build: allow IWYU to fix includes for all .c files

Allow Include What You Use to remove unnecessary includes and only
include what is necessary. This helps with reducing compilation times
and makes it easier to visualise which dependencies are actually
required.

Work on https://github.com/neovim/neovim/issues/549, but doesn't close
it since this only works fully for .c files and not headers.

18 files changed, 127 insertions, 54 deletions

diff --git a/src/nvim/os/dl.c b/src/nvim/os/dl.c
index 7d095d31e3..519cef7876 100644
--- a/src/nvim/os/dl.c
+++ b/src/nvim/os/dl.c
@@ -4,13 +4,14 @@
 /// Functions for using external native libraries
 
 #include <stdbool.h>
+#include <stddef.h>
 #include <stdint.h>
 #include <uv.h>
 
+#include "nvim/gettext.h"
 #include "nvim/memory.h"
 #include "nvim/message.h"
 #include "nvim/os/dl.h"
-#include "nvim/os/os.h"
 
 /// possible function prototypes that can be called by os_libcall()
 /// int -> int
diff --git a/src/nvim/os/env.c b/src/nvim/os/env.c
index ca6bff662d..8f58f5217e 100644
--- a/src/nvim/os/env.c
+++ b/src/nvim/os/env.c
@@ -4,19 +4,32 @@
 // Environment inspection
 
 #include <assert.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
 #include <uv.h>
 
+#include "auto/config.h"
 #include "nvim/ascii.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cmdexpand.h"
 #include "nvim/eval.h"
+#include "nvim/ex_cmds_defs.h"
+#include "nvim/gettext.h"
+#include "nvim/globals.h"
+#include "nvim/log.h"
 #include "nvim/macros.h"
 #include "nvim/map.h"
 #include "nvim/memory.h"
 #include "nvim/message.h"
+#include "nvim/option_defs.h"
 #include "nvim/os/os.h"
 #include "nvim/path.h"
 #include "nvim/strings.h"
+#include "nvim/types.h"
 #include "nvim/version.h"
 #include "nvim/vim.h"
 
diff --git a/src/nvim/os/fileio.c b/src/nvim/os/fileio.c
index 280a9c2bee..bdea82f1ff 100644
--- a/src/nvim/os/fileio.c
+++ b/src/nvim/os/fileio.c
@@ -11,22 +11,19 @@
 #include <fcntl.h>
 #include <stdbool.h>
 #include <stddef.h>
-
-#include "auto/config.h"
-
-#ifdef HAVE_SYS_UIO_H
-# include <sys/uio.h>
-#endif
-
+#include <stdint.h>
 #include <uv.h>
 
-#include "nvim/globals.h"
+#include "auto/config.h"
+#include "nvim/gettext.h"
 #include "nvim/macros.h"
 #include "nvim/memory.h"
 #include "nvim/message.h"
 #include "nvim/os/fileio.h"
 #include "nvim/os/os.h"
+#include "nvim/os/os_defs.h"
 #include "nvim/rbuffer.h"
+#include "nvim/types.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "os/fileio.c.generated.h"
diff --git a/src/nvim/os/fs.c b/src/nvim/os/fs.c
index 0cadabbb47..2ae0a81e3d 100644
--- a/src/nvim/os/fs.c
+++ b/src/nvim/os/fs.c
@@ -5,11 +5,23 @@
 #include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
-#include <limits.h>
 #include <stdbool.h>
 #include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
 
 #include "auto/config.h"
+#include "nvim/gettext.h"
+#include "nvim/globals.h"
+#include "nvim/log.h"
+#include "nvim/macros.h"
+#include "nvim/option_defs.h"
+#include "nvim/os/fs_defs.h"
+#include "nvim/types.h"
+#include "nvim/vim.h"
 
 #ifdef HAVE_SYS_UIO_H
 # include <sys/uio.h>
@@ -18,14 +30,12 @@
 #include <uv.h>
 
 #include "nvim/ascii.h"
-#include "nvim/assert.h"
 #include "nvim/memory.h"
 #include "nvim/message.h"
-#include "nvim/option.h"
 #include "nvim/os/os.h"
-#include "nvim/os/os_defs.h"
 #include "nvim/path.h"
-#include "nvim/strings.h"
+
+struct iovec;
 
 #ifdef MSWIN
 # include "nvim/mbyte.h"  // for utf8_to_utf16, utf16_to_utf8
diff --git a/src/nvim/os/fs.h b/src/nvim/os/fs.h
index c68081da02..75c24b8db2 100644
--- a/src/nvim/os/fs.h
+++ b/src/nvim/os/fs.h
@@ -1,8 +1,8 @@
 #ifndef NVIM_OS_FS_H
 #define NVIM_OS_FS_H
 
-#include "nvim/os/fs_defs.h"  // for uv_*
-#include "nvim/types.h"  // for char_u
+#include "nvim/os/fs_defs.h"
+#include "nvim/types.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "os/fs.h.generated.h"
diff --git a/src/nvim/os/input.c b/src/nvim/os/input.c
index f8c1ee57ea..d6afb1b62a 100644
--- a/src/nvim/os/input.c
+++ b/src/nvim/os/input.c
@@ -3,25 +3,33 @@
 
 #include <assert.h>
 #include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
 #include <string.h>
 #include <uv.h>
 
 #include "nvim/api/private/defs.h"
 #include "nvim/ascii.h"
 #include "nvim/autocmd.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/event/loop.h"
+#include "nvim/event/multiqueue.h"
 #include "nvim/event/rstream.h"
+#include "nvim/event/stream.h"
 #include "nvim/getchar.h"
+#include "nvim/gettext.h"
+#include "nvim/globals.h"
 #include "nvim/keycodes.h"
+#include "nvim/log.h"
+#include "nvim/macros.h"
 #include "nvim/main.h"
-#include "nvim/mbyte.h"
-#include "nvim/memory.h"
 #include "nvim/msgpack_rpc/channel.h"
+#include "nvim/option_defs.h"
 #include "nvim/os/input.h"
+#include "nvim/os/time.h"
 #include "nvim/profile.h"
-#include "nvim/screen.h"
+#include "nvim/rbuffer.h"
 #include "nvim/state.h"
-#include "nvim/ui.h"
 #include "nvim/vim.h"
 
 #define READ_BUFFER_SIZE 0xfff
diff --git a/src/nvim/os/lang.c b/src/nvim/os/lang.c
index 28f43ff3af..57c82bba86 100644
--- a/src/nvim/os/lang.c
+++ b/src/nvim/os/lang.c
@@ -7,16 +7,16 @@
 # include <CoreServices/CoreServices.h>
 # undef Boolean
 # undef FileInfo
-#endif
 
-#include "auto/config.h"
+# include "auto/config.h"
+# ifdef HAVE_LOCALE_H
+#  include <locale.h>
+# endif
+# include "nvim/os/os.h"
 
-#ifdef HAVE_LOCALE_H
-# include <locale.h>
 #endif
 
 #include "nvim/os/lang.h"
-#include "nvim/os/os.h"
 
 void lang_init(void)
 {
diff --git a/src/nvim/os/mem.c b/src/nvim/os/mem.c
index eccb3c97e5..0b7e8065ef 100644
--- a/src/nvim/os/mem.c
+++ b/src/nvim/os/mem.c
@@ -3,6 +3,7 @@
 
 /// Functions for accessing system memory information.
 
+#include <stdint.h>
 #include <uv.h>
 
 #include "nvim/os/os.h"
diff --git a/src/nvim/os/process.c b/src/nvim/os/process.c
index 28aea08595..d9273e69da 100644
--- a/src/nvim/os/process.c
+++ b/src/nvim/os/process.c
@@ -6,10 +6,21 @@
 /// psutil is a good reference for cross-platform syscall voodoo:
 /// https://github.com/giampaolo/psutil/tree/master/psutil/arch
 
-#include <uv.h>  // for HANDLE (win32)
+#include <assert.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <uv.h>
+
+#include "nvim/log.h"
+#include "nvim/memory.h"
+#include "nvim/os/process.h"
 
 #ifdef MSWIN
-# include <tlhelp32.h>  // for CreateToolhelp32Snapshot
+# include <tlhelp32.h>
+
+# include "nvim/api/private/helpers.h"
 #endif
 
 #if defined(__FreeBSD__)  // XXX: OpenBSD ?
@@ -27,15 +38,8 @@
 # include <sys/sysctl.h>
 #endif
 
-#include "nvim/api/private/helpers.h"
-#include "nvim/globals.h"
-#include "nvim/log.h"
-#include "nvim/os/os.h"
-#include "nvim/os/os_defs.h"
-#include "nvim/os/process.h"
-
 #ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "os/process.c.generated.h"
+# include "os/process.c.generated.h"  // IWYU pragma: export
 #endif
 
 #ifdef MSWIN
diff --git a/src/nvim/os/pty_process_unix.c b/src/nvim/os/pty_process_unix.c
index 0b7af87267..143f0b3900 100644
--- a/src/nvim/os/pty_process_unix.c
+++ b/src/nvim/os/pty_process_unix.c
@@ -2,13 +2,15 @@
 // it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
 // Some of the code came from pangoterm and libuv
-#include <stdbool.h>
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/ioctl.h>
-#include <sys/types.h>
 #include <sys/wait.h>
-#include <termios.h>
 
 // forkpty is not in POSIX, so headers are platform-specific
 #if defined(__FreeBSD__) || defined(__DragonFly__)
@@ -31,13 +33,16 @@
 
 #include <uv.h>
 
+#include "auto/config.h"
 #include "klib/klist.h"
+#include "nvim/eval/typval.h"
 #include "nvim/event/loop.h"
 #include "nvim/event/process.h"
-#include "nvim/event/rstream.h"
-#include "nvim/event/wstream.h"
+#include "nvim/event/stream.h"
 #include "nvim/log.h"
 #include "nvim/os/os.h"
+#include "nvim/os/os_defs.h"
+#include "nvim/os/pty_process.h"
 #include "nvim/os/pty_process_unix.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
diff --git a/src/nvim/os/pty_process_unix.h b/src/nvim/os/pty_process_unix.h
index 765490b92b..0cc68cf3e9 100644
--- a/src/nvim/os/pty_process_unix.h
+++ b/src/nvim/os/pty_process_unix.h
@@ -1,8 +1,10 @@
 #ifndef NVIM_OS_PTY_PROCESS_UNIX_H
 #define NVIM_OS_PTY_PROCESS_UNIX_H
 
+#include <stdint.h>
 #include <sys/ioctl.h>
 
+#include "nvim/event/loop.h"
 #include "nvim/event/process.h"
 
 typedef struct pty_process {
diff --git a/src/nvim/os/shell.c b/src/nvim/os/shell.c
index 750d2f342f..b4bee6e550 100644
--- a/src/nvim/os/shell.c
+++ b/src/nvim/os/shell.c
@@ -3,30 +3,45 @@
 
 #include <assert.h>
 #include <stdbool.h>
-#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
 #include <string.h>
 #include <uv.h>
 
+#include "auto/config.h"
 #include "klib/kvec.h"
 #include "nvim/ascii.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/eval.h"
+#include "nvim/eval/typval_defs.h"
 #include "nvim/event/libuv_process.h"
 #include "nvim/event/loop.h"
+#include "nvim/event/multiqueue.h"
+#include "nvim/event/process.h"
 #include "nvim/event/rstream.h"
+#include "nvim/event/stream.h"
+#include "nvim/event/wstream.h"
 #include "nvim/ex_cmds.h"
 #include "nvim/fileio.h"
-#include "nvim/log.h"
+#include "nvim/gettext.h"
+#include "nvim/globals.h"
+#include "nvim/macros.h"
 #include "nvim/main.h"
+#include "nvim/mbyte.h"
 #include "nvim/memline.h"
 #include "nvim/memory.h"
 #include "nvim/message.h"
 #include "nvim/option_defs.h"
+#include "nvim/os/fs.h"
+#include "nvim/os/os_defs.h"
 #include "nvim/os/shell.h"
 #include "nvim/os/signal.h"
+#include "nvim/os/time.h"
 #include "nvim/path.h"
+#include "nvim/pos.h"
 #include "nvim/profile.h"
-#include "nvim/screen.h"
+#include "nvim/rbuffer.h"
 #include "nvim/strings.h"
 #include "nvim/tag.h"
 #include "nvim/types.h"
diff --git a/src/nvim/os/signal.c b/src/nvim/os/signal.c
index 9aa8d8051b..08d24d47e2 100644
--- a/src/nvim/os/signal.c
+++ b/src/nvim/os/signal.c
@@ -3,23 +3,20 @@
 
 #include <assert.h>
 #include <stdbool.h>
-#include <uv.h>
+#include <stdio.h>
 #ifndef MSWIN
 # include <signal.h>  // for sigset_t
 #endif
 
-#include "nvim/ascii.h"
 #include "nvim/autocmd.h"
+#include "nvim/buffer_defs.h"
 #include "nvim/eval.h"
-#include "nvim/event/loop.h"
 #include "nvim/event/signal.h"
 #include "nvim/globals.h"
 #include "nvim/log.h"
 #include "nvim/main.h"
 #include "nvim/memline.h"
-#include "nvim/memory.h"
 #include "nvim/os/signal.h"
-#include "nvim/vim.h"
 
 static SignalWatcher spipe, shup, squit, sterm, susr1, swinch;
 #ifdef SIGPWR
diff --git a/src/nvim/os/stdpaths.c b/src/nvim/os/stdpaths.c
index 2aaf776fc6..a99a8d25ce 100644
--- a/src/nvim/os/stdpaths.c
+++ b/src/nvim/os/stdpaths.c
@@ -2,6 +2,7 @@
 // it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
 #include <stdbool.h>
+#include <string.h>
 
 #include "nvim/ascii.h"
 #include "nvim/fileio.h"
diff --git a/src/nvim/os/time.c b/src/nvim/os/time.c
index 161c8d28b8..7ba2bd155e 100644
--- a/src/nvim/os/time.c
+++ b/src/nvim/os/time.c
@@ -1,22 +1,34 @@
 // This is an open source non-commercial project. Dear PVS-Studio, please check
 // it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
 
-#include <assert.h>
+#include <inttypes.h>
 #include <limits.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
 #include <uv.h>
 
-#include "nvim/assert.h"
+#include "auto/config.h"
 #include "nvim/event/loop.h"
+#include "nvim/gettext.h"
+#include "nvim/globals.h"
+#include "nvim/log.h"
+#include "nvim/macros.h"
 #include "nvim/main.h"
+#include "nvim/memory.h"
 #include "nvim/os/input.h"
 #include "nvim/os/os.h"
 #include "nvim/os/time.h"
 
+struct tm;
+
 static uv_mutex_t delay_mutex;
 static uv_cond_t delay_cond;
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "os/time.c.generated.h"
+# include "os/time.c.generated.h"  // IWYU pragma: export
 #endif
 
 /// Initializes the time module
diff --git a/src/nvim/os/tty.c b/src/nvim/os/tty.c
index 1b15613a93..b5124bd83a 100644
--- a/src/nvim/os/tty.c
+++ b/src/nvim/os/tty.c
@@ -5,11 +5,11 @@
 // Terminal/console utils
 //
 
-#include "nvim/os/os.h"
+#include "nvim/os/os.h"  // IWYU pragma: keep (Windows)
 #include "nvim/os/tty.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "os/tty.c.generated.h"
+# include "os/tty.c.generated.h"  // IWYU pragma: export
 #endif
 
 #ifdef MSWIN
diff --git a/src/nvim/os/unix_defs.h b/src/nvim/os/unix_defs.h
index 4ed3b51694..8d002fc5e9 100644
--- a/src/nvim/os/unix_defs.h
+++ b/src/nvim/os/unix_defs.h
@@ -3,6 +3,9 @@
 
 #include <sys/param.h>
 #include <unistd.h>
+#if defined(HAVE_TERMIOS_H)
+# include <termios.h>
+#endif
 
 // POSIX.1-2008 says that NAME_MAX should be in here
 #include <limits.h>
diff --git a/src/nvim/os/users.c b/src/nvim/os/users.c
index 33e6563c4c..1865d6789e 100644
--- a/src/nvim/os/users.c
+++ b/src/nvim/os/users.c
@@ -3,6 +3,9 @@
 
 // users.c -- operating system user information
 
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
 #include <uv.h>
 
 #include "auto/config.h"
@@ -10,7 +13,8 @@
 #include "nvim/garray.h"
 #include "nvim/memory.h"
 #include "nvim/os/os.h"
-#include "nvim/strings.h"
+#include "nvim/types.h"
+#include "nvim/vim.h"
 #ifdef HAVE_PWD_H
 # include <pwd.h>
 #endif