keycodes.h",
             "src/nvim/linematch.h",
             "src/nvim/log.h",
-            "src/nvim/lua/base64.h",
             "src/nvim/lua/executor.h",
-            "src/nvim/lua/secure.h",
-            "src/nvim/lua/spell.h",
-            "src/nvim/lua/stdlib.h",
-            "src/nvim/lua/treesitter.h",
-            "src/nvim/lua/xdiff.h",
             "src/nvim/macros.h",
             "src/nvim/main.h",
             "src/nvim/map.h",
@@ -1012,7 +997,6 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/match.h",
             "src/nvim/mbyte.h",
             "src/nvim/mbyte_defs.h",
-            "src/nvim/memfile.h",
             "src/nvim/memfile_defs.h",
             "src/nvim/memline.h",
             "src/nvim/memory.h",
@@ -1023,16 +1007,12 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/msgpack_rpc/channel.h",
             "src/nvim/msgpack_rpc/channel_defs.h",
             "src/nvim/msgpack_rpc/helpers.h",
-            "src/nvim/msgpack_rpc/server.h",
             "src/nvim/msgpack_rpc/unpacker.h",
             "src/nvim/normal.h",
-            "src/nvim/nvim/extmark.h",
             "src/nvim/ops.h",
             "src/nvim/option.h",
             "src/nvim/option_defs.h",
             "src/nvim/option_vars.h",
-            "src/nvim/optionstr.h",
-            "src/nvim/os/dl.h",
             "src/nvim/os/fileio.h",
             "src/nvim/os/fs.h",
             "src/nvim/os/input.h",
@@ -1041,9 +1021,6 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/os/pty_conpty_win.h",
             "src/nvim/os/pty_process_unix.h",
             "src/nvim/os/pty_process_win.h",
-            "src/nvim/os/shell.h",
-            "src/nvim/os/time.h",
-            "src/nvim/os/tty.h",
             "src/nvim/path.h",
             "src/nvim/plines.h",
             "src/nvim/popupmenu.h",
@@ -1053,20 +1030,13 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/regexp_defs.h",
             "src/nvim/runtime.h",
             "src/nvim/search.h",
-            "src/nvim/sha256.h",
-            "src/nvim/shada.h",
             "src/nvim/sign.h",
-            "src/nvim/sign_defs.h",
             "src/nvim/spell.h",
             "src/nvim/spell_defs.h",
-            "src/nvim/spellfile.h",
-            "src/nvim/state.h",
             "src/nvim/statusline.h",
             "src/nvim/statusline_defs.h",
             "src/nvim/strings.h",
             "src/nvim/syntax.h",
-            "src/nvim/tag.h",
-            "src/nvim/terminal.h",
             "src/nvim/testing.h",
             "src/nvim/textformat.h",
             "src/nvim/textobject.h",
diff --git a/src/nvim/api/autocmd.c b/src/nvim/api/autocmd.c
index c15095243d..15a76cb8b0 100644
--- a/src/nvim/api/autocmd.c
+++ b/src/nvim/api/autocmd.c
@@ -1,4 +1,5 @@
 #include <assert.h>
+#include <lauxlib.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -6,7 +7,6 @@
 #include <string.h>
 
 #include "klib/kvec.h"
-#include "lauxlib.h"
 #include "nvim/api/autocmd.h"
 #include "nvim/api/keysets.h"
 #include "nvim/api/private/defs.h"
diff --git a/src/nvim/api/autocmd.h b/src/nvim/api/autocmd.h
index 8aefd45793..c2ba59734f 100644
--- a/src/nvim/api/autocmd.h
+++ b/src/nvim/api/autocmd.h
@@ -1,9 +1,9 @@
 #pragma once
 
-#include <stdint.h>
+#include <stdint.h>  // IWYU pragma: keep
 
 #include "nvim/api/keysets.h"
-#include "nvim/api/private/defs.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/autocmd.h.generated.h"
diff --git a/src/nvim/api/buffer.h b/src/nvim/api/buffer.h
index 0f18f5368e..927afe61d0 100644
--- a/src/nvim/api/buffer.h
+++ b/src/nvim/api/buffer.h
@@ -1,9 +1,10 @@
 #pragma once
 
-#include <lauxlib.h>
+#include <lua.h>  // IWYU pragma: keep
+#include <stdint.h>  // IWYU pragma: keep
 
 #include "nvim/api/keysets.h"
-#include "nvim/api/private/defs.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 #include "nvim/buffer_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/api/command.c b/src/nvim/api/command.c
index e1691bb910..5e46797ca4 100644
--- a/src/nvim/api/command.c
+++ b/src/nvim/api/command.c
@@ -1,10 +1,10 @@
 #include <inttypes.h>
+#include <lauxlib.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "klib/kvec.h"
-#include "lauxlib.h"
 #include "nvim/api/command.h"
 #include "nvim/api/keysets.h"
 #include "nvim/api/private/defs.h"
@@ -15,7 +15,6 @@
 #include "nvim/autocmd.h"
 #include "nvim/buffer_defs.h"
 #include "nvim/cmdexpand_defs.h"
-#include "nvim/decoration.h"
 #include "nvim/ex_cmds.h"
 #include "nvim/ex_docmd.h"
 #include "nvim/ex_eval.h"
diff --git a/src/nvim/api/command.h b/src/nvim/api/command.h
index 78af5cbf64..7f8c35f89a 100644
--- a/src/nvim/api/command.h
+++ b/src/nvim/api/command.h
@@ -1,9 +1,9 @@
 #pragma once
 
+#include <stdint.h>  // IWYU pragma: keep
+
 #include "nvim/api/keysets.h"
-#include "nvim/api/private/defs.h"
-#include "nvim/decoration.h"
-#include "nvim/ex_cmds.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/command.h.generated.h"
diff --git a/src/nvim/api/extmark.c b/src/nvim/api/extmark.c
index 5112d2474d..28fcf7dd0f 100644
--- a/src/nvim/api/extmark.c
+++ b/src/nvim/api/extmark.c
@@ -1,10 +1,10 @@
 #include <assert.h>
+#include <lauxlib.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <string.h>
 
 #include "klib/kvec.h"
-#include "lauxlib.h"
 #include "nvim/api/extmark.h"
 #include "nvim/api/keysets.h"
 #include "nvim/api/private/defs.h"
diff --git a/src/nvim/api/extmark.h b/src/nvim/api/extmark.h
index 88f1e9e8ad..d41a9828be 100644
--- a/src/nvim/api/extmark.h
+++ b/src/nvim/api/extmark.h
@@ -1,8 +1,10 @@
 #pragma once
 
+#include <stdint.h>  // IWYU pragma: keep
+
 #include "nvim/api/keysets.h"
-#include "nvim/api/private/defs.h"
-#include "nvim/decoration.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
+#include "nvim/decoration_defs.h"  // IWYU pragma: keep
 #include "nvim/macros.h"
 #include "nvim/map.h"
 #include "nvim/types.h"
diff --git a/src/nvim/api/options.c b/src/nvim/api/options.c
index f1aa69f48b..4cd5359cab 100644
--- a/src/nvim/api/options.c
+++ b/src/nvim/api/options.c
@@ -1,5 +1,4 @@
 #include <assert.h>
-#include <inttypes.h>
 #include <stdbool.h>
 #include <string.h>
 
diff --git a/src/nvim/api/options.h b/src/nvim/api/options.h
index 79aeead205..2a7385eb56 100644
--- a/src/nvim/api/options.h
+++ b/src/nvim/api/options.h
@@ -1,8 +1,10 @@
 #pragma once
 
+#include <stdint.h>  // IWYU pragma: keep
+
 #include "nvim/api/keysets.h"
-#include "nvim/api/private/defs.h"
-#include "nvim/option.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
+#include "nvim/option_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/options.h.generated.h"
diff --git a/src/nvim/api/ui.h b/src/nvim/api/ui.h
index 0101e5d31b..ecfbb2d9f6 100644
--- a/src/nvim/api/ui.h
+++ b/src/nvim/api/ui.h
@@ -1,8 +1,10 @@
 #pragma once
 
-#include <stdint.h>
+#include <stdint.h>  // IWYU pragma: keep
 
-#include "nvim/api/private/defs.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
+#include "nvim/grid_defs.h"  // IWYU pragma: keep
+#include "nvim/highlight_defs.h"  // IWYU pragma: keep
 #include "nvim/map.h"
 #include "nvim/ui.h"
 
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index b4e9af491f..7279cb9b1a 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -1,5 +1,6 @@
 #include <assert.h>
 #include <inttypes.h>
+#include <lauxlib.h>
 #include <limits.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -8,7 +9,6 @@
 #include <string.h>
 
 #include "klib/kvec.h"
-#include "lauxlib.h"
 #include "nvim/api/buffer.h"
 #include "nvim/api/deprecated.h"
 #include "nvim/api/keysets.h"
diff --git a/src/nvim/api/vim.h b/src/nvim/api/vim.h
index 81cb563aaf..eb165f285f 100644
--- a/src/nvim/api/vim.h
+++ b/src/nvim/api/vim.h
@@ -1,7 +1,9 @@
 #pragma once
 
+#include <stdint.h>  // IWYU pragma: keep
+
 #include "nvim/api/keysets.h"
-#include "nvim/api/private/defs.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/vim.h.generated.h"
diff --git a/src/nvim/api/vimscript.h b/src/nvim/api/vimscript.h
index ee056999ed..d782f63aec 100644
--- a/src/nvim/api/vimscript.h
+++ b/src/nvim/api/vimscript.h
@@ -1,7 +1,9 @@
 #pragma once
 
+#include <stdint.h>  // IWYU pragma: keep
+
 #include "nvim/api/keysets.h"
-#include "nvim/api/private/defs.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/vimscript.h.generated.h"
diff --git a/src/nvim/api/win_config.c b/src/nvim/api/win_config.c
index de26c1255c..8b9f73ae87 100644
--- a/src/nvim/api/win_config.c
+++ b/src/nvim/api/win_config.c
@@ -255,8 +255,8 @@ void nvim_win_set_config(Window window, Dict(float_config) *config, Error *err)
   }
 }
 
-Dictionary config_put_bordertext(Dictionary config, FloatConfig *fconfig,
-                                 BorderTextType bordertext_type)
+static Dictionary config_put_bordertext(Dictionary config, FloatConfig *fconfig,
+                                        BorderTextType bordertext_type)
 {
   VirtText vt;
   AlignTextPos align;
diff --git a/src/nvim/api/win_config.h b/src/nvim/api/win_config.h
index f9befa6806..36f0e2bcf7 100644
--- a/src/nvim/api/win_config.h
+++ b/src/nvim/api/win_config.h
@@ -1,8 +1,9 @@
 #pragma once
 
+#include <stdint.h>  // IWYU pragma: keep
+
 #include "nvim/api/keysets.h"
-#include "nvim/api/private/defs.h"
-#include "nvim/buffer_defs.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/win_config.h.generated.h"
diff --git a/src/nvim/api/window.h b/src/nvim/api/window.h
index 1a3da7be75..0255193ac7 100644
--- a/src/nvim/api/window.h
+++ b/src/nvim/api/window.h
@@ -1,7 +1,7 @@
 #pragma once
 
 #include "nvim/api/keysets.h"
-#include "nvim/api/private/defs.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/window.h.generated.h"
diff --git a/src/nvim/base64.h b/src/nvim/base64.h
index 39e04b3565..511aa27d10 100644
--- a/src/nvim/base64.h
+++ b/src/nvim/base64.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include <stddef.h>
+#include <stddef.h>  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "base64.h.generated.h"
diff --git a/src/nvim/buffer_updates.c b/src/nvim/buffer_updates.c
index 39f2e07759..0f5d64cc62 100644
--- a/src/nvim/buffer_updates.c
+++ b/src/nvim/buffer_updates.c
@@ -1,9 +1,9 @@
 #include <inttypes.h>
+#include <lauxlib.h>
 #include <stdbool.h>
 #include <stddef.h>
 
 #include "klib/kvec.h"
-#include "lauxlib.h"
 #include "nvim/api/buffer.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
diff --git a/src/nvim/buffer_updates.h b/src/nvim/buffer_updates.h
index f072434e81..5e40657537 100644
--- a/src/nvim/buffer_updates.h
+++ b/src/nvim/buffer_updates.h
@@ -1,7 +1,10 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"
+#include <stdint.h>  // IWYU pragma: keep
+
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/extmark.h"
+#include "nvim/pos.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "buffer_updates.h.generated.h"
diff --git a/src/nvim/bufwrite.h b/src/nvim/bufwrite.h
index f8b9d93318..41e1911d7c 100644
--- a/src/nvim/bufwrite.h
+++ b/src/nvim/bufwrite.h
@@ -1,7 +1,8 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
+#include "nvim/pos.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "bufwrite.h.generated.h"
diff --git a/src/nvim/change.h b/src/nvim/change.h
index e6a78e966f..34cea981d1 100644
--- a/src/nvim/change.h
+++ b/src/nvim/change.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/pos.h"
 
 // flags for open_line()
diff --git a/src/nvim/channel.c b/src/nvim/channel.c
index b601d50b49..e8fe80a3b6 100644
--- a/src/nvim/channel.c
+++ b/src/nvim/channel.c
@@ -1,11 +1,11 @@
 #include <assert.h>
 #include <inttypes.h>
+#include <lauxlib.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "klib/kvec.h"
-#include "lauxlib.h"
 #include "nvim/api/private/converter.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
diff --git a/src/nvim/cmdhist.h b/src/nvim/cmdhist.h
index 260730f7df..ed616ba801 100644
--- a/src/nvim/cmdhist.h
+++ b/src/nvim/cmdhist.h
@@ -1,9 +1,10 @@
 #pragma once
 
-#include "nvim/cmdexpand_defs.h"
+#include "nvim/cmdexpand_defs.h"  // IWYU pragma: export
 #include "nvim/eval/typval_defs.h"
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: export
 #include "nvim/os/time.h"
+#include "nvim/types.h"
 
 /// Present history tables
 typedef enum {
diff --git a/src/nvim/cursor.h b/src/nvim/cursor.h
index 1baa83d327..bd70ccfe60 100644
--- a/src/nvim/cursor.h
+++ b/src/nvim/cursor.h
@@ -1,8 +1,7 @@
 #pragma once
 
-#include <stdbool.h>
-
-#include "nvim/vim.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/pos.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "cursor.h.generated.h"
diff --git a/src/nvim/cursor_shape.c b/src/nvim/cursor_shape.c
index 2e5a28b07b..7fd4151f54 100644
--- a/src/nvim/cursor_shape.c
+++ b/src/nvim/cursor_shape.c
@@ -13,7 +13,6 @@
 #include "nvim/highlight_group.h"
 #include "nvim/log.h"
 #include "nvim/macros.h"
-#include "nvim/memory.h"
 #include "nvim/option_vars.h"
 #include "nvim/strings.h"
 #include "nvim/ui.h"
diff --git a/src/nvim/cursor_shape.h b/src/nvim/cursor_shape.h
index 1d4e1796f6..4c1d6d4eec 100644
--- a/src/nvim/cursor_shape.h
+++ b/src/nvim/cursor_shape.h
@@ -1,7 +1,7 @@
 #pragma once
 
-#include "nvim/api/private/defs.h"
-#include "nvim/types.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
+#include "nvim/memory_defs.h"  // IWYU pragma: keep
 
 /// struct to store values from 'guicursor' and 'mouseshape'
 /// Indexes in shape_table[]
diff --git a/src/nvim/debugger.h b/src/nvim/debugger.h
index 8b79fcf955..c4caeffd66 100644
--- a/src/nvim/debugger.h
+++ b/src/nvim/debugger.h
@@ -1,8 +1,6 @@
 #pragma once
 
-#include <stdbool.h>
-
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "debugger.h.generated.h"
diff --git a/src/nvim/decoration_provider.c b/src/nvim/decoration_provider.c
index 2c0be2fe8a..852a4c4b10 100644
--- a/src/nvim/decoration_provider.c
+++ b/src/nvim/decoration_provider.c
@@ -1,8 +1,8 @@
 #include <assert.h>
+#include <lauxlib.h>
 #include <string.h>
 
 #include "klib/kvec.h"
-#include "lauxlib.h"
 #include "nvim/api/extmark.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
diff --git a/src/nvim/digraph.h b/src/nvim/digraph.h
index d7662785fe..0a83ccbd3e 100644
--- a/src/nvim/digraph.h
+++ b/src/nvim/digraph.h
@@ -1,6 +1,9 @@
 #pragma once
 
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
+#include "nvim/garray_defs.h"  // IWYU pragma: keep
 #include "nvim/types.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/edit.h b/src/nvim/edit.h
index c50b3bb0fb..33087f718f 100644
--- a/src/nvim/edit.h
+++ b/src/nvim/edit.h
@@ -1,7 +1,8 @@
 #pragma once
 
-#include "nvim/autocmd_defs.h"
-#include "nvim/vim.h"
+#include "nvim/autocmd_defs.h"  // IWYU pragma: keep
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/pos.h"
 
 // Values for in_cinkeys()
 #define KEY_OPEN_FORW   0x101
diff --git a/src/nvim/eval.h b/src/nvim/eval.h
index d4bf52c619..8d2e34b842 100644
--- a/src/nvim/eval.h
+++ b/src/nvim/eval.h
@@ -10,6 +10,7 @@
 #include "nvim/eval/typval_defs.h"
 #include "nvim/event/time.h"
 #include "nvim/ex_cmds_defs.h"
+#include "nvim/globals.h"
 #include "nvim/hashtab.h"
 #include "nvim/macros.h"
 #include "nvim/os/fileio.h"
diff --git a/src/nvim/eval/buffer.h b/src/nvim/eval/buffer.h
index fdd146885a..b0fc0f9208 100644
--- a/src/nvim/eval/buffer.h
+++ b/src/nvim/eval/buffer.h
@@ -1,7 +1,8 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"
-#include "nvim/eval/typval_defs.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
+#include "nvim/types.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "eval/buffer.h.generated.h"
diff --git a/src/nvim/eval/decode.h b/src/nvim/eval/decode.h
index 3000cd3211..b80786bc32 100644
--- a/src/nvim/eval/decode.h
+++ b/src/nvim/eval/decode.h
@@ -1,9 +1,9 @@
 #pragma once
 
-#include <msgpack.h>
-#include <stddef.h>
+#include <msgpack.h>  // IWYU pragma: keep
+#include <stddef.h>  // IWYU pragma: keep
 
-#include "nvim/eval/typval_defs.h"
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/types.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/eval/executor.h b/src/nvim/eval/executor.h
index 58edf7216b..d36ce08542 100644
--- a/src/nvim/eval/executor.h
+++ b/src/nvim/eval/executor.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "nvim/eval/typval_defs.h"
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 
 extern char *e_list_index_out_of_range_nr;
 
diff --git a/src/nvim/eval/gc.h b/src/nvim/eval/gc.h
index ea91952fff..36149ec060 100644
--- a/src/nvim/eval/gc.h
+++ b/src/nvim/eval/gc.h
@@ -6,5 +6,5 @@ extern dict_T *gc_first_dict;
 extern list_T *gc_first_list;
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "eval/gc.h.generated.h"
+# include "eval/gc.h.generated.h"  // IWYU pragma: export
 #endif
diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index a0329221d5..e8ed6e5d32 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -1,11 +1,11 @@
 #include <assert.h>
+#include <lauxlib.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
-#include "lauxlib.h"
 #include "nvim/ascii.h"
 #include "nvim/assert.h"
 #include "nvim/charset.h"
diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index cd1ee94298..13d1290fa2 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -3,11 +3,11 @@
 #include <assert.h>
 #include <ctype.h>
 #include <inttypes.h>
+#include <lauxlib.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
-#include "lauxlib.h"
 #include "nvim/ascii.h"
 #include "nvim/autocmd.h"
 #include "nvim/charset.h"
diff --git a/src/nvim/eval/vars.h b/src/nvim/eval/vars.h
index 124d73825b..646c6f24e3 100644
--- a/src/nvim/eval/vars.h
+++ b/src/nvim/eval/vars.h
@@ -1,7 +1,12 @@
 #pragma once
 
-#include "nvim/ex_cmds_defs.h"
-#include "nvim/option_defs.h"
+#include <stddef.h>  // IWYU pragma: keep
+
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
+#include "nvim/garray_defs.h"  // IWYU pragma: keep
+#include "nvim/hashtab.h"
+#include "nvim/option_defs.h"  // IWYU pragma: keep
+#include "nvim/types.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "eval/vars.h.generated.h"
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 8378c04197..267137cd0a 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -25,7 +25,6 @@
 #include "nvim/change.h"
 #include "nvim/channel.h"
 #include "nvim/charset.h"
-#include "nvim/cmdexpand_defs.h"
 #include "nvim/cmdhist.h"
 #include "nvim/cursor.h"
 #include "nvim/decoration.h"
diff --git a/src/nvim/ex_cmds.h b/src/nvim/ex_cmds.h
index c1cbaffa0b..7b7889e71f 100644
--- a/src/nvim/ex_cmds.h
+++ b/src/nvim/ex_cmds.h
@@ -2,7 +2,7 @@
 
 #include <stdbool.h>
 
-#include "nvim/buffer_defs.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"
diff --git a/src/nvim/ex_cmds2.h b/src/nvim/ex_cmds2.h
index ad5008f310..4f41f2cc41 100644
--- a/src/nvim/ex_cmds2.h
+++ b/src/nvim/ex_cmds2.h
@@ -1,15 +1,16 @@
 #pragma once
 
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 
-//
-// flags for check_changed()
-//
-#define CCGD_AW         1       // do autowrite if buffer was changed
-#define CCGD_MULTWIN    2       // check also when several wins for the buf
-#define CCGD_FORCEIT    4       // ! used
-#define CCGD_ALLBUF     8       // may write all buffers
-#define CCGD_EXCMD      16      // may suggest using !
+/// flags for check_changed()
+enum {
+  CCGD_AW      = 1,   ///< do autowrite if buffer was changed
+  CCGD_MULTWIN = 2,   ///< check also when several wins for the buf
+  CCGD_FORCEIT = 4,   ///< ! used
+  CCGD_ALLBUF  = 8,   ///< may write all buffers
+  CCGD_EXCMD   = 16,  ///< may suggest using !
+};
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "ex_cmds2.h.generated.h"
diff --git a/src/nvim/ex_session.h b/src/nvim/ex_session.h
index 51917ebfb2..275f20e4a8 100644
--- a/src/nvim/ex_session.h
+++ b/src/nvim/ex_session.h
@@ -1,8 +1,8 @@
 #pragma once
 
-#include <stdio.h>
+#include <stdio.h>  // IWYU pragma: keep
 
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "ex_session.h.generated.h"
diff --git a/src/nvim/getchar.c b/src/nvim/getchar.c
index 8fc480009a..6c08987cdd 100644
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -2,6 +2,7 @@
 // file, manipulations with redo buffer and stuff buffer.
 
 #include <assert.h>
+#include <lauxlib.h>
 #include <limits.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -10,7 +11,6 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "lauxlib.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
 #include "nvim/ascii.h"
diff --git a/src/nvim/grid.h b/src/nvim/grid.h
index b2766c27bd..0a0fe68cde 100644
--- a/src/nvim/grid.h
+++ b/src/nvim/grid.h
@@ -1,14 +1,13 @@
 #pragma once
 
 #include <stdbool.h>
+#include <stddef.h>  // IWYU pragma: keep
 #include <string.h>
 
-#include "nvim/ascii.h"
 #include "nvim/buffer_defs.h"
 #include "nvim/grid_defs.h"  // IWYU pragma: export
 #include "nvim/macros.h"
 #include "nvim/mbyte.h"
-#include "nvim/memory.h"
 #include "nvim/pos.h"
 
 /// By default, all windows are drawn on a single rectangular grid, represented by
diff --git a/src/nvim/help.h b/src/nvim/help.h
index 7e65e9e133..f60f14c748 100644
--- a/src/nvim/help.h
+++ b/src/nvim/help.h
@@ -1,8 +1,6 @@
 #pragma once
 
-#include <stdbool.h>
-
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "help.h.generated.h"
diff --git a/src/nvim/highlight.c b/src/nvim/highlight.c
index cff62e736b..dcd6e0e8ad 100644
--- a/src/nvim/highlight.c
+++ b/src/nvim/highlight.c
@@ -2,9 +2,9 @@
 
 #include <assert.h>
 #include <inttypes.h>
+#include <lauxlib.h>
 #include <string.h>
 
-#include "lauxlib.h"
 #include "nvim/api/keysets.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/dispatch.h"
diff --git a/src/nvim/highlight_group.h b/src/nvim/highlight_group.h
index f40a741003..857121b5ca 100644
--- a/src/nvim/highlight_group.h
+++ b/src/nvim/highlight_group.h
@@ -1,8 +1,9 @@
 #pragma once
 
 #include "nvim/api/keysets.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 #include "nvim/api/private/helpers.h"
-#include "nvim/cmdexpand_defs.h"
+#include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/highlight_defs.h"
 #include "nvim/types.h"
 
diff --git a/src/nvim/iconv.h b/src/nvim/iconv.h
index 02470c4207..b6456b94ba 100644
--- a/src/nvim/iconv.h
+++ b/src/nvim/iconv.h
@@ -3,8 +3,6 @@
 #include <errno.h>
 #include <iconv.h>
 
-#include "auto/config.h"
-
 // define some missing constants if necessary
 #ifndef EILSEQ
 # define EILSEQ 123
diff --git a/src/nvim/indent.h b/src/nvim/indent.h
index 0da2fbea47..c35338637f 100644
--- a/src/nvim/indent.h
+++ b/src/nvim/indent.h
@@ -1,6 +1,9 @@
 #pragma once
 
-#include "nvim/vim.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
+#include "nvim/pos.h"
+#include "nvim/types.h"
 
 typedef int (*IndentGetter)(void);
 
diff --git a/src/nvim/indent_c.h b/src/nvim/indent_c.h
index 140faaa33d..aa82bde4dc 100644
--- a/src/nvim/indent_c.h
+++ b/src/nvim/indent_c.h
@@ -1,6 +1,7 @@
 #pragma once
 
-#include "nvim/vim.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/pos.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "indent_c.h.generated.h"
diff --git a/src/nvim/input.h b/src/nvim/input.h
index fbb8dec265..3d948fa4ca 100644
--- a/src/nvim/input.h
+++ b/src/nvim/input.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "nvim/vim.h"
+#include "nvim/event/multiqueue.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "input.h.generated.h"
diff --git a/src/nvim/insexpand.h b/src/nvim/insexpand.h
index 9098c50499..164aa5edce 100644
--- a/src/nvim/insexpand.h
+++ b/src/nvim/insexpand.h
@@ -1,9 +1,9 @@
 #pragma once
 
-#include <stdbool.h>
-
 #include "nvim/macros.h"
-#include "nvim/option_defs.h"
+#include "nvim/option_defs.h"  // IWYU pragma: keep
+#include "nvim/pos.h"
+#include "nvim/types.h"
 #include "nvim/vim.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/linematch.h b/src/nvim/linematch.h
index a2c72d26e7..2d765b0b70 100644
--- a/src/nvim/linematch.h
+++ b/src/nvim/linematch.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include <stddef.h>
+#include <stddef.h>  // IWYU pragma: keep
 
 #include "nvim/pos.h"
 
diff --git a/src/nvim/lua/base64.h b/src/nvim/lua/base64.h
index feb409ef38..3c95968cda 100644
--- a/src/nvim/lua/base64.h
+++ b/src/nvim/lua/base64.h
@@ -1,8 +1,6 @@
 #pragma once
 
-#include <lauxlib.h>
-#include <lua.h>
-#include <lualib.h>
+#include <lua.h>  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "lua/base64.h.generated.h"
diff --git a/src/nvim/lua/secure.h b/src/nvim/lua/secure.h
index b363a243a5..c69c0d4f8f 100644
--- a/src/nvim/lua/secure.h
+++ b/src/nvim/lua/secure.h
@@ -1,8 +1,6 @@
 #pragma once
 
-#include <lua.h>
-
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "lua/secure.h.generated.h"
diff --git a/src/nvim/lua/spell.h b/src/nvim/lua/spell.h
index adf3e9dd60..6f1b322e5b 100644
--- a/src/nvim/lua/spell.h
+++ b/src/nvim/lua/spell.h
@@ -1,8 +1,6 @@
 #pragma once
 
-#include <lauxlib.h>
-#include <lua.h>
-#include <lualib.h>
+#include <lua.h>  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "lua/spell.h.generated.h"
diff --git a/src/nvim/lua/stdlib.h b/src/nvim/lua/stdlib.h
index b2be54af90..26e96055ae 100644
--- a/src/nvim/lua/stdlib.h
+++ b/src/nvim/lua/stdlib.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include <lua.h>
+#include <lua.h>  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "lua/stdlib.h.generated.h"
diff --git a/src/nvim/lua/treesitter.c b/src/nvim/lua/treesitter.c
index ff942630a0..e5de369ed9 100644
--- a/src/nvim/lua/treesitter.c
+++ b/src/nvim/lua/treesitter.c
@@ -12,6 +12,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <tree_sitter/api.h>
 #include <uv.h>
 
 #include "klib/kvec.h"
@@ -26,7 +27,6 @@
 #include "nvim/pos.h"
 #include "nvim/strings.h"
 #include "nvim/types.h"
-#include "tree_sitter/api.h"
 
 #define TS_META_PARSER "treesitter_parser"
 #define TS_META_TREE "treesitter_tree"
diff --git a/src/nvim/lua/treesitter.h b/src/nvim/lua/treesitter.h
index c1c78b8a6a..4ef9a10602 100644
--- a/src/nvim/lua/treesitter.h
+++ b/src/nvim/lua/treesitter.h
@@ -1,10 +1,6 @@
 #pragma once
 
-#include <lauxlib.h>
-#include <lua.h>
-#include <lualib.h>
-
-#include "tree_sitter/api.h"
+#include <lua.h>  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "lua/treesitter.h.generated.h"
diff --git a/src/nvim/lua/xdiff.h b/src/nvim/lua/xdiff.h
index 9cb5cabbfb..2ea74a79e8 100644
--- a/src/nvim/lua/xdiff.h
+++ b/src/nvim/lua/xdiff.h
@@ -1,8 +1,6 @@
 #pragma once
 
-#include <lauxlib.h>
-#include <lua.h>
-#include <lualib.h>
+#include <lua.h>  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "lua/xdiff.h.generated.h"
diff --git a/src/nvim/match.h b/src/nvim/match.h
index 3e5ab04ddf..a4b0dc19b7 100644
--- a/src/nvim/match.h
+++ b/src/nvim/match.h
@@ -1,7 +1,9 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
+#include "nvim/types.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "match.h.generated.h"
diff --git a/src/nvim/memfile.h b/src/nvim/memfile.h
index 753806b3c3..2d1930e95c 100644
--- a/src/nvim/memfile.h
+++ b/src/nvim/memfile.h
@@ -4,10 +4,12 @@
 #include "nvim/memfile_defs.h"  // IWYU pragma: export
 
 /// flags for mf_sync()
-#define MFS_ALL         1       /// also sync blocks with negative numbers
-#define MFS_STOP        2       /// stop syncing when a character is available
-#define MFS_FLUSH       4       /// flushed file to disk
-#define MFS_ZERO        8       /// only write block 0
+enum {
+  MFS_ALL   = 1,  ///< also sync blocks with negative numbers
+  MFS_STOP  = 2,  ///< stop syncing when a character is available
+  MFS_FLUSH = 4,  ///< flushed file to disk
+  MFS_ZERO  = 8,  ///< only write block 0
+};
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "memfile.h.generated.h"
diff --git a/src/nvim/memory.c b/src/nvim/memory.c
index 732c9ca39d..eee8e25086 100644
--- a/src/nvim/memory.c
+++ b/src/nvim/memory.c
@@ -577,7 +577,9 @@ void alloc_block(Arena *arena)
 
 static size_t arena_align_offset(uint64_t off)
 {
+#define ARENA_ALIGN MAX(sizeof(void *), sizeof(double))
   return ((off + (ARENA_ALIGN - 1)) & ~(ARENA_ALIGN - 1));
+#undef ARENA_ALIGN
 }
 
 /// @param arena if NULL, do a global allocation. caller must then free the value!
diff --git a/src/nvim/memory.h b/src/nvim/memory.h
index 100d991656..18bcf11111 100644
--- a/src/nvim/memory.h
+++ b/src/nvim/memory.h
@@ -6,6 +6,7 @@
 #include <time.h>
 
 #include "nvim/macros.h"
+#include "nvim/memory_defs.h"  // IWYU pragma: export
 
 /// `malloc()` function signature
 typedef void *(*MemMalloc)(size_t);
@@ -40,20 +41,6 @@ extern bool entered_free_all_mem;
 
 EXTERN size_t arena_alloc_count INIT( = 0);
 
-typedef struct consumed_blk {
-  struct consumed_blk *prev;
-} *ArenaMem;
-
-#define ARENA_ALIGN MAX(sizeof(void *), sizeof(double))
-
-typedef struct {
-  char *cur_blk;
-  size_t pos, size;
-} Arena;
-
-// inits an empty arena.
-#define ARENA_EMPTY { .cur_blk = NULL, .pos = 0, .size = 0 }
-
 #define kv_fixsize_arena(a, v, s) \
   ((v).capacity = (s), \
    (v).items = (void *)arena_alloc(a, sizeof((v).items[0]) * (v).capacity, true))
diff --git a/src/nvim/memory_defs.h b/src/nvim/memory_defs.h
new file mode 100644
index 0000000000..bde0e54f54
--- /dev/null
+++ b/src/nvim/memory_defs.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#include <stddef.h>
+
+typedef struct consumed_blk {
+  struct consumed_blk *prev;
+} *ArenaMem;
+
+typedef struct {
+  char *cur_blk;
+  size_t pos, size;
+} Arena;
+
+// inits an empty arena.
+#define ARENA_EMPTY { .cur_blk = NULL, .pos = 0, .size = 0 }
diff --git a/src/nvim/move.h b/src/nvim/move.h
index 846a316309..575da2f41e 100644
--- a/src/nvim/move.h
+++ b/src/nvim/move.h
@@ -2,6 +2,9 @@
 
 #include <stdbool.h>
 
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
+#include "nvim/types.h"
 #include "nvim/vim.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/msgpack_rpc/channel.h b/src/nvim/msgpack_rpc/channel.h
index ac189c98dc..e8ea71173a 100644
--- a/src/nvim/msgpack_rpc/channel.h
+++ b/src/nvim/msgpack_rpc/channel.h
@@ -1,16 +1,16 @@
 #pragma once
 
-#include <stdbool.h>
-#include <uv.h>
+#include <stdint.h>  // IWYU pragma: keep
 
-#include "nvim/api/private/defs.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 #include "nvim/channel.h"
 #include "nvim/event/multiqueue.h"
 #include "nvim/event/process.h"
 #include "nvim/event/socket.h"
+#include "nvim/event/wstream.h"
 #include "nvim/macros.h"
+#include "nvim/memory_defs.h"  // IWYU pragma: keep
 #include "nvim/msgpack_rpc/channel_defs.h"  // IWYU pragma: export
-#include "nvim/vim.h"
 
 #define METHOD_MAXLEN 512
 
diff --git a/src/nvim/msgpack_rpc/channel_defs.h b/src/nvim/msgpack_rpc/channel_defs.h
index 0bbffb8beb..1e3f8a72c1 100644
--- a/src/nvim/msgpack_rpc/channel_defs.h
+++ b/src/nvim/msgpack_rpc/channel_defs.h
@@ -4,10 +4,12 @@
 #include <stdbool.h>
 #include <uv.h>
 
+#include "klib/kvec.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/dispatch.h"
 #include "nvim/event/process.h"
 #include "nvim/event/socket.h"
+#include "nvim/map.h"
 #include "nvim/vim.h"
 
 typedef struct Channel Channel;
diff --git a/src/nvim/msgpack_rpc/server.h b/src/nvim/msgpack_rpc/server.h
index c6a240cd55..71b578a14b 100644
--- a/src/nvim/msgpack_rpc/server.h
+++ b/src/nvim/msgpack_rpc/server.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include <stdio.h>
+#include <stddef.h>  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "msgpack_rpc/server.h.generated.h"
diff --git a/src/nvim/msgpack_rpc/unpacker.h b/src/nvim/msgpack_rpc/unpacker.h
index 72e1b04511..0317255df3 100644
--- a/src/nvim/msgpack_rpc/unpacker.h
+++ b/src/nvim/msgpack_rpc/unpacker.h
@@ -10,7 +10,7 @@
 #include "nvim/api/private/dispatch.h"
 #include "nvim/api/private/helpers.h"
 #include "nvim/grid_defs.h"
-#include "nvim/memory.h"
+#include "nvim/memory_defs.h"
 #include "nvim/msgpack_rpc/channel_defs.h"
 #include "nvim/types.h"
 #include "nvim/ui_client.h"
diff --git a/src/nvim/ops.h b/src/nvim/ops.h
index dfd3946432..7c8e7b4640 100644
--- a/src/nvim/ops.h
+++ b/src/nvim/ops.h
@@ -1,9 +1,9 @@
 #pragma once
 
+#include <lauxlib.h>
 #include <stdbool.h>
 #include <stddef.h>
 
-#include "lauxlib.h"
 #include "nvim/ascii.h"
 #include "nvim/eval/typval_defs.h"
 #include "nvim/ex_cmds_defs.h"
diff --git a/src/nvim/option.h b/src/nvim/option.h
index a36c57eab0..a7d02cc1cd 100644
--- a/src/nvim/option.h
+++ b/src/nvim/option.h
@@ -2,12 +2,14 @@
 
 #include <stdint.h>
 
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 #include "nvim/api/private/helpers.h"
 #include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/option_defs.h"  // IWYU pragma: export
 #include "nvim/search.h"
+#include "nvim/types.h"
 
 /// The options that are local to a window or buffer have "indir" set to one of
 /// these values.  Special values:
@@ -94,13 +96,6 @@ enum {
   SOPT_BUF    = 0x20,  ///< Option has buffer-local value
 };
 
-/// Requested option scopes for various functions in option.c
-typedef enum {
-  kOptReqGlobal = 0,  ///< Request global option value
-  kOptReqWin    = 1,  ///< Request window-local option value
-  kOptReqBuf    = 2,  ///< Request buffer-local option value
-} OptReqScope;
-
 // OptVal helper macros.
 #define NIL_OPTVAL ((OptVal) { .type = kOptValTypeNil })
 #define BOOLEAN_OPTVAL(b) ((OptVal) { .type = kOptValTypeBoolean, .data.boolean = b })
diff --git a/src/nvim/option_defs.h b/src/nvim/option_defs.h
index 4ea543e79e..19fab293aa 100644
--- a/src/nvim/option_defs.h
+++ b/src/nvim/option_defs.h
@@ -114,3 +114,10 @@ typedef struct {
 /// Note: If returned FAIL or *numMatches is 0, *matches will NOT be freed by
 /// caller.
 typedef int (*opt_expand_cb_T)(optexpand_T *args, int *numMatches, char ***matches);
+
+/// Requested option scopes for various functions in option.c
+typedef enum {
+  kOptReqGlobal = 0,  ///< Request global option value
+  kOptReqWin    = 1,  ///< Request window-local option value
+  kOptReqBuf    = 2,  ///< Request buffer-local option value
+} OptReqScope;
diff --git a/src/nvim/optionstr.h b/src/nvim/optionstr.h
index 03d6f840b4..b317e55b7e 100644
--- a/src/nvim/optionstr.h
+++ b/src/nvim/optionstr.h
@@ -1,8 +1,10 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"
-#include "nvim/cmdexpand_defs.h"
-#include "nvim/option_defs.h"
+#include <stdint.h>  // IWYU pragma: keep
+
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
+#include "nvim/option_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "optionstr.h.generated.h"
diff --git a/src/nvim/os/dl.h b/src/nvim/os/dl.h
index 9c41a28f69..0787c7fe46 100644
--- a/src/nvim/os/dl.h
+++ b/src/nvim/os/dl.h
@@ -1,8 +1,5 @@
 #pragma once
 
-#include <stdbool.h>
-#include <stdint.h>
-
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "os/dl.h.generated.h"
 #endif
diff --git a/src/nvim/os/fs.h b/src/nvim/os/fs.h
index aacb1c2f48..3e910be801 100644
--- a/src/nvim/os/fs.h
+++ b/src/nvim/os/fs.h
@@ -1,5 +1,10 @@
 #pragma once
 
+#include <stddef.h>  // IWYU pragma: keep
+#include <stdint.h>  // IWYU pragma: keep
+#include <stdio.h>  // IWYU pragma: keep
+#include <uv.h>  // IWYU pragma: keep
+
 #include "nvim/os/fs_defs.h"  // IWYU pragma: export
 #include "nvim/types.h"
 
diff --git a/src/nvim/os/input.h b/src/nvim/os/input.h
index 113dbbb8d5..b077f80860 100644
--- a/src/nvim/os/input.h
+++ b/src/nvim/os/input.h
@@ -1,9 +1,9 @@
 #pragma once
 
 #include <stdbool.h>
-#include <stdint.h>
+#include <stdint.h>  // IWYU pragma: keep
 
-#include "nvim/api/private/defs.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 #include "nvim/event/multiqueue.h"
 #include "nvim/macros.h"
 
diff --git a/src/nvim/os/shell.h b/src/nvim/os/shell.h
index 498c72e63d..82c83543af 100644
--- a/src/nvim/os/shell.h
+++ b/src/nvim/os/shell.h
@@ -1,8 +1,6 @@
 #pragma once
 
-#include <stdio.h>
-
-#include "nvim/types.h"
+#include <stddef.h>  // IWYU pragma: keep
 
 // Flags for os_call_shell() second argument
 typedef enum {
diff --git a/src/nvim/os/time.h b/src/nvim/os/time.h
index 8f8b5511bd..fa9989c757 100644
--- a/src/nvim/os/time.h
+++ b/src/nvim/os/time.h
@@ -1,8 +1,8 @@
 #pragma once
 
-#include <stdbool.h>
+#include <stddef.h>  // IWYU pragma: keep
 #include <stdint.h>
-#include <time.h>
+#include <time.h>  // IWYU pragma: keep
 
 typedef uint64_t Timestamp;
 
diff --git a/src/nvim/os/tty.h b/src/nvim/os/tty.h
index 3a78573189..a24d875c05 100644
--- a/src/nvim/os/tty.h
+++ b/src/nvim/os/tty.h
@@ -1,5 +1,5 @@
 #pragma once
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "os/tty.h.generated.h"
+# include "os/tty.h.generated.h"  // IWYU pragma: export
 #endif
diff --git a/src/nvim/path.h b/src/nvim/path.h
index 66dbb53fb6..0116e2ac97 100644
--- a/src/nvim/path.h
+++ b/src/nvim/path.h
@@ -1,7 +1,9 @@
 #pragma once
 
+#include <stddef.h>  // IWYU pragma: keep
+
 #include "nvim/func_attr.h"
-#include "nvim/garray_defs.h"
+#include "nvim/garray_defs.h"  // IWYU pragma: keep
 #include "nvim/types.h"
 
 // Flags for expand_wildcards()
diff --git a/src/nvim/popupmenu.h b/src/nvim/popupmenu.h
index 737e3b2f68..8f2b665174 100644
--- a/src/nvim/popupmenu.h
+++ b/src/nvim/popupmenu.h
@@ -2,10 +2,10 @@
 
 #include <stdbool.h>
 
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/grid_defs.h"
 #include "nvim/macros.h"
-#include "nvim/types.h"
-#include "nvim/vim.h"
+#include "nvim/menu_defs.h"  // IWYU pragma: keep
 
 /// Used for popup menu items.
 typedef struct {
diff --git a/src/nvim/profile.h b/src/nvim/profile.h
index 117e15d4bc..839c435b3e 100644
--- a/src/nvim/profile.h
+++ b/src/nvim/profile.h
@@ -1,10 +1,10 @@
 #pragma once
 
-#include <stdint.h>
+#include <stdint.h>  // IWYU pragma: keep
 #include <time.h>
 
-#include "nvim/cmdexpand_defs.h"
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/runtime.h"
 
 #define TIME_MSG(s) do { \
diff --git a/src/nvim/quickfix.h b/src/nvim/quickfix.h
index e406679dcb..ecbde31512 100644
--- a/src/nvim/quickfix.h
+++ b/src/nvim/quickfix.h
@@ -1,7 +1,9 @@
 #pragma once
 
-#include "nvim/ex_cmds_defs.h"
-#include "nvim/option_defs.h"
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
+#include "nvim/option_defs.h"  // IWYU pragma: keep
+#include "nvim/pos.h"
 #include "nvim/types.h"
 
 // flags for skip_vimgrep_pat()
diff --git a/src/nvim/regexp.h b/src/nvim/regexp.h
index 1f0e59aa89..3a490aec55 100644
--- a/src/nvim/regexp.h
+++ b/src/nvim/regexp.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/pos.h"
 #include "nvim/regexp_defs.h"  // IWYU pragma: export
 #include "nvim/types.h"
 
diff --git a/src/nvim/sha256.h b/src/nvim/sha256.h
index d0e6fb2a4e..942836a411 100644
--- a/src/nvim/sha256.h
+++ b/src/nvim/sha256.h
@@ -1,10 +1,8 @@
 #pragma once
 
-#include <stddef.h>
+#include <stddef.h>  // IWYU pragma: keep
 #include <stdint.h>
 
-#include "nvim/types.h"
-
 #define SHA256_BUFFER_SIZE 64
 #define SHA256_SUM_SIZE    32
 
diff --git a/src/nvim/shada.h b/src/nvim/shada.h
index 234006bde4..d7cac24afc 100644
--- a/src/nvim/shada.h
+++ b/src/nvim/shada.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include <msgpack.h>
+#include <msgpack.h>  // IWYU pragma: keep
 
 /// Flags for shada_read_file and children
 typedef enum {
diff --git a/src/nvim/sign.h b/src/nvim/sign.h
index febde551f6..890c8fdfba 100644
--- a/src/nvim/sign.h
+++ b/src/nvim/sign.h
@@ -1,11 +1,10 @@
 #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/sign_defs.h"  // IWYU pragma: export
+#include "nvim/types.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "sign.h.generated.h"
diff --git a/src/nvim/sign_defs.h b/src/nvim/sign_defs.h
index 6b8deca02f..79d21585fc 100644
--- a/src/nvim/sign_defs.h
+++ b/src/nvim/sign_defs.h
@@ -1,10 +1,5 @@
 #pragma once
 
-#include <stdbool.h>
-
-#include "nvim/pos.h"
-#include "nvim/types.h"
-
 /// Sign attributes. Used by the screen refresh routines.
 typedef struct {
   char *text;
@@ -22,6 +17,6 @@ typedef struct sign {
   int sn_num_hl;   // highlight ID for line number
 } sign_T;
 
-#define SIGN_WIDTH 2      // Number of display cells for a sign in the signcolumn
-#define SIGN_SHOW_MAX 9   // Maximum number of signs shown on a single line
-#define SIGN_DEF_PRIO 10  // Default sign highlight priority
+enum { SIGN_WIDTH = 2, };  ///< Number of display cells for a sign in the signcolumn
+enum { SIGN_SHOW_MAX = 9, };  ///< Maximum number of signs shown on a single line
+enum { SIGN_DEF_PRIO = 10, };  ///< Default sign highlight priority
diff --git a/src/nvim/spell.h b/src/nvim/spell.h
index 839c76e6e7..17e7dd6c40 100644
--- a/src/nvim/spell.h
+++ b/src/nvim/spell.h
@@ -7,6 +7,21 @@
 #include "nvim/spell_defs.h"  // IWYU pragma: export
 #include "nvim/vim.h"
 
+/// First language that is loaded, start of the linked list of loaded languages.
+extern slang_T *first_lang;
+
+/// file used for "zG" and "zW"
+extern char *int_wordlist;
+
+extern spelltab_T spelltab;
+extern int did_set_spelltab;
+
+extern char *e_format;
+
+// Remember what "z?" replaced.
+extern char *repl_from;
+extern char *repl_to;
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "spell.h.generated.h"
 #endif
diff --git a/src/nvim/spell_defs.h b/src/nvim/spell_defs.h
index 234ecd5804..bb5ebb8ec4 100644
--- a/src/nvim/spell_defs.h
+++ b/src/nvim/spell_defs.h
@@ -5,8 +5,8 @@
 
 #include "nvim/buffer_defs.h"
 #include "nvim/garray_defs.h"
+#include "nvim/hashtab.h"
 #include "nvim/regexp_defs.h"
-#include "nvim/types.h"
 
 #define MAXWLEN 254             // Assume max. word len is this many bytes.
                                 // Some places assume a word length fits in a
@@ -221,18 +221,6 @@ typedef struct {
 
 #define SPELL_ISUPPER(c) ((c) >= 128 ? mb_isupper(c) : spelltab.st_isu[c])
 
-// First language that is loaded, start of the linked list of loaded
-// languages.
-extern slang_T *first_lang;
-
-// file used for "zG" and "zW"
-extern char *int_wordlist;
-
-extern spelltab_T spelltab;
-extern int did_set_spelltab;
-
-extern char *e_format;
-
 // Values for "what" argument of spell_add_word()
 typedef enum {
   SPELL_ADD_GOOD = 0,
@@ -248,7 +236,3 @@ typedef struct wordcount_S {
 #define WC_KEY_OFF   offsetof(wordcount_T, wc_word)
 #define HI2WC(hi)    ((wordcount_T *)((hi)->hi_key - WC_KEY_OFF))
 #define MAXWORDCOUNT 0xffff
-
-// Remember what "z?" replaced.
-extern char *repl_from;
-extern char *repl_to;
diff --git a/src/nvim/spellfile.h b/src/nvim/spellfile.h
index ba5f193f33..3e68ddd5a4 100644
--- a/src/nvim/spellfile.h
+++ b/src/nvim/spellfile.h
@@ -1,10 +1,7 @@
 #pragma once
 
-#include <stdbool.h>
-
-#include "nvim/ex_cmds_defs.h"
-#include "nvim/spell_defs.h"
-#include "nvim/types.h"
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
+#include "nvim/spell_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "spellfile.h.generated.h"
diff --git a/src/nvim/state.c b/src/nvim/state.c
index 1c00a00d8c..dfe1af7ab3 100644
--- a/src/nvim/state.c
+++ b/src/nvim/state.c
@@ -1,5 +1,4 @@
 #include <stdbool.h>
-#include <stddef.h>
 #include <string.h>
 
 #include "nvim/ascii.h"
diff --git a/src/nvim/state.h b/src/nvim/state.h
index 326beaa9d9..6617b77fa0 100644
--- a/src/nvim/state.h
+++ b/src/nvim/state.h
@@ -1,9 +1,5 @@
 #pragma once
 
-#include <stddef.h>
-
-struct vim_state;
-
 typedef struct vim_state VimState;
 
 typedef int (*state_check_callback)(VimState *state);
diff --git a/src/nvim/statusline_defs.h b/src/nvim/statusline_defs.h
index f502f33c49..e0beff9528 100644
--- a/src/nvim/statusline_defs.h
+++ b/src/nvim/statusline_defs.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <stdbool.h>
 #include <stddef.h>
 
 #include "nvim/fold_defs.h"
diff --git a/src/nvim/tag.h b/src/nvim/tag.h
index c5178503f1..f628d23fbe 100644
--- a/src/nvim/tag.h
+++ b/src/nvim/tag.h
@@ -1,39 +1,42 @@
 #pragma once
 
-#include "nvim/ex_cmds_defs.h"
-#include "nvim/option_defs.h"
-#include "nvim/types.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
+#include "nvim/option_defs.h"  // IWYU pragma: keep
 
-// Values for do_tag().
-#define DT_TAG          1       // jump to newer position or same tag again
-#define DT_POP          2       // jump to older position
-#define DT_NEXT         3       // jump to next match of same tag
-#define DT_PREV         4       // jump to previous match of same tag
-#define DT_FIRST        5       // jump to first match of same tag
-#define DT_LAST         6       // jump to first match of same tag
-#define DT_SELECT       7       // jump to selection from list
-#define DT_HELP         8       // like DT_TAG, but no wildcards
-#define DT_JUMP         9       // jump to new tag or selection from list
-#define DT_LTAG         11      // tag using location list
-#define DT_FREE         99      // free cached matches
+/// Values for do_tag().
+enum {
+  DT_TAG    = 1,   ///< jump to newer position or same tag again
+  DT_POP    = 2,   ///< jump to older position
+  DT_NEXT   = 3,   ///< jump to next match of same tag
+  DT_PREV   = 4,   ///< jump to previous match of same tag
+  DT_FIRST  = 5,   ///< jump to first match of same tag
+  DT_LAST   = 6,   ///< jump to first match of same tag
+  DT_SELECT = 7,   ///< jump to selection from list
+  DT_HELP   = 8,   ///< like DT_TAG, but no wildcards
+  DT_JUMP   = 9,   ///< jump to new tag or selection from list
+  DT_LTAG   = 11,  ///< tag using location list
+  DT_FREE   = 99,  ///< free cached matches
+};
 
-// flags for find_tags().
-#define TAG_HELP        1       // only search for help tags
-#define TAG_NAMES       2       // only return name of tag
-#define TAG_REGEXP      4       // use tag pattern as regexp
-#define TAG_NOIC        8       // don't always ignore case
-#define TAG_VERBOSE     32      // message verbosity
-#define TAG_INS_COMP    64      // Currently doing insert completion
-#define TAG_KEEP_LANG   128     // keep current language
-#define TAG_NO_TAGFUNC  256     // do not use 'tagfunc'
+/// flags for find_tags().
+enum {
+  TAG_HELP       = 1,    ///< only search for help tags
+  TAG_NAMES      = 2,    ///< only return name of tag
+  TAG_REGEXP     = 4,    ///< use tag pattern as regexp
+  TAG_NOIC       = 8,    ///< don't always ignore case
+  TAG_VERBOSE    = 32,   ///< message verbosity
+  TAG_INS_COMP   = 64,   ///< Currently doing insert completion
+  TAG_KEEP_LANG  = 128,  ///< keep current language
+  TAG_NO_TAGFUNC = 256,  ///< do not use 'tagfunc'
+  TAG_MANY       = 300,  ///< When finding many tags (for completion), find up to this many tags
+};
 
-#define TAG_MANY        300     // When finding many tags (for completion),
-                                // find up to this many tags
-
-// Structure used for get_tagfname().
+/// Structure used for get_tagfname().
 typedef struct {
-  char *tn_tags;           // value of 'tags' when starting
-  char *tn_np;             // current position in tn_tags
+  char *tn_tags;           ///< value of 'tags' when starting
+  char *tn_np;             ///< current position in tn_tags
   int tn_did_filefind_init;
   int tn_hf_idx;
   void *tn_search_ctx;
diff --git a/src/nvim/terminal.h b/src/nvim/terminal.h
index 0704423f1f..66cad7ee7a 100644
--- a/src/nvim/terminal.h
+++ b/src/nvim/terminal.h
@@ -1,6 +1,5 @@
 #pragma once
 
-#include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ -9,7 +8,7 @@ typedef void (*terminal_write_cb)(char *buffer, size_t size, void *data);
 typedef void (*terminal_resize_cb)(uint16_t width, uint16_t height, void *data);
 typedef void (*terminal_close_cb)(void *data);
 
-#include "nvim/buffer_defs.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 
 typedef struct {
   void *data;  // PTY process channel
diff --git a/src/nvim/testing.h b/src/nvim/testing.h
index 64e74bc46a..563ce21302 100644
--- a/src/nvim/testing.h
+++ b/src/nvim/testing.h
@@ -1,6 +1,7 @@
 #pragma once
 
-#include "nvim/eval/typval_defs.h"
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
+#include "nvim/types.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "testing.h.generated.h"
diff --git a/src/nvim/tui/tui.c b/src/nvim/tui/tui.c
index 4bbdea8def..0272c974d5 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -1051,7 +1051,7 @@ void tui_grid_cursor_goto(TUIData *tui, Integer grid, Integer row, Integer col)
   tui->col = (int)col;
 }
 
-CursorShape tui_cursor_decode_shape(const char *shape_str)
+static CursorShape tui_cursor_decode_shape(const char *shape_str)
 {
   CursorShape shape;
   if (strequal(shape_str, "block")) {
@@ -1144,7 +1144,7 @@ void tui_mouse_off(TUIData *tui)
   }
 }
 
-void tui_set_mode(TUIData *tui, ModeShape mode)
+static void tui_set_mode(TUIData *tui, ModeShape mode)
 {
   if (!cursor_style_enabled) {
     return;
diff --git a/src/nvim/tui/tui.h b/src/nvim/tui/tui.h
index 1cd283cf49..76a5ef9a6b 100644
--- a/src/nvim/tui/tui.h
+++ b/src/nvim/tui/tui.h
@@ -1,6 +1,8 @@
 #pragma once
 
-#include "nvim/cursor_shape.h"
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
+#include "nvim/grid_defs.h"  // IWYU pragma: keep
+#include "nvim/highlight_defs.h"  // IWYU pragma: keep
 #include "nvim/ui.h"
 
 typedef struct TUIData TUIData;
diff --git a/src/nvim/ui_compositor.h b/src/nvim/ui_compositor.h
index 7b177838e4..951160deaf 100644
--- a/src/nvim/ui_compositor.h
+++ b/src/nvim/ui_compositor.h
@@ -1,6 +1,8 @@
 #pragma once
 
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 #include "nvim/event/defs.h"
+#include "nvim/grid_defs.h"  // IWYU pragma: keep
 #include "nvim/ui.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/undo.h b/src/nvim/undo.h
index b2d7bef843..8282bd8d6e 100644
--- a/src/nvim/undo.h
+++ b/src/nvim/undo.h
@@ -2,6 +2,8 @@
 
 #include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
+#include "nvim/pos.h"
+#include "nvim/types.h"
 #include "nvim/undo_defs.h"  // IWYU pragma: export
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/usercmd.c b/src/nvim/usercmd.c
index 0aec9388c7..69fed19388 100644
--- a/src/nvim/usercmd.c
+++ b/src/nvim/usercmd.c
@@ -2,12 +2,12 @@
 
 #include <assert.h>
 #include <inttypes.h>
+#include <lauxlib.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "auto/config.h"
-#include "lauxlib.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
 #include "nvim/ascii.h"
diff --git a/src/nvim/usercmd.h b/src/nvim/usercmd.h
index b1485ca707..09b5dac958 100644
--- a/src/nvim/usercmd.h
+++ b/src/nvim/usercmd.h
@@ -2,9 +2,9 @@
 
 #include <stdint.h>
 
-#include "nvim/cmdexpand_defs.h"
+#include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/garray_defs.h"
 #include "nvim/types.h"
 
diff --git a/src/nvim/version.h b/src/nvim/version.h
index 0e313bb30c..6e5862501a 100644
--- a/src/nvim/version.h
+++ b/src/nvim/version.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "nvim/ex_cmds_defs.h"
+#include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/macros.h"
 
 // defined in version.c
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 95098ddc11..bed47670cc 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -3,7 +3,6 @@
 #include <inttypes.h>
 #include <limits.h>
 #include <stdbool.h>
-#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/src/nvim/window.h b/src/nvim/window.h
index 734fa71d72..e38fb953ab 100644
--- a/src/nvim/window.h
+++ b/src/nvim/window.h
@@ -1,11 +1,12 @@
 #pragma once
 
 #include <stdbool.h>
-#include <stddef.h>
 
-#include "nvim/buffer_defs.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/garray_defs.h"  // IWYU pragma: keep
 #include "nvim/macros.h"
-#include "nvim/option_defs.h"
+#include "nvim/option_defs.h"  // IWYU pragma: keep
+#include "nvim/types.h"
 
 // Values for file_name_in_line()
 #define FNAME_MESS      1       // give error message