commit b209b86e6636a16088ccacdac98213416c065bf2
author Yegappan Lakshmanan <yegappan@yahoo.com> Tue Aug 15 23:01:44 2023 +0200
committer Christian Brabandt <cb@256bit.org> Tue Aug 15 23:01:44 2023 +0200
tree b6eb5f5ab5c0ab74a46a7d1ba0cd6e61e5548780
parent 15a0a0281a060fd5968ca2f3c80e750137106adb

patch 9.0.1717: virtcol2col returns last byte of a multi-byte char

Problem: virtcol2col returns last byte of a multi-byte char
Solution: Make it return the first byte for a multi-byte char

closes: #12786
closes: #12799

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

src/move.c

diff --git a/src/move.c b/src/move.c
index 22c37ce..94dc7dc 100644
--- a/src/move.c
+++ b/src/move.c
@@ -1557,6 +1557,25 @@
 }
 
 /*
+ * Convert a virtual (screen) column to a character column.  The first column
+ * is one.  For a multibyte character, the column number of the first byte is
+ * returned.
+ */
+    static int
+virtcol2col(win_T *wp, linenr_T lnum, int vcol)
+{
+    int		offset = vcol2col(wp, lnum, vcol);
+    char_u	*line = ml_get_buf(wp->w_buffer, lnum, FALSE);
+    char_u	*p = line + offset;
+
+    // For a multibyte character, need to return the column number of the first
+    // byte.
+    MB_PTR_BACK(line, p);
+
+    return (int)(p - line + 1);
+}
+
+/*
  * "virtcol2col({winid}, {lnum}, {col})" function
  */
     void
@@ -1586,7 +1605,7 @@
     if (error || screencol < 0)
 	return;
 
-    rettv->vval.v_number = vcol2col(wp, lnum, screencol);
+    rettv->vval.v_number = virtcol2col(wp, lnum, screencol);
 }
 #endif
 

src/testdir/test_cursor_func.vim

diff --git a/src/testdir/test_cursor_func.vim b/src/testdir/test_cursor_func.vim
index 74d7581..2ae7580 100644
--- a/src/testdir/test_cursor_func.vim
+++ b/src/testdir/test_cursor_func.vim
@@ -531,6 +531,15 @@
   call assert_equal(-1, virtcol2col(0, -1, 1))
   call assert_equal(-1, virtcol2col(0, 1, -1))
   call assert_equal(5, virtcol2col(0, 1, 20))
+
+  " Multibyte character
+  call setline(1, ['a✅✅✅'])
+  call assert_equal(1, virtcol2col(0, 1, 1))
+  call assert_equal(2, virtcol2col(0, 1, 3))
+  call assert_equal(5, virtcol2col(0, 1, 5))
+  call assert_equal(8, virtcol2col(0, 1, 7))
+  call assert_equal(8, virtcol2col(0, 1, 8))
+
   call assert_fails('echo virtcol2col("0", 1, 20)', 'E1210:')
   call assert_fails('echo virtcol2col(0, "1", 20)', 'E1210:')
   call assert_fails('echo virtcol2col(0, 1, "1")', 'E1210:')

src/version.c

diff --git a/src/version.c b/src/version.c
index 80bd77d..d5d1855 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1717,
+/**/
     1716,
 /**/
     1715,