patch 9.0.0861: solution for "!!sort" in closed fold is not optimal

Problem:    Solution for "!!sort" in closed fold is not optimal.
Solution:   Use a different range instead of the subtle difference in handling
            a range with an offset. (issue #11487)

runtime/doc/cmdline.txt

@@ -736,7 +736,9 @@ Line numbers may be specified with:		*:range* *{address}*
 	'T		position of mark T (uppercase); when the mark is in
 			another file it cannot be used in a range
 	/{pattern}[/]	the next line where {pattern} matches	  *:/*
+				also see |:range-pattern| below
 	?{pattern}[?]	the previous line where {pattern} matches *:?*
+				also see |:range-pattern| below
 	\/		the next line where the previously used search
 			pattern matches
 	\?		the previous line where the previously used search
@@ -744,11 +746,49 @@ Line numbers may be specified with:		*:range* *{address}*
 	\&		the next line where the previously used substitute
 			pattern matches
 
+						*:range-offset*
 Each may be followed (several times) by '+' or '-' and an optional number.
 This number is added or subtracted from the preceding line number.  If the
 number is omitted, 1 is used.  If there is nothing before the '+' or '-' then
 the current line is used.
+						*:range-closed-fold*
+When a line number after the comma is in a closed fold it is adjusted to the
+last line of the fold, thus the whole fold is included.
 
+When a number is added this is done after the adjustment to the last line of
+the fold.  This means these lines are additionally included in the range.  For
+example: >
+   :3,4+2print
+On this text:
+	1 one ~
+	2 two ~
+	3 three ~
+	4 four FOLDED ~
+	5 five FOLDED ~
+	6 six ~
+	7 seven ~
+	8 eight ~
+Where lines four and five are a closed fold, ends up printing lines 3 to 7.
+The 7 comes from the "4" in the range, which is adjusted to the end of the
+closed fold, which is 5, and then the offset 2 is added.
+
+An example for subtracting (which isn't very useful): >
+   :2,4-1print
+On this text:
+	1 one ~
+	2 two ~
+	3 three FOLDED~
+	4 four FOLDED ~
+	5 five FOLDED ~
+	6 six FOLDED ~
+	7 seven ~
+	8 eight ~
+Where lines three to six are a closed fold, ends up printing lines 2 to 6.
+The 6 comes from the "4" in the range, which is adjusted to the end of the
+closed fold, which is 6, and then 1 is subtracted, then this is still in the
+closed fold and the last line of that fold is used, which is 6.
+
+							*:range-pattern*
 The "/" and "?" after {pattern} are required to separate the pattern from
 anything that follows.
 

src/ex_docmd.c

@@ -4308,9 +4308,6 @@ get_address(
     lnum = MAXLNUM;
     do
     {
-#ifdef FEAT_FOLDING
-	int base_char = *cmd;
-#endif
 	switch (*cmd)
 	{
 	    case '.':			    // '.' - Cursor position
@@ -4631,16 +4628,10 @@ get_address(
 	    else
 	    {
 #ifdef FEAT_FOLDING
-		// Relative line addressing: need to adjust for closed folds
-		// after the first address.
-		// Subtle difference: "number,+number" and "number,-number"
-		// adjusts to end of closed fold before adding/subtracting,
-		// while "number,.+number" adjusts to end of closed fold after
-		// adding to make "!!" expanded into ".,.+N" work correctly.
-		int adjust_for_folding = addr_type == ADDR_LINES
-						      && (i == '-' || i == '+')
-						      && address_count >= 2;
-		if (adjust_for_folding && (i == '-' || base_char != '.'))
+		// Relative line addressing: need to adjust for lines in a
+		// closed fold after the first address.
+		if (addr_type == ADDR_LINES && (i == '-' || i == '+')
+							 && address_count >= 2)
 		    (void)hasFolding(lnum, NULL, &lnum);
 #endif
 		if (i == '-')
@@ -4653,12 +4644,6 @@ get_address(
 			goto error;
 		    }
 		    lnum += n;
-#ifdef FEAT_FOLDING
-		    // ".+number" rounds up to the end of a closed fold after
-		    // adding, so that ":!!sort" sorts one closed fold.
-		    if (adjust_for_folding && base_char == '.')
-			(void)hasFolding(lnum, NULL, &lnum);
-#endif
 		}
 	    }
 	}

src/ops.c

@@ -3333,14 +3333,32 @@ op_colon(oparg_T *oap)
 	    stuffcharReadbuff('.');
 	else
 	    stuffnumReadbuff((long)oap->start.lnum);
-	if (oap->end.lnum != oap->start.lnum)
+
+#ifdef FEAT_FOLDING
+	// When using !! on a closed fold the range ".!" works best to operate
+	// on, it will be made the whole closed fold later.
+	linenr_T endOfStartFold = oap->start.lnum;
+	(void)hasFolding(oap->start.lnum, NULL, &endOfStartFold);
+#endif
+	if (oap->end.lnum != oap->start.lnum
+#ifdef FEAT_FOLDING
+		&& oap->end.lnum != endOfStartFold
+#endif
+	   )
 	{
+	    // Make it a range with the end line.
 	    stuffcharReadbuff(',');
 	    if (oap->end.lnum == curwin->w_cursor.lnum)
 		stuffcharReadbuff('.');
 	    else if (oap->end.lnum == curbuf->b_ml.ml_line_count)
 		stuffcharReadbuff('$');
-	    else if (oap->start.lnum == curwin->w_cursor.lnum)
+	    else if (oap->start.lnum == curwin->w_cursor.lnum
+#ifdef FEAT_FOLDING
+		    // do not use ".+number" for a closed fold, it would count
+		    // folded lines twice
+		    && !hasFolding(oap->end.lnum, NULL, NULL)
+#endif
+		    )
 	    {
 		stuffReadbuff((char_u *)".+");
 		stuffnumReadbuff((long)oap->line_count - 1);

src/testdir/test_fold.vim

@@ -72,6 +72,54 @@ func Test_address_fold()
   quit!
 endfunc
 
+func Test_address_offsets()
+  " check the help for :range-closed-fold
+  enew
+  call setline(1, [
+        \ '1 one',
+        \ '2 two',
+        \ '3 three',
+        \ '4 four FOLDED',
+        \ '5 five FOLDED',
+        \ '6 six',
+        \ '7 seven',
+        \ '8 eight',
+        \])
+  set foldmethod=manual
+  normal 4Gvjzf
+  3,4+2yank
+  call assert_equal([
+        \ '3 three',
+        \ '4 four FOLDED',
+        \ '5 five FOLDED',
+        \ '6 six',
+        \ '7 seven',
+        \ ], getreg(0,1,1))
+
+  enew!
+  call setline(1, [
+        \ '1 one',
+        \ '2 two',
+        \ '3 three FOLDED',
+        \ '4 four FOLDED',
+        \ '5 five FOLDED',
+        \ '6 six FOLDED',
+        \ '7 seven',
+        \ '8 eight',
+        \])
+  normal 3Gv3jzf
+  2,4-1yank
+  call assert_equal([
+        \ '2 two',
+        \ '3 three FOLDED',
+        \ '4 four FOLDED',
+        \ '5 five FOLDED',
+        \ '6 six FOLDED',
+        \ ], getreg(0,1,1))
+
+  bwipe!
+endfunc
+
 func Test_indent_fold()
     new
     call setline(1, ['', 'a', '    b', '    c'])

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    861,
 /**/
     860,
 /**/