vim-patch:8.2.0945: cannot use "z=" when 'spell' is off

Problem:    Cannot use "z=" when 'spell' is off.
Solution:   Make "z=" work even when 'spell' is off. (Christian Brabandt,
            Gary Johnson, closes vim/vim#6227)
152e79e94b

runtime/doc/eval.txt

@@ -8230,9 +8230,8 @@ spellbadword([{sentence}])
 			echo spellbadword("the quik brown fox")
 <			['quik', 'bad'] ~
 
-		The spelling information for the current window is used.  The
-		'spell' option must be set and the value of 'spelllang' is
-		used.
+		The spelling information for the current window and the value
+		of 'spelllang' are used.
 
 							*spellsuggest()*
 spellsuggest({word} [, {max} [, {capital}]])
@@ -8254,8 +8253,7 @@ spellsuggest({word} [, {max} [, {capital}]])
 		although it may appear capitalized.
 
 		The spelling information for the current window is used.  The
-		'spell' option must be set and the values of 'spelllang' and
-		'spellsuggest' are used.
+		values of 'spelllang' and 'spellsuggest' are used.
 
 
 split({expr} [, {pattern} [, {keepempty}]])			*split()*

src/nvim/eval/funcs.c

@@ -9661,6 +9661,18 @@ static void f_spellbadword(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   const char *word = "";
   hlf_T attr = HLF_COUNT;
   size_t len = 0;
+  const int wo_spell_save = curwin->w_p_spell;
+
+  if (!curwin->w_p_spell) {
+    did_set_spelllang(curwin);
+    curwin->w_p_spell = true;
+  }
+
+  if (*curwin->w_s->b_p_spl == NUL) {
+    EMSG(_(e_no_spell));
+    curwin->w_p_spell = wo_spell_save;
+    return;
+  }
 
   if (argvars[0].v_type == VAR_UNKNOWN) {
     // Find the start and length of the badly spelled word.
@@ -9669,7 +9681,7 @@ static void f_spellbadword(typval_T *argvars, typval_T *rettv, FunPtr fptr)
       word = (char *)get_cursor_pos_ptr();
       curwin->w_set_curswant = true;
     }
-  } else if (curwin->w_p_spell && *curbuf->b_s.b_p_spl != NUL) {
+  } else if (*curbuf->b_s.b_p_spl != NUL) {
     const char *str = tv_get_string_chk(&argvars[0]);
     int capcol = -1;
 
@@ -9687,6 +9699,7 @@ static void f_spellbadword(typval_T *argvars, typval_T *rettv, FunPtr fptr)
       }
     }
   }
+  curwin->w_p_spell = wo_spell_save;
 
   assert(len <= INT_MAX);
   tv_list_alloc_ret(rettv, 2);
@@ -9708,8 +9721,20 @@ static void f_spellsuggest(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   int maxcount;
   garray_T ga = GA_EMPTY_INIT_VALUE;
   bool need_capital = false;
+  const int wo_spell_save = curwin->w_p_spell;
 
-  if (curwin->w_p_spell && *curwin->w_s->b_p_spl != NUL) {
+  if (!curwin->w_p_spell) {
+    did_set_spelllang(curwin);
+    curwin->w_p_spell = true;
+  }
+
+  if (*curwin->w_s->b_p_spl == NUL) {
+    EMSG(_(e_no_spell));
+    curwin->w_p_spell = wo_spell_save;
+    return;
+  }
+
+  if (*curwin->w_s->b_p_spl != NUL) {
     const char *const str = tv_get_string(&argvars[0]);
     if (argvars[1].v_type != VAR_UNKNOWN) {
       maxcount = tv_get_number_chk(&argvars[1], &typeerr);
@@ -9736,6 +9761,7 @@ f_spellsuggest_return:
     tv_list_append_allocated_string(rettv->vval.v_list, p);
   }
   ga_clear(&ga);
+  curwin->w_p_spell = wo_spell_save;
 }
 
 static void f_split(typval_T *argvars, typval_T *rettv, FunPtr fptr)

src/nvim/globals.h

@@ -878,6 +878,7 @@ EXTERN char_u e_invexpr2[] INIT(= N_("E15: Invalid expression: %s"));
 EXTERN char_u e_invrange[] INIT(= N_("E16: Invalid range"));
 EXTERN char_u e_invcmd[] INIT(= N_("E476: Invalid command"));
 EXTERN char_u e_isadir2[] INIT(= N_("E17: \"%s\" is a directory"));
+EXTERN char_u e_no_spell[] INIT(= N_("E756: Spell checking is not possible"));
 EXTERN char_u e_invchan[] INIT(= N_("E900: Invalid channel id"));
 EXTERN char_u e_invchanjob[] INIT(= N_("E900: Invalid channel id: not a job"));
 EXTERN char_u e_jobtblfull[] INIT(= N_("E901: Job table is full"));

src/nvim/spell.c

@@ -1343,7 +1343,7 @@ static bool no_spell_checking(win_T *wp)
 {
   if (!wp->w_p_spell || *wp->w_s->b_p_spl == NUL
       || GA_EMPTY(&wp->w_s->b_langp)) {
-    EMSG(_("E756: Spell checking is not enabled"));
+    EMSG(_(e_no_spell));
     return true;
   }
   return false;
@@ -2771,9 +2771,17 @@ void spell_suggest(int count)
   int selected = count;
   int badlen = 0;
   int msg_scroll_save = msg_scroll;
+  const int wo_spell_save = curwin->w_p_spell;
 
-  if (no_spell_checking(curwin))
+  if (!curwin->w_p_spell) {
+    did_set_spelllang(curwin);
+    curwin->w_p_spell = true;
+  }
+
+  if (*curwin->w_s->b_p_spl == NUL) {
+    EMSG(_(e_no_spell));
     return;
+  }
 
   if (VIsual_active) {
     // Use the Visually selected text as the bad word.  But reject
@@ -2966,6 +2974,7 @@ void spell_suggest(int count)
 
   spell_find_cleanup(&sug);
   xfree(line);
+  curwin->w_p_spell = wo_spell_save;
 }
 
 // Check if the word at line "lnum" column "col" is required to start with a

src/nvim/testdir/test_spell.vim

@@ -106,11 +106,14 @@ foobar/?
    set spelllang=Xwords.spl
    call assert_equal(['foobar', 'rare'], spellbadword('foo foobar'))
 
-  " Typo should not be detected without the 'spell' option.
+  " Typo should be detected even without the 'spell' option.
   set spelllang=en_gb nospell
   call assert_equal(['', ''], spellbadword('centre'))
-  call assert_equal(['', ''], spellbadword('My bycycle.'))
-  call assert_equal(['', ''], spellbadword('A sentence. another sentence'))
+  call assert_equal(['bycycle', 'bad'], spellbadword('My bycycle.'))
+  call assert_equal(['another', 'caps'], spellbadword('A sentence. another sentence'))
+
+  set spelllang=
+  call assert_fails("call spellbadword('maxch')", 'E756:')
 
   call delete('Xwords.spl')
   call delete('Xwords')
@@ -174,9 +177,9 @@ endfunc
 
 " Test spellsuggest({word} [, {max} [, {capital}]])
 func Test_spellsuggest()
-  " No suggestions when spell checking is not enabled.
+  " Verify suggestions are given even when spell checking is not enabled.
   set nospell
-  call assert_equal([], spellsuggest('marrch'))
+  call assert_equal(['march', 'March'], spellsuggest('marrch', 2))
 
   set spell
 
@@ -204,6 +207,13 @@ func Test_spellsuggest()
   call assert_equal(['Third'], spellsuggest('THird', 1))
   call assert_equal(['All'],      spellsuggest('ALl', 1))
 
+  call assert_fails("call spellsuggest('maxch', [])", 'E745:')
+  call assert_fails("call spellsuggest('maxch', 2, [])", 'E745:')
+
+  set spelllang=
+  call assert_fails("call spellsuggest('maxch')", 'E756:')
+  set spelllang&
+
   set spell&
 endfunc
 
@@ -631,6 +641,34 @@ func Test_zeq_crash()
   bwipe!
 endfunc
 
+" Check that z= works even when 'nospell' is set.  This test uses one of the
+" tests in Test_spellsuggest_option_number() just to verify that z= basically
+" works and that "E756: Spell checking is not enabled" is not generated.
+func Test_zeq_nospell()
+  new
+  set nospell spellsuggest=1,best
+  call setline(1, 'A baord')
+  try
+    norm $1z=
+    call assert_equal('A board', getline(1))
+  catch
+    call assert_report("Caught exception: " . v:exception)
+  endtry
+  set spell& spellsuggest&
+  bwipe!
+endfunc
+
+" Check that "E756: Spell checking is not possible" is reported when z= is
+" executed and 'spelllang' is empty.
+func Test_zeq_no_spelllang()
+  new
+  set spelllang= spellsuggest=1,best
+  call setline(1, 'A baord')
+  call assert_fails('normal $1z=', 'E756:')
+  set spelllang& spellsuggest&
+  bwipe!
+endfunc
+
 " Check handling a word longer than MAXWLEN.
 func Test_spell_long_word()
   set enc=utf-8