fix(source): make changing 'shellslash' change expand() result

src/nvim/lua/executor.c

@@ -1906,7 +1906,7 @@ void nlua_set_sctx(sctx_T *current)
     break;
   }
   char *source_path = fix_fname(info->source + 1);
-  get_current_script_id((char_u *)source_path, current);
+  get_current_script_id(&source_path, current);
   xfree(source_path);
   current->sc_lnum = info->currentline;
   current->sc_seq = -1;

src/nvim/runtime.c

@@ -1964,7 +1964,7 @@ int do_source(char *fname, int check_other, int is_vimrc)
   save_funccal(&funccalp_entry);
 
   const sctx_T save_current_sctx = current_sctx;
-  si = get_current_script_id((char_u *)fname_exp, &current_sctx);
+  si = get_current_script_id(&fname_exp, &current_sctx);
 
   if (l_do_profiling == PROF_YES) {
     bool forceit = false;
@@ -2077,9 +2077,9 @@ theend:
 /// Check if fname was sourced before to finds its SID.
 /// If it's new, generate a new SID.
 ///
-/// @param[in] fname file path of script
+/// @param[in,out] fnamep  pointer to file path of script
-/// @param[out] ret_sctx sctx of this script
+/// @param[out] ret_sctx   sctx of this script
-scriptitem_T *get_current_script_id(char_u *fname, sctx_T *ret_sctx)
+scriptitem_T *get_current_script_id(char **fnamep, sctx_T *ret_sctx)
 {
   static int last_current_SID_seq = 0;
 
@@ -2096,13 +2096,14 @@ scriptitem_T *get_current_script_id(char_u *fname, sctx_T *ret_sctx)
     // - If a script is deleted and another script is written, with a
     //   different name, the inode may be re-used.
     si = &SCRIPT_ITEM(script_sctx.sc_sid);
-    if (si->sn_name != NULL && FNAMECMP(si->sn_name, fname) == 0) {
+    if (si->sn_name != NULL && FNAMECMP(si->sn_name, *fnamep) == 0) {
       // Found it!
       break;
     }
   }
   if (script_sctx.sc_sid == 0) {
-    si = new_script_item((char *)vim_strsave(fname), &script_sctx.sc_sid);
+    si = new_script_item(*fnamep, &script_sctx.sc_sid);
+    *fnamep = xstrdup((char *)si->sn_name);
   }
   if (ret_sctx != NULL) {
     *ret_sctx = script_sctx;

test/functional/ex_cmds/source_spec.lua

@@ -13,6 +13,10 @@ local exec_lua = helpers.exec_lua
 local eval = helpers.eval
 local exec_capture = helpers.exec_capture
 local neq = helpers.neq
+local matches = helpers.matches
+local iswin = helpers.iswin
+local mkdir = helpers.mkdir
+local rmdir = helpers.rmdir
 
 describe(':source', function()
   before_each(function()
@@ -39,6 +43,30 @@ describe(':source', function()
     os.remove(test_file)
   end)
 
+  it("changing 'shellslash' changes the result of expand()", function()
+    if not iswin() then
+      pending("'shellslash' only works on Windows")
+      return
+    end
+    mkdir('Xshellslash')
+    local script = [[
+      let g:result1 = expand('<stack>')
+      set shellslash
+      let g:result2 = expand('<stack>')
+      set noshellslash
+      let g:result3 = expand('<stack>')
+    ]]
+    write_file([[Xshellslash/Xexpand.vim]], script)
+
+    meths.set_option('shellslash', false)
+    command([[source Xshellslash/Xexpand.vim]])
+    matches([[Xshellslash\Xexpand%.vim]], meths.get_var('result1'))
+    matches([[Xshellslash/Xexpand%.vim]], meths.get_var('result2'))
+    matches([[Xshellslash\Xexpand%.vim]], meths.get_var('result3'))
+
+    rmdir('Xshellslash')
+  end)
+
   it('current buffer', function()
     insert([[
       let a = 2