patch 8.2.4050: Vim9: need to prefix every item in an autoload scriptv8.2.4050

Problem:    Vim9: need to prefix every item in an autoload script.
Solution:   First step in supporting "vim9script autoload" and "import
            autoload".

15 files changed, 403 insertions, 118 deletions

diff --git a/runtime/doc/repeat.txt b/runtime/doc/repeat.txt
index 25f375e6f..407c23c23 100644
--- a/runtime/doc/repeat.txt
+++ b/runtime/doc/repeat.txt
@@ -365,11 +365,12 @@ For writing a Vim script, see chapter 41 of the user manual |usr_41.txt|.
 			Vim version, or update Vim to a newer version.  See
 			|vimscript-version| for what changed between versions.
 
-:vim9s[cript] [noclear]				*:vim9s* *:vim9script*
+:vim9s[cript] [noclear] [autoload]			*:vim9s* *:vim9script*
 			Marks a script file as containing |Vim9-script|
 			commands.  Also see |vim9-namespace|.
 			Must be the first command in the file.
 			For [noclear] see |vim9-reload|.
+			For [autoload] see |vim9-autoload|.
 			Without the |+eval| feature this changes the syntax
 			for some commands.
 			See |:vim9cmd| for executing one command with Vim9
diff --git a/runtime/doc/vim9.txt b/runtime/doc/vim9.txt
index 0af6dff33..8942466e3 100644
--- a/runtime/doc/vim9.txt
+++ b/runtime/doc/vim9.txt
@@ -1501,37 +1501,43 @@ result in undefined items.
 
 
 Import in an autoload script ~
-
+							*vim9-autoload*
 For optimal startup speed, loading scripts should be postponed until they are
-actually needed.  A recommended mechanism:
+actually needed.  Using the autoload mechanism is recommended:
 
 1. In the plugin define user commands, functions and/or mappings that refer to
-   an autoload script. >
-	command -nargs=1 SearchForStuff searchfor#Stuff(<f-args>)
+   items imported from an autoload script. >
+	import autoload 'for/search.vim'
+	command -nargs=1 SearchForStuff search.Stuff(<f-args>)
 
 <   This goes in .../plugin/anyname.vim.  "anyname.vim" can be freely chosen.
+   The "SearchForStuff" command is now available to the user.
 
-2. In the autoload script do the actual work.  You can import items from
-   other files to split up functionality in appropriate pieces. >
-	vim9script
-	import "../import/someother.vim" as other
-	def searchfor#Stuff(arg: string)
-	  var filtered = other.FilterFunc(arg)
+   The "autoload" argument to `:import` means that the script is not loaded
+   until one of the items is actually used.  The script will be found under
+   the "autoload" directory in 'runtimepath' instead of the "import"
+   directory.
+
+2. In the autoload script put the bulk of the code. >
+	vim9script autoload
+	export def Stuff(arg: string)
 	  ...
-<   This goes in .../autoload/searchfor.vim.  "searchfor" in the file name
-   must be exactly the same as the prefix for the function name, that is how
-   Vim finds the file.
 
-3. Other functionality, possibly shared between plugins, contains the exported
-   items and any private items. >
-	vim9script
-	var localVar = 'local'
-	export def FilterFunc(arg: string): string
-	   ...
-<   This goes in .../import/someother.vim.
+<   This goes in .../autoload/for/search.vim.
+
+   Adding "autoload" to `:vim9script` has the effect that "for#search#" will
+   be prefixed to every exported item.  The prefix is obtained from the file
+   name, as you would to manually in a legacy autoload script.  Thus the
+   exported function can be found with "for#search#Stuff", but you would
+   normally use `import autoload` and not need to specify the prefix.
+
+   You can split up the functionality and import other scripts from the
+   autoload script as you like.  This way you can share code between plugins.
 
 When compiling a `:def` function and a function in an autoload script is
 encountered, the script is not loaded until the `:def` function is called.
+This also means you get any errors only at runtime, since the argument and
+return types are not known yet.
 
 
 Import in legacy Vim script ~
diff --git a/src/errors.h b/src/errors.h
index d30b4b0f0..7059b28da 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -3203,4 +3203,8 @@ EXTERN char e_cannot_import_dot_vim_without_using_as[]
 	INIT(= N_("E1261: Cannot import .vim without using \"as\""));
 EXTERN char e_cannot_import_same_script_twice_str[]
 	INIT(= N_("E1262: Cannot import the same script twice: %s"));
+EXTERN char e_using_autoload_in_script_not_under_autoload_directory[]
+	INIT(= N_("E1263: Using autoload in a script not under an autoload directory"));
+EXTERN char e_autoload_import_cannot_use_absolute_or_relative_path[]
+	INIT(= N_("E1264: Autoload import cannot use absolute or relative path: %s"));
 #endif
diff --git a/src/eval.c b/src/eval.c
index 390bb5811..7a23876f9 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -886,7 +886,9 @@ get_lval(
 
     if (*p == '.' && in_vim9script())
     {
-	imported_T *import = find_imported(lp->ll_name, p - lp->ll_name, NULL);
+	imported_T *import = find_imported(lp->ll_name, p - lp->ll_name,
+								   TRUE, NULL);
+
 	if (import != NULL)
 	{
 	    ufunc_T *ufunc;
diff --git a/src/evalvars.c b/src/evalvars.c
index d93fed5b0..1d5aedf4c 100644
--- a/src/evalvars.c
+++ b/src/evalvars.c
@@ -2683,7 +2683,7 @@ eval_variable(
 	char_u	    *p = STRNCMP(name, "s:", 2) == 0 ? name + 2 : name;
 
 	if (sid == 0)
-	    import = find_imported(p, 0, NULL);
+	    import = find_imported(p, 0, TRUE, NULL);
 
 	// imported variable from another script
 	if (import != NULL || sid != 0)
@@ -3015,7 +3015,7 @@ lookup_scriptitem(
     res = HASHITEM_EMPTY(hi) ? FAIL : OK;
 
     // if not script-local, then perhaps imported
-    if (res == FAIL && find_imported(p, 0, NULL) != NULL)
+    if (res == FAIL && find_imported(p, 0, FALSE, NULL) != NULL)
 	res = OK;
     if (p != buffer)
 	vim_free(p);
@@ -3388,7 +3388,7 @@ set_var_const(
 
     if (di == NULL && var_in_vim9script)
     {
-	imported_T  *import = find_imported(varname, 0, NULL);
+	imported_T  *import = find_imported(varname, 0, FALSE, NULL);
 
 	if (import != NULL)
 	{
diff --git a/src/proto/scriptfile.pro b/src/proto/scriptfile.pro
index cbb9253c5..140d67bbb 100644
--- a/src/proto/scriptfile.pro
+++ b/src/proto/scriptfile.pro
@@ -10,6 +10,7 @@ int do_in_path(char_u *path, char_u *name, int flags, void (*callback)(char_u *f
 int do_in_runtimepath(char_u *name, int flags, void (*callback)(char_u *fname, void *ck), void *cookie);
 int source_runtime(char_u *name, int flags);
 int source_in_path(char_u *path, char_u *name, int flags, int *ret_sid);
+int find_script_in_rtp(char_u *name);
 void add_pack_start_dirs(void);
 void load_start_packages(void);
 void ex_packloadall(exarg_T *eap);
@@ -36,6 +37,8 @@ void ex_scriptversion(exarg_T *eap);
 void ex_finish(exarg_T *eap);
 void do_finish(exarg_T *eap, int reanimate);
 int source_finished(char_u *(*fgetline)(int, void *, int, getline_opt_T), void *cookie);
+char_u *script_name_after_autoload(scriptitem_T *si);
+char_u *may_prefix_autoload(char_u *name);
 char_u *autoload_name(char_u *name);
 int script_autoload(char_u *name, int reload);
 /* vim: set ft=c : */
diff --git a/src/proto/vim9compile.pro b/src/proto/vim9compile.pro
index 98c40c86c..cb95fdfb6 100644
--- a/src/proto/vim9compile.pro
+++ b/src/proto/vim9compile.pro
@@ -7,7 +7,7 @@ int check_defined(char_u *p, size_t len, cctx_T *cctx, int is_arg);
 int need_type(type_T *actual, type_T *expected, int offset, int arg_idx, cctx_T *cctx, int silent, int actual_is_const);
 lvar_T *reserve_local(cctx_T *cctx, char_u *name, size_t len, int isConst, type_T *type);
 int get_script_item_idx(int sid, char_u *name, int check_writable, cctx_T *cctx);
-imported_T *find_imported(char_u *name, size_t len, cctx_T *cctx);
+imported_T *find_imported(char_u *name, size_t len, int load, cctx_T *cctx);
 char_u *may_peek_next_line(cctx_T *cctx, char_u *arg, char_u **nextp);
 char_u *peek_next_line_from_context(cctx_T *cctx);
 char_u *next_line_from_context(cctx_T *cctx, int skip_comment);
diff --git a/src/scriptfile.c b/src/scriptfile.c
index c10a82f2c..c1ab41503 100644
--- a/src/scriptfile.c
+++ b/src/scriptfile.c
@@ -239,6 +239,102 @@ source_callback(char_u *fname, void *cookie)
     (void)do_source(fname, FALSE, DOSO_NONE, cookie);
 }
 
+#ifdef FEAT_EVAL
+/*
+ * Find an already loaded script "name".
+ * If found returns its script ID.  If not found returns -1.
+ */
+    static int
+find_script_by_name(char_u *name)
+{
+    int		    sid;
+    scriptitem_T    *si;
+
+    for (sid = script_items.ga_len; sid > 0; --sid)
+    {
+	// We used to check inode here, but that doesn't work:
+	// - If a script is edited and written, it may get a different
+	//   inode number, even though to the user it is the same script.
+	// - If a script is deleted and another script is written, with a
+	//   different name, the inode may be re-used.
+	si = SCRIPT_ITEM(sid);
+	if (si->sn_name != NULL && fnamecmp(si->sn_name, name) == 0)
+	    return sid;
+    }
+    return -1;
+}
+
+/*
+ * Add a new scriptitem with all items initialized.
+ * When running out of memory "error" is set to FAIL.
+ * Returns the script ID.
+ */
+    static int
+get_new_scriptitem(int *error)
+{
+    static scid_T   last_current_SID = 0;
+    int		    sid = ++last_current_SID;
+    scriptitem_T    *si;
+
+    if (ga_grow(&script_items, (int)(sid - script_items.ga_len)) == FAIL)
+    {
+	*error = FAIL;
+	return sid;
+    }
+    while (script_items.ga_len < sid)
+    {
+	si = ALLOC_CLEAR_ONE(scriptitem_T);
+	if (si == NULL)
+	{
+	    *error = FAIL;
+	    return sid;
+	}
+	++script_items.ga_len;
+	SCRIPT_ITEM(script_items.ga_len) = si;
+	si->sn_name = NULL;
+	si->sn_version = 1;
+
+	// Allocate the local script variables to use for this script.
+	new_script_vars(script_items.ga_len);
+	ga_init2(&si->sn_var_vals, sizeof(svar_T), 10);
+	hash_init(&si->sn_all_vars.dv_hashtab);
+	ga_init2(&si->sn_imports, sizeof(imported_T), 10);
+	ga_init2(&si->sn_type_list, sizeof(type_T), 10);
+# ifdef FEAT_PROFILE
+	si->sn_prof_on = FALSE;
+# endif
+    }
+
+    // Used to check script variable index is still valid.
+    si->sn_script_seq = current_sctx.sc_seq;
+
+    return sid;
+}
+
+    static void
+find_script_callback(char_u *fname, void *cookie)
+{
+    int sid;
+    int error = OK;
+    int *ret_sid = cookie;
+
+    sid = find_script_by_name(fname);
+    if (sid < 0)
+    {
+	// script does not exist yet, create a new scriptitem
+	sid = get_new_scriptitem(&error);
+	if (error == OK)
+	{
+	    scriptitem_T *si = SCRIPT_ITEM(sid);
+
+	    si->sn_name = vim_strsave(fname);
+	    si->sn_state = SN_STATE_NOT_LOADED;
+	}
+    }
+    *ret_sid = sid;
+}
+#endif
+
 /*
  * Find the file "name" in all directories in "path" and invoke
  * "callback(fname, cookie)".
@@ -455,7 +551,8 @@ source_runtime(char_u *name, int flags)
 }
 
 /*
- * Just like source_runtime(), but use "path" instead of 'runtimepath'.
+ * Just like source_runtime(), but use "path" instead of 'runtimepath'
+ * and return the script ID in "ret_sid".
  */
     int
 source_in_path(char_u *path, char_u *name, int flags, int *ret_sid)
@@ -463,10 +560,24 @@ source_in_path(char_u *path, char_u *name, int flags, int *ret_sid)
     return do_in_path_and_pp(path, name, flags, source_callback, ret_sid);
 }
 
-
 #if defined(FEAT_EVAL) || defined(PROTO)
 
 /*
+ * Find "name" in 'runtimepath'. If found a new scriptitem is created for it
+ * and it's script ID is returned.
+ * If not found returns -1.
+ */
+    int
+find_script_in_rtp(char_u *name)
+{
+    int sid = -1;
+
+    (void)do_in_path_and_pp(p_rtp, name, DIP_NOAFTER,
+						   find_script_callback, &sid);
+    return sid;
+}
+
+/*
  * Expand wildcards in "pat" and invoke do_source() for each match.
  */
     static void
@@ -1127,7 +1238,6 @@ do_source(
     int			    retval = FAIL;
     sctx_T		    save_current_sctx;
 #ifdef FEAT_EVAL
-    static scid_T	    last_current_SID = 0;
     static int		    last_current_SID_seq = 0;
     funccal_entry_T	    funccalp_entry;
     int			    save_debug_break_level = debug_break_level;
@@ -1161,18 +1271,7 @@ do_source(
     estack_compiling = FALSE;
 
     // See if we loaded this script before.
-    for (sid = script_items.ga_len; sid > 0; --sid)
-    {
-	// We used to check inode here, but that doesn't work:
-	// - If a script is edited and written, it may get a different
-	//   inode number, even though to the user it is the same script.
-	// - If a script is deleted and another script is written, with a
-	//   different name, the inode may be re-used.
-	si = SCRIPT_ITEM(sid);
-	if (si->sn_name != NULL && fnamecmp(si->sn_name, fname_exp) == 0)
-		// Found it!
-		break;
-    }
+    sid = find_script_by_name(fname_exp);
     if (sid > 0 && ret_sid != NULL)
     {
 	// Already loaded and no need to load again, return here.
@@ -1318,54 +1417,44 @@ do_source(
 	dictitem_T	*di;
 
 	// loading the same script again
-	si->sn_state = SN_STATE_RELOAD;
 	current_sctx.sc_sid = sid;
+	si = SCRIPT_ITEM(sid);
+	if (si->sn_state == SN_STATE_NOT_LOADED)
+	{
+	    // this script was found but not loaded yet
+	    si->sn_state = SN_STATE_NEW;
+	}
+	else
+	{
+	    si->sn_state = SN_STATE_RELOAD;
+
+	    // Script-local variables remain but "const" can be set again.
+	    // In Vim9 script variables will be cleared when "vim9script" is
+	    // encountered without the "noclear" argument.
+	    ht = &SCRIPT_VARS(sid);
+	    todo = (int)ht->ht_used;
+	    for (hi = ht->ht_array; todo > 0; ++hi)
+		if (!HASHITEM_EMPTY(hi))
+		{
+		    --todo;
+		    di = HI2DI(hi);
+		    di->di_flags |= DI_FLAGS_RELOAD;
+		}
+	    // imports can be redefined once
+	    mark_imports_for_reload(sid);
 
-	// Script-local variables remain but "const" can be set again.
-	// In Vim9 script variables will be cleared when "vim9script" is
-	// encountered without the "noclear" argument.
-	ht = &SCRIPT_VARS(sid);
-	todo = (int)ht->ht_used;
-	for (hi = ht->ht_array; todo > 0; ++hi)
-	    if (!HASHITEM_EMPTY(hi))
-	    {
-		--todo;
-		di = HI2DI(hi);
-		di->di_flags |= DI_FLAGS_RELOAD;
-	    }
-	// imports can be redefined once
-	mark_imports_for_reload(sid);
-
-	// reset version, "vim9script" may have been added or removed.
-	si->sn_version = 1;
+	    // reset version, "vim9script" may have been added or removed.
+	    si->sn_version = 1;
+	}
     }
     else
     {
-	// It's new, generate a new SID.
-	current_sctx.sc_sid = ++last_current_SID;
-	if (ga_grow(&script_items,
-		     (int)(current_sctx.sc_sid - script_items.ga_len)) == FAIL)
-	    goto almosttheend;
-	while (script_items.ga_len < current_sctx.sc_sid)
-	{
-	    si = ALLOC_CLEAR_ONE(scriptitem_T);
-	    if (si == NULL)
-		goto almosttheend;
-	    ++script_items.ga_len;
-	    SCRIPT_ITEM(script_items.ga_len) = si;
-	    si->sn_name = NULL;
-	    si->sn_version = 1;
+	int error = OK;
 
-	    // Allocate the local script variables to use for this script.
-	    new_script_vars(script_items.ga_len);
-	    ga_init2(&si->sn_var_vals, sizeof(svar_T), 10);
-	    hash_init(&si->sn_all_vars.dv_hashtab);
-	    ga_init2(&si->sn_imports, sizeof(imported_T), 10);
-	    ga_init2(&si->sn_type_list, sizeof(type_T), 10);
-# ifdef FEAT_PROFILE
-	    si->sn_prof_on = FALSE;
-# endif
-	}
+	// It's new, generate a new SID and initialize the scriptitem.
+	current_sctx.sc_sid = get_new_scriptitem(&error);
+	if (error == FAIL)
+	    goto almosttheend;
 	si = SCRIPT_ITEM(current_sctx.sc_sid);
 	si->sn_name = fname_exp;
 	fname_exp = vim_strsave(si->sn_name);  // used for autocmd
@@ -1374,9 +1463,6 @@ do_source(
 
 	// Remember the "is_vimrc" flag for when the file is sourced again.
 	si->sn_is_vimrc = is_vimrc;
-
-	// Used to check script variable index is still valid.
-	si->sn_script_seq = current_sctx.sc_seq;
     }
 
 # ifdef FEAT_PROFILE
@@ -2031,6 +2117,78 @@ source_finished(
 }
 
 /*
+ * Find the path of a script below the "autoload" directory.
+ * Returns NULL if there is no "/autoload/" in the script name.
+ */
+    char_u *
+script_name_after_autoload(scriptitem_T *si)
+{
+    char_u	*p = si->sn_name;
+    char_u	*res = NULL;
+
+    for (;;)
+    {
+	char_u *n = (char_u *)strstr((char *)p, "autoload");
+
+	if (n == NULL)
+	    break;
+	if (n > p && vim_ispathsep(n[-1]) && vim_ispathsep(n[8]))
+	    res = n + 9;
+	p = n + 8;
+    }
+    return res;
+}
+
+/*
+ * If in a Vim9 autoload script return "name" with the autoload prefix for the
+ * script.  If successful "name" is freed, the returned name is allocated.
+ * Otherwise it returns "name" unmodified.
+ */
+    char_u *
+may_prefix_autoload(char_u *name)
+{
+    if (SCRIPT_ID_VALID(current_sctx.sc_sid))
+    {
+	scriptitem_T *si = SCRIPT_ITEM(current_sctx.sc_sid);
+
+	if (si->sn_is_autoload)
+	{
+	    char_u *p = script_name_after_autoload(si);
+
+	    if (p != NULL)
+	    {
+		char_u *tail = vim_strsave(p);
+
+		if (tail != NULL)
+		{
+		    for (p = tail; *p != NUL; p += mb_ptr2len(p))
+		    {
+			if (vim_ispathsep(*p))
+			    *p = '#';
+			else if (STRCMP(p, ".vim"))
+			{
+			    size_t  len = (p - tail) + STRLEN(name) + 2;
+			    char_u  *res = alloc(len);
+
+			    if (res == NULL)
+				break;
+			    *p = NUL;
+			    vim_snprintf((char *)res, len, "%s#%s", tail, name);
+			    vim_free(name);
+			    vim_free(tail);
+			    return res;
+			}
+		    }
+		}
+		// did not find ".vim" at the end
+		vim_free(tail);
+	    }
+	}
+    }
+    return name;
+}
+
+/*
  * Return the autoload script name for a function or variable name.
  * Returns NULL when out of memory.
  * Caller must make sure that "name" contains AUTOLOAD_CHAR.
diff --git a/src/structs.h b/src/structs.h
index 9d5768175..fd4be4fe9 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1827,6 +1827,7 @@ typedef struct {
 } imported_T;
 
 #define IMP_FLAGS_RELOAD	2   // script reloaded, OK to redefine
+#define IMP_FLAGS_AUTOLOAD	4   // script still needs to be loaded
 
 /*
  * Info about an already sourced scripts.
@@ -1863,6 +1864,7 @@ typedef struct
     int		sn_state;	// SN_STATE_ values
     char_u	*sn_save_cpo;	// 'cpo' value when :vim9script found
     char	sn_is_vimrc;	// .vimrc file, do not restore 'cpo'
+    char	sn_is_autoload;	// "vim9script autoload"
 
 # ifdef FEAT_PROFILE
     int		sn_prof_on;	// TRUE when script is/was profiled
@@ -1886,7 +1888,8 @@ typedef struct
 } scriptitem_T;
 
 #define SN_STATE_NEW		0   // newly loaded script, nothing done
-#define SN_STATE_RELOAD		1   // script loaded before, nothing done
+#define SN_STATE_NOT_LOADED	1   // script located but not loaded
+#define SN_STATE_RELOAD		2   // script loaded before, nothing done
 #define SN_STATE_HAD_COMMAND	9   // a command was executed
 
 // Struct passed through eval() functions.
diff --git a/src/testdir/test_vim9_script.vim b/src/testdir/test_vim9_script.vim
index 8c7f85f16..97a51a51c 100644
--- a/src/testdir/test_vim9_script.vim
+++ b/src/testdir/test_vim9_script.vim
@@ -3032,6 +3032,26 @@ def Test_vim9_autoload()
   writefile(lines, 'Xdir/autoload/Other.vim')
   assert_equal('other', g:Other#getOther())
 
+  # using "vim9script autoload" prefix is not needed
+  lines =<< trim END
+     vim9script autoload
+     g:prefixed_loaded = 'yes'
+     export def Gettest(): string
+       return 'test'
+     enddef
+     export var name = 'name'
+  END
+  writefile(lines, 'Xdir/autoload/prefixed.vim')
+
+  lines =<< trim END
+      vim9script
+      import autoload 'prefixed.vim'
+      assert_false(exists('g:prefixed_loaded'))
+      assert_equal('test', prefixed.Gettest())
+      assert_equal('yes', g:prefixed_loaded)
+  END
+  CheckScriptSuccess(lines)
+
   delete('Xdir', 'rf')
   &rtp = save_rtp
 enddef
diff --git a/src/userfunc.c b/src/userfunc.c
index b772913f1..ecd2e7c1a 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -1608,7 +1608,7 @@ deref_func_name(
 	    p = name + 2;
 	    len -= 2;
 	}
-	import = find_imported(p, len, NULL);
+	import = find_imported(p, len, FALSE, NULL);
 
 	// imported function from another script
 	if (import != NULL)
@@ -4079,6 +4079,9 @@ define_function(exarg_T *eap, char_u *name_arg, garray_T *lines_to_free)
 	    else
 		eap->skip = TRUE;
 	}
+
+//	if (is_export)
+//	    name = may_prefix_autoload(name);
     }
 
     // An error in a function call during evaluation of an expression in magic
@@ -4363,7 +4366,7 @@ define_function(exarg_T *eap, char_u *name_arg, garray_T *lines_to_free)
 	{
 	    char_u *uname = untrans_function_name(name);
 
-	    import = find_imported(uname == NULL ? name : uname, 0, NULL);
+	    import = find_imported(uname == NULL ? name : uname, 0, FALSE, NULL);
 	}
 
 	if (fp != NULL || import != NULL)
diff --git a/src/version.c b/src/version.c
index cf0665c02..a2ce58e4b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4050,
+/**/
     4049,
 /**/
     4048,
diff --git a/src/vim9compile.c b/src/vim9compile.c
index 11e322645..993bb1c68 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -268,7 +268,7 @@ variable_exists(char_u *name, size_t len, cctx_T *cctx)
 		&& (lookup_local(name, len, NULL, cctx) == OK
 		    || arg_exists(name, len, NULL, NULL, NULL, cctx) == OK))
 	    || script_var_exists(name, len, cctx) == OK
-	    || find_imported(name, len, cctx) != NULL;
+	    || find_imported(name, len, FALSE, cctx) != NULL;
 }
 
 /*
@@ -331,7 +331,7 @@ check_defined(char_u *p, size_t len, cctx_T *cctx, int is_arg)
     if ((cctx != NULL
 		&& (lookup_local(p, len, NULL, cctx) == OK
 		    || arg_exists(p, len, NULL, NULL, NULL, cctx) == OK))
-	    || find_imported(p, len, cctx) != NULL
+	    || find_imported(p, len, FALSE, cctx) != NULL
 	    || (ufunc = find_func_even_dead(p, FALSE, cctx)) != NULL)
     {
 	// A local or script-local function can shadow a global function.
@@ -581,11 +581,13 @@ find_imported_in_script(char_u *name, size_t len, int sid)
 /*
  * Find "name" in imported items of the current script or in "cctx" if not
  * NULL.
+ * If "load" is TRUE and the script was not loaded yet, load it now.
  */
     imported_T *
-find_imported(char_u *name, size_t len, cctx_T *cctx)
+find_imported(char_u *name, size_t len, int load, cctx_T *cctx)
 {
     int		    idx;
+    imported_T	    *ret = NULL;
 
     if (!SCRIPT_ID_VALID(current_sctx.sc_sid))
 	return NULL;
@@ -598,10 +600,23 @@ find_imported(char_u *name, size_t len, cctx_T *cctx)
 	    if (len == 0 ? STRCMP(name, import->imp_name) == 0
 			 : STRLEN(import->imp_name) == len
 				  && STRNCMP(name, import->imp_name, len) == 0)
-		return import;
+	    {
+		ret = import;
+		break;
+	    }
 	}
 
-    return find_imported_in_script(name, len, current_sctx.sc_sid);
+    if (ret == NULL)
+	ret = find_imported_in_script(name, len, current_sctx.sc_sid);
+
+    if (ret != NULL && load && ret->imp_flags == IMP_FLAGS_AUTOLOAD)
+    {
+	// script found before but not loaded yet
+	ret->imp_flags = 0;
+	(void)do_source(SCRIPT_ITEM(ret->imp_sid)->sn_name, FALSE,
+							      DOSO_NONE, NULL);
+    }
+    return ret;
 }
 
 /*
@@ -1326,7 +1341,7 @@ compile_lhs(
 			  : script_var_exists(var_start, lhs->lhs_varlen,
 								  cctx)) == OK;
 		imported_T  *import =
-			       find_imported(var_start, lhs->lhs_varlen, cctx);
+			find_imported(var_start, lhs->lhs_varlen, FALSE, cctx);
 
 		if (script_namespace || script_var || import != NULL)
 		{
diff --git a/src/vim9expr.c b/src/vim9expr.c
index edaee5099..f12acf65a 100644
--- a/src/vim9expr.c
+++ b/src/vim9expr.c
@@ -266,7 +266,7 @@ compile_load_scriptvar(
 	return OK;
     }
 
-    import = end == NULL ? NULL : find_imported(name, 0, cctx);
+    import = end == NULL ? NULL : find_imported(name, 0, FALSE, cctx);
     if (import != NULL)
     {
 	char_u	*p = skipwhite(*end);
@@ -275,6 +275,7 @@ compile_load_scriptvar(
 	ufunc_T	*ufunc;
 	type_T	*type;
 
+	// TODO: if this is an autoload import do something else.
 	// Need to lookup the member.
 	if (*p != '.')
 	{
@@ -474,7 +475,7 @@ compile_load(
 		// "var" can be script-local even without using "s:" if it
 		// already exists in a Vim9 script or when it's imported.
 		if (script_var_exists(*arg, len, cctx) == OK
-			|| find_imported(name, 0, cctx) != NULL)
+			|| find_imported(name, 0, FALSE, cctx) != NULL)
 		   res = compile_load_scriptvar(cctx, name, *arg, &end, FALSE);
 
 		// When evaluating an expression and the name starts with an
diff --git a/src/vim9script.c b/src/vim9script.c
index 3ebeab366..a8b76bb6c 100644
--- a/src/vim9script.c
+++ b/src/vim9script.c
@@ -68,6 +68,9 @@ ex_vim9script(exarg_T *eap UNUSED)
 #ifdef FEAT_EVAL
     int		    sid = current_sctx.sc_sid;
     scriptitem_T    *si;
+    int		    found_noclear = FALSE;
+    int		    found_autoload = FALSE;
+    char_u	    *p;
 
     if (!getline_equal(eap->getline, eap->cookie, getsourceline))
     {
@@ -81,12 +84,40 @@ ex_vim9script(exarg_T *eap UNUSED)
 	emsg(_(e_vim9script_must_be_first_command_in_script));
 	return;
     }
-    if (!IS_WHITE_OR_NUL(*eap->arg) && STRCMP(eap->arg, "noclear") != 0)
+
+    for (p = eap->arg; !IS_WHITE_OR_NUL(*p); p = skipwhite(skiptowhite(p)))
     {
-	semsg(_(e_invalid_argument_str), eap->arg);
-	return;
+	if (STRNCMP(p, "noclear", 7) == 0 && IS_WHITE_OR_NUL(p[7]))
+	{
+	    if (found_noclear)
+	    {
+		semsg(_(e_duplicate_argument_str), p);
+		return;
+	    }
+	    found_noclear = TRUE;
+	}
+	else if (STRNCMP(p, "autoload", 8) == 0 && IS_WHITE_OR_NUL(p[8]))
+	{
+	    if (found_autoload)
+	    {
+		semsg(_(e_duplicate_argument_str), p);
+		return;
+	    }
+	    found_autoload = TRUE;
+	    if (script_name_after_autoload(si) == NULL)
+	    {
+		emsg(_(e_using_autoload_in_script_not_under_autoload_directory));
+		return;
+	    }
+	}
+	else
+	{
+	    semsg(_(e_invalid_argument_str), eap->arg);
+	    return;
+	}
     }
-    if (si->sn_state == SN_STATE_RELOAD && IS_WHITE_OR_NUL(*eap->arg))
+
+    if (si->sn_state == SN_STATE_RELOAD && !found_noclear)
     {
 	hashtab_T	*ht = &SCRIPT_VARS(sid);
 
@@ -101,6 +132,8 @@ ex_vim9script(exarg_T *eap UNUSED)
     }
     si->sn_state = SN_STATE_HAD_COMMAND;
 
+    si->sn_is_autoload = found_autoload;
+
     current_sctx.sc_version = SCRIPT_VERSION_VIM9;
     si->sn_version = SCRIPT_VERSION_VIM9;
 
@@ -366,6 +399,7 @@ handle_import(
 {
     char_u	*arg = arg_start;
     char_u	*nextarg;
+    int		is_autoload = FALSE;
     int		getnext;
     char_u	*expr_end;
     int		ret = FAIL;
@@ -377,6 +411,12 @@ handle_import(
     garray_T	*import_gap;
     int		i;
 
+    if (STRNCMP(arg, "autoload", 8) == 0 && VIM_ISWHITE(arg[8]))
+    {
+	is_autoload = TRUE;
+	arg = skipwhite(arg + 8);
+    }
+
     // The name of the file can be an expression, which must evaluate to a
     // string.
     ret = eval0_retarg(arg, &tv, NULL, evalarg, &expr_end);
@@ -402,23 +442,48 @@ handle_import(
 	char_u		*tail = gettail(si->sn_name);
 	char_u		*from_name;
 
-	// Relative to current script: "./name.vim", "../../name.vim".
-	len = STRLEN(si->sn_name) - STRLEN(tail) + STRLEN(tv.vval.v_string) + 2;
-	from_name = alloc((int)len);
-	if (from_name == NULL)
-	    goto erret;
-	vim_strncpy(from_name, si->sn_name, tail - si->sn_name);
-	add_pathsep(from_name);
-	STRCAT(from_name, tv.vval.v_string);
-	simplify_filename(from_name);
+	if (is_autoload)
+	    res = FAIL;
+	else
+	{
 
-	res = do_source(from_name, FALSE, DOSO_NONE, &sid);
-	vim_free(from_name);
+	    // Relative to current script: "./name.vim", "../../name.vim".
+	    len = STRLEN(si->sn_name) - STRLEN(tail)
+						+ STRLEN(tv.vval.v_string) + 2;
+	    from_name = alloc((int)len);
+	    if (from_name == NULL)
+		goto erret;
+	    vim_strncpy(from_name, si->sn_name, tail - si->sn_name);
+	    add_pathsep(from_name);
+	    STRCAT(from_name, tv.vval.v_string);
+	    simplify_filename(from_name);
+
+	    res = do_source(from_name, FALSE, DOSO_NONE, &sid);
+	    vim_free(from_name);
+	}
     }
     else if (mch_isFullName(tv.vval.v_string))
     {
 	// Absolute path: "/tmp/name.vim"
-	res = do_source(tv.vval.v_string, FALSE, DOSO_NONE, &sid);
+	if (is_autoload)
+	    res = FAIL;
+	else
+	    res = do_source(tv.vval.v_string, FALSE, DOSO_NONE, &sid);
+    }
+    else if (is_autoload)
+    {
+	size_t	    len = 9 + STRLEN(tv.vval.v_string) + 1;
+	char_u	    *from_name;
+
+	// Find file in "autoload" subdirs in 'runtimepath'.
+	from_name = alloc((int)len);
+	if (from_name == NULL)
+	    goto erret;
+	vim_snprintf((char *)from_name, len, "autoload/%s", tv.vval.v_string);
+	// we need a scriptitem without loading the script
+	sid = find_script_in_rtp(from_name);
+	vim_free(from_name);
+	res = SCRIPT_ID_VALID(sid) ? OK : FAIL;
     }
     else
     {
@@ -428,9 +493,7 @@ handle_import(
 	// Find file in "import" subdirs in 'runtimepath'.
 	from_name = alloc((int)len);
 	if (from_name == NULL)
-	{
 	    goto erret;
-	}
 	vim_snprintf((char *)from_name, len, "import/%s", tv.vval.v_string);
 	res = source_in_path(p_rtp, from_name, DIP_NOAFTER, &sid);
 	vim_free(from_name);
@@ -438,7 +501,9 @@ handle_import(
 
     if (res == FAIL || sid <= 0)
     {
-	semsg(_(e_could_not_import_str), tv.vval.v_string);
+	semsg(_(is_autoload && sid <= 0
+		    ? e_autoload_import_cannot_use_absolute_or_relative_path
+		    : e_could_not_import_str), tv.vval.v_string);
 	goto erret;
     }
 
@@ -451,7 +516,7 @@ handle_import(
 	{
 	    if (import->imp_flags & IMP_FLAGS_RELOAD)
 	    {
-		// encountering same script first ime on a reload is OK
+		// encountering same script first time on a reload is OK
 		import->imp_flags &= ~IMP_FLAGS_RELOAD;
 		break;
 	    }
@@ -513,7 +578,7 @@ handle_import(
     {
 	imported_T  *imported;
 
-	imported = find_imported(as_name, STRLEN(as_name), cctx);
+	imported = find_imported(as_name, FALSE, STRLEN(as_name), cctx);
 	if (imported != NULL && imported->imp_sid != sid)
 	{
 	    semsg(_(e_name_already_defined_str), as_name);
@@ -529,6 +594,8 @@ handle_import(
 	imported->imp_name = as_name;
 	as_name = NULL;
 	imported->imp_sid = sid;
+	if (is_autoload)
+	    imported->imp_flags = IMP_FLAGS_AUTOLOAD;
     }
 
 erret: