vim-patch:9.0.0712: wrong column when calling setcursorcharpos() with zero lnum

Problem:    Wrong column when calling setcursorcharpos() with zero lnum.
Solution:   Set the line number before calling buf_charidx_to_byteidx().
            (closes vim/vim#11329)
https://github.com/vim/vim/commit/79f234499b6692cc16970b7455bc9b002242632f

3 files changed, 25 insertions, 11 deletions

diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 6eaf3d1f5e..ebc60ea5c7 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -6454,11 +6454,14 @@ pos_T *var2fpos(const typval_T *const tv, const bool dollar_lnum, int *const ret
   return NULL;
 }
 
-/// Convert list in "arg" into a position and optional file number.
-/// When "fnump" is NULL there is no file number, only 3 items.
+/// Convert list in "arg" into position "posp" and optional file number "fnump".
+/// When "fnump" is NULL there is no file number, only 3 items: [lnum, col, off]
 /// Note that the column is passed on as-is, the caller may want to decrement
 /// it to use 1 for the first column.
 ///
+/// @param charcol  if true, use the column as the character index instead of the
+///                 byte index.
+///
 /// @return  FAIL when conversion is not possible, doesn't check the position for
 ///          validity.
 int list2fpos(typval_T *arg, pos_T *posp, int *fnump, colnr_T *curswantp, bool charcol)
@@ -6498,13 +6501,16 @@ int list2fpos(typval_T *arg, pos_T *posp, int *fnump, colnr_T *curswantp, bool c
     return FAIL;
   }
   // If character position is specified, then convert to byte position
+  // If the line number is zero use the cursor line.
   if (charcol) {
     // Get the text for the specified line in a loaded buffer
     buf_T *buf = buflist_findnr(fnump == NULL ? curbuf->b_fnum : *fnump);
     if (buf == NULL || buf->b_ml.ml_mfp == NULL) {
       return FAIL;
     }
-    n = buf_charidx_to_byteidx(buf, posp->lnum, (int)n) + 1;
+    n = buf_charidx_to_byteidx(buf,
+                               posp->lnum == 0 ? curwin->w_cursor.lnum : posp->lnum,
+                               (int)n) + 1;
   }
   posp->col = (colnr_T)n;
 
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 9f7076366d..a326c44371 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -1270,7 +1270,7 @@ static void f_ctxsize(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 /// Otherwise use the column number as a byte offset.
 static void set_cursorpos(typval_T *argvars, typval_T *rettv, bool charcol)
 {
-  long line, col;
+  long lnum, col;
   long coladd = 0;
   bool set_curswant = true;
 
@@ -1284,7 +1284,7 @@ static void set_cursorpos(typval_T *argvars, typval_T *rettv, bool charcol)
       return;
     }
 
-    line = pos.lnum;
+    lnum = pos.lnum;
     col = pos.col;
     coladd = pos.coladd;
     if (curswant >= 0) {
@@ -1293,13 +1293,15 @@ static void set_cursorpos(typval_T *argvars, typval_T *rettv, bool charcol)
     }
   } else if ((argvars[0].v_type == VAR_NUMBER || argvars[0].v_type == VAR_STRING)
              && (argvars[1].v_type == VAR_NUMBER || argvars[1].v_type == VAR_STRING)) {
-    line = tv_get_lnum(argvars);
-    if (line < 0) {
+    lnum = tv_get_lnum(argvars);
+    if (lnum < 0) {
       semsg(_(e_invarg2), tv_get_string(&argvars[0]));
+    } else if (lnum == 0) {
+      lnum = curwin->w_cursor.lnum;
     }
     col = (long)tv_get_number_chk(&argvars[1], NULL);
     if (charcol) {
-      col = buf_charidx_to_byteidx(curbuf, (linenr_T)line, (int)col) + 1;
+      col = buf_charidx_to_byteidx(curbuf, (linenr_T)lnum, (int)col) + 1;
     }
     if (argvars[2].v_type != VAR_UNKNOWN) {
       coladd = (long)tv_get_number_chk(&argvars[2], NULL);
@@ -1308,11 +1310,11 @@ static void set_cursorpos(typval_T *argvars, typval_T *rettv, bool charcol)
     emsg(_(e_invarg));
     return;
   }
-  if (line < 0 || col < 0 || coladd < 0) {
+  if (lnum < 0 || col < 0 || coladd < 0) {
     return;  // type error; errmsg already given
   }
-  if (line > 0) {
-    curwin->w_cursor.lnum = (linenr_T)line;
+  if (lnum > 0) {
+    curwin->w_cursor.lnum = (linenr_T)lnum;
   }
   if (col > 0) {
     curwin->w_cursor.col = (colnr_T)col - 1;
diff --git a/src/nvim/testdir/test_cursor_func.vim b/src/nvim/testdir/test_cursor_func.vim
index e428bf3e23..9801a45915 100644
--- a/src/nvim/testdir/test_cursor_func.vim
+++ b/src/nvim/testdir/test_cursor_func.vim
@@ -353,8 +353,14 @@ func Test_setcursorcharpos()
   normal G
   call setcursorcharpos([1, 1])
   call assert_equal([1, 1], [line('.'), col('.')])
+
   call setcursorcharpos([2, 7, 0])
   call assert_equal([2, 9], [line('.'), col('.')])
+  call setcursorcharpos([0, 7, 0])
+  call assert_equal([2, 9], [line('.'), col('.')])
+  call setcursorcharpos(0, 7, 0)
+  call assert_equal([2, 9], [line('.'), col('.')])
+
   call setcursorcharpos(3, 4)
   call assert_equal([3, 1], [line('.'), col('.')])
   call setcursorcharpos([3, 1])