vim-patch:8.1.1835: cannot use printf() as a method

Problem:    Cannot use printf() as a method.
Solution:   Pass the base as the second argument to printf().
fd8ca21b3f

runtime/doc/eval.txt

@@ -6653,7 +6653,11 @@ printf({fmt}, {expr1} ...)				*printf()*
 <		May result in:
 			"  99: E42 asdfasdfasdfasdfasdfasdfasdfas" ~
 
-		Often used items are:
+		When used as a |method| the base is passed as the second
+		argument: >
+			Compute()->printf("result: %d")
+
+<		Often used items are:
 		  %s	string
 		  %6S	string right-aligned in 6 display cells
 		  %6s	string right-aligned in 6 bytes

src/nvim/eval.lua

@@ -258,7 +258,7 @@ return {
     pathshorten={args=1},
     pow={args=2},
     prevnonblank={args=1},
-    printf={args=varargs(1)},
+    printf={args=varargs(1), base=2},
     prompt_getprompt={args=1},
     prompt_setcallback={args={2, 2}},
     prompt_setinterrupt={args={2, 2}},

src/nvim/testdir/test_method.vim

@@ -72,13 +72,15 @@ func Test_dict_method()
 endfunc
 
 func Test_string_method()
-  call assert_equal(['1', '2', '3'], '1 2 3'->split())
+  eval '1 2 3'->split()->assert_equal(['1', '2', '3'])
-  call assert_equal([1, 2, 3], '1 2 3'->split()->map({i, v -> str2nr(v)}))
+  eval '1 2 3'->split()->map({i, v -> str2nr(v)})->assert_equal([1, 2, 3])
-  call assert_equal([65, 66, 67], 'ABC'->str2list())
+  eval 'ABC'->str2list()->assert_equal([65, 66, 67])
-  call assert_equal(3, 'ABC'->strlen())
+  eval 'ABC'->strlen()->assert_equal(3)
-  call assert_equal('a^Mb^[c', "a\rb\ec"->strtrans())
+  eval "a\rb\ec"->strtrans()->assert_equal('a^Mb^[c')
-  call assert_equal(4, "aあb"->strwidth())
+  eval "aあb"->strwidth()->assert_equal(4)
-  call assert_equal('axc', 'abc'->substitute('b', 'x', ''))
+  eval 'abc'->substitute('b', 'x', '')->assert_equal('axc')
+
+  eval 'abc'->printf('the %s arg')->assert_equal('the abc arg')
 endfunc
 
 func Test_method_append()