patch 8.2.2225: Vim9: error when using :import in legacy script twice

Problem:    Vim9: error when using :import in legacy script twice.
Solution:   Make it possible to redefine an import when reloading.

Author: brammool

src/evalvars.c

@@ -2531,7 +2531,7 @@ eval_variable(
 		    rettv->vval.v_string = vim_strsave(import->imp_funcname);
 		}
 	    }
-	    else if (import->imp_all)
+	    else if (import->imp_flags & IMP_FLAGS_STAR)
 	    {
 		emsg("Sorry, 'import * as X' not implemented yet");
 		ret = FAIL;

src/proto/vim9script.pro

@@ -4,6 +4,7 @@ void ex_vim9script(exarg_T *eap);
 int not_in_vim9(exarg_T *eap);
 void ex_export(exarg_T *eap);
 void free_imports_and_script_vars(int sid);
+void mark_imports_for_reload(int sid);
 void ex_import(exarg_T *eap);
 int find_exported(int sid, char_u *name, ufunc_T **ufunc, type_T **type, cctx_T *cctx);
 char_u *handle_import(char_u *arg_start, garray_T *gap, int import_sid, evalarg_T *evalarg, void *cctx);

src/structs.h

@@ -1778,17 +1778,19 @@ typedef struct {
     char_u	*imp_name;	    // name imported as (allocated)
     int		imp_sid;	    // script ID of "from"
 
-    // for "import * as Name", "imp_name" is "Name"
-    int		imp_all;
+    int		imp_flags;	    // IMP_FLAGS_ values
 
-    // for variable
+    // for a variable
     type_T	*imp_type;
     int		imp_var_vals_idx;   // index in sn_var_vals of "from"
 
-    // for function
+    // for a function
     char_u	*imp_funcname;	    // user func name (NOT allocated)
 } imported_T;
 
+#define IMP_FLAGS_STAR		1   // using "import * as Name"
+#define IMP_FLAGS_RELOAD	2   // script reloaded, OK to redefine
+
 /*
  * Info about an already sourced scripts.
  */

src/testdir/test_vim9_script.vim

@@ -899,6 +899,16 @@ def Test_vim9_import_export()
   writefile(import_star_as_lines_dot_space, 'Ximport.vim')
   assert_fails('source Ximport.vim', 'E1074:', '', 1, 'Func')
 
+  var import_star_as_duplicated =<< trim END
+    vim9script
+    import * as Export from './Xexport.vim'
+    var some = 'other'
+    import * as Export from './Xexport.vim'
+    defcompile
+  END
+  writefile(import_star_as_duplicated, 'Ximport.vim')
+  assert_fails('source Ximport.vim', 'E1073:', '', 4, 'Ximport.vim')
+
   var import_star_as_lines_missing_name =<< trim END
     vim9script
     import * as Export from './Xexport.vim'
@@ -1160,9 +1170,15 @@ enddef
 
 def Test_vim9script_reload_noclear()
   var lines =<< trim END
+    vim9script
+    export var exported = 'thexport'
+  END
+  writefile(lines, 'XExportReload')
+  lines =<< trim END
     vim9script noclear
     g:loadCount += 1
     var s:reloaded = 'init'
+    import exported from './XExportReload'
 
     def Again(): string
       return 'again'
@@ -1174,7 +1190,7 @@ def Test_vim9script_reload_noclear()
     var s:notReloaded = 'yes'
     s:reloaded = 'first'
     def g:Values(): list<string>
-      return [s:reloaded, s:notReloaded, Again(), Once()]
+      return [s:reloaded, s:notReloaded, Again(), Once(), exported]
     enddef
 
     def Once(): string
@@ -1185,15 +1201,16 @@ def Test_vim9script_reload_noclear()
   g:loadCount = 0
   source XReloaded
   assert_equal(1, g:loadCount)
-  assert_equal(['first', 'yes', 'again', 'once'], g:Values())
+  assert_equal(['first', 'yes', 'again', 'once', 'thexport'], g:Values())
   source XReloaded
   assert_equal(2, g:loadCount)
-  assert_equal(['init', 'yes', 'again', 'once'], g:Values())
+  assert_equal(['init', 'yes', 'again', 'once', 'thexport'], g:Values())
   source XReloaded
   assert_equal(3, g:loadCount)
-  assert_equal(['init', 'yes', 'again', 'once'], g:Values())
+  assert_equal(['init', 'yes', 'again', 'once', 'thexport'], g:Values())
 
   delete('Xreloaded')
+  delete('XExportReload')
   delfunc g:Values
   unlet g:loadCount
 enddef
@@ -2762,6 +2779,17 @@ def Test_forward_declaration()
 enddef
 
 def Test_source_vim9_from_legacy()
+  var vim9_lines =<< trim END
+    vim9script
+    var local = 'local'
+    g:global = 'global'
+    export var exported = 'exported'
+    export def GetText(): string
+       return 'text'
+    enddef
+  END
+  writefile(vim9_lines, 'Xvim9_script.vim')
+
   var legacy_lines =<< trim END
     source Xvim9_script.vim
 
@@ -2783,19 +2811,7 @@ def Test_source_vim9_from_legacy()
   END
   writefile(legacy_lines, 'Xlegacy_script.vim')
 
-  var vim9_lines =<< trim END
-    vim9script
-    var local = 'local'
-    g:global = 'global'
-    export var exported = 'exported'
-    export def GetText(): string
-       return 'text'
-    enddef
-  END
-  writefile(vim9_lines, 'Xvim9_script.vim')
-
   source Xlegacy_script.vim
-
   assert_equal('global', g:global)
   unlet g:global
 

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2225,
 /**/
     2224,
 /**/

src/vim9compile.c

@@ -2416,7 +2416,7 @@ compile_load_scriptvar(
     import = find_imported(name, 0, cctx);
     if (import != NULL)
     {
-	if (import->imp_all)
+	if (import->imp_flags & IMP_FLAGS_STAR)
 	{
 	    char_u	*p = skipwhite(*end);
 	    char_u	*exp_name;

src/vim9script.c

@@ -173,6 +173,24 @@ free_imports_and_script_vars(int sid)
     clear_type_list(&si->sn_type_list);
 }
 
+/*
+ * Mark all imports as possible to redefine.  Used when a script is loaded
+ * again but not cleared.
+ */
+    void
+mark_imports_for_reload(int sid)
+{
+    scriptitem_T    *si = SCRIPT_ITEM(sid);
+    int		    idx;
+
+    for (idx = 0; idx < si->sn_imports.ga_len; ++idx)
+    {
+	imported_T *imp = ((imported_T *)si->sn_imports.ga_data) + idx;
+
+	imp->imp_flags |= IMP_FLAGS_RELOAD;
+    }
+}
+
 /*
  * ":import Item from 'filename'"
  * ":import Item as Alias from 'filename'"
@@ -459,15 +477,29 @@ handle_import(
 
     if (*arg_start == '*')
     {
-	imported_T *imported = new_imported(gap != NULL ? gap
-					: &SCRIPT_ITEM(import_sid)->sn_imports);
+	imported_T *imported;
 
+	imported = find_imported(as_name, STRLEN(as_name), cctx);
+	if (imported != NULL && imported->imp_sid == sid)
+	{
+	    if (imported->imp_flags & IMP_FLAGS_RELOAD)
+		// import already defined on a previous script load
+		imported->imp_flags &= ~IMP_FLAGS_RELOAD;
+	    else
+	    {
+		semsg(_(e_name_already_defined_str), as_name);
+		goto erret;
+	    }
+	}
+
+	imported = new_imported(gap != NULL ? gap
+					: &SCRIPT_ITEM(import_sid)->sn_imports);
 	if (imported == NULL)
 	    goto erret;
 	imported->imp_name = as_name;
 	as_name = NULL;
 	imported->imp_sid = sid;
-	imported->imp_all = TRUE;
+	imported->imp_flags = IMP_FLAGS_STAR;
     }
     else
     {
@@ -479,6 +511,7 @@ handle_import(
 	for (i = 0; i < names.ga_len; ++i)
 	{
 	    char_u	*name = ((char_u **)names.ga_data)[i];
+	    size_t	len = STRLEN(name);
 	    int		idx;
 	    imported_T	*imported;
 	    ufunc_T	*ufunc = NULL;
@@ -489,28 +522,47 @@ handle_import(
 	    if (idx < 0 && ufunc == NULL)
 		goto erret;
 
-	    if (check_defined(name, STRLEN(name), cctx) == FAIL)
-		goto erret;
-
-	    imported = new_imported(gap != NULL ? gap
-				       : &SCRIPT_ITEM(import_sid)->sn_imports);
-	    if (imported == NULL)
-		goto erret;
-
-	    // TODO: check for "as" following
-	    // imported->imp_name = vim_strsave(as_name);
-	    imported->imp_name = name;
-	    ((char_u **)names.ga_data)[i] = NULL;
-	    imported->imp_sid = sid;
-	    if (idx >= 0)
+	    // If already imported with the same propertis and the
+	    // IMP_FLAGS_RELOAD set then we keep that entry.  Otherwise create
+	    // a new one (and give an error for an existing import).
+	    imported = find_imported(name, len, cctx);
+	    if (imported != NULL
+		    && (imported->imp_flags & IMP_FLAGS_RELOAD)
+		    && imported->imp_sid == sid
+		    && (idx >= 0
+			? (equal_type(imported->imp_type, type)
+			    && imported->imp_var_vals_idx == idx)
+			: (equal_type(imported->imp_type, ufunc->uf_func_type)
+			    && STRCMP(imported->imp_funcname,
+							ufunc->uf_name) == 0)))
 	    {
-		imported->imp_type = type;
-		imported->imp_var_vals_idx = idx;
+		imported->imp_flags &= ~IMP_FLAGS_RELOAD;
 	    }
 	    else
 	    {
-		imported->imp_type = ufunc->uf_func_type;
-		imported->imp_funcname = ufunc->uf_name;
+		if (check_defined(name, len, cctx) == FAIL)
+		    goto erret;
+
+		imported = new_imported(gap != NULL ? gap
+				       : &SCRIPT_ITEM(import_sid)->sn_imports);
+		if (imported == NULL)
+		    goto erret;
+
+		// TODO: check for "as" following
+		// imported->imp_name = vim_strsave(as_name);
+		imported->imp_name = name;
+		((char_u **)names.ga_data)[i] = NULL;
+		imported->imp_sid = sid;
+		if (idx >= 0)
+		{
+		    imported->imp_type = type;
+		    imported->imp_var_vals_idx = idx;
+		}
+		else
+		{
+		    imported->imp_type = ufunc->uf_func_type;
+		    imported->imp_funcname = ufunc->uf_name;
+		}
 	    }
 	}
     }