patch 9.1.0007: can select empty inner text blocks

Problem:  can select empty inner text blocks
          (laurentalacoque)
Solution: make selecting empty inner text blocks an error

textobjects: Make selecting inner empty blocks an error

fixes: #13514
closes: #13523

Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/motion.txt

@@ -600,7 +600,8 @@ i]						*v_i]* *v_i[* *i]* *i[*
 i[			"inner [] block", select [count] '[' ']' blocks.  This
 			goes backwards to the [count] unclosed '[', and finds
 			the matching ']'.  The enclosed text is selected,
-			excluding the '[' and ']'.  The |cpo-M| option flag
+			excluding the '[' and ']'.  It's an error to select an
+			empty inner block like "[]".  The |cpo-M| option flag
 			is used to handle escaped brackets.
 			When used in Visual mode it is made characterwise.
 
@@ -618,7 +619,8 @@ i(							*vib* *v_ib* *v_i(* *ib*
 ib			"inner block", select [count] blocks, from "[count] [("
 			to the matching ')', excluding the '(' and ')' (see
 			|[(|).  If the cursor is not inside a () block, then
-			find the next "(".  The |cpo-M| option flag
+			find the next "(".  It's an error to select an empty
+			inner block like "()".  The |cpo-M| option flag
 			is used to handle escaped parenthesis.
 			When used in Visual mode it is made characterwise.
 
@@ -632,8 +634,9 @@ a<			"a <> block", select [count] <> blocks, from the
 i>						*v_i>* *v_i<* *i>* *i<*
 i<			"inner <> block", select [count] <> blocks, from
 			the [count]'th unmatched '<' backwards to the matching
-			'>', excluding the '<' and '>'.  The |cpo-M| option flag
-			is used to handle escaped '<' and '>'.
+			'>', excluding the '<' and '>'.  It's an error to
+			select an empty inner block like "<>".  The |cpo-M|
+			option flag is used to handle escaped '<' and '>'.
 			When used in Visual mode it is made characterwise.
 
 						*v_at* *at*
@@ -663,7 +666,8 @@ i}							*v_i}* *i}* *i{*
 i{							*v_iB* *v_i{* *iB*
 iB			"inner Block", select [count] Blocks, from "[count] [{"
 			to the matching '}', excluding the '{' and '}' (see
-			|[{|).  The |cpo-M| option flag is used to handle
+			|[{|).  It's an error to select an empty inner block
+			like "{}".  The |cpo-M| option flag is used to handle
 			escaped braces.
 			When used in Visual mode it is made characterwise.
 

src/testdir/test_textobjects.vim

@@ -400,7 +400,7 @@ func Test_paragraph()
   call assert_beeps("normal Vipip")
   exe "normal \<C-C>"
 
-  close!
+  bw!
 endfunc
 
 " Tests for text object aw
@@ -606,7 +606,7 @@ func Test_textobj_quote()
   normal $hhyi"
   call assert_equal('bar', @")
 
-  close!
+  bw!
 endfunc
 
 " Test for i(, i<, etc. when cursor is in front of a block
@@ -638,7 +638,115 @@ func Test_textobj_find_paren_forward()
   normal 0di)
   call assert_equal('foo ()', getline(1))
 
-  close!
+  bw!
+endfunc
+
+func Test_inner_block_empty_paren()
+  new
+  call setline(1, ["(text)()", "", "(text)(", ")", "", "()()"])
+
+  " Example 1
+  call cursor(1, 1)
+  let @" = ''
+  call assert_beeps(':call feedkeys("0f(viby","xt")')
+  call assert_equal(7, getpos('.')[2])
+  call assert_equal('(', @")
+
+  " Example 2
+  call cursor(3, 1)
+  let @" = ''
+  call assert_beeps('call feedkeys("0f(viby", "xt")')
+  call assert_equal(7, getpos('.')[2])
+  call assert_equal('(', @")
+
+  " Example 3
+  call cursor(6, 1)
+  let @" = ''
+  call assert_beeps('call feedkeys("0f(viby", "xt")')
+  call assert_equal(3, getpos('.')[2])
+  call assert_equal('(', @")
+  bwipe!
+endfunc
+
+func Test_inner_block_empty_bracket()
+  new
+  call setline(1, ["[text][]", "", "[text][", "]", "", "[][]"])
+
+  " Example 1
+  call cursor(1, 1)
+  let @" = ''
+  call assert_beeps(':call feedkeys("0f[viby","xt")')
+  call assert_equal(7, getpos('.')[2])
+  call assert_equal('[', @")
+
+  " Example 2
+  call cursor(3, 1)
+  let @" = ''
+  call assert_beeps('call feedkeys("0f[viby", "xt")')
+  call assert_equal(7, getpos('.')[2])
+  call assert_equal('[', @")
+
+  " Example 3
+  call cursor(6, 1)
+  let @" = ''
+  call assert_beeps('call feedkeys("0f[viby", "xt")')
+  call assert_equal(3, getpos('.')[2])
+  call assert_equal('[', @")
+  bwipe!
+endfunc
+
+func Test_inner_block_empty_brace()
+  new
+  call setline(1, ["{text}{}", "", "{text}{", "}", "", "{}{}"])
+
+  " Example 1
+  call cursor(1, 1)
+  let @" = ''
+  call assert_beeps(':call feedkeys("0f{viby","xt")')
+  call assert_equal(7, getpos('.')[2])
+  call assert_equal('{', @")
+
+  " Example 2
+  call cursor(3, 1)
+  let @" = ''
+  call assert_beeps('call feedkeys("0f{viby", "xt")')
+  call assert_equal(7, getpos('.')[2])
+  call assert_equal('{', @")
+
+  " Example 3
+  call cursor(6, 1)
+  let @" = ''
+  call assert_beeps('call feedkeys("0f{viby", "xt")')
+  call assert_equal(3, getpos('.')[2])
+  call assert_equal('{', @")
+  bwipe!
+endfunc
+
+func Test_inner_block_empty_lessthan()
+  new
+  call setline(1, ["<text><>", "", "<text><", ">", "", "<><>"])
+
+  " Example 1
+  call cursor(1, 1)
+  let @" = ''
+  call assert_beeps(':call feedkeys("0f<viby","xt")')
+  call assert_equal(7, getpos('.')[2])
+  call assert_equal('<', @")
+
+  " Example 2
+  call cursor(3, 1)
+  let @" = ''
+  call assert_beeps('call feedkeys("0f<viby", "xt")')
+  call assert_equal(7, getpos('.')[2])
+  call assert_equal('<', @")
+
+  " Example 3
+  call cursor(6, 1)
+  let @" = ''
+  call assert_beeps('call feedkeys("0f<viby", "xt")')
+  call assert_equal(3, getpos('.')[2])
+  call assert_equal('<', @")
+  bwipe!
 endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab

src/textobject.c

@@ -1131,6 +1131,11 @@ current_block(
 		break;
 	}
 
+	if (EQUAL_POS(start_pos, *end_pos))
+	    // empty block like this: ()
+	    // there is no inner block to select, abort
+	    return FAIL;
+
 	/*
 	 * In Visual mode, when the resulting area is not bigger than what we
 	 * started with, extend it to the next block, and then exclude again.

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    7,
 /**/
     6,
 /**/