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>
diff --git a/src/testdir/test_textobjects.vim b/src/testdir/test_textobjects.vim
index 746b326..89e741c 100644
--- a/src/testdir/test_textobjects.vim
+++ b/src/testdir/test_textobjects.vim
@@ -400,7 +400,7 @@
   call assert_beeps("normal Vipip")
   exe "normal \<C-C>"
 
-  close!
+  bw!
 endfunc
 
 " Tests for text object aw
@@ -606,7 +606,7 @@
   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 @@
   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
diff --git a/src/textobject.c b/src/textobject.c
index d03b624..af94d06 100644
--- a/src/textobject.c
+++ b/src/textobject.c
@@ -1131,6 +1131,11 @@
 		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.
diff --git a/src/version.c b/src/version.c
index 3dc537d..d00e802 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    7,
+/**/
     6,
 /**/
     5,