patch 8.1.0542: shiftwidth() does not take 'vartabstop' into account

Problem:    shiftwidth() does not take 'vartabstop' into account.
Solution:   Use the cursor position or a position explicitly passed.
            Also make >> and << work better with 'vartabstop'. (Christian
            Brabandt)

runtime/doc/change.txt

@@ -476,6 +476,10 @@ SHIFTING LINES LEFT OR RIGHT				*shift-left-right*
 							*<*
 <{motion}		Shift {motion} lines one 'shiftwidth' leftwards.
 
+			If the 'vartabstop' feature is enabled, and the
+			'shiftwidth' option is set to zero, the amount of
+			indent is calculated at the first non-blank character
+			in the line.
 							*<<*
 <<			Shift [count] lines one 'shiftwidth' leftwards.
 
@@ -487,6 +491,10 @@ SHIFTING LINES LEFT OR RIGHT				*shift-left-right*
 							*>*
  >{motion}		Shift {motion} lines one 'shiftwidth' rightwards.
 
+			If the 'vartabstop' feature is enabled, and the
+			'shiftwidth' option is set to zero, the amount of
+			indent is calculated at the first non-blank character
+			in the line.
 							*>>*
  >>			Shift [count] lines one 'shiftwidth' rightwards.
 

runtime/doc/eval.txt

@@ -2308,7 +2308,6 @@ perleval({expr})		any	evaluate |Perl| expression
 pow({x}, {y})			Float	{x} to the power of {y}
 prevnonblank({lnum})		Number	line nr of non-blank line <= {lnum}
 printf({fmt}, {expr1}...)	String	format text
-prompt_addtext({buf}, {expr})	none	add text to a prompt buffer
 prompt_setcallback({buf}, {expr}) none	set prompt callback function
 prompt_setinterrupt({buf}, {text}) none	set prompt interrupt function
 prompt_setprompt({buf}, {text}) none	set prompt text
@@ -2386,7 +2385,7 @@ sha256({string})		String	SHA256 checksum of {string}
 shellescape({string} [, {special}])
 				String	escape {string} for use as shell
 					command argument
-shiftwidth([{list}])		Number	effective value of 'shiftwidth'
+shiftwidth([{col}])		Number	effective value of 'shiftwidth'
 simplify({filename})		String	simplify filename as much as possible
 sin({expr})			Float	sine of {expr}
 sinh({expr})			Float	hyperbolic sine of {expr}
@@ -7639,19 +7638,17 @@ shellescape({string} [, {special}])			*shellescape()*
 <		See also |::S|.
 
 
-shiftwidth([{list}])						*shiftwidth()*
+shiftwidth([{col}])						*shiftwidth()*
 		Returns the effective value of 'shiftwidth'. This is the
 		'shiftwidth' value unless it is zero, in which case it is the
 		'tabstop' value.  This function was introduced with patch
-		7.3.694 in 2012, everybody should have it by now.
+		7.3.694 in 2012, everybody should have it by now (however it
+		did not allow for the optional {col} argument until 8.1.542).
 
-		When there is one argument {list} this is used as position
-		|List| for which to return the 'shiftwidth' value (actually
-		only the column number is relevant). This matters for the
-		'vartabstop' feature. For the {list} arguments see |cursor()|
-		function. If the 'vartabstop' setting is enabled and no
-		{list} argument is given, the current cursor position is
-		taken into account.
+		When there is one argument {col} this is used as column number
+		for which to return the 'shiftwidth' value. This matters for the
+		'vartabstop' feature. If the 'vartabstop' setting is enabled and
+		no {col} argument is given, column 1 will be assumed.
 
 
 simplify({filename})					*simplify()*

src/edit.c

@@ -262,7 +262,6 @@ static int  ins_ctrl_ey(int tc);
 #ifdef FEAT_SMARTINDENT
 static void ins_try_si(int c);
 #endif
-static colnr_T get_nolist_virtcol(void);
 #if defined(FEAT_EVAL)
 static char_u *do_insert_char_pre(int c);
 #endif
@@ -10681,9 +10680,14 @@ ins_try_si(int c)
  * Get the value that w_virtcol would have when 'list' is off.
  * Unless 'cpo' contains the 'L' flag.
  */
-    static colnr_T
+    colnr_T
 get_nolist_virtcol(void)
 {
+    // check validity of cursor in current buffer
+    if (curwin->w_buffer == NULL
+	|| curwin->w_buffer->b_ml.ml_mfp == NULL
+	|| curwin->w_cursor.lnum > curwin->w_buffer->b_ml.ml_line_count)
+	return 0;
     if (curwin->w_p_list && vim_strchr(p_cpo, CPO_LISTWM) == NULL)
 	return getvcol_nolist(&curwin->w_cursor);
     validate_virtcol();

src/evalfunc.c

@@ -835,7 +835,7 @@ static struct fst
     {"sha256",		1, 1, f_sha256},
 #endif
     {"shellescape",	1, 2, f_shellescape},
-    {"shiftwidth",	0, 0, f_shiftwidth},
+    {"shiftwidth",	0, 1, f_shiftwidth},
     {"simplify",	1, 1, f_simplify},
 #ifdef FEAT_FLOAT
     {"sin",		1, 1, f_sin},
@@ -11241,6 +11241,21 @@ f_shellescape(typval_T *argvars, typval_T *rettv)
     static void
 f_shiftwidth(typval_T *argvars UNUSED, typval_T *rettv)
 {
+    rettv->vval.v_number = 0;
+
+    if (argvars[0].v_type != VAR_UNKNOWN)
+    {
+	long	col;
+
+	col = (long)get_tv_number_chk(argvars, NULL);
+	if (col < 0)
+	    return;	// type error; errmsg already given
+#ifdef FEAT_VARTABS
+	rettv->vval.v_number = get_sw_value_col(curbuf, col);
+	return;
+#endif
+    }
+
     rettv->vval.v_number = get_sw_value(curbuf);
 }
 

src/normal.c

@@ -8143,6 +8143,7 @@ nv_g_cmd(cmdarg_T *cap)
 	    do
 		i = gchar_cursor();
 	    while (VIM_ISWHITE(i) && oneright() == OK);
+	    curwin->w_valid &= ~VALID_WCOL;
 	}
 	curwin->w_set_curswant = TRUE;
 	break;

src/ops.c

@@ -334,7 +334,7 @@ shift_line(
 {
     int		count;
     int		i, j;
-    int		p_sw = (int)get_sw_value(curbuf);
+    int		p_sw = (int)get_sw_value_indent(curbuf);
 
     count = get_indent();	/* get current indent */
 
@@ -386,7 +386,7 @@ shift_block(oparg_T *oap, int amount)
     int			total;
     char_u		*newp, *oldp;
     int			oldcol = curwin->w_cursor.col;
-    int			p_sw = (int)get_sw_value(curbuf);
+    int			p_sw = (int)get_sw_value_indent(curbuf);
 #ifdef FEAT_VARTABS
     int			*p_vts = curbuf->b_p_vts_array;
 #endif

src/option.c

@@ -13113,7 +13113,48 @@ tabstop_first(int *ts)
     long
 get_sw_value(buf_T *buf)
 {
-    return buf->b_p_sw ? buf->b_p_sw : buf->b_p_ts;
+    return get_sw_value_col(buf, 0);
+}
+
+/*
+ * Idem, using the first non-black in the current line.
+ */
+    long
+get_sw_value_indent(buf_T *buf)
+{
+    pos_T pos = curwin->w_cursor;
+
+    pos.col = getwhitecols_curline();
+    return get_sw_value_pos(buf, &pos);
+}
+
+/*
+ * Idem, using "pos".
+ */
+    long
+get_sw_value_pos(buf_T *buf, pos_T *pos)
+{
+    pos_T save_cursor = curwin->w_cursor;
+    long sw_value;
+
+    curwin->w_cursor = *pos;
+    sw_value = get_sw_value_col(buf, get_nolist_virtcol());
+    curwin->w_cursor = save_cursor;
+    return sw_value;
+}
+
+/*
+ * Idem, using virtual column "col".
+ */
+    long
+get_sw_value_col(buf_T *buf, colnr_T col UNUSED)
+{
+    return buf->b_p_sw ? buf->b_p_sw :
+ #ifdef FEAT_VARTABS
+	tabstop_at(col, buf->b_p_ts, buf->b_p_vts_array);
+ #else
+	buf->b_p_ts;
+ #endif
 }
 
 /*

src/proto/edit.pro

@@ -46,4 +46,5 @@ int bracketed_paste(paste_mode_T mode, int drop, garray_T *gap);
 void ins_scroll(void);
 void ins_horscroll(void);
 int ins_copychar(linenr_T lnum);
+colnr_T get_nolist_virtcol(void);
 /* vim: set ft=c : */

src/proto/option.pro

@@ -72,6 +72,9 @@ int *tabstop_copy(int *oldts);
 int tabstop_count(int *ts);
 int tabstop_first(int *ts);
 long get_sw_value(buf_T *buf);
+long get_sw_value_indent(buf_T *buf);
+long get_sw_value_pos(buf_T *buf, pos_T *pos);
+long get_sw_value_col(buf_T *buf, colnr_T col);
 long get_sts_value(void);
 void find_mps_values(int *initc, int *findc, int *backwards, int switchit);
 unsigned int get_bkc_value(buf_T *buf);

src/testdir/test_vartabs.vim

@@ -297,6 +297,71 @@ func Test_vartabs_linebreak()
   set nolist listchars&vim
 endfunc
 
+func Test_vartabs_shiftwidth()
+  "return
+  if winwidth(0) < 40
+    return
+  endif
+  new
+  40vnew
+  %d
+"  setl varsofttabstop=10,20,30,40
+  setl shiftwidth=0 vartabstop=10,20,30,40
+  call setline(1, "x")
+
+  " Check without any change.
+  let expect = ['x                                       ']
+  let lines = ScreenLines(1, winwidth(0))
+  call s:compare_lines(expect, lines)
+  " Test 1:
+  " shiftwidth depends on the indent, first check with cursor at the end of the
+  " line (which is the same as the start of the line, since there is only one
+  " character).
+  norm! $>>
+  let expect1 = ['          x                             ']
+  let lines = ScreenLines(1, winwidth(0))
+  call s:compare_lines(expect1, lines)
+  call assert_equal(10, shiftwidth())
+  call assert_equal(10, shiftwidth(1))
+  call assert_equal(20, shiftwidth(virtcol('.')))
+  norm! $>>
+  let expect2 = ['                              x         ', '~                                       ']
+  let lines = ScreenLines([1, 2], winwidth(0))
+  call s:compare_lines(expect2, lines)
+  call assert_equal(20, shiftwidth(virtcol('.')-2))
+  call assert_equal(30, shiftwidth(virtcol('.')))
+  norm! $>>
+  let expect3 = ['                                        ', '                    x                   ', '~                                       ']
+  let lines = ScreenLines([1, 3], winwidth(0))
+  call s:compare_lines(expect3, lines)
+  call assert_equal(30, shiftwidth(virtcol('.')-2))
+  call assert_equal(40, shiftwidth(virtcol('.')))
+  norm! $>>
+  let expect4 = ['                                        ', '                                        ', '                    x                   ']
+  let lines = ScreenLines([1, 3], winwidth(0))
+  call assert_equal(40, shiftwidth(virtcol('.')))
+  call s:compare_lines(expect4, lines)
+
+  " Test 2: Put the cursor at the first column, result should be the same
+  call setline(1, "x")
+  norm! 0>>
+  let lines = ScreenLines(1, winwidth(0))
+  call s:compare_lines(expect1, lines)
+  norm! 0>>
+  let lines = ScreenLines([1, 2], winwidth(0))
+  call s:compare_lines(expect2, lines)
+  norm! 0>>
+  let lines = ScreenLines([1, 3], winwidth(0))
+  call s:compare_lines(expect3, lines)
+  norm! 0>>
+  let lines = ScreenLines([1, 3], winwidth(0))
+  call s:compare_lines(expect4, lines)
+
+  " cleanup
+  bw!
+  bw!
+endfunc
+
 func Test_vartabs_failures()
   call assert_fails('set vts=8,')
   call assert_fails('set vsts=8,')

src/version.c

@@ -792,6 +792,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    542,
 /**/
     541,
 /**/