vim-patch:8.2.1747: result of expand() unexpectedly depends on 'completeslash'

Problem:    Result of expand() unexpectedly depends on 'completeslash'.
Solution:   Temporarily reset 'completeslash'. (Yasuhiro Matsumoto,
            closes vim/vim#7021)
8f187fc630

src/nvim/eval/funcs.c

@@ -2071,6 +2071,12 @@ static void f_expand(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   expand_T xpc;
   bool error = false;
   char_u *result;
+#ifdef BACKSLASH_IN_FILENAME
+  char_u *p_csl_save = p_csl;
+
+  // avoid using 'completeslash' here
+  p_csl = empty_option;
+#endif
 
   rettv->v_type = VAR_STRING;
   if (argvars[1].v_type != VAR_UNKNOWN
@@ -2123,6 +2129,9 @@ static void f_expand(typval_T *argvars, typval_T *rettv, FunPtr fptr)
       rettv->vval.v_string = NULL;
     }
   }
+#ifdef BACKSLASH_IN_FILENAME
+  p_csl = p_csl_save;
+#endif
 }
 
 

src/nvim/testdir/test_ins_complete.vim

@@ -414,6 +414,19 @@ func Test_ins_completeslash()
   set completeslash=
 endfunc
 
+func Test_issue_7021()
+  CheckMSWindows
+
+  let orig_shellslash = &shellslash
+  set noshellslash
+
+  set completeslash=slash
+  call assert_false(expand('~') =~ '/')
+
+  let &shellslash = orig_shellslash
+  set completeslash=
+endfunc
+
 func Test_pum_with_folds_two_tabs()
   CheckScreendump