vim-patch:9.0.0176: checking character options is duplicated and incomplete (#19690)

Problem:    Checking character options is duplicated and incomplete.
Solution:   Move checking to check_chars_options(). (closes vim/vim#10863)
https://github.com/vim/vim/commit/8ca29b6a3599b82b8822b7697cad63d0244c2d59

4 files changed, 40 insertions, 38 deletions

diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 23870a572e..317423ffa0 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -1000,11 +1000,6 @@ EXTERN char e_fnametoolong[] INIT(= N_("E856: Filename too long"));
 EXTERN char e_float_as_string[] INIT(= N_("E806: using Float as a String"));
 EXTERN char e_cannot_edit_other_buf[] INIT(= N_("E788: Not allowed to edit another buffer now"));
 
-EXTERN char e_conflicts_with_value_of_listchars[]
-INIT(= N_("E834: Conflicts with value of 'listchars'"));
-EXTERN char e_conflicts_with_value_of_fillchars[]
-INIT(= N_("E835: Conflicts with value of 'fillchars'"));
-
 EXTERN char e_autocmd_err[] INIT(= N_("E5500: autocmd has thrown an exception: %s"));
 EXTERN char e_cmdmap_err[] INIT(= N_("E5520: <Cmd> mapping must end with <CR>"));
 EXTERN char e_cmdmap_repeated[]
diff --git a/src/nvim/mbyte.c b/src/nvim/mbyte.c
index e156fa58d1..8e8cf962c7 100644
--- a/src/nvim/mbyte.c
+++ b/src/nvim/mbyte.c
@@ -2844,25 +2844,9 @@ void f_setcellwidths(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   cw_table = table;
   cw_table_size = (size_t)tv_list_len(l);
 
-  // Check that the new value does not conflict with 'fillchars' or
-  // 'listchars'.
-  char *error = NULL;
-  if (set_chars_option(curwin, &p_fcs, false) != NULL) {
-    error = e_conflicts_with_value_of_fillchars;
-  } else if (set_chars_option(curwin, &p_lcs, false) != NULL) {
-    error = e_conflicts_with_value_of_listchars;
-  } else {
-    FOR_ALL_TAB_WINDOWS(tp, wp) {
-      if (set_chars_option(wp, &wp->w_p_lcs, true) != NULL) {
-        error = e_conflicts_with_value_of_listchars;
-        break;
-      }
-      if (set_chars_option(wp, &wp->w_p_fcs, true) != NULL) {
-        error = e_conflicts_with_value_of_fillchars;
-        break;
-      }
-    }
-  }
+  // Check that the new value does not conflict with 'listchars' or
+  // 'fillchars'.
+  const char *const error = check_chars_options();
   if (error != NULL) {
     emsg(_(error));
     cw_table = cw_table_save;
diff --git a/src/nvim/option.c b/src/nvim/option.c
index d7443bc593..8eb3b64e5b 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -339,6 +339,9 @@ static char_u SHM_ALL[] = {
 static char e_unclosed_expression_sequence[] = N_("E540: Unclosed expression sequence");
 static char e_unbalanced_groups[] = N_("E542: unbalanced groups");
 
+static char e_conflicts_with_value_of_listchars[] = N_("E834: Conflicts with value of 'listchars'");
+static char e_conflicts_with_value_of_fillchars[] = N_("E835: Conflicts with value of 'fillchars'");
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "option.c.generated.h"
 #endif
@@ -2578,18 +2581,7 @@ static char *did_set_string_option(int opt_idx, char_u **varp, char_u *oldval, c
     if (check_opt_strings(p_ambw, p_ambw_values, false) != OK) {
       errmsg = e_invarg;
     } else {
-      FOR_ALL_TAB_WINDOWS(tp, wp) {
-        if (set_chars_option(wp, &wp->w_p_lcs, true) != NULL) {
-          errmsg = _(e_conflicts_with_value_of_listchars);
-          goto ambw_end;
-        }
-        if (set_chars_option(wp, &wp->w_p_fcs, true) != NULL) {
-          errmsg = _(e_conflicts_with_value_of_fillchars);
-          goto ambw_end;
-        }
-      }
-ambw_end:
-      {}  // clint prefers {} over ; as an empty statement
+      errmsg = check_chars_options();
     }
   } else if (varp == &p_bg) {  // 'background'
     if (check_opt_strings(p_bg, p_bg_values, false) == OK) {
@@ -3823,6 +3815,29 @@ char *set_chars_option(win_T *wp, char_u **varp, bool set)
   return NULL;          // no error
 }
 
+/// Check all global and local values of 'listchars' and 'fillchars'.
+/// May set different defaults in case character widths change.
+///
+/// @return  an untranslated error message if any of them is invalid, NULL otherwise.
+char *check_chars_options(void)
+{
+  if (set_chars_option(curwin, &p_lcs, false) != NULL) {
+    return e_conflicts_with_value_of_listchars;
+  }
+  if (set_chars_option(curwin, &p_fcs, false) != NULL) {
+    return e_conflicts_with_value_of_fillchars;
+  }
+  FOR_ALL_TAB_WINDOWS(tp, wp) {
+    if (set_chars_option(wp, &wp->w_p_lcs, true) != NULL) {
+      return e_conflicts_with_value_of_listchars;
+    }
+    if (set_chars_option(wp, &wp->w_p_fcs, true) != NULL) {
+      return e_conflicts_with_value_of_fillchars;
+    }
+  }
+  return NULL;
+}
+
 /// Check validity of options with the 'statusline' format.
 /// Return an untranslated error message or NULL.
 char *check_stl_option(char *s)
diff --git a/src/nvim/testdir/test_options.vim b/src/nvim/testdir/test_options.vim
index b10f0f5030..6e9f2d2377 100644
--- a/src/nvim/testdir/test_options.vim
+++ b/src/nvim/testdir/test_options.vim
@@ -368,9 +368,17 @@ func Test_set_errors()
   call assert_fails('set sessionoptions=curdir,sesdir', 'E474:')
   call assert_fails('set foldmarker={{{,', 'E474:')
   call assert_fails('set sessionoptions=sesdir,curdir', 'E474:')
-  call assert_fails('set listchars=trail:· ambiwidth=double', 'E834:')
+  setlocal listchars=trail:·
+  call assert_fails('set ambiwidth=double', 'E834:')
+  setlocal listchars=trail:-
+  setglobal listchars=trail:·
+  call assert_fails('set ambiwidth=double', 'E834:')
   set listchars&
-  call assert_fails('set fillchars=stl:· ambiwidth=double', 'E835:')
+  setlocal fillchars=stl:·
+  call assert_fails('set ambiwidth=double', 'E835:')
+  setlocal fillchars=stl:-
+  setglobal fillchars=stl:·
+  call assert_fails('set ambiwidth=double', 'E835:')
   set fillchars&
   call assert_fails('set fileencoding=latin1,utf-8', 'E474:')
   set nomodifiable