vim-patch:8.1.1144: too strict checking of the 'spellfile' option

Problem:    Too strict checking of the 'spellfile' option.
Solution:   Allow for a path.
https://github.com/vim/vim/commit/862f1e17eaf2b9c6617dfba31d8487cde462658d

2 files changed, 22 insertions, 2 deletions

diff --git a/src/nvim/option.c b/src/nvim/option.c
index 9168509aa8..52742c8b64 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -2538,6 +2538,18 @@ bool valid_spellang(const char_u *val)
   return valid_name(val, ".-_,");
 }
 
+/// Return true if "val" is a valid 'spellfile' value.
+static bool valid_spellfile(const char_u *val)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
+{
+  for (const char_u *s = val; *s != NUL; s++) {
+    if (!vim_isfilec(*s) && *s != ',') {
+      return false;
+    }
+  }
+  return true;
+}
+
 /// Handle string options that need some action to perform when changed.
 /// Returns NULL for success, or an error message for an error.
 static char_u *
@@ -3049,10 +3061,13 @@ ambw_end:
              || varp == &(curwin->w_s->b_p_spf)) {
     // When 'spelllang' or 'spellfile' is set and there is a window for this
     // buffer in which 'spell' is set load the wordlists.
-    if (!valid_spellang(*varp)) {
+    const bool is_spellfile = varp == &(curwin->w_s->b_p_spf);
+
+    if ((is_spellfile && !valid_spellfile(*varp))
+        || (!is_spellfile && !valid_spellang(*varp))) {
       errmsg = e_invarg;
     } else {
-      errmsg = did_set_spell_option(varp == &(curwin->w_s->b_p_spf));
+      errmsg = did_set_spell_option(is_spellfile);
     }
   } else if (varp == &(curwin->w_s->b_p_spc)) {
     // When 'spellcapcheck' is set compile the regexp program.
diff --git a/src/nvim/testdir/test_spell.vim b/src/nvim/testdir/test_spell.vim
index 098cd957ae..94789d6ea3 100644
--- a/src/nvim/testdir/test_spell.vim
+++ b/src/nvim/testdir/test_spell.vim
@@ -392,6 +392,11 @@ func Test_zz_sal_and_addition()
   call assert_equal("elekwint", SecondSpellWord())
 endfunc
 
+func Test_spellfile_value()
+  set spellfile=Xdir/Xtest.latin1.add
+  set spellfile=Xdir/Xtest.utf-8.add,Xtest_other.add
+endfunc
+
 func Test_region_error()
   messages clear
   call writefile(["/regions=usgbnz", "elequint/0"], "Xtest.latin1.add")