fix(mark): give correct error message when mark is in another buffer (#19454)

src/nvim/mark.c

@@ -339,11 +339,11 @@ fmark_T *mark_get(buf_T *buf, win_T *win, fmark_T *fmp, MarkGet flag, int name)
   fmark_T *fm = NULL;
   if (ASCII_ISUPPER(name) || ascii_isdigit(name)) {
     // Global marks
-    xfmark_T *xfm = mark_get_global(!(flag & kMarkAllNoResolve), name);
+    xfmark_T *xfm = mark_get_global(flag != kMarkAllNoResolve, name);
     fm = &xfm->fmark;
-    // Only wanted marks belonging to the buffer
-    if ((flag & kMarkBufLocal) && xfm->fmark.fnum != buf->handle) {
-      return NULL;
+    if (flag == kMarkBufLocal && xfm->fmark.fnum != buf->handle) {
+      // Only wanted marks belonging to the buffer
+      return pos_to_mark(buf, NULL, (pos_T){ .lnum = 0 });
     }
   } else if (name > 0 && name < NMARK_LOCAL_MAX) {
     // Local Marks
@@ -508,11 +508,12 @@ fmark_T *mark_get_visual(buf_T *buf, int name)
 /// Pass an fmp if multiple c
 /// @note  view fields are set to 0.
 /// @param buf  for fmark->fnum.
-/// @param pos  for fmrak->mark.
+/// @param pos  for fmark->mark.
 /// @param fmp pointer to save the mark.
 ///
 /// @return[static] Mark with the given information.
 fmark_T *pos_to_mark(buf_T *buf, fmark_T *fmp, pos_T pos)
+  FUNC_ATTR_NONNULL_RET
 {
   static fmark_T fms = INIT_FMARK;
   fmark_T *fm = fmp == NULL ? &fms : fmp;

src/nvim/regexp_bt.c

@@ -3705,8 +3705,6 @@ static bool regmatch(char_u *scan, proftime_T *tm, int *timed_out)
           int cmp = OPERAND(scan)[1];
           pos_T *pos;
           size_t col = REG_MULTI ? rex.input - rex.line : 0;
-
-          // fm will be NULL if the mark is not set in reg_buf
           fmark_T *fm = mark_get(rex.reg_buf, curwin, NULL, kMarkBufLocal, mark);
 
           // Line may have been freed, get it again.

src/nvim/regexp_nfa.c

@@ -6930,10 +6930,8 @@ static int nfa_regmatch(nfa_regprog_T *prog, nfa_state_T *start, regsubs_T *subm
       case NFA_MARK:
       case NFA_MARK_GT:
       case NFA_MARK_LT: {
-        fmark_T *fm;
         size_t col = REG_MULTI ? rex.input - rex.line : 0;
-        // fm will be NULL if the mark is not set, doesn't belong to reg_buf
-        fm = mark_get(rex.reg_buf, curwin, NULL, kMarkBufLocal, t->state->val);
+        fmark_T *fm = mark_get(rex.reg_buf, curwin, NULL, kMarkBufLocal, t->state->val);
 
         // Line may have been freed, get it again.
         if (REG_MULTI) {

test/functional/editor/mark_spec.lua

@@ -157,6 +157,13 @@ describe('named marks', function()
     os.remove(file1)
   end)
 
+  it("errors when using a mark in another buffer in command range", function()
+    feed('ifoo<Esc>mA')
+    command('enew')
+    feed('ibar<Esc>')
+    eq('Vim(print):E20: Mark not set', pcall_err(command, [['Aprint]]))
+  end)
+
   it("leave a context mark when moving with '", function()
     command("edit " .. file1)
     feed("llmamA")