Merge pull request #22442 from bfredl/quickmake

refactor(build): spring cleaning of compile time checks

26 files changed, 392 insertions, 578 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1334dececd..0c445b27b4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -120,17 +120,11 @@ if(CMAKE_C_FLAGS_RELEASE MATCHES "-O3")
   string(REPLACE "-O3" "-O2" CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE}")
 endif()
 
-if(CMAKE_C_COMPILER_ID MATCHES "GNU")
-  check_c_compiler_flag(-Og HAS_OG_FLAG)
-else()
-  set(HAS_OG_FLAG 0)
-endif()
-
-#
 # Build-type: RelWithDebInfo
-#
-if(HAS_OG_FLAG)
-  set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -Og -g")
+
+# /Og means something different in MSVC
+if(CMAKE_C_COMPILER_ID MATCHES "GNU" OR CMAKE_C_COMPILER_ID MATCHES "Clang")
+   set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -Og -g")
 endif()
 # We _want_ assertions in RelWithDebInfo build-type.
 if(CMAKE_C_FLAGS_RELWITHDEBINFO MATCHES DNDEBUG)
diff --git a/cmake.config/CMakeLists.txt b/cmake.config/CMakeLists.txt
index 1a06eccf68..6bf4a60cf1 100644
--- a/cmake.config/CMakeLists.txt
+++ b/cmake.config/CMakeLists.txt
@@ -28,17 +28,13 @@ int main(void)
 check_type_size("int" SIZEOF_INT LANGUAGE C)
 check_type_size("long" SIZEOF_LONG LANGUAGE C)
 check_type_size("intmax_t" SIZEOF_INTMAX_T LANGUAGE C)
-check_type_size("int32_t" SIZEOF_INT32_T LANGUAGE C)
 check_type_size("size_t" SIZEOF_SIZE_T LANGUAGE C)
-check_type_size("long long" SIZEOF_LONG_LONG LANGUAGE C)
 check_type_size("void *" SIZEOF_VOID_PTR LANGUAGE C)
 
 check_symbol_exists(_NSGetEnviron crt_externs.h HAVE__NSGETENVIRON)
 
 # Headers
 check_include_files(langinfo.h HAVE_LANGINFO_H)
-check_include_files(locale.h HAVE_LOCALE_H)
-check_include_files(pwd.h HAVE_PWD_H)
 check_include_files(strings.h HAVE_STRINGS_H)
 check_include_files(sys/utsname.h HAVE_SYS_UTSNAME_H)
 check_include_files(termios.h HAVE_TERMIOS_H)
@@ -47,15 +43,8 @@ check_include_files(sys/sdt.h HAVE_SYS_SDT_H)
 
 # Functions
 check_function_exists(fseeko HAVE_FSEEKO)
-check_function_exists(getpwent HAVE_GETPWENT)
-check_function_exists(getpwnam HAVE_GETPWNAM)
-check_function_exists(getpwuid HAVE_GETPWUID)
 check_function_exists(readv HAVE_READV)
-check_function_exists(opendir HAVE_OPENDIR)
 check_function_exists(readlink HAVE_READLINK)
-check_function_exists(setpgid HAVE_SETPGID)
-check_function_exists(setsid HAVE_SETSID)
-check_function_exists(sigaction HAVE_SIGACTION)
 check_function_exists(strnlen HAVE_STRNLEN)
 check_function_exists(strcasecmp HAVE_STRCASECMP)
 check_function_exists(strncasecmp HAVE_STRNCASECMP)
@@ -64,22 +53,28 @@ check_function_exists(strptime HAVE_STRPTIME)
 check_c_source_compiles("
 #include <sys/types.h>
 #include <dirent.h>
+#include <sys/file.h>
 int main(void)
 {
   DIR *dir = opendir(\"dirname\");
   dirfd(dir);
+  flock(10, LOCK_SH);
   return 0;
 }
-" HAVE_DIRFD)
+" HAVE_DIRFD_AND_FLOCK)
+
 
 check_c_source_compiles("
-#include <sys/file.h>
+#include <pwd.h>
 int main(void)
 {
-  flock(10, LOCK_SH);
+  getpwent();
+  getpwuid(0);
+  getpwnam(\"root\");
   return 0;
 }
-" HAVE_FLOCK)
+" HAVE_PWD_FUNCS)
+
 
 if(CMAKE_SYSTEM_NAME STREQUAL "SunOS")
   check_c_source_compiles("
@@ -101,11 +96,13 @@ if(HAVE_LANGINFO_H)
 endif()
 
 check_include_files("endian.h" HAVE_ENDIAN_H)
-check_include_files("sys/endian.h" HAVE_SYS_ENDIAN_H)
 
 set(ENDIAN_INCLUDE_FILE "endian.h")
-if(HAVE_SYS_ENDIAN_H AND NOT HAVE_ENDIAN_H)
-  set(ENDIAN_INCLUDE_FILE "sys/endian.h")
+if(NOT HAVE_ENDIAN_H)
+  check_include_files("sys/endian.h" HAVE_SYS_ENDIAN_H)
+  if (HAVE_SYS_ENDIAN_H)
+    set(ENDIAN_INCLUDE_FILE "sys/endian.h")
+  endif()
 endif()
 
 set(SI "#include <stdint.h>\n")
diff --git a/cmake.config/config.h.in b/cmake.config/config.h.in
index 4669e42c0f..87b39e8f6f 100644
--- a/cmake.config/config.h.in
+++ b/cmake.config/config.h.in
@@ -3,9 +3,7 @@
 
 #cmakedefine SIZEOF_INT @SIZEOF_INT@
 #cmakedefine SIZEOF_INTMAX_T @SIZEOF_INTMAX_T@
-#cmakedefine SIZEOF_INT32_T @SIZEOF_INT32_T@
 #cmakedefine SIZEOF_LONG @SIZEOF_LONG@
-#cmakedefine SIZEOF_LONG_LONG @SIZEOF_LONG_LONG@
 #cmakedefine SIZEOF_SIZE_T @SIZEOF_SIZE_T@
 
 #if @SIZEOF_VOID_PTR@ == 8
@@ -19,18 +17,11 @@
 #cmakedefine HAVE__NSGETENVIRON
 #cmakedefine HAVE_FD_CLOEXEC
 #cmakedefine HAVE_FSEEKO
-#cmakedefine HAVE_GETPWENT
-#cmakedefine HAVE_GETPWNAM
-#cmakedefine HAVE_GETPWUID
 #cmakedefine HAVE_LANGINFO_H
-#cmakedefine HAVE_LOCALE_H
 #cmakedefine HAVE_NL_LANGINFO_CODESET
 #cmakedefine HAVE_NL_MSG_CAT_CNTR
-#cmakedefine HAVE_PWD_H
+#cmakedefine HAVE_PWD_FUNCS
 #cmakedefine HAVE_READLINK
-#cmakedefine HAVE_SETPGID
-#cmakedefine HAVE_SETSID
-#cmakedefine HAVE_SIGACTION
 #cmakedefine HAVE_STRNLEN
 #cmakedefine HAVE_STRCASECMP
 #cmakedefine HAVE_STRINGS_H
@@ -51,8 +42,7 @@
 #  undef HAVE_SYS_UIO_H
 # endif
 #endif
-#cmakedefine HAVE_DIRFD
-#cmakedefine HAVE_FLOCK
+#cmakedefine HAVE_DIRFD_AND_FLOCK
 #cmakedefine HAVE_FORKPTY
 
 #ifndef UNIT_TESTING
diff --git a/cmake/FindMsgpack.cmake b/cmake/FindMsgpack.cmake
index 43c4c3c16b..b1888560c3 100644
--- a/cmake/FindMsgpack.cmake
+++ b/cmake/FindMsgpack.cmake
@@ -29,18 +29,3 @@ find_package_handle_standard_args(Msgpack
 add_library(msgpack INTERFACE)
 target_include_directories(msgpack SYSTEM BEFORE INTERFACE ${MSGPACK_INCLUDE_DIR})
 target_link_libraries(msgpack INTERFACE ${MSGPACK_LIBRARY})
-
-list(APPEND CMAKE_REQUIRED_INCLUDES "${MSGPACK_INCLUDE_DIR}")
-check_c_source_compiles("
-#include <msgpack.h>
-
-int
-main(void)
-{
-  return MSGPACK_OBJECT_FLOAT32;
-}
-" MSGPACK_HAS_FLOAT32)
-list(REMOVE_ITEM CMAKE_REQUIRED_INCLUDES "${MSGPACK_INCLUDE_DIR}")
-if(MSGPACK_HAS_FLOAT32)
-  target_compile_definitions(msgpack INTERFACE NVIM_MSGPACK_HAS_FLOAT32)
-endif()
diff --git a/cmake/FindTreesitter.cmake b/cmake/FindTreesitter.cmake
index ef308ad5e1..ddea35fe66 100644
--- a/cmake/FindTreesitter.cmake
+++ b/cmake/FindTreesitter.cmake
@@ -7,34 +7,3 @@ mark_as_advanced(TREESITTER_LIBRARY TREESITTER_INCLUDE_DIR)
 add_library(treesitter INTERFACE)
 target_include_directories(treesitter SYSTEM BEFORE INTERFACE ${TREESITTER_INCLUDE_DIR})
 target_link_libraries(treesitter INTERFACE ${TREESITTER_LIBRARY})
-
-list(APPEND CMAKE_REQUIRED_INCLUDES "${TREESITTER_INCLUDE_DIR}")
-list(APPEND CMAKE_REQUIRED_LIBRARIES "${TREESITTER_LIBRARY}")
-check_c_source_compiles("
-#include <tree_sitter/api.h>
-int
-main(void)
-{
-  TSQueryCursor *cursor = ts_query_cursor_new();
-  ts_query_cursor_set_match_limit(cursor, 32);
-  return 0;
-}
-" TS_HAS_SET_MATCH_LIMIT)
-if(TS_HAS_SET_MATCH_LIMIT)
-  target_compile_definitions(treesitter INTERFACE NVIM_TS_HAS_SET_MATCH_LIMIT)
-endif()
-check_c_source_compiles("
-#include <stdlib.h>
-#include <tree_sitter/api.h>
-int
-main(void)
-{
-  ts_set_allocator(malloc, calloc, realloc, free);
-  return 0;
-}
-" TS_HAS_SET_ALLOCATOR)
-if(TS_HAS_SET_ALLOCATOR)
-  target_compile_definitions(treesitter INTERFACE NVIM_TS_HAS_SET_ALLOCATOR)
-endif()
-list(REMOVE_ITEM CMAKE_REQUIRED_INCLUDES "${TREESITTER_INCLUDE_DIR}")
-list(REMOVE_ITEM CMAKE_REQUIRED_LIBRARIES "${TREESITTER_LIBRARY}")
diff --git a/cmake/FindUnibilium.cmake b/cmake/FindUnibilium.cmake
index 35a9016b19..91906e6660 100644
--- a/cmake/FindUnibilium.cmake
+++ b/cmake/FindUnibilium.cmake
@@ -8,22 +8,4 @@ add_library(unibilium INTERFACE)
 target_include_directories(unibilium SYSTEM BEFORE INTERFACE ${UNIBILIUM_INCLUDE_DIR})
 target_link_libraries(unibilium INTERFACE ${UNIBILIUM_LIBRARY})
 
-list(APPEND CMAKE_REQUIRED_INCLUDES "${UNIBILIUM_INCLUDE_DIR}")
-list(APPEND CMAKE_REQUIRED_LIBRARIES "${UNIBILIUM_LIBRARY}")
-check_c_source_compiles("
-#include <unibilium.h>
-
-int
-main(void)
-{
-  unibi_str_from_var(unibi_var_from_str(\"\"));
-  return unibi_num_from_var(unibi_var_from_num(0));
-}
-" UNIBI_HAS_VAR_FROM)
-list(REMOVE_ITEM CMAKE_REQUIRED_INCLUDES "${UNIBILIUM_INCLUDE_DIR}")
-list(REMOVE_ITEM CMAKE_REQUIRED_LIBRARIES "${UNIBILIUM_LIBRARY}")
-if(UNIBI_HAS_VAR_FROM)
-  target_compile_definitions(unibilium INTERFACE NVIM_UNIBI_HAS_VAR_FROM)
-endif()
-
 mark_as_advanced(UNIBILIUM_INCLUDE_DIR UNIBILIUM_LIBRARY)
diff --git a/src/nvim/CMakeLists.txt b/src/nvim/CMakeLists.txt
index 8c23b501f9..10f44c428c 100755
--- a/src/nvim/CMakeLists.txt
+++ b/src/nvim/CMakeLists.txt
@@ -87,14 +87,14 @@ if(MSVC)
   target_sources(main_lib INTERFACE ${CMAKE_CURRENT_LIST_DIR}/os/nvim.manifest)
 else()
   target_compile_options(main_lib INTERFACE -Wall -Wextra -pedantic -Wno-unused-parameter
-    -Wstrict-prototypes -std=gnu99 -Wshadow -Wconversion
+    -Wstrict-prototypes -std=gnu99 -Wshadow -Wconversion -Wvla
     -Wdouble-promotion
     -Wmissing-noreturn
     -Wmissing-format-attribute
     -Wmissing-prototypes)
 
   if(CMAKE_C_COMPILER_ID STREQUAL "GNU")
-    target_compile_options(main_lib INTERFACE
+    target_compile_options(main_lib INTERFACE -fno-common
       $<$<CONFIG:Release>:-Wno-unused-result>
       $<$<CONFIG:RelWithDebInfo>:-Wno-unused-result>
       $<$<CONFIG:MinSizeRel>:-Wno-unused-result>)
@@ -144,17 +144,6 @@ if(WIN32)
   target_compile_definitions(main_lib INTERFACE _WIN32_WINNT=0x0602 MSWIN)
 endif()
 
-# OpenBSD's GCC (4.2.1) doesn't have -Wvla
-check_c_compiler_flag(-Wvla HAS_WVLA_FLAG)
-if(HAS_WVLA_FLAG)
-  target_compile_options(main_lib INTERFACE -Wvla)
-endif()
-
-check_c_compiler_flag(-fno-common HAVE_FNO_COMMON)
-if (HAVE_FNO_COMMON)
-  target_compile_options(main_lib INTERFACE -fno-common)
-endif()
-
 check_c_compiler_flag(-fdiagnostics-color=auto HAS_DIAG_COLOR_FLAG)
 if(HAS_DIAG_COLOR_FLAG)
   if(CMAKE_GENERATOR MATCHES "Ninja")
@@ -240,13 +229,15 @@ endif()
 if(UNIX)
   # -fstack-protector breaks non Unix builds even in Mingw-w64
   check_c_compiler_flag(-fstack-protector-strong HAS_FSTACK_PROTECTOR_STRONG_FLAG)
-  check_c_compiler_flag(-fstack-protector HAS_FSTACK_PROTECTOR_FLAG)
   if(HAS_FSTACK_PROTECTOR_STRONG_FLAG)
     target_compile_options(main_lib INTERFACE -fstack-protector-strong)
     target_link_libraries(main_lib INTERFACE -fstack-protector-strong)
-  elseif(HAS_FSTACK_PROTECTOR_FLAG)
-    target_compile_options(main_lib INTERFACE -fstack-protector --param ssp-buffer-size=4)
-    target_link_libraries(main_lib INTERFACE -fstack-protector --param ssp-buffer-size=4)
+  else()
+    check_c_compiler_flag(-fstack-protector HAS_FSTACK_PROTECTOR_FLAG)
+    if(HAS_FSTACK_PROTECTOR_FLAG)
+      target_compile_options(main_lib INTERFACE -fstack-protector --param ssp-buffer-size=4)
+      target_link_libraries(main_lib INTERFACE -fstack-protector --param ssp-buffer-size=4)
+    endif()
   endif()
 endif()
 
diff --git a/src/nvim/charset.c b/src/nvim/charset.c
index 1cfb5350f3..bf18d110c0 100644
--- a/src/nvim/charset.c
+++ b/src/nvim/charset.c
@@ -1446,7 +1446,7 @@ long getdigits_long(char **pp, bool strict, long def)
 int32_t getdigits_int32(char **pp, bool strict, long def)
 {
   intmax_t number = getdigits(pp, strict, def);
-#if SIZEOF_INTMAX_T > SIZEOF_INT32_T
+#if SIZEOF_INTMAX_T > 4
   if (strict) {
     assert(number >= INT32_MIN && number <= INT32_MAX);
   } else if (!(number >= INT32_MIN && number <= INT32_MAX)) {
diff --git a/src/nvim/cmdexpand.c b/src/nvim/cmdexpand.c
index fcd6a73b2d..18d35e1e20 100644
--- a/src/nvim/cmdexpand.c
+++ b/src/nvim/cmdexpand.c
@@ -40,7 +40,6 @@
 #include "nvim/highlight_defs.h"
 #include "nvim/highlight_group.h"
 #include "nvim/keycodes.h"
-#include "nvim/locale.h"
 #include "nvim/log.h"
 #include "nvim/lua/executor.h"
 #include "nvim/macros.h"
@@ -50,6 +49,7 @@
 #include "nvim/menu.h"
 #include "nvim/message.h"
 #include "nvim/option.h"
+#include "nvim/os/lang.h"
 #include "nvim/os/os.h"
 #include "nvim/path.h"
 #include "nvim/popupmenu.h"
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 0fbf31a8cd..da2a88346a 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -45,7 +45,6 @@
 #include "nvim/insexpand.h"
 #include "nvim/keycodes.h"
 #include "nvim/lib/queue.h"
-#include "nvim/locale.h"
 #include "nvim/lua/executor.h"
 #include "nvim/macros.h"
 #include "nvim/main.h"
@@ -62,6 +61,7 @@
 #include "nvim/optionstr.h"
 #include "nvim/os/fileio.h"
 #include "nvim/os/fs_defs.h"
+#include "nvim/os/lang.h"
 #include "nvim/os/os.h"
 #include "nvim/os/shell.h"
 #include "nvim/os/stdpaths_defs.h"
diff --git a/src/nvim/eval/decode.c b/src/nvim/eval/decode.c
index cd1479f150..f57d06c83b 100644
--- a/src/nvim/eval/decode.c
+++ b/src/nvim/eval/decode.c
@@ -987,12 +987,8 @@ int msgpack_to_vim(const msgpack_object mobj, typval_T *const rettv)
       tv_list_append_number(list, (varnumber_T)(n & 0x7FFFFFFF));
     }
     break;
-#ifdef NVIM_MSGPACK_HAS_FLOAT32
   case MSGPACK_OBJECT_FLOAT32:
   case MSGPACK_OBJECT_FLOAT64:
-#else
-  case MSGPACK_OBJECT_FLOAT:
-#endif
     *rettv = (typval_T) {
       .v_type = VAR_FLOAT,
       .v_lock = VAR_UNLOCKED,
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 755b8e0834..c93df43cff 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -68,7 +68,7 @@
 # include "nvim/charset.h"
 #endif
 
-#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+#ifdef HAVE_DIRFD_AND_FLOCK
 # include <dirent.h>
 # include <sys/file.h>
 #endif
@@ -5146,7 +5146,7 @@ void forward_slash(char *fname)
 
 /// Path to Nvim's own temp dir. Ends in a slash.
 static char *vim_tempdir = NULL;
-#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+#ifdef HAVE_DIRFD_AND_FLOCK
 DIR *vim_tempdir_dp = NULL;  ///< File descriptor of temp dir
 #endif
 
@@ -5316,7 +5316,7 @@ int delete_recursive(const char *name)
   return result;
 }
 
-#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+#ifdef HAVE_DIRFD_AND_FLOCK
 /// Open temporary directory and take file lock to prevent
 /// to be auto-cleaned.
 static void vim_opentempdir(void)
@@ -5353,7 +5353,7 @@ void vim_deltempdir(void)
     return;
   }
 
-#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+#ifdef HAVE_DIRFD_AND_FLOCK
   vim_closetempdir();
 #endif
   // remove the trailing path separator
@@ -5391,7 +5391,7 @@ static bool vim_settempdir(char *tempdir)
   vim_FullName(tempdir, buf, MAXPATHL, false);
   add_pathsep(buf);
   vim_tempdir = xstrdup(buf);
-#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+#ifdef HAVE_DIRFD_AND_FLOCK
   vim_opentempdir();
 #endif
   xfree(buf);
diff --git a/src/nvim/generators/gen_ex_cmds.lua b/src/nvim/generators/gen_ex_cmds.lua
index 0c1051b04e..935d7b333e 100644
--- a/src/nvim/generators/gen_ex_cmds.lua
+++ b/src/nvim/generators/gen_ex_cmds.lua
@@ -66,7 +66,6 @@ defsfile:write(string.format([[
 #include "nvim/ex_session.h"
 #include "nvim/help.h"
 #include "nvim/indent.h"
-#include "nvim/locale.h"
 #include "nvim/lua/executor.h"
 #include "nvim/mapping.h"
 #include "nvim/mark.h"
@@ -75,6 +74,7 @@ defsfile:write(string.format([[
 #include "nvim/message.h"
 #include "nvim/ops.h"
 #include "nvim/option.h"
+#include "nvim/os/lang.h"
 #include "nvim/profile.h"
 #include "nvim/quickfix.h"
 #include "nvim/runtime.h"
diff --git a/src/nvim/locale.c b/src/nvim/locale.c
deleted file mode 100644
index c3cfd3bedb..0000000000
--- a/src/nvim/locale.c
+++ /dev/null
@@ -1,377 +0,0 @@
-// 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
-
-// locale.c: functions for language/locale configuration
-
-#include <stdbool.h>
-#include <stdio.h>
-
-#include "auto/config.h"
-#ifdef HAVE_LOCALE_H
-# include <locale.h>
-#endif
-
-#include "nvim/ascii.h"
-#include "nvim/buffer.h"
-#include "nvim/charset.h"
-#include "nvim/eval.h"
-#include "nvim/ex_cmds_defs.h"
-#include "nvim/garray.h"
-#include "nvim/gettext.h"
-#include "nvim/locale.h"
-#include "nvim/macros.h"
-#include "nvim/memory.h"
-#include "nvim/message.h"
-#include "nvim/option.h"
-#include "nvim/os/os.h"
-#include "nvim/os/shell.h"
-#include "nvim/path.h"
-#include "nvim/profile.h"
-#include "nvim/types.h"
-#include "nvim/vim.h"
-
-#ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "locale.c.generated.h"
-#endif
-
-#if defined(HAVE_LOCALE_H)
-# define HAVE_GET_LOCALE_VAL
-
-static char *get_locale_val(int what)
-{
-  // Obtain the locale value from the libraries.
-  char *loc = setlocale(what, NULL);
-
-  return loc;
-}
-#endif
-
-/// @return  true when "lang" starts with a valid language name.
-///          Rejects NULL, empty string, "C", "C.UTF-8" and others.
-static bool is_valid_mess_lang(const char *lang)
-{
-  return lang != NULL && ASCII_ISALPHA(lang[0]) && ASCII_ISALPHA(lang[1]);
-}
-
-/// Obtain the current messages language.  Used to set the default for
-/// 'helplang'.  May return NULL or an empty string.
-char *get_mess_lang(void)
-{
-  char *p;
-
-#ifdef HAVE_GET_LOCALE_VAL
-# if defined(LC_MESSAGES)
-  p = get_locale_val(LC_MESSAGES);
-# else
-  // This is necessary for Win32, where LC_MESSAGES is not defined and $LANG
-  // may be set to the LCID number.  LC_COLLATE is the best guess, LC_TIME
-  // and LC_MONETARY may be set differently for a Japanese working in the
-  // US.
-  p = get_locale_val(LC_COLLATE);
-# endif
-#else
-  p = os_getenv("LC_ALL");
-  if (!is_valid_mess_lang(p)) {
-    p = os_getenv("LC_MESSAGES");
-    if (!is_valid_mess_lang(p)) {
-      p = os_getenv("LANG");
-    }
-  }
-#endif
-  return is_valid_mess_lang(p) ? p : NULL;
-}
-
-// Complicated #if; matches with where get_mess_env() is used below.
-#ifdef HAVE_WORKING_LIBINTL
-/// Get the language used for messages from the environment.
-static char *get_mess_env(void)
-{
-  char *p;
-
-  p = (char *)os_getenv("LC_ALL");
-  if (p == NULL) {
-    p = (char *)os_getenv("LC_MESSAGES");
-    if (p == NULL) {
-      p = (char *)os_getenv("LANG");
-      if (p != NULL && ascii_isdigit(*p)) {
-        p = NULL;                       // ignore something like "1043"
-      }
-# ifdef HAVE_GET_LOCALE_VAL
-      if (p == NULL) {
-        p = get_locale_val(LC_CTYPE);
-      }
-# endif
-    }
-  }
-  return p;
-}
-#endif
-
-/// Set the "v:lang" variable according to the current locale setting.
-/// Also do "v:lc_time"and "v:ctype".
-void set_lang_var(void)
-{
-  const char *loc;
-
-#ifdef HAVE_GET_LOCALE_VAL
-  loc = get_locale_val(LC_CTYPE);
-#else
-  // setlocale() not supported: use the default value
-  loc = "C";
-#endif
-  set_vim_var_string(VV_CTYPE, loc, -1);
-
-  // When LC_MESSAGES isn't defined use the value from $LC_MESSAGES, fall
-  // back to LC_CTYPE if it's empty.
-#ifdef HAVE_WORKING_LIBINTL
-  loc = get_mess_env();
-#elif defined(LC_MESSAGES)
-  loc = get_locale_val(LC_MESSAGES);
-#else
-  // In Windows LC_MESSAGES is not defined fallback to LC_CTYPE
-  loc = get_locale_val(LC_CTYPE);
-#endif
-  set_vim_var_string(VV_LANG, loc, -1);
-
-#ifdef HAVE_GET_LOCALE_VAL
-  loc = get_locale_val(LC_TIME);
-#endif
-  set_vim_var_string(VV_LC_TIME, loc, -1);
-
-#ifdef HAVE_GET_LOCALE_VAL
-  loc = get_locale_val(LC_COLLATE);
-#else
-  // setlocale() not supported: use the default value
-  loc = "C";
-#endif
-  set_vim_var_string(VV_COLLATE, loc, -1);
-}
-
-#if defined(HAVE_LOCALE_H)
-/// Setup to use the current locale (for ctype() and many other things).
-void init_locale(void)
-{
-  setlocale(LC_ALL, "");
-
-# ifdef LC_NUMERIC
-  // Make sure strtod() uses a decimal point, not a comma.
-  setlocale(LC_NUMERIC, "C");
-# endif
-
-  char localepath[MAXPATHL] = { 0 };
-  snprintf(localepath, sizeof(localepath), "%s", get_vim_var_str(VV_PROGPATH));
-  char *tail = path_tail_with_sep(localepath);
-  *tail = NUL;
-  tail = path_tail(localepath);
-  xstrlcpy(tail, "share/locale",
-           sizeof(localepath) - (size_t)(tail - localepath));
-  bindtextdomain(PROJECT_NAME, localepath);
-  textdomain(PROJECT_NAME);
-  TIME_MSG("locale set");
-}
-#endif
-
-#ifdef HAVE_WORKING_LIBINTL
-
-/// ":language":  Set the language (locale).
-///
-/// @param eap
-void ex_language(exarg_T *eap)
-{
-  char *loc;
-  char *p;
-  char *name;
-  int what = LC_ALL;
-  char *whatstr = "";
-# ifdef LC_MESSAGES
-#  define VIM_LC_MESSAGES LC_MESSAGES
-# else
-#  define VIM_LC_MESSAGES 6789
-# endif
-
-  name = eap->arg;
-
-  // Check for "messages {name}", "ctype {name}" or "time {name}" argument.
-  // Allow abbreviation, but require at least 3 characters to avoid
-  // confusion with a two letter language name "me" or "ct".
-  p = skiptowhite(eap->arg);
-  if ((*p == NUL || ascii_iswhite(*p)) && p - eap->arg >= 3) {
-    if (STRNICMP(eap->arg, "messages", p - eap->arg) == 0) {
-      what = VIM_LC_MESSAGES;
-      name = skipwhite(p);
-      whatstr = "messages ";
-    } else if (STRNICMP(eap->arg, "ctype", p - eap->arg) == 0) {
-      what = LC_CTYPE;
-      name = skipwhite(p);
-      whatstr = "ctype ";
-    } else if (STRNICMP(eap->arg, "time", p - eap->arg) == 0) {
-      what = LC_TIME;
-      name = skipwhite(p);
-      whatstr = "time ";
-    } else if (STRNICMP(eap->arg, "collate", p - eap->arg) == 0) {
-      what = LC_COLLATE;
-      name = skipwhite(p);
-      whatstr = "collate ";
-    }
-  }
-
-  if (*name == NUL) {
-    if (what == VIM_LC_MESSAGES) {
-      p = get_mess_env();
-    } else {
-      p = setlocale(what, NULL);
-    }
-    if (p == NULL || *p == NUL) {
-      p = "Unknown";
-    }
-    smsg(_("Current %slanguage: \"%s\""), whatstr, p);
-  } else {
-# ifndef LC_MESSAGES
-    if (what == VIM_LC_MESSAGES) {
-      loc = "";
-    } else {
-# endif
-    loc = setlocale(what, name);
-# ifdef LC_NUMERIC
-    // Make sure strtod() uses a decimal point, not a comma.
-    setlocale(LC_NUMERIC, "C");
-# endif
-# ifndef LC_MESSAGES
-  }
-# endif
-    if (loc == NULL) {
-      semsg(_("E197: Cannot set language to \"%s\""), name);
-    } else {
-# ifdef HAVE_NL_MSG_CAT_CNTR
-      // Need to do this for GNU gettext, otherwise cached translations
-      // will be used again.
-      extern int _nl_msg_cat_cntr;
-
-      _nl_msg_cat_cntr++;
-# endif
-      // Reset $LC_ALL, otherwise it would overrule everything.
-      os_setenv("LC_ALL", "", 1);
-
-      if (what != LC_TIME && what != LC_COLLATE) {
-        // Tell gettext() what to translate to.  It apparently doesn't
-        // use the currently effective locale.
-        if (what == LC_ALL) {
-          os_setenv("LANG", name, 1);
-
-          // Clear $LANGUAGE because GNU gettext uses it.
-          os_setenv("LANGUAGE", "", 1);
-        }
-        if (what != LC_CTYPE) {
-          os_setenv("LC_MESSAGES", name, 1);
-          set_helplang_default(name);
-        }
-      }
-
-      // Set v:lang, v:lc_time, v:collate and v:ctype to the final result.
-      set_lang_var();
-      maketitle();
-    }
-  }
-}
-
-static char **locales = NULL;       // Array of all available locales
-
-# ifndef MSWIN
-static bool did_init_locales = false;
-
-/// @return  an array of strings for all available locales + NULL for the
-///          last element or,
-///          NULL in case of error.
-static char **find_locales(void)
-{
-  garray_T locales_ga;
-  char *loc;
-  char *saveptr = NULL;
-
-  // Find all available locales by running command "locale -a".  If this
-  // doesn't work we won't have completion.
-  char *locale_a = get_cmd_output("locale -a", NULL, kShellOptSilent, NULL);
-  if (locale_a == NULL) {
-    return NULL;
-  }
-  ga_init(&locales_ga, sizeof(char *), 20);
-
-  // Transform locale_a string where each locale is separated by "\n"
-  // into an array of locale strings.
-  loc = os_strtok(locale_a, "\n", &saveptr);
-
-  while (loc != NULL) {
-    loc = xstrdup(loc);
-    GA_APPEND(char *, &locales_ga, loc);
-    loc = os_strtok(NULL, "\n", &saveptr);
-  }
-  xfree(locale_a);
-  // Guarantee that .ga_data is NULL terminated
-  ga_grow(&locales_ga, 1);
-  ((char **)locales_ga.ga_data)[locales_ga.ga_len] = NULL;
-  return locales_ga.ga_data;
-}
-# endif
-
-/// Lazy initialization of all available locales.
-static void init_locales(void)
-{
-# ifndef MSWIN
-  if (did_init_locales) {
-    return;
-  }
-
-  did_init_locales = true;
-  locales = find_locales();
-# endif
-}
-
-# if defined(EXITFREE)
-void free_locales(void)
-{
-  if (locales == NULL) {
-    return;
-  }
-
-  for (int i = 0; locales[i] != NULL; i++) {
-    xfree(locales[i]);
-  }
-  XFREE_CLEAR(locales);
-}
-# endif
-
-/// Function given to ExpandGeneric() to obtain the possible arguments of the
-/// ":language" command.
-char *get_lang_arg(expand_T *xp, int idx)
-{
-  if (idx == 0) {
-    return "messages";
-  }
-  if (idx == 1) {
-    return "ctype";
-  }
-  if (idx == 2) {
-    return "time";
-  }
-  if (idx == 3) {
-    return "collate";
-  }
-
-  init_locales();
-  if (locales == NULL) {
-    return NULL;
-  }
-  return locales[idx - 4];
-}
-
-/// Function given to ExpandGeneric() to obtain the available locales.
-char *get_locales(expand_T *xp, int idx)
-{
-  init_locales();
-  if (locales == NULL) {
-    return NULL;
-  }
-  return locales[idx];
-}
-
-#endif
diff --git a/src/nvim/locale.h b/src/nvim/locale.h
deleted file mode 100644
index 39735d371f..0000000000
--- a/src/nvim/locale.h
+++ /dev/null
@@ -1,10 +0,0 @@
-#ifndef NVIM_LOCALE_H
-#define NVIM_LOCALE_H
-
-#include "nvim/ex_cmds_defs.h"
-#include "nvim/types.h"
-
-#ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "locale.h.generated.h"
-#endif
-#endif  // NVIM_LOCALE_H
diff --git a/src/nvim/lua/treesitter.c b/src/nvim/lua/treesitter.c
index d72e7a1825..2db12b8ded 100644
--- a/src/nvim/lua/treesitter.c
+++ b/src/nvim/lua/treesitter.c
@@ -152,9 +152,7 @@ void tslua_init(lua_State *L)
   build_meta(L, TS_META_QUERYCURSOR, querycursor_meta);
   build_meta(L, TS_META_TREECURSOR, treecursor_meta);
 
-#ifdef NVIM_TS_HAS_SET_ALLOCATOR
   ts_set_allocator(xmalloc, xcalloc, xrealloc, xfree);
-#endif
 }
 
 int tslua_has_language(lua_State *L)
@@ -1321,11 +1319,7 @@ static int node_rawquery(lua_State *L)
   } else {
     cursor = ts_query_cursor_new();
   }
-  // TODO(clason): API introduced after tree-sitter release 0.19.5
-  // remove guard when minimum ts version is bumped to 0.19.6+
-#ifdef NVIM_TS_HAS_SET_MATCH_LIMIT
   ts_query_cursor_set_match_limit(cursor, 64);
-#endif
   ts_query_cursor_exec(cursor, query, node);
 
   bool captures = lua_toboolean(L, 3);
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 975772169b..71c5c2af46 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -41,7 +41,6 @@
 #include "nvim/highlight.h"
 #include "nvim/highlight_group.h"
 #include "nvim/keycodes.h"
-#include "nvim/locale.h"
 #include "nvim/log.h"
 #include "nvim/lua/executor.h"
 #include "nvim/macros.h"
@@ -60,6 +59,7 @@
 #include "nvim/optionstr.h"
 #include "nvim/os/fileio.h"
 #include "nvim/os/input.h"
+#include "nvim/os/lang.h"
 #include "nvim/os/os.h"
 #include "nvim/os/stdpaths_defs.h"
 #include "nvim/os/time.h"
@@ -192,12 +192,10 @@ void early_init(mparm_T *paramp)
 
   TIME_MSG("early init");
 
-#if defined(HAVE_LOCALE_H)
   // Setup to use the current locale (for ctype() and many other things).
   // NOTE: Translated messages with encodings other than latin1 will not
   // work until set_init_1() has been called!
   init_locale();
-#endif
 
   // tabpage local options (p_ch) must be set before allocating first tabpage.
   set_init_tablocal();
diff --git a/src/nvim/mbyte.c b/src/nvim/mbyte.c
index e27bb003e7..d8be4f4997 100644
--- a/src/nvim/mbyte.c
+++ b/src/nvim/mbyte.c
@@ -29,6 +29,7 @@
 #include <ctype.h>
 #include <errno.h>
 #include <iconv.h>
+#include <locale.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -67,10 +68,6 @@
 #include "nvim/types.h"
 #include "nvim/vim.h"
 
-#ifdef HAVE_LOCALE_H
-# include <locale.h>
-#endif
-
 typedef struct {
   int rangeStart;
   int rangeEnd;
@@ -2193,10 +2190,7 @@ char *enc_locale(void)
   if (!(s = nl_langinfo(CODESET)) || *s == NUL)
 #endif
   {
-#if defined(HAVE_LOCALE_H)
-    if (!(s = setlocale(LC_CTYPE, NULL)) || *s == NUL)
-#endif
-    {
+    if (!(s = setlocale(LC_CTYPE, NULL)) || *s == NUL) {
       if ((s = os_getenv("LC_ALL"))) {
         if ((s = os_getenv("LC_CTYPE"))) {
           s = os_getenv("LANG");
diff --git a/src/nvim/msgpack_rpc/helpers.c b/src/nvim/msgpack_rpc/helpers.c
index 5f0f03dd69..d1fd28f882 100644
--- a/src/nvim/msgpack_rpc/helpers.c
+++ b/src/nvim/msgpack_rpc/helpers.c
@@ -84,12 +84,8 @@ bool msgpack_rpc_to_object(const msgpack_object *const obj, Object *const arg)
         *cur.aobj = INTEGER_OBJ((Integer)cur.mobj->via.u64);
       }
       break;
-#ifdef NVIM_MSGPACK_HAS_FLOAT32
     case MSGPACK_OBJECT_FLOAT32:
     case MSGPACK_OBJECT_FLOAT64:
-#else
-    case MSGPACK_OBJECT_FLOAT:
-#endif
     {
       STATIC_ASSERT(sizeof(Float) == sizeof(cur.mobj->via.f64),
                     "Msgpack floating-point size does not match API integer");
@@ -156,12 +152,8 @@ bool msgpack_rpc_to_object(const msgpack_object *const obj, Object *const arg)
           case MSGPACK_OBJECT_BOOLEAN:
           case MSGPACK_OBJECT_POSITIVE_INTEGER:
           case MSGPACK_OBJECT_NEGATIVE_INTEGER:
-#ifdef NVIM_MSGPACK_HAS_FLOAT32
           case MSGPACK_OBJECT_FLOAT32:
           case MSGPACK_OBJECT_FLOAT64:
-#else
-          case MSGPACK_OBJECT_FLOAT:
-#endif
           case MSGPACK_OBJECT_EXT:
           case MSGPACK_OBJECT_MAP:
           case MSGPACK_OBJECT_ARRAY:
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 0303f0bccd..6ddc3b5cfb 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -62,7 +62,6 @@
 #include "nvim/indent_c.h"
 #include "nvim/insexpand.h"
 #include "nvim/keycodes.h"
-#include "nvim/locale.h"
 #include "nvim/log.h"
 #include "nvim/lua/executor.h"
 #include "nvim/macros.h"
diff --git a/src/nvim/os/lang.c b/src/nvim/os/lang.c
index 57c82bba86..8ca2aa3a4b 100644
--- a/src/nvim/os/lang.c
+++ b/src/nvim/os/lang.c
@@ -7,16 +7,347 @@
 # include <CoreServices/CoreServices.h>
 # undef Boolean
 # undef FileInfo
+#endif
 
-# include "auto/config.h"
-# ifdef HAVE_LOCALE_H
-#  include <locale.h>
-# endif
-# include "nvim/os/os.h"
+#include <locale.h>
+#include <stdbool.h>
+#include <stdio.h>
+
+#include "auto/config.h"
+#include "nvim/ascii.h"
+#include "nvim/buffer.h"
+#include "nvim/charset.h"
+#include "nvim/eval.h"
+#include "nvim/ex_cmds_defs.h"
+#include "nvim/garray.h"
+#include "nvim/gettext.h"
+#include "nvim/macros.h"
+#include "nvim/memory.h"
+#include "nvim/message.h"
+#include "nvim/option.h"
+#include "nvim/os/lang.h"
+#include "nvim/os/os.h"
+#include "nvim/os/shell.h"
+#include "nvim/path.h"
+#include "nvim/profile.h"
+#include "nvim/types.h"
+#include "nvim/vim.h"
 
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "os/lang.c.generated.h"
 #endif
 
-#include "nvim/os/lang.h"
+static char *get_locale_val(int what)
+{
+  // Obtain the locale value from the libraries.
+  char *loc = setlocale(what, NULL);
+
+  return loc;
+}
+
+/// @return  true when "lang" starts with a valid language name.
+///          Rejects NULL, empty string, "C", "C.UTF-8" and others.
+static bool is_valid_mess_lang(const char *lang)
+{
+  return lang != NULL && ASCII_ISALPHA(lang[0]) && ASCII_ISALPHA(lang[1]);
+}
+
+/// Obtain the current messages language.  Used to set the default for
+/// 'helplang'.  May return NULL or an empty string.
+char *get_mess_lang(void)
+{
+  char *p;
+
+#if defined(LC_MESSAGES)
+  p = get_locale_val(LC_MESSAGES);
+#else
+  // This is necessary for Win32, where LC_MESSAGES is not defined and $LANG
+  // may be set to the LCID number.  LC_COLLATE is the best guess, LC_TIME
+  // and LC_MONETARY may be set differently for a Japanese working in the
+  // US.
+  p = get_locale_val(LC_COLLATE);
+#endif
+  return is_valid_mess_lang(p) ? p : NULL;
+}
+
+// Complicated #if; matches with where get_mess_env() is used below.
+#ifdef HAVE_WORKING_LIBINTL
+/// Get the language used for messages from the environment.
+static char *get_mess_env(void)
+{
+  char *p;
+
+  p = (char *)os_getenv("LC_ALL");
+  if (p == NULL) {
+    p = (char *)os_getenv("LC_MESSAGES");
+    if (p == NULL) {
+      p = (char *)os_getenv("LANG");
+      if (p != NULL && ascii_isdigit(*p)) {
+        p = NULL;                       // ignore something like "1043"
+      }
+      if (p == NULL) {
+        p = get_locale_val(LC_CTYPE);
+      }
+    }
+  }
+  return p;
+}
+#endif
+
+/// Set the "v:lang" variable according to the current locale setting.
+/// Also do "v:lc_time"and "v:ctype".
+void set_lang_var(void)
+{
+  const char *loc;
+
+  loc = get_locale_val(LC_CTYPE);
+  set_vim_var_string(VV_CTYPE, loc, -1);
+
+  // When LC_MESSAGES isn't defined use the value from $LC_MESSAGES, fall
+  // back to LC_CTYPE if it's empty.
+#ifdef HAVE_WORKING_LIBINTL
+  loc = get_mess_env();
+#elif defined(LC_MESSAGES)
+  loc = get_locale_val(LC_MESSAGES);
+#else
+  // In Windows LC_MESSAGES is not defined fallback to LC_CTYPE
+  loc = get_locale_val(LC_CTYPE);
+#endif
+  set_vim_var_string(VV_LANG, loc, -1);
+
+  loc = get_locale_val(LC_TIME);
+  set_vim_var_string(VV_LC_TIME, loc, -1);
+
+  loc = get_locale_val(LC_COLLATE);
+  set_vim_var_string(VV_COLLATE, loc, -1);
+}
+
+/// Setup to use the current locale (for ctype() and many other things).
+void init_locale(void)
+{
+  setlocale(LC_ALL, "");
+
+#ifdef LC_NUMERIC
+  // Make sure strtod() uses a decimal point, not a comma.
+  setlocale(LC_NUMERIC, "C");
+#endif
+
+  char localepath[MAXPATHL] = { 0 };
+  snprintf(localepath, sizeof(localepath), "%s", get_vim_var_str(VV_PROGPATH));
+  char *tail = path_tail_with_sep(localepath);
+  *tail = NUL;
+  tail = path_tail(localepath);
+  xstrlcpy(tail, "share/locale",
+           sizeof(localepath) - (size_t)(tail - localepath));
+  bindtextdomain(PROJECT_NAME, localepath);
+  textdomain(PROJECT_NAME);
+  TIME_MSG("locale set");
+}
+
+#ifdef HAVE_WORKING_LIBINTL
+
+/// ":language":  Set the language (locale).
+///
+/// @param eap
+void ex_language(exarg_T *eap)
+{
+  char *loc;
+  char *p;
+  char *name;
+  int what = LC_ALL;
+  char *whatstr = "";
+# ifdef LC_MESSAGES
+#  define VIM_LC_MESSAGES LC_MESSAGES
+# else
+#  define VIM_LC_MESSAGES 6789
+# endif
+
+  name = eap->arg;
+
+  // Check for "messages {name}", "ctype {name}" or "time {name}" argument.
+  // Allow abbreviation, but require at least 3 characters to avoid
+  // confusion with a two letter language name "me" or "ct".
+  p = skiptowhite(eap->arg);
+  if ((*p == NUL || ascii_iswhite(*p)) && p - eap->arg >= 3) {
+    if (STRNICMP(eap->arg, "messages", p - eap->arg) == 0) {
+      what = VIM_LC_MESSAGES;
+      name = skipwhite(p);
+      whatstr = "messages ";
+    } else if (STRNICMP(eap->arg, "ctype", p - eap->arg) == 0) {
+      what = LC_CTYPE;
+      name = skipwhite(p);
+      whatstr = "ctype ";
+    } else if (STRNICMP(eap->arg, "time", p - eap->arg) == 0) {
+      what = LC_TIME;
+      name = skipwhite(p);
+      whatstr = "time ";
+    } else if (STRNICMP(eap->arg, "collate", p - eap->arg) == 0) {
+      what = LC_COLLATE;
+      name = skipwhite(p);
+      whatstr = "collate ";
+    }
+  }
+
+  if (*name == NUL) {
+    if (what == VIM_LC_MESSAGES) {
+      p = get_mess_env();
+    } else {
+      p = setlocale(what, NULL);
+    }
+    if (p == NULL || *p == NUL) {
+      p = "Unknown";
+    }
+    smsg(_("Current %slanguage: \"%s\""), whatstr, p);
+  } else {
+# ifndef LC_MESSAGES
+    if (what == VIM_LC_MESSAGES) {
+      loc = "";
+    } else {
+# endif
+    loc = setlocale(what, name);
+# ifdef LC_NUMERIC
+    // Make sure strtod() uses a decimal point, not a comma.
+    setlocale(LC_NUMERIC, "C");
+# endif
+# ifndef LC_MESSAGES
+  }
+# endif
+    if (loc == NULL) {
+      semsg(_("E197: Cannot set language to \"%s\""), name);
+    } else {
+# ifdef HAVE_NL_MSG_CAT_CNTR
+      // Need to do this for GNU gettext, otherwise cached translations
+      // will be used again.
+      extern int _nl_msg_cat_cntr;
+
+      _nl_msg_cat_cntr++;
+# endif
+      // Reset $LC_ALL, otherwise it would overrule everything.
+      os_setenv("LC_ALL", "", 1);
+
+      if (what != LC_TIME && what != LC_COLLATE) {
+        // Tell gettext() what to translate to.  It apparently doesn't
+        // use the currently effective locale.
+        if (what == LC_ALL) {
+          os_setenv("LANG", name, 1);
+
+          // Clear $LANGUAGE because GNU gettext uses it.
+          os_setenv("LANGUAGE", "", 1);
+        }
+        if (what != LC_CTYPE) {
+          os_setenv("LC_MESSAGES", name, 1);
+          set_helplang_default(name);
+        }
+      }
+
+      // Set v:lang, v:lc_time, v:collate and v:ctype to the final result.
+      set_lang_var();
+      maketitle();
+    }
+  }
+}
+
+static char **locales = NULL;       // Array of all available locales
+
+# ifndef MSWIN
+static bool did_init_locales = false;
+
+/// @return  an array of strings for all available locales + NULL for the
+///          last element or,
+///          NULL in case of error.
+static char **find_locales(void)
+{
+  garray_T locales_ga;
+  char *loc;
+  char *saveptr = NULL;
+
+  // Find all available locales by running command "locale -a".  If this
+  // doesn't work we won't have completion.
+  char *locale_a = get_cmd_output("locale -a", NULL, kShellOptSilent, NULL);
+  if (locale_a == NULL) {
+    return NULL;
+  }
+  ga_init(&locales_ga, sizeof(char *), 20);
+
+  // Transform locale_a string where each locale is separated by "\n"
+  // into an array of locale strings.
+  loc = os_strtok(locale_a, "\n", &saveptr);
+
+  while (loc != NULL) {
+    loc = xstrdup(loc);
+    GA_APPEND(char *, &locales_ga, loc);
+    loc = os_strtok(NULL, "\n", &saveptr);
+  }
+  xfree(locale_a);
+  // Guarantee that .ga_data is NULL terminated
+  ga_grow(&locales_ga, 1);
+  ((char **)locales_ga.ga_data)[locales_ga.ga_len] = NULL;
+  return locales_ga.ga_data;
+}
+# endif
+
+/// Lazy initialization of all available locales.
+static void init_locales(void)
+{
+# ifndef MSWIN
+  if (did_init_locales) {
+    return;
+  }
+
+  did_init_locales = true;
+  locales = find_locales();
+# endif
+}
+
+# if defined(EXITFREE)
+void free_locales(void)
+{
+  if (locales == NULL) {
+    return;
+  }
+
+  for (int i = 0; locales[i] != NULL; i++) {
+    xfree(locales[i]);
+  }
+  XFREE_CLEAR(locales);
+}
+# endif
+
+/// Function given to ExpandGeneric() to obtain the possible arguments of the
+/// ":language" command.
+char *get_lang_arg(expand_T *xp, int idx)
+{
+  if (idx == 0) {
+    return "messages";
+  }
+  if (idx == 1) {
+    return "ctype";
+  }
+  if (idx == 2) {
+    return "time";
+  }
+  if (idx == 3) {
+    return "collate";
+  }
+
+  init_locales();
+  if (locales == NULL) {
+    return NULL;
+  }
+  return locales[idx - 4];
+}
+
+/// Function given to ExpandGeneric() to obtain the available locales.
+char *get_locales(expand_T *xp, int idx)
+{
+  init_locales();
+  if (locales == NULL) {
+    return NULL;
+  }
+  return locales[idx];
+}
+
+#endif
 
 void lang_init(void)
 {
diff --git a/src/nvim/os/lang.h b/src/nvim/os/lang.h
index f60e064f57..bb1ebfb721 100644
--- a/src/nvim/os/lang.h
+++ b/src/nvim/os/lang.h
@@ -1,6 +1,9 @@
 #ifndef NVIM_OS_LANG_H
 #define NVIM_OS_LANG_H
 
+#include "nvim/ex_cmds_defs.h"
+#include "nvim/types.h"
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "os/lang.h.generated.h"
 #endif
diff --git a/src/nvim/os/os_defs.h b/src/nvim/os/os_defs.h
index f86c0d3483..9e201f1dfa 100644
--- a/src/nvim/os/os_defs.h
+++ b/src/nvim/os/os_defs.h
@@ -36,10 +36,9 @@
 // Command-processing buffer. Use large buffers for all platforms.
 #define CMDBUFFSIZE 1024
 
-// Note: Some systems need both string.h and strings.h (Savage).  However,
-// some systems can't handle both, only use string.h in that case.
+// Note: Some systems need both string.h and strings.h (Savage).
 #include <string.h>
-#if defined(HAVE_STRINGS_H) && !defined(NO_STRINGS_WITH_STRING_H)
+#ifdef HAVE_STRINGS_H
 # include <strings.h>
 #endif
 
diff --git a/src/nvim/os/shell.c b/src/nvim/os/shell.c
index f1e2c5440f..f7d1154169 100644
--- a/src/nvim/os/shell.c
+++ b/src/nvim/os/shell.c
@@ -399,8 +399,8 @@ int os_expand_wildcards(int num_pat, char **pat, int *num_file, char ***file, in
     fclose(fd);
     return FAIL;
   }
-#if SIZEOF_LONG_LONG > SIZEOF_SIZE_T
-  assert(templen <= (long long)SIZE_MAX);  // NOLINT(runtime/int)
+#if 8 > SIZEOF_SIZE_T
+  assert(templen <= SIZE_MAX);  // NOLINT(runtime/int)
 #endif
   len = (size_t)templen;
   fseek(fd, 0L, SEEK_SET);
diff --git a/src/nvim/os/users.c b/src/nvim/os/users.c
index ef2986246b..411ba91fa7 100644
--- a/src/nvim/os/users.c
+++ b/src/nvim/os/users.c
@@ -15,7 +15,7 @@
 #include "nvim/os/os.h"
 #include "nvim/types.h"
 #include "nvim/vim.h"
-#ifdef HAVE_PWD_H
+#ifdef HAVE_PWD_FUNCS
 # include <pwd.h>
 #endif
 #ifdef MSWIN
@@ -50,7 +50,7 @@ int os_get_usernames(garray_T *users)
   }
   ga_init(users, sizeof(char *), 20);
 
-#if defined(HAVE_GETPWENT) && defined(HAVE_PWD_H)
+#ifdef HAVE_PWD_FUNCS
   {
     struct passwd *pw;
 
@@ -81,7 +81,7 @@ int os_get_usernames(garray_T *users)
     }
   }
 #endif
-#if defined(HAVE_GETPWNAM)
+#ifdef HAVE_PWD_FUNCS
   {
     const char *user_env = os_getenv("USER");
 
@@ -141,7 +141,7 @@ int os_get_username(char *s, size_t len)
 /// @return OK if a username was found, else FAIL.
 int os_get_uname(uv_uid_t uid, char *s, size_t len)
 {
-#if defined(HAVE_PWD_H) && defined(HAVE_GETPWUID)
+#ifdef HAVE_PWD_FUNCS
   struct passwd *pw;
 
   if ((pw = getpwuid(uid)) != NULL  // NOLINT(runtime/threadsafe_fn)
@@ -159,7 +159,7 @@ int os_get_uname(uv_uid_t uid, char *s, size_t len)
 /// Caller must free() the returned string.
 char *os_get_userdir(const char *name)
 {
-#if defined(HAVE_GETPWNAM) && defined(HAVE_PWD_H)
+#ifdef HAVE_PWD_FUNCS
   if (name == NULL || *name == NUL) {
     return NULL;
   }
diff --git a/src/nvim/tui/tui.c b/src/nvim/tui/tui.c
index 48dc860ebd..df7c87ad60 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -60,27 +60,14 @@
 #define LINUXSET0C "\x1b[?0c"
 #define LINUXSET1C "\x1b[?1c"
 
-#ifdef NVIM_UNIBI_HAS_VAR_FROM
-# define UNIBI_SET_NUM_VAR(var, num) \
+#define UNIBI_SET_NUM_VAR(var, num) \
   do { \
     (var) = unibi_var_from_num((num)); \
   } while (0)
-# define UNIBI_SET_STR_VAR(var, str) \
+#define UNIBI_SET_STR_VAR(var, str) \
   do { \
     (var) = unibi_var_from_str((str)); \
   } while (0)
-#else
-# define UNIBI_SET_NUM_VAR(var, num) \
-  do { \
-    (var).p = NULL; \
-    (var).i = (num); \
-  } while (0)
-# define UNIBI_SET_STR_VAR(var, str) \
-  do { \
-    (var).i = INT_MIN; \
-    (var).p = str; \
-  } while (0)
-#endif
 
 typedef struct {
   int top, bot, left, right;