diff --git a/.clang-tidy b/.clang-tidy
index 927909cf8d..6776d86d21 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -46,7 +46,6 @@ Checks: >
   -cppcoreguidelines-init-variables,
   -llvm-header-guard, We use #pragma once,
   -llvmlibc-restrict-system-libc-headers, We want to use glibc,
-  -misc-header-include-cycle, Looks useful but redundant with IWYU. We may replace IWYU with this one day,
   -misc-include-cleaner, Looks useful but redundant with IWYU. We may replace IWYU with this one day,
   -misc-misplaced-const,
   -misc-no-recursion,
diff --git a/src/nvim/api/autocmd.c b/src/nvim/api/autocmd.c
index 2ce08bdf40..88d7d985e8 100644
--- a/src/nvim/api/autocmd.c
+++ b/src/nvim/api/autocmd.c
@@ -20,6 +20,7 @@
 #include "nvim/globals.h"
 #include "nvim/lua/executor.h"
 #include "nvim/memory.h"
+#include "nvim/types_defs.h"
 #include "nvim/vim_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/api/deprecated.c b/src/nvim/api/deprecated.c
index 27af581ef4..f7bbd61cd3 100644
--- a/src/nvim/api/deprecated.c
+++ b/src/nvim/api/deprecated.c
@@ -21,6 +21,7 @@
 #include "nvim/memory.h"
 #include "nvim/option.h"
 #include "nvim/pos_defs.h"
+#include "nvim/types_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/deprecated.c.generated.h"
diff --git a/src/nvim/api/options.c b/src/nvim/api/options.c
index ea617dffaf..fb461152b4 100644
--- a/src/nvim/api/options.c
+++ b/src/nvim/api/options.c
@@ -15,6 +15,7 @@
 #include "nvim/macros_defs.h"
 #include "nvim/memory.h"
 #include "nvim/option.h"
+#include "nvim/types_defs.h"
 #include "nvim/vim_defs.h"
 #include "nvim/window.h"
 
diff --git a/src/nvim/api/vimscript.c b/src/nvim/api/vimscript.c
index 3bca988030..6f3f0127d1 100644
--- a/src/nvim/api/vimscript.c
+++ b/src/nvim/api/vimscript.c
@@ -11,6 +11,7 @@
 #include "nvim/api/private/helpers.h"
 #include "nvim/api/vimscript.h"
 #include "nvim/ascii_defs.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
 #include "nvim/eval/userfunc.h"
diff --git a/src/nvim/api/win_config.c b/src/nvim/api/win_config.c
index 4ffe3478d7..be18dba315 100644
--- a/src/nvim/api/win_config.c
+++ b/src/nvim/api/win_config.c
@@ -23,6 +23,7 @@
 #include "nvim/pos_defs.h"
 #include "nvim/strings.h"
 #include "nvim/syntax.h"
+#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/window.h"
 #include "nvim/winfloat.h"
diff --git a/src/nvim/autocmd.h b/src/nvim/autocmd.h
index b0a5a13026..4aefe8e71b 100644
--- a/src/nvim/autocmd.h
+++ b/src/nvim/autocmd.h
@@ -13,6 +13,7 @@
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/macros_defs.h"
 #include "nvim/pos_defs.h"
+#include "nvim/types_defs.h"
 
 // Set by the apply_autocmds_group function if the given event is equal to
 // EVENT_FILETYPE. Used by the readfile function in order to determine if
diff --git a/src/nvim/base64.c b/src/nvim/base64.c
index 7f7d121442..a0ba219fa2 100644
--- a/src/nvim/base64.c
+++ b/src/nvim/base64.c
@@ -3,7 +3,6 @@
 #include <stdint.h>
 #include <string.h>
 
-#include "auto/config.h"
 #include "nvim/base64.h"
 #include "nvim/memory.h"
 
diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index dc93243fad..49d2126801 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -4,16 +4,6 @@
 #include <stdint.h>
 #include <stdio.h>
 
-typedef struct file_buffer buf_T;
-
-/// Reference to a buffer that stores the value of buf_free_count.
-/// bufref_valid() only needs to check "buf" when the count differs.
-typedef struct {
-  buf_T *br_buf;
-  int br_fnum;
-  int br_buf_free_count;
-} bufref_T;
-
 #include "klib/kvec.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/arglist_defs.h"
@@ -27,11 +17,24 @@ typedef struct {
 #include "nvim/mapping_defs.h"
 #include "nvim/mark_defs.h"
 #include "nvim/marktree_defs.h"
+#include "nvim/memline_defs.h"
 #include "nvim/option_vars.h"
+#include "nvim/os/fs_defs.h"
 #include "nvim/pos_defs.h"
+#include "nvim/regexp_defs.h"
+#include "nvim/sign_defs.h"
 #include "nvim/statusline_defs.h"
+#include "nvim/terminal.h"
 #include "nvim/undo_defs.h"
 
+/// Reference to a buffer that stores the value of buf_free_count.
+/// bufref_valid() only needs to check "buf" when the count differs.
+typedef struct {
+  buf_T *br_buf;
+  int br_fnum;
+  int br_buf_free_count;
+} bufref_T;
+
 #define GETFILE_SUCCESS(x)    ((x) <= 0)
 #define MODIFIABLE(buf) (buf->b_p_ma)
 
@@ -80,18 +83,10 @@ typedef struct {
 // Mask to check for flags that prevent normal writing
 #define BF_WRITE_MASK   (BF_NOTEDITED + BF_NEW + BF_READERR)
 
-typedef struct window_S win_T;
 typedef struct wininfo_S wininfo_T;
 typedef struct frame_S frame_T;
 typedef uint64_t disptick_T;  // display tick type
 
-#include "nvim/memline_defs.h"
-#include "nvim/os/fs_defs.h"
-#include "nvim/regexp_defs.h"
-#include "nvim/sign_defs.h"
-#include "nvim/syntax_defs.h"
-#include "nvim/terminal.h"
-
 // The taggy struct is used to store the information about a :tag command.
 typedef struct taggy {
   char *tagname;                // tag name
diff --git a/src/nvim/change.c b/src/nvim/change.c
index 99698f2e5d..0154ead8fb 100644
--- a/src/nvim/change.c
+++ b/src/nvim/change.c
@@ -44,6 +44,7 @@
 #include "nvim/state.h"
 #include "nvim/strings.h"
 #include "nvim/textformat.h"
+#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/undo.h"
 #include "nvim/vim_defs.h"
diff --git a/src/nvim/channel.c b/src/nvim/channel.c
index 42935933e0..8c4fa8f5ad 100644
--- a/src/nvim/channel.c
+++ b/src/nvim/channel.c
@@ -34,6 +34,7 @@
 #include "nvim/os/shell.h"
 #include "nvim/path.h"
 #include "nvim/rbuffer.h"
+#include "nvim/terminal.h"
 #include "nvim/types_defs.h"
 
 #ifdef MSWIN
diff --git a/src/nvim/charset.c b/src/nvim/charset.c
index 48a9808b31..60a0c77cfa 100644
--- a/src/nvim/charset.c
+++ b/src/nvim/charset.c
@@ -27,6 +27,7 @@
 #include "nvim/path.h"
 #include "nvim/pos_defs.h"
 #include "nvim/strings.h"
+#include "nvim/types_defs.h"
 #include "nvim/vim_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/cursor.c b/src/nvim/cursor.c
index 1110fe1e64..bcb2810095 100644
--- a/src/nvim/cursor.c
+++ b/src/nvim/cursor.c
@@ -22,6 +22,7 @@
 #include "nvim/plines.h"
 #include "nvim/pos_defs.h"
 #include "nvim/state.h"
+#include "nvim/types_defs.h"
 #include "nvim/vim_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/debugger.c b/src/nvim/debugger.c
index 000fe13502..35333e4b12 100644
--- a/src/nvim/debugger.c
+++ b/src/nvim/debugger.c
@@ -8,6 +8,7 @@
 #include <string.h>
 
 #include "nvim/ascii_defs.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cmdexpand_defs.h"
 #include "nvim/debugger.h"
@@ -32,6 +33,7 @@
 #include "nvim/regexp.h"
 #include "nvim/runtime.h"
 #include "nvim/state_defs.h"
+#include "nvim/types_defs.h"
 #include "nvim/vim_defs.h"
 
 /// batch mode debugging: don't save and restore typeahead.
diff --git a/src/nvim/decoration.c b/src/nvim/decoration.c
index b3fad78f84..a18f30ed41 100644
--- a/src/nvim/decoration.c
+++ b/src/nvim/decoration.c
@@ -6,6 +6,7 @@
 #include "nvim/api/extmark.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/decoration.h"
 #include "nvim/drawscreen.h"
 #include "nvim/extmark.h"
diff --git a/src/nvim/decoration.h b/src/nvim/decoration.h
index 92e0cbc76b..1c072eab20 100644
--- a/src/nvim/decoration.h
+++ b/src/nvim/decoration.h
@@ -5,7 +5,7 @@
 #include <stdint.h>
 
 #include "klib/kvec.h"
-#include "nvim/buffer_defs.h"
+#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/decoration_defs.h"  // IWYU pragma: export
 #include "nvim/macros_defs.h"
 #include "nvim/marktree_defs.h"
diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index 5e943711d1..d0b3fe7993 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -10,6 +10,7 @@
 
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cmdexpand_defs.h"
 #include "nvim/debugger.h"
diff --git a/src/nvim/ex_cmds2.c b/src/nvim/ex_cmds2.c
index 1722b7902b..975335ba20 100644
--- a/src/nvim/ex_cmds2.c
+++ b/src/nvim/ex_cmds2.c
@@ -39,6 +39,7 @@
 #include "nvim/pos_defs.h"
 #include "nvim/quickfix.h"
 #include "nvim/runtime.h"
+#include "nvim/types_defs.h"
 #include "nvim/undo.h"
 #include "nvim/vim_defs.h"
 #include "nvim/window.h"
diff --git a/src/nvim/ex_cmds_defs.h b/src/nvim/ex_cmds_defs.h
index cf6282ad06..4abc286a96 100644
--- a/src/nvim/ex_cmds_defs.h
+++ b/src/nvim/ex_cmds_defs.h
@@ -6,6 +6,7 @@
 #include "nvim/eval/typval_defs.h"
 #include "nvim/ex_eval_defs.h"
 #include "nvim/normal_defs.h"
+#include "nvim/os/time_defs.h"
 #include "nvim/pos_defs.h"
 #include "nvim/regexp_defs.h"
 
diff --git a/src/nvim/ex_session.c b/src/nvim/ex_session.c
index 6ae401a58c..47f92920eb 100644
--- a/src/nvim/ex_session.c
+++ b/src/nvim/ex_session.c
@@ -34,6 +34,7 @@
 #include "nvim/path.h"
 #include "nvim/pos_defs.h"
 #include "nvim/runtime.h"
+#include "nvim/types_defs.h"
 #include "nvim/vim_defs.h"
 #include "nvim/window.h"
 
diff --git a/src/nvim/extmark.c b/src/nvim/extmark.c
index f305b6d506..69b10dd674 100644
--- a/src/nvim/extmark.c
+++ b/src/nvim/extmark.c
@@ -39,6 +39,7 @@
 #include "nvim/marktree.h"
 #include "nvim/memline.h"
 #include "nvim/pos_defs.h"
+#include "nvim/types_defs.h"
 #include "nvim/undo.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/file_search.c b/src/nvim/file_search.c
index acbcaa16c2..76f7b7e1af 100644
--- a/src/nvim/file_search.c
+++ b/src/nvim/file_search.c
@@ -51,6 +51,7 @@
 
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
 #include "nvim/file_search.h"
diff --git a/src/nvim/help.c b/src/nvim/help.c
index b1b53bc0c3..92807039b3 100644
--- a/src/nvim/help.c
+++ b/src/nvim/help.c
@@ -36,7 +36,6 @@
 #include "nvim/pos_defs.h"
 #include "nvim/runtime.h"
 #include "nvim/strings.h"
-#include "nvim/syntax.h"
 #include "nvim/tag.h"
 #include "nvim/types_defs.h"
 #include "nvim/vim_defs.h"
diff --git a/src/nvim/highlight_group.c b/src/nvim/highlight_group.c
index 683ad0c8a3..1364d9373c 100644
--- a/src/nvim/highlight_group.c
+++ b/src/nvim/highlight_group.c
@@ -15,6 +15,7 @@
 #include "nvim/api/private/validate.h"
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cmdexpand_defs.h"
 #include "nvim/cursor_shape.h"
diff --git a/src/nvim/indent_c.c b/src/nvim/indent_c.c
index 6c133c1e99..377bd3bfec 100644
--- a/src/nvim/indent_c.c
+++ b/src/nvim/indent_c.c
@@ -23,6 +23,7 @@
 #include "nvim/search.h"
 #include "nvim/state_defs.h"
 #include "nvim/strings.h"
+#include "nvim/types_defs.h"
 #include "nvim/vim_defs.h"
 
 // Find result cache for cpp_baseclass
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 77c3f22da8..43a6a12fda 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -16,6 +16,7 @@
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
 #include "nvim/ascii_defs.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/change.h"
 #include "nvim/cmdexpand_defs.h"
 #include "nvim/cursor.h"
diff --git a/src/nvim/mark.c b/src/nvim/mark.c
index 54b1df99a2..69042a6034 100644
--- a/src/nvim/mark.c
+++ b/src/nvim/mark.c
@@ -16,6 +16,7 @@
 #include "nvim/eval/typval.h"
 #include "nvim/ex_cmds_defs.h"
 #include "nvim/extmark.h"
+#include "nvim/extmark_defs.h"
 #include "nvim/fold.h"
 #include "nvim/gettext.h"
 #include "nvim/globals.h"
@@ -37,6 +38,7 @@
 #include "nvim/quickfix.h"
 #include "nvim/strings.h"
 #include "nvim/textobject.h"
+#include "nvim/types_defs.h"
 #include "nvim/vim_defs.h"
 
 // This file contains routines to maintain and manipulate marks.
diff --git a/src/nvim/mark.h b/src/nvim/mark.h
index b1a093bee0..ec6862b38f 100644
--- a/src/nvim/mark.h
+++ b/src/nvim/mark.h
@@ -2,6 +2,7 @@
 
 #include "nvim/ascii_defs.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/mark_defs.h"  // IWYU pragma: export
diff --git a/src/nvim/memfile.c b/src/nvim/memfile.c
index d989600d45..fc877d08a3 100644
--- a/src/nvim/memfile.c
+++ b/src/nvim/memfile.c
@@ -60,6 +60,7 @@
 #include "nvim/os/os.h"
 #include "nvim/path.h"
 #include "nvim/pos_defs.h"
+#include "nvim/types_defs.h"
 #include "nvim/vim_defs.h"
 
 #define MEMFILE_PAGE_SIZE 4096       /// default page size
diff --git a/src/nvim/memory.c b/src/nvim/memory.c
index feb13384be..3e43771cdf 100644
--- a/src/nvim/memory.c
+++ b/src/nvim/memory.c
@@ -36,6 +36,7 @@
 #include "nvim/sign.h"
 #include "nvim/state_defs.h"
 #include "nvim/statusline.h"
+#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/ui_client.h"
 #include "nvim/ui_compositor.h"
diff --git a/src/nvim/memory.h b/src/nvim/memory.h
index ffdc4c7366..d425249ab6 100644
--- a/src/nvim/memory.h
+++ b/src/nvim/memory.h
@@ -2,6 +2,7 @@
 
 #include <stdbool.h>
 #include <stdint.h>  // IWYU pragma: keep
+#include <string.h>
 #include <time.h>  // IWYU pragma: keep
 
 #include "auto/config.h"
diff --git a/src/nvim/menu.c b/src/nvim/menu.c
index 68a8c9f873..383c9e7817 100644
--- a/src/nvim/menu.c
+++ b/src/nvim/menu.c
@@ -8,6 +8,7 @@
 
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cmdexpand_defs.h"
 #include "nvim/cursor.h"
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index d9988cb94b..dbcec0721f 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -70,6 +70,7 @@
 #include "nvim/tag.h"
 #include "nvim/textformat.h"
 #include "nvim/textobject.h"
+#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/undo.h"
 #include "nvim/vim_defs.h"
diff --git a/src/nvim/os/env.c b/src/nvim/os/env.c
index 6c14f3d593..5d3fa9f0e6 100644
--- a/src/nvim/os/env.c
+++ b/src/nvim/os/env.c
@@ -26,6 +26,7 @@
 #include "nvim/os/os.h"
 #include "nvim/path.h"
 #include "nvim/strings.h"
+#include "nvim/types_defs.h"
 #include "nvim/version.h"
 #include "nvim/vim_defs.h"
 
diff --git a/src/nvim/os/input.c b/src/nvim/os/input.c
index ed4267dcbb..8765fdea4f 100644
--- a/src/nvim/os/input.c
+++ b/src/nvim/os/input.c
@@ -8,6 +8,7 @@
 #include "nvim/api/private/defs.h"
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/event/defs.h"
 #include "nvim/event/loop.h"
 #include "nvim/event/multiqueue.h"
diff --git a/src/nvim/os/shell.c b/src/nvim/os/shell.c
index 26e3171c5b..26c202741a 100644
--- a/src/nvim/os/shell.c
+++ b/src/nvim/os/shell.c
@@ -8,6 +8,7 @@
 #include "auto/config.h"
 #include "klib/kvec.h"
 #include "nvim/ascii_defs.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval_defs.h"
diff --git a/src/nvim/os/signal.c b/src/nvim/os/signal.c
index 4960fa6a19..0b0e59946c 100644
--- a/src/nvim/os/signal.c
+++ b/src/nvim/os/signal.c
@@ -7,6 +7,7 @@
 #endif
 
 #include "nvim/autocmd.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/eval.h"
 #include "nvim/event/defs.h"
 #include "nvim/event/signal.h"
diff --git a/src/nvim/path.c b/src/nvim/path.c
index 1d34f5400e..be3a2dacb2 100644
--- a/src/nvim/path.c
+++ b/src/nvim/path.c
@@ -8,6 +8,7 @@
 
 #include "auto/config.h"
 #include "nvim/ascii_defs.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cmdexpand.h"
 #include "nvim/eval.h"
diff --git a/src/nvim/plines.c b/src/nvim/plines.c
index cbfaa4ace3..461f69ae6c 100644
--- a/src/nvim/plines.c
+++ b/src/nvim/plines.c
@@ -6,6 +6,7 @@
 #include <string.h>
 
 #include "nvim/ascii_defs.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/decoration.h"
 #include "nvim/diff.h"
diff --git a/src/nvim/plines.h b/src/nvim/plines.h
index 7227db4524..38024e622e 100644
--- a/src/nvim/plines.h
+++ b/src/nvim/plines.h
@@ -3,9 +3,9 @@
 #include <stdbool.h>
 #include <stdint.h>  // IWYU pragma: keep
 
-#include "nvim/buffer_defs.h"
 #include "nvim/marktree_defs.h"
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"
 
 /// Argument for lbr_chartabsize().
 typedef struct {
diff --git a/src/nvim/popupmenu.c b/src/nvim/popupmenu.c
index c1f13c1115..386c13f630 100644
--- a/src/nvim/popupmenu.c
+++ b/src/nvim/popupmenu.c
@@ -38,6 +38,7 @@
 #include "nvim/pos_defs.h"
 #include "nvim/state_defs.h"
 #include "nvim/strings.h"
+#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/ui_compositor.h"
 #include "nvim/vim_defs.h"
diff --git a/src/nvim/quickfix.c b/src/nvim/quickfix.c
index e25f6b9b5e..59207dba17 100644
--- a/src/nvim/quickfix.c
+++ b/src/nvim/quickfix.c
@@ -14,6 +14,7 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cursor.h"
 #include "nvim/drawscreen.h"
diff --git a/src/nvim/quickfix.h b/src/nvim/quickfix.h
index 9c49564d57..941aa2f991 100644
--- a/src/nvim/quickfix.h
+++ b/src/nvim/quickfix.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#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
diff --git a/src/nvim/regexp_defs.h b/src/nvim/regexp_defs.h
index 31bc0e86e8..91d897ee7b 100644
--- a/src/nvim/regexp_defs.h
+++ b/src/nvim/regexp_defs.h
@@ -15,6 +15,32 @@
 #include "nvim/pos_defs.h"
 #include "nvim/types_defs.h"
 
+enum {
+  /// The number of sub-matches is limited to 10.
+  /// The first one (index 0) is the whole match, referenced with "\0".
+  /// The second one (index 1) is the first sub-match, referenced with "\1".
+  /// This goes up to the tenth (index 9), referenced with "\9".
+  NSUBEXP = 10,
+};
+
+typedef struct regengine regengine_T;
+
+/// Structure to be used for multi-line matching.
+/// Sub-match "no" starts in line "startpos[no].lnum" column "startpos[no].col"
+/// and ends in line "endpos[no].lnum" just before column "endpos[no].col".
+/// The line numbers are relative to the first line, thus startpos[0].lnum is
+/// always 0.
+/// When there is no match, the line number is -1.
+typedef struct {
+  regprog_T *regprog;
+  lpos_T startpos[NSUBEXP];
+  lpos_T endpos[NSUBEXP];
+
+  colnr_T rmm_matchcol;  ///< match start without "\zs"
+  int rmm_ic;
+  colnr_T rmm_maxcol;  ///< when not zero: maximum column
+} regmmatch_T;
+
 /// Used for "magic_overruled".
 typedef enum {
   OPTION_MAGIC_NOT_SET,  ///< p_magic not overruled
@@ -33,14 +59,6 @@ typedef enum {
   MAGIC_ALL = 4,   ///< "\v" very magic
 } magic_T;
 
-enum {
-  /// The number of sub-matches is limited to 10.
-  /// The first one (index 0) is the whole match, referenced with "\0".
-  /// The second one (index 1) is the first sub-match, referenced with "\1".
-  /// This goes up to the tenth (index 9), referenced with "\9".
-  NSUBEXP = 10,
-};
-
 enum {
   /// In the NFA engine: how many braces are allowed.
   /// TODO(RE): Use dynamic memory allocation instead of static, like here
@@ -61,28 +79,6 @@ enum {
   NFA_ENGINE          = 2,
 };
 
-typedef struct regengine regengine_T;
-typedef struct regprog regprog_T;
-typedef struct reg_extmatch reg_extmatch_T;
-
-/// Structure to be used for multi-line matching.
-/// Sub-match "no" starts in line "startpos[no].lnum" column "startpos[no].col"
-/// and ends in line "endpos[no].lnum" just before column "endpos[no].col".
-/// The line numbers are relative to the first line, thus startpos[0].lnum is
-/// always 0.
-/// When there is no match, the line number is -1.
-typedef struct {
-  regprog_T *regprog;
-  lpos_T startpos[NSUBEXP];
-  lpos_T endpos[NSUBEXP];
-
-  colnr_T rmm_matchcol;  ///< match start without "\zs"
-  int rmm_ic;
-  colnr_T rmm_maxcol;  ///< when not zero: maximum column
-} regmmatch_T;
-
-#include "nvim/buffer_defs.h"
-
 /// Structure returned by vim_regcomp() to pass on to vim_regexec().
 /// This is the general structure. For the actual matcher, two specific
 /// structures are used. See code below.
@@ -164,10 +160,10 @@ typedef struct {
 /// Structure used to store external references: "\z\(\)" to "\z\1".
 /// Use a reference count to avoid the need to copy this around.  When it goes
 /// from 1 to zero the matches need to be freed.
-struct reg_extmatch {
+typedef struct {
   int16_t refcnt;
   uint8_t *matches[NSUBEXP];
-};
+} reg_extmatch_T;
 
 struct regengine {
   /// bt_regcomp or nfa_regcomp
diff --git a/src/nvim/runtime.c b/src/nvim/runtime.c
index 7dfbdd888a..29b70e05ca 100644
--- a/src/nvim/runtime.c
+++ b/src/nvim/runtime.c
@@ -17,6 +17,7 @@
 #include "nvim/api/private/helpers.h"
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cmdexpand.h"
 #include "nvim/debugger.h"
diff --git a/src/nvim/shada.c b/src/nvim/shada.c
index 02e7c3cc68..5c479bb1c6 100644
--- a/src/nvim/shada.c
+++ b/src/nvim/shada.c
@@ -50,6 +50,7 @@
 #include "nvim/search.h"
 #include "nvim/shada.h"
 #include "nvim/strings.h"
+#include "nvim/types_defs.h"
 #include "nvim/version.h"
 #include "nvim/vim_defs.h"
 
diff --git a/src/nvim/spellfile.c b/src/nvim/spellfile.c
index 027013c5f0..979495e810 100644
--- a/src/nvim/spellfile.c
+++ b/src/nvim/spellfile.c
@@ -264,6 +264,7 @@
 #include "nvim/spell_defs.h"
 #include "nvim/spellfile.h"
 #include "nvim/strings.h"
+#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/undo.h"
 #include "nvim/vim_defs.h"
diff --git a/src/nvim/state.c b/src/nvim/state.c
index 199003b61c..518ceb8c88 100644
--- a/src/nvim/state.c
+++ b/src/nvim/state.c
@@ -3,6 +3,7 @@
 
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/drawscreen.h"
 #include "nvim/eval.h"
 #include "nvim/eval/typval.h"
diff --git a/src/nvim/statusline.c b/src/nvim/statusline.c
index 7fda93834d..d31b8ef0b1 100644
--- a/src/nvim/statusline.c
+++ b/src/nvim/statusline.c
@@ -40,6 +40,7 @@
 #include "nvim/state_defs.h"
 #include "nvim/statusline.h"
 #include "nvim/strings.h"
+#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/undo.h"
 #include "nvim/window.h"
diff --git a/src/nvim/syntax_defs.h b/src/nvim/syntax_defs.h
index ae4997154e..8fd8b0638f 100644
--- a/src/nvim/syntax_defs.h
+++ b/src/nvim/syntax_defs.h
@@ -1,6 +1,9 @@
 #pragma once
 
+#include "nvim/buffer_defs.h"
+#include "nvim/garray_defs.h"
 #include "nvim/highlight_defs.h"
+#include "nvim/regexp_defs.h"
 
 #define SST_MIN_ENTRIES 150    // minimal size for state stack array
 #define SST_MAX_ENTRIES 1000   // maximal size for state stack array
@@ -8,11 +11,6 @@
 #define SST_DIST        16     // normal distance between entries
 #define SST_INVALID    ((synstate_T *)-1)      // invalid syn_state pointer
 
-typedef struct syn_state synstate_T;
-
-#include "nvim/buffer_defs.h"
-#include "nvim/regexp_defs.h"
-
 // struct passed to in_id_list()
 struct sp_syn {
   int inc_tag;                  // ":syn include" unique tag
diff --git a/src/nvim/tag.c b/src/nvim/tag.c
index fb798a06fd..8c7b6171aa 100644
--- a/src/nvim/tag.c
+++ b/src/nvim/tag.c
@@ -54,6 +54,7 @@
 #include "nvim/state_defs.h"
 #include "nvim/strings.h"
 #include "nvim/tag.h"
+#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/vim_defs.h"
 #include "nvim/window.h"
diff --git a/src/nvim/terminal.c b/src/nvim/terminal.c
index da6bf134de..1586dd3d8e 100644
--- a/src/nvim/terminal.c
+++ b/src/nvim/terminal.c
@@ -49,7 +49,6 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/change.h"
 #include "nvim/channel.h"
 #include "nvim/cursor.h"
diff --git a/src/nvim/terminal.h b/src/nvim/terminal.h
index dd0ef3f47c..1bbc1abd4a 100644
--- a/src/nvim/terminal.h
+++ b/src/nvim/terminal.h
@@ -4,13 +4,12 @@
 #include <stddef.h>
 #include <stdint.h>
 
-typedef struct terminal Terminal;
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
+
 typedef void (*terminal_write_cb)(const 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"  // IWYU pragma: keep
-
 typedef struct {
   void *data;  // PTY process channel
   uint16_t width, height;
diff --git a/src/nvim/textobject.c b/src/nvim/textobject.c
index 3a7cc2a633..9c601769c0 100644
--- a/src/nvim/textobject.c
+++ b/src/nvim/textobject.c
@@ -6,6 +6,7 @@
 #include <string.h>
 
 #include "nvim/ascii_defs.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/cursor.h"
 #include "nvim/drawscreen.h"
 #include "nvim/edit.h"
diff --git a/src/nvim/types_defs.h b/src/nvim/types_defs.h
index 27227685fa..cc9deb9630 100644
--- a/src/nvim/types_defs.h
+++ b/src/nvim/types_defs.h
@@ -55,3 +55,9 @@ typedef struct {
   int add;  // Number of signs added in the invalid range, negative for deleted signs.
 } SignRange;
 #define SIGNRANGE_INIT { 0, 0 }
+
+typedef struct file_buffer buf_T;
+typedef struct syn_state synstate_T;
+typedef struct terminal Terminal;
+typedef struct window_S win_T;
+typedef struct regprog regprog_T;
diff --git a/src/nvim/ui_compositor.c b/src/nvim/ui_compositor.c
index baad8f3c29..d8969b0061 100644
--- a/src/nvim/ui_compositor.c
+++ b/src/nvim/ui_compositor.c
@@ -14,6 +14,7 @@
 #include "klib/kvec.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/ascii_defs.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/globals.h"
 #include "nvim/grid.h"
 #include "nvim/highlight.h"
diff --git a/src/nvim/undo_defs.h b/src/nvim/undo_defs.h
index 09a9689f67..e38b5e88fe 100644
--- a/src/nvim/undo_defs.h
+++ b/src/nvim/undo_defs.h
@@ -18,8 +18,6 @@ typedef struct {
   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
diff --git a/src/nvim/usercmd.h b/src/nvim/usercmd.h
index bcabf9460b..4d6d154b79 100644
--- a/src/nvim/usercmd.h
+++ b/src/nvim/usercmd.h
@@ -3,6 +3,7 @@
 #include <stddef.h>  // IWYU pragma: keep
 #include <stdint.h>
 
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 #include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"
 #include "nvim/ex_cmds_defs.h"
diff --git a/src/nvim/version.h b/src/nvim/version.h
index 94219aaddc..cc355f2df5 100644
--- a/src/nvim/version.h
+++ b/src/nvim/version.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "nvim/api/private/defs.h"  // IWYU pragma: keep
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/macros_defs.h"
 
diff --git a/src/nvim/vim_defs.h b/src/nvim/vim_defs.h
index b6cf402b02..4cd0097cdf 100644
--- a/src/nvim/vim_defs.h
+++ b/src/nvim/vim_defs.h
@@ -1,13 +1,14 @@
 #pragma once
 
+#include "auto/config.h"
+#include "nvim/os/os_defs.h"  // IWYU pragma: keep
+
 // Some defines from the old feature.h
 #define SESSION_FILE "Session.vim"
 #define MAX_MSG_HIST_LEN 200
 #define SYS_OPTWIN_FILE "$VIMRUNTIME/optwin.vim"
 #define RUNTIME_DIRNAME "runtime"
 
-#include "auto/config.h"
-
 enum {
   /// length of a buffer to store a number in ASCII (64 bits binary + NUL)
   NUMBUFLEN = 65,
@@ -56,8 +57,6 @@ typedef enum {
   kCdCauseAuto,    ///< On 'autochdir'.
 } CdCause;
 
-#include "nvim/os/os_defs.h"  // IWYU pragma: keep
-
 // return values for functions
 #if !(defined(OK) && (OK == 1))
 // OK already defined to 1 in MacOS X curses, skip this
diff --git a/src/nvim/winfloat.c b/src/nvim/winfloat.c
index 87069d5682..dc29c08c14 100644
--- a/src/nvim/winfloat.c
+++ b/src/nvim/winfloat.c
@@ -19,6 +19,7 @@
 #include "nvim/optionstr.h"
 #include "nvim/pos_defs.h"
 #include "nvim/strings.h"
+#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/vim_defs.h"
 #include "nvim/window.h"