Merge pull request #5540 from bfredl/api_since

allow specify api since field and more api compatibility checks

11 files changed, 206 insertions, 45 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2fd5209396..1a058f2bff 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -68,9 +68,9 @@ set(NVIM_VERSION_PATCH 0)
 set(NVIM_VERSION_PRERELEASE "-dev") # for package maintainers
 
 # API level
-set(NVIM_API_LEVEL 1)         # Bump this after any API change.
+set(NVIM_API_LEVEL 2)         # Bump this after any API change.
 set(NVIM_API_LEVEL_COMPAT 0)  # Adjust this after a _breaking_ API change.
-set(NVIM_API_PRERELEASE false)
+set(NVIM_API_PRERELEASE true)
 
 file(TO_CMAKE_PATH ${CMAKE_CURRENT_LIST_DIR}/.git FORCED_GIT_DIR)
 include(GetGitRevisionDescription)
diff --git a/scripts/gendispatch.lua b/scripts/gendispatch.lua
index 397ccc9aaf..45a4f4a4de 100644
--- a/scripts/gendispatch.lua
+++ b/scripts/gendispatch.lua
@@ -9,7 +9,8 @@ C, Ct, Cc, Cg = lpeg.C, lpeg.Ct, lpeg.Cc, lpeg.Cg
 
 any = P(1) -- (consume one character)
 letter = R('az', 'AZ') + S('_$')
-alpha = letter + R('09')
+num = R('09')
+alpha = letter + num
 nl = P('\r\n') + P('\n')
 not_nl = any - nl
 ws = S(' \t') + nl
@@ -35,6 +36,7 @@ c_proto = Ct(
   Cg(c_type, 'return_type') * Cg(c_id, 'name') *
   fill * P('(') * fill * Cg(c_params, 'parameters') * fill * P(')') *
   Cg(Cc(false), 'async') *
+  (fill * Cg((P('FUNC_API_SINCE(') * C(num ^ 1)) * P(')'), 'since') ^ -1) *
   (fill * Cg((P('FUNC_API_ASYNC') * Cc(true)), 'async') ^ -1) *
   (fill * Cg((P('FUNC_API_NOEXPORT') * Cc(true)), 'noexport') ^ -1) *
   (fill * Cg((P('FUNC_API_NOEVAL') * Cc(true)), 'noeval') ^ -1) *
@@ -52,6 +54,7 @@ package.path = nvimsrcdir .. '/?.lua;' .. package.path
 -- names of all headers relative to the source root (for inclusion in the
 -- generated file)
 headers = {}
+
 -- output h file with generated dispatch functions
 dispatch_outputf = arg[#arg-2]
 -- output h file with packed metadata
@@ -114,9 +117,11 @@ local deprecated_aliases = require("api.dispatch_deprecated")
 for i,f in ipairs(shallowcopy(functions)) do
   local ismethod = false
   if startswith(f.name, "nvim_") then
-    -- TODO(bfredl) after 0.1.6 allow method definitions
-    -- to specify the since and deprecated_since field
-    f.since = 1
+    if f.since == nil then
+      print("Function "..f.name.." lacks since field.\n")
+      os.exit(1)
+    end
+    f.since = tonumber(f.since)
     if startswith(f.name, "nvim_buf_") then
       ismethod = true
     elseif startswith(f.name, "nvim_win_") then
diff --git a/scripts/release.sh b/scripts/release.sh
index 93f9fa3d35..dac5e9b177 100755
--- a/scripts/release.sh
+++ b/scripts/release.sh
@@ -31,6 +31,8 @@ __VERSION_MINOR=$(grep 'set(NVIM_VERSION_MINOR' CMakeLists.txt\
 __VERSION_PATCH=$(grep 'set(NVIM_VERSION_PATCH' CMakeLists.txt\
   |$__sed 's/.*NVIM_VERSION_PATCH ([[:digit:]]).*/\1/')
 __VERSION="${__VERSION_MAJOR}.${__VERSION_MINOR}.${__VERSION_PATCH}"
+__API_LEVEL=$(grep 'set(NVIM_API_LEVEL ' CMakeLists.txt\
+  |$__sed 's/.*NVIM_API_LEVEL ([[:digit:]]).*/\1/')
 { [ -z "$__VERSION_MAJOR" ] || [ -z "$__VERSION_MINOR" ] || [ -z "$__VERSION_PATCH" ]; } \
   &&  { echo "ERROR: version parse failed: '${__VERSION}'"; exit 1; }
 __RELEASE_MSG="NVIM v${__VERSION}
@@ -47,7 +49,12 @@ __BUMP_MSG="version bump"
 echo "Most recent tag: ${__LAST_TAG}"
 echo "Release version: ${__VERSION}"
 $__sed -i.bk 's/(NVIM_VERSION_PRERELEASE) "-dev"/\1 ""/' CMakeLists.txt
-$__sed -i.bk 's/(NVIM_API_PRERELEASE) true/\1 false/' CMakeLists.txt
+if grep '(NVIM_API_PRERELEASE true)' CMakeLists.txt > /dev/null; then
+  $__sed -i.bk 's/(NVIM_API_PRERELEASE) true/\1 false/' CMakeLists.txt
+  cp build/funcs_data.mpack test/functional/fixtures/api_level_$__API_LEVEL.mpack
+  git add test/functional/fixtures/api_level_$__API_LEVEL.mpack
+fi
+
 echo "Building changelog since ${__LAST_TAG}..."
 __CHANGELOG="$(./scripts/git-log-pretty-since.sh "$__LAST_TAG" 'vim-patch:\S')"
 
diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index c7e535228a..b75a2c7211 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -32,6 +32,7 @@
 /// @param[out] err Error details, if any
 /// @return Line count
 Integer nvim_buf_line_count(Buffer buffer, Error *err)
+    FUNC_API_SINCE(1)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
 
@@ -132,7 +133,6 @@ ArrayOf(String) buffer_get_line_slice(Buffer buffer,
   return nvim_buf_get_lines(0, buffer, start , end, false, err);
 }
 
-
 /// Retrieves a line range from the buffer
 ///
 /// Indexing is zero-based, end-exclusive. Negative indices are interpreted
@@ -154,6 +154,7 @@ ArrayOf(String) nvim_buf_get_lines(uint64_t channel_id,
                                    Integer end,
                                    Boolean strict_indexing,
                                    Error *err)
+    FUNC_API_SINCE(1)
 {
   Array rv = ARRAY_DICT_INIT;
   buf_T *buf = find_buffer_by_handle(buffer, err);
@@ -266,6 +267,7 @@ void nvim_buf_set_lines(uint64_t channel_id,
                         Boolean strict_indexing,
                         ArrayOf(String) replacement,  // NOLINT
                         Error *err)
+    FUNC_API_SINCE(1)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
 
@@ -416,6 +418,7 @@ end:
 /// @param[out] err   Error details, if any
 /// @return Variable value
 Object nvim_buf_get_var(Buffer buffer, String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
 
@@ -432,6 +435,7 @@ Object nvim_buf_get_var(Buffer buffer, String name, Error *err)
 ///
 /// @return `b:changedtick` value.
 Integer nvim_buf_get_changedtick(Buffer buffer, Error *err)
+    FUNC_API_SINCE(2)
 {
   const buf_T *const buf = find_buffer_by_handle(buffer, err);
 
@@ -449,6 +453,7 @@ Integer nvim_buf_get_changedtick(Buffer buffer, Error *err)
 /// @param value      Variable value
 /// @param[out] err   Error details, if any
 void nvim_buf_set_var(Buffer buffer, String name, Object value, Error *err)
+    FUNC_API_SINCE(1)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
 
@@ -465,6 +470,7 @@ void nvim_buf_set_var(Buffer buffer, String name, Object value, Error *err)
 /// @param name       Variable name
 /// @param[out] err   Error details, if any
 void nvim_buf_del_var(Buffer buffer, String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
 
@@ -525,6 +531,7 @@ Object buffer_del_var(Buffer buffer, String name, Error *err)
 /// @param[out] err   Error details, if any
 /// @return Option value
 Object nvim_buf_get_option(Buffer buffer, String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
 
@@ -543,6 +550,7 @@ Object nvim_buf_get_option(Buffer buffer, String name, Error *err)
 /// @param value      Option value
 /// @param[out] err   Error details, if any
 void nvim_buf_set_option(Buffer buffer, String name, Object value, Error *err)
+    FUNC_API_SINCE(1)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
 
@@ -559,6 +567,7 @@ void nvim_buf_set_option(Buffer buffer, String name, Object value, Error *err)
 /// @param[out] err   Error details, if any
 /// @return Buffer number
 Integer nvim_buf_get_number(Buffer buffer, Error *err)
+    FUNC_API_SINCE(1)
 {
   Integer rv = 0;
   buf_T *buf = find_buffer_by_handle(buffer, err);
@@ -576,6 +585,7 @@ Integer nvim_buf_get_number(Buffer buffer, Error *err)
 /// @param[out] err   Error details, if any
 /// @return Buffer name
 String nvim_buf_get_name(Buffer buffer, Error *err)
+    FUNC_API_SINCE(1)
 {
   String rv = STRING_INIT;
   buf_T *buf = find_buffer_by_handle(buffer, err);
@@ -593,6 +603,7 @@ String nvim_buf_get_name(Buffer buffer, Error *err)
 /// @param name       Buffer name
 /// @param[out] err   Error details, if any
 void nvim_buf_set_name(Buffer buffer, String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
 
@@ -622,6 +633,7 @@ void nvim_buf_set_name(Buffer buffer, String name, Error *err)
 /// @param buffer Buffer handle
 /// @return true if the buffer is valid, false otherwise
 Boolean nvim_buf_is_valid(Buffer buffer)
+    FUNC_API_SINCE(1)
 {
   Error stub = ERROR_INIT;
   return find_buffer_by_handle(buffer, &stub) != NULL;
@@ -653,6 +665,7 @@ void buffer_insert(Buffer buffer,
 /// @param[out] err   Error details, if any
 /// @return (row, col) tuple
 ArrayOf(Integer, 2) nvim_buf_get_mark(Buffer buffer, String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   Array rv = ARRAY_DICT_INIT;
   buf_T *buf = find_buffer_by_handle(buffer, err);
@@ -727,6 +740,7 @@ Integer nvim_buf_add_highlight(Buffer buffer,
                                Integer col_start,
                                Integer col_end,
                                Error *err)
+    FUNC_API_SINCE(1)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
   if (!buf) {
@@ -767,6 +781,7 @@ void nvim_buf_clear_highlight(Buffer buffer,
                               Integer line_start,
                               Integer line_end,
                               Error *err)
+    FUNC_API_SINCE(1)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
   if (!buf) {
diff --git a/src/nvim/api/tabpage.c b/src/nvim/api/tabpage.c
index d24250d032..0f0c33f621 100644
--- a/src/nvim/api/tabpage.c
+++ b/src/nvim/api/tabpage.c
@@ -15,6 +15,7 @@
 /// @param[out] err Error details, if any
 /// @return List of windows in `tabpage`
 ArrayOf(Window) nvim_tabpage_list_wins(Tabpage tabpage, Error *err)
+    FUNC_API_SINCE(1)
 {
   Array rv = ARRAY_DICT_INIT;
   tabpage_T *tab = find_tab_by_handle(tabpage, err);
@@ -44,6 +45,7 @@ ArrayOf(Window) nvim_tabpage_list_wins(Tabpage tabpage, Error *err)
 /// @param[out] err Error details, if any
 /// @return Variable value
 Object nvim_tabpage_get_var(Tabpage tabpage, String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   tabpage_T *tab = find_tab_by_handle(tabpage, err);
 
@@ -64,6 +66,7 @@ void nvim_tabpage_set_var(Tabpage tabpage,
                           String name,
                           Object value,
                           Error *err)
+    FUNC_API_SINCE(1)
 {
   tabpage_T *tab = find_tab_by_handle(tabpage, err);
 
@@ -80,6 +83,7 @@ void nvim_tabpage_set_var(Tabpage tabpage,
 /// @param name     Variable name
 /// @param[out] err Error details, if any
 void nvim_tabpage_del_var(Tabpage tabpage, String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   tabpage_T *tab = find_tab_by_handle(tabpage, err);
 
@@ -138,6 +142,7 @@ Object tabpage_del_var(Tabpage tabpage, String name, Error *err)
 /// @param[out] err Error details, if any
 /// @return Window handle
 Window nvim_tabpage_get_win(Tabpage tabpage, Error *err)
+    FUNC_API_SINCE(1)
 {
   Window rv = 0;
   tabpage_T *tab = find_tab_by_handle(tabpage, err);
@@ -165,6 +170,7 @@ Window nvim_tabpage_get_win(Tabpage tabpage, Error *err)
 /// @param[out] err Error details, if any
 /// @return Tabpage number
 Integer nvim_tabpage_get_number(Tabpage tabpage, Error *err)
+    FUNC_API_SINCE(1)
 {
   Integer rv = 0;
   tabpage_T *tab = find_tab_by_handle(tabpage, err);
@@ -181,6 +187,7 @@ Integer nvim_tabpage_get_number(Tabpage tabpage, Error *err)
 /// @param tabpage Tabpage handle
 /// @return true if the tabpage is valid, false otherwise
 Boolean nvim_tabpage_is_valid(Tabpage tabpage)
+    FUNC_API_SINCE(1)
 {
   Error stub = ERROR_INIT;
   return find_tab_by_handle(tabpage, &stub) != NULL;
diff --git a/src/nvim/api/ui.c b/src/nvim/api/ui.c
index 9178538110..625bcc6b4b 100644
--- a/src/nvim/api/ui.c
+++ b/src/nvim/api/ui.c
@@ -48,7 +48,7 @@ void remote_ui_disconnect(uint64_t channel_id)
 
 void nvim_ui_attach(uint64_t channel_id, Integer width, Integer height,
                     Dictionary options, Error *err)
-    FUNC_API_NOEVAL
+    FUNC_API_SINCE(1) FUNC_API_NOEVAL
 {
   if (pmap_has(uint64_t)(connected_uis, channel_id)) {
     api_set_error(err, Exception, _("UI already attached for channel"));
@@ -118,7 +118,7 @@ void ui_attach(uint64_t channel_id, Integer width, Integer height,
 }
 
 void nvim_ui_detach(uint64_t channel_id, Error *err)
-    FUNC_API_NOEVAL
+    FUNC_API_SINCE(1) FUNC_API_NOEVAL
 {
   if (!pmap_has(uint64_t)(connected_uis, channel_id)) {
     api_set_error(err, Exception, _("UI is not attached for channel"));
@@ -130,7 +130,7 @@ void nvim_ui_detach(uint64_t channel_id, Error *err)
 
 void nvim_ui_try_resize(uint64_t channel_id, Integer width,
                         Integer height, Error *err)
-    FUNC_API_NOEVAL
+    FUNC_API_SINCE(1) FUNC_API_NOEVAL
 {
   if (!pmap_has(uint64_t)(connected_uis, channel_id)) {
     api_set_error(err, Exception, _("UI is not attached for channel"));
@@ -151,7 +151,7 @@ void nvim_ui_try_resize(uint64_t channel_id, Integer width,
 
 void nvim_ui_set_option(uint64_t channel_id, String name,
                         Object value, Error *error)
-    FUNC_API_NOEVAL
+    FUNC_API_SINCE(1) FUNC_API_NOEVAL
 {
   if (!pmap_has(uint64_t)(connected_uis, channel_id)) {
     api_set_error(error, Exception, _("UI is not attached for channel"));
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index bf11795d9e..413456c615 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -39,6 +39,7 @@
 /// @param command  Ex-command string
 /// @param[out] err Error details (including actual VimL error), if any
 void nvim_command(String command, Error *err)
+    FUNC_API_SINCE(1)
 {
   // Run the command
   try_start();
@@ -56,6 +57,7 @@ void nvim_command(String command, Error *err)
 /// @see feedkeys()
 /// @see vim_strsave_escape_csi
 void nvim_feedkeys(String keys, String mode, Boolean escape_csi)
+    FUNC_API_SINCE(1)
 {
   bool remap = true;
   bool insert = false;
@@ -122,7 +124,7 @@ void nvim_feedkeys(String keys, String mode, Boolean escape_csi)
 /// @return Number of bytes actually written (can be fewer than
 ///         requested if the buffer becomes full).
 Integer nvim_input(String keys)
-    FUNC_API_ASYNC
+    FUNC_API_SINCE(1) FUNC_API_ASYNC
 {
   return (Integer)input_enqueue(keys);
 }
@@ -133,6 +135,7 @@ Integer nvim_input(String keys)
 /// @see cpoptions
 String nvim_replace_termcodes(String str, Boolean from_part, Boolean do_lt,
                               Boolean special)
+    FUNC_API_SINCE(1)
 {
   if (str.size == 0) {
     // Empty string
@@ -152,6 +155,7 @@ String nvim_replace_termcodes(String str, Boolean from_part, Boolean do_lt,
 }
 
 String nvim_command_output(String str, Error *err)
+    FUNC_API_SINCE(1)
 {
   do_cmdline_cmd("redir => v:command_output");
   nvim_command(str, err);
@@ -172,6 +176,7 @@ String nvim_command_output(String str, Error *err)
 /// @param[out] err Error details, if any
 /// @return         Evaluation result or expanded object
 Object nvim_eval(String expr, Error *err)
+    FUNC_API_SINCE(1)
 {
   Object rv = OBJECT_INIT;
   // Evaluate the expression
@@ -200,6 +205,7 @@ Object nvim_eval(String expr, Error *err)
 /// @param[out] err Error details, if any
 /// @return Result of the function call
 Object nvim_call_function(String fname, Array args, Error *err)
+    FUNC_API_SINCE(1)
 {
   Object rv = OBJECT_INIT;
   if (args.size > MAX_FUNC_ARGS) {
@@ -248,6 +254,7 @@ free_vim_args:
 /// @param[out] err   Error details, if any
 /// @return Number of cells
 Integer nvim_strwidth(String str, Error *err)
+    FUNC_API_SINCE(1)
 {
   if (str.size > INT_MAX) {
     api_set_error(err, Validation, _("String length is too high"));
@@ -261,6 +268,7 @@ Integer nvim_strwidth(String str, Error *err)
 ///
 /// @return List of paths
 ArrayOf(String) nvim_list_runtime_paths(void)
+    FUNC_API_SINCE(1)
 {
   Array rv = ARRAY_DICT_INIT;
   uint8_t *rtp = p_rtp;
@@ -302,6 +310,7 @@ ArrayOf(String) nvim_list_runtime_paths(void)
 /// @param dir      Directory path
 /// @param[out] err Error details, if any
 void nvim_set_current_dir(String dir, Error *err)
+    FUNC_API_SINCE(1)
 {
   if (dir.size >= MAXPATHL) {
     api_set_error(err, Validation, _("Directory string is too long"));
@@ -330,6 +339,7 @@ void nvim_set_current_dir(String dir, Error *err)
 /// @param[out] err Error details, if any
 /// @return Current line string
 String nvim_get_current_line(Error *err)
+    FUNC_API_SINCE(1)
 {
   return buffer_get_line(curbuf->handle, curwin->w_cursor.lnum - 1, err);
 }
@@ -339,6 +349,7 @@ String nvim_get_current_line(Error *err)
 /// @param line     Line contents
 /// @param[out] err Error details, if any
 void nvim_set_current_line(String line, Error *err)
+    FUNC_API_SINCE(1)
 {
   buffer_set_line(curbuf->handle, curwin->w_cursor.lnum - 1, line, err);
 }
@@ -347,6 +358,7 @@ void nvim_set_current_line(String line, Error *err)
 ///
 /// @param[out] err Error details, if any
 void nvim_del_current_line(Error *err)
+    FUNC_API_SINCE(1)
 {
   buffer_del_line(curbuf->handle, curwin->w_cursor.lnum - 1, err);
 }
@@ -357,6 +369,7 @@ void nvim_del_current_line(Error *err)
 /// @param[out] err Error details, if any
 /// @return Variable value
 Object nvim_get_var(String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   return dict_get_value(&globvardict, name, err);
 }
@@ -367,6 +380,7 @@ Object nvim_get_var(String name, Error *err)
 /// @param value    Variable value
 /// @param[out] err Error details, if any
 void nvim_set_var(String name, Object value, Error *err)
+    FUNC_API_SINCE(1)
 {
   dict_set_var(&globvardict, name, value, false, false, err);
 }
@@ -376,6 +390,7 @@ void nvim_set_var(String name, Object value, Error *err)
 /// @param name     Variable name
 /// @param[out] err Error details, if any
 void nvim_del_var(String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   dict_set_var(&globvardict, name, NIL, true, false, err);
 }
@@ -414,6 +429,7 @@ Object vim_del_var(String name, Error *err)
 /// @param[out] err Error details, if any
 /// @return         Variable value
 Object nvim_get_vvar(String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   return dict_get_value(&vimvardict, name, err);
 }
@@ -424,6 +440,7 @@ Object nvim_get_vvar(String name, Error *err)
 /// @param[out] err Error details, if any
 /// @return         Option value
 Object nvim_get_option(String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   return get_option_from(NULL, SREQ_GLOBAL, name, err);
 }
@@ -434,6 +451,7 @@ Object nvim_get_option(String name, Error *err)
 /// @param value    New option value
 /// @param[out] err Error details, if any
 void nvim_set_option(String name, Object value, Error *err)
+    FUNC_API_SINCE(1)
 {
   set_option_to(NULL, SREQ_GLOBAL, name, value, err);
 }
@@ -442,6 +460,7 @@ void nvim_set_option(String name, Object value, Error *err)
 ///
 /// @param str Message
 void nvim_out_write(String str)
+    FUNC_API_SINCE(1)
 {
   write_msg(str, false);
 }
@@ -450,6 +469,7 @@ void nvim_out_write(String str)
 ///
 /// @param str Message
 void nvim_err_write(String str)
+    FUNC_API_SINCE(1)
 {
   write_msg(str, true);
 }
@@ -460,6 +480,7 @@ void nvim_err_write(String str)
 /// @param str Message
 /// @see nvim_err_write()
 void nvim_err_writeln(String str)
+    FUNC_API_SINCE(1)
 {
   nvim_err_write(str);
   nvim_err_write((String) { .data = "\n", .size = 1 });
@@ -469,6 +490,7 @@ void nvim_err_writeln(String str)
 ///
 /// @return List of buffer handles
 ArrayOf(Buffer) nvim_list_bufs(void)
+    FUNC_API_SINCE(1)
 {
   Array rv = ARRAY_DICT_INIT;
 
@@ -490,6 +512,7 @@ ArrayOf(Buffer) nvim_list_bufs(void)
 ///
 /// @return Buffer handle
 Buffer nvim_get_current_buf(void)
+    FUNC_API_SINCE(1)
 {
   return curbuf->handle;
 }
@@ -499,6 +522,7 @@ Buffer nvim_get_current_buf(void)
 /// @param id       Buffer handle
 /// @param[out] err Error details, if any
 void nvim_set_current_buf(Buffer buffer, Error *err)
+    FUNC_API_SINCE(1)
 {
   buf_T *buf = find_buffer_by_handle(buffer, err);
 
@@ -520,6 +544,7 @@ void nvim_set_current_buf(Buffer buffer, Error *err)
 ///
 /// @return List of window handles
 ArrayOf(Window) nvim_list_wins(void)
+    FUNC_API_SINCE(1)
 {
   Array rv = ARRAY_DICT_INIT;
 
@@ -541,6 +566,7 @@ ArrayOf(Window) nvim_list_wins(void)
 ///
 /// @return Window handle
 Window nvim_get_current_win(void)
+    FUNC_API_SINCE(1)
 {
   return curwin->handle;
 }
@@ -549,6 +575,7 @@ Window nvim_get_current_win(void)
 ///
 /// @param handle Window handle
 void nvim_set_current_win(Window window, Error *err)
+    FUNC_API_SINCE(1)
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -570,6 +597,7 @@ void nvim_set_current_win(Window window, Error *err)
 ///
 /// @return List of tabpage handles
 ArrayOf(Tabpage) nvim_list_tabpages(void)
+    FUNC_API_SINCE(1)
 {
   Array rv = ARRAY_DICT_INIT;
 
@@ -591,6 +619,7 @@ ArrayOf(Tabpage) nvim_list_tabpages(void)
 ///
 /// @return Tabpage handle
 Tabpage nvim_get_current_tabpage(void)
+    FUNC_API_SINCE(1)
 {
   return curtab->handle;
 }
@@ -600,6 +629,7 @@ Tabpage nvim_get_current_tabpage(void)
 /// @param handle   Tabpage handle
 /// @param[out] err Error details, if any
 void nvim_set_current_tabpage(Tabpage tabpage, Error *err)
+    FUNC_API_SINCE(1)
 {
   tabpage_T *tp = find_tab_by_handle(tabpage, err);
 
@@ -622,7 +652,7 @@ void nvim_set_current_tabpage(Tabpage tabpage, Error *err)
 /// @param channel_id Channel id (passed automatically by the dispatcher)
 /// @param event      Event type string
 void nvim_subscribe(uint64_t channel_id, String event)
-    FUNC_API_NOEVAL
+    FUNC_API_SINCE(1) FUNC_API_NOEVAL
 {
   size_t length = (event.size < METHOD_MAXLEN ? event.size : METHOD_MAXLEN);
   char e[METHOD_MAXLEN + 1];
@@ -636,7 +666,7 @@ void nvim_subscribe(uint64_t channel_id, String event)
 /// @param channel_id Channel id (passed automatically by the dispatcher)
 /// @param event      Event type string
 void nvim_unsubscribe(uint64_t channel_id, String event)
-    FUNC_API_NOEVAL
+    FUNC_API_SINCE(1) FUNC_API_NOEVAL
 {
   size_t length = (event.size < METHOD_MAXLEN ?
                    event.size :
@@ -648,11 +678,13 @@ void nvim_unsubscribe(uint64_t channel_id, String event)
 }
 
 Integer nvim_get_color_by_name(String name)
+    FUNC_API_SINCE(1)
 {
   return name_to_color((uint8_t *)name.data);
 }
 
 Dictionary nvim_get_color_map(void)
+    FUNC_API_SINCE(1)
 {
   Dictionary colors = ARRAY_DICT_INIT;
 
@@ -665,7 +697,7 @@ Dictionary nvim_get_color_map(void)
 
 
 Array nvim_get_api_info(uint64_t channel_id)
-    FUNC_API_ASYNC FUNC_API_NOEVAL
+    FUNC_API_SINCE(1) FUNC_API_ASYNC FUNC_API_NOEVAL
 {
   Array rv = ARRAY_DICT_INIT;
 
@@ -698,7 +730,7 @@ Array nvim_get_api_info(uint64_t channel_id)
 /// which resulted in an error, the error type and the error message. If an
 /// error ocurred, the values from all preceding calls will still be returned.
 Array nvim_call_atomic(uint64_t channel_id, Array calls, Error *err)
-  FUNC_API_NOEVAL
+    FUNC_API_SINCE(1) FUNC_API_NOEVAL
 {
   Array rv = ARRAY_DICT_INIT;
   Array results = ARRAY_DICT_INIT;
diff --git a/src/nvim/api/window.c b/src/nvim/api/window.c
index 13294e6bf2..3c564ada99 100644
--- a/src/nvim/api/window.c
+++ b/src/nvim/api/window.c
@@ -19,6 +19,7 @@
 /// @param[out] err Error details, if any
 /// @return Buffer handle
 Buffer nvim_win_get_buf(Window window, Error *err)
+    FUNC_API_SINCE(1)
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -35,6 +36,7 @@ Buffer nvim_win_get_buf(Window window, Error *err)
 /// @param[out] err Error details, if any
 /// @return (row, col) tuple
 ArrayOf(Integer, 2) nvim_win_get_cursor(Window window, Error *err)
+    FUNC_API_SINCE(1)
 {
   Array rv = ARRAY_DICT_INIT;
   win_T *win = find_window_by_handle(window, err);
@@ -53,6 +55,7 @@ ArrayOf(Integer, 2) nvim_win_get_cursor(Window window, Error *err)
 /// @param pos      (row, col) tuple representing the new position
 /// @param[out] err Error details, if any
 void nvim_win_set_cursor(Window window, ArrayOf(Integer, 2) pos, Error *err)
+    FUNC_API_SINCE(1)
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -99,6 +102,7 @@ void nvim_win_set_cursor(Window window, ArrayOf(Integer, 2) pos, Error *err)
 /// @param[out] err Error details, if any
 /// @return Height as a count of rows
 Integer nvim_win_get_height(Window window, Error *err)
+    FUNC_API_SINCE(1)
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -116,6 +120,7 @@ Integer nvim_win_get_height(Window window, Error *err)
 /// @param height   Height as a count of rows
 /// @param[out] err Error details, if any
 void nvim_win_set_height(Window window, Integer height, Error *err)
+    FUNC_API_SINCE(1)
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -142,6 +147,7 @@ void nvim_win_set_height(Window window, Integer height, Error *err)
 /// @param[out] err Error details, if any
 /// @return Width as a count of columns
 Integer nvim_win_get_width(Window window, Error *err)
+    FUNC_API_SINCE(1)
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -159,6 +165,7 @@ Integer nvim_win_get_width(Window window, Error *err)
 /// @param width    Width as a count of columns
 /// @param[out] err Error details, if any
 void nvim_win_set_width(Window window, Integer width, Error *err)
+    FUNC_API_SINCE(1)
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -186,6 +193,7 @@ void nvim_win_set_width(Window window, Integer width, Error *err)
 /// @param[out] err Error details, if any
 /// @return Variable value
 Object nvim_win_get_var(Window window, String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -203,6 +211,7 @@ Object nvim_win_get_var(Window window, String name, Error *err)
 /// @param value    Variable value
 /// @param[out] err Error details, if any
 void nvim_win_set_var(Window window, String name, Object value, Error *err)
+    FUNC_API_SINCE(1)
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -219,6 +228,7 @@ void nvim_win_set_var(Window window, String name, Object value, Error *err)
 /// @param name     Variable name
 /// @param[out] err Error details, if any
 void nvim_win_del_var(Window window, String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -278,6 +288,7 @@ Object window_del_var(Window window, String name, Error *err)
 /// @param[out] err Error details, if any
 /// @return Option value
 Object nvim_win_get_option(Window window, String name, Error *err)
+    FUNC_API_SINCE(1)
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -296,6 +307,7 @@ Object nvim_win_get_option(Window window, String name, Error *err)
 /// @param value    Option value
 /// @param[out] err Error details, if any
 void nvim_win_set_option(Window window, String name, Object value, Error *err)
+    FUNC_API_SINCE(1)
 {
   win_T *win = find_window_by_handle(window, err);
 
@@ -312,6 +324,7 @@ void nvim_win_set_option(Window window, String name, Object value, Error *err)
 /// @param[out] err Error details, if any
 /// @return (row, col) tuple with the window position
 ArrayOf(Integer, 2) nvim_win_get_position(Window window, Error *err)
+    FUNC_API_SINCE(1)
 {
   Array rv = ARRAY_DICT_INIT;
   win_T *win = find_window_by_handle(window, err);
@@ -330,6 +343,7 @@ ArrayOf(Integer, 2) nvim_win_get_position(Window window, Error *err)
 /// @param[out] err Error details, if any
 /// @return Tabpage that contains the window
 Tabpage nvim_win_get_tabpage(Window window, Error *err)
+    FUNC_API_SINCE(1)
 {
   Tabpage rv = 0;
   win_T *win = find_window_by_handle(window, err);
@@ -347,6 +361,7 @@ Tabpage nvim_win_get_tabpage(Window window, Error *err)
 /// @param[out] err Error details, if any
 /// @return Window number
 Integer nvim_win_get_number(Window window, Error *err)
+    FUNC_API_SINCE(1)
 {
   int rv = 0;
   win_T *win = find_window_by_handle(window, err);
@@ -366,6 +381,7 @@ Integer nvim_win_get_number(Window window, Error *err)
 /// @param window Window handle
 /// @return true if the window is valid, false otherwise
 Boolean nvim_win_is_valid(Window window)
+    FUNC_API_SINCE(1)
 {
   Error stub = ERROR_INIT;
   return find_window_by_handle(window, &stub) != NULL;
diff --git a/src/nvim/func_attr.h b/src/nvim/func_attr.h
index d98fe5b22b..18410445e1 100644
--- a/src/nvim/func_attr.h
+++ b/src/nvim/func_attr.h
@@ -186,6 +186,7 @@
 # define FUNC_API_ASYNC
 # define FUNC_API_NOEXPORT
 # define FUNC_API_NOEVAL
+# define FUNC_API_SINCE(X)
 # define FUNC_ATTR_MALLOC REAL_FATTR_MALLOC
 # define FUNC_ATTR_ALLOC_SIZE(x) REAL_FATTR_ALLOC_SIZE(x)
 # define FUNC_ATTR_ALLOC_SIZE_PROD(x, y) REAL_FATTR_ALLOC_SIZE_PROD(x, y)
diff --git a/test/functional/api/version_spec.lua b/test/functional/api/version_spec.lua
index 3efd00ddbe..d23f058f69 100644
--- a/test/functional/api/version_spec.lua
+++ b/test/functional/api/version_spec.lua
@@ -4,26 +4,16 @@ local clear, funcs, eq = helpers.clear, helpers.funcs, helpers.eq
 
 local function read_mpack_file(fname)
   local fd = io.open(fname, 'rb')
+  if fd == nil then
+    return nil
+  end
+
   local data = fd:read('*a')
   fd:close()
   local unpack = mpack.Unpacker()
   return unpack(data)
 end
 
--- Remove metadata that is not essential to backwards-compatibility.
-local function remove_function_metadata(fspec)
-  fspec['can_fail'] = nil
-  fspec['async'] = nil
-  fspec['method'] = nil
-  fspec['since'] = nil
-  fspec['deprecated_since'] = nil
-  fspec['receives_channel_id'] = nil
-  for idx, _ in ipairs(fspec['parameters']) do
-    fspec['parameters'][idx][2] = ''  -- Remove parameter name.
-  end
-  return fspec
-end
-
 describe("api_info()['version']", function()
   before_each(clear)
 
@@ -49,23 +39,111 @@ describe("api_info()['version']", function()
     eq(0, funcs.has("nvim-"..major.."."..(minor + 1).."."..patch))
     eq(0, funcs.has("nvim-"..(major + 1).."."..minor.."."..patch))
   end)
+end)
+
+
+describe("api functions", function()
+  before_each(clear)
+
+  local function func_table(metadata)
+    local functions = {}
+    for _,f in ipairs(metadata.functions) do
+      functions[f.name] = f
+    end
+    return functions
+  end
+
+  -- Remove metadata that is not essential to backwards-compatibility.
+  local function filter_function_metadata(f)
+    f.deprecated_since = nil
+    for idx, _ in ipairs(f.parameters) do
+      f.parameters[idx][2] = ''  -- Remove parameter name.
+    end
+
+    if string.sub(f.name, 1, 4) ~= "nvim" then
+      f.method = nil
+    end
+    return f
+  end
 
-  it("api_compatible level is valid", function()
-    local api     = helpers.call('api_info')
-    local compat  = api['version']['api_compatible']
-    local path    = 'test/functional/fixtures/api_level_'
-                    ..tostring(compat)..'.mpack'
-
-    -- Verify that the current API function signatures match those of the API
-    -- level for which we claim compatibility.
-    local old_api = read_mpack_file(path)
-    for _, fn_old in ipairs(old_api['functions']) do
-      for _, fn_new in ipairs(api['functions']) do
-        if fn_old['name'] == fn_new['name'] then
-          eq(remove_function_metadata(fn_old),
-             remove_function_metadata(fn_new))
+  -- Level 0 represents methods from 0.1.5 and earlier, when 'since' was not
+  -- yet defined, and metadata was not filtered of internal keys like 'async'.
+  local function clean_level_0(metadata)
+    for _, f in ipairs(metadata.functions) do
+      f.can_fail = nil
+      f.async = nil
+      f.receives_channel_id = nil
+      f.since = 0
+    end
+  end
+
+  it("are compatible with old metadata or have new level", function()
+    local api = helpers.call('api_info')
+    local compat  = api.version.api_compatible
+    local api_level = api.version.api_level
+    local stable
+    if api.version.api_prerelease then
+      stable = api_level-1
+    else
+      stable = api_level
+    end
+
+    local funcs_new = func_table(api)
+    local funcs_compat = {}
+    for level = compat, stable do
+      local path = ('test/functional/fixtures/api_level_'..
+                   tostring(level)..'.mpack')
+      local old_api = read_mpack_file(path)
+      if old_api == nil then
+        local errstr = "missing metadata fixture for stable level "..level..". "
+        if level == api_level and not api.version.api_prerelease then
+          errstr = (errstr.."If NVIM_API_CURRENT was bumped, "..
+                    "don't forget to set NVIM_API_PRERELEASE to true.")
+        end
+        error(errstr)
+      end
+
+      if level == 0 then
+        clean_level_0(old_api)
+      end
+
+      for _,f in ipairs(old_api.functions) do
+        if funcs_new[f.name] == nil then
+          if f.since >= compat then
+            error('function '..f.name..' was removed but exists in level '..
+                  f.since..' which nvim should be compatible with')
+          end
+        else
+          eq(filter_function_metadata(f),
+             filter_function_metadata(funcs_new[f.name]))
+        end
+      end
+
+      funcs_compat[level] = func_table(old_api)
+    end
+
+    for _,f in ipairs(api.functions) do
+      if f.since <= stable then
+        local f_old = funcs_compat[f.since][f.name]
+        if f_old == nil then
+          if string.sub(f.name, 1, 4) == "nvim" then
+            local errstr = ("function "..f.name.." has too low since value. "..
+                            "For new functions set it to "..(stable+1)..".")
+            if not api.version.api_prerelease then
+              errstr = (errstr.." Also bump NVIM_API_CURRENT and set "..
+                        "NVIM_API_PRERELEASE to true in CMakeLists.txt.")
+            end
+            error(errstr)
+          else
+            error("function name '"..f.name.."' doesn't begin with 'nvim_'")
+          end
         end
+      elseif f.since > api_level then
+        error("function "..f.name.." has since value > api_level. "..
+             "Please bump NVIM_API_CURRENT and set "..
+             "NVIM_API_PRERELEASE to true in CMakeLists.txt.")
       end
     end
   end)
+
 end)
diff --git a/test/functional/fixtures/api_level_1.mpack b/test/functional/fixtures/api_level_1.mpack
new file mode 100644
index 0000000000..66ea9c2e5d
--- /dev/null
+++ b/test/functional/fixtures/api_level_1.mpack