patch 8.1.1114: confusing overloaded operator "." for string concatenation
Problem: Confusing overloaded operator "." for string concatenation.
Solution: Add ".." for string concatenation. Also "let a ..= b".
diff --git a/src/testdir/test_eval_stuff.vim b/src/testdir/test_eval_stuff.vim
index f4b3598..6d61ce9 100644
--- a/src/testdir/test_eval_stuff.vim
+++ b/src/testdir/test_eval_stuff.vim
@@ -94,3 +94,32 @@
call assert_fails('let v:errmsg = []', 'E730:')
let v:errmsg = ''
endfunc
+
+func Test_string_concatenation()
+ call assert_equal('ab', 'a'.'b')
+ call assert_equal('ab', 'a' .'b')
+ call assert_equal('ab', 'a'. 'b')
+ call assert_equal('ab', 'a' . 'b')
+
+ call assert_equal('ab', 'a'..'b')
+ call assert_equal('ab', 'a' ..'b')
+ call assert_equal('ab', 'a'.. 'b')
+ call assert_equal('ab', 'a' .. 'b')
+
+ let a = 'a'
+ let b = 'b'
+ let a .= b
+ call assert_equal('ab', a)
+
+ let a = 'a'
+ let a.=b
+ call assert_equal('ab', a)
+
+ let a = 'a'
+ let a ..= b
+ call assert_equal('ab', a)
+
+ let a = 'a'
+ let a..=b
+ call assert_equal('ab', a)
+endfunc