patch 8.1.1828: not strict enough checking syntax of method invocation

Problem:    Not strict enough checking syntax of method invocation.
Solution:   Check there is no white space inside ->method(.

runtime/doc/eval.txt

@@ -1223,12 +1223,19 @@ For methods that are also available as global functions this is the same as: >
 	name(expr8 [, args])
 There can also be methods specifically for the type of "expr8".
 
-"->name(" must not contain white space.  There can be white space before "->"
-and after the "(".
-
-This allows for chaining, using the type that the method returns: >
+This allows for chaining, passing the value that one method returns to the
+next method: >
 	mylist->filter(filterexpr)->map(mapexpr)->sort()->join()
 <
+							*E274*
+"->name(" must not contain white space.  There can be white space before the
+"->" and after the "(", thus you can split the lines like this: >
+	mylist
+	\ ->filter(filterexpr)
+	\ ->map(mapexpr)
+	\ ->sort()
+	\ ->join()
+<
 
 							*expr9*
 number

src/eval.c

@@ -4862,6 +4862,12 @@ eval_method(
 		semsg(_(e_missingparen), name);
 	    ret = FAIL;
 	}
+	else if (VIM_ISWHITE((*arg)[-1]))
+	{
+	    if (verbose)
+		semsg(_("E274: No white space allowed before parenthesis"));
+	    ret = FAIL;
+	}
 	else
 	    ret = eval_func(arg, name, len, rettv, evaluate, &base);
     }

src/testdir/test_method.vim

@@ -112,3 +112,13 @@ func Test_method_funcref()
 
   delfunc Concat
 endfunc
+
+func Test_method_syntax()
+  eval [1, 2, 3]  ->sort( )
+  eval [1, 2, 3]  
+	\ ->sort(
+	\ )
+  call assert_fails('eval [1, 2, 3]-> sort()', 'E260:')
+  call assert_fails('eval [1, 2, 3]->sort ()', 'E274:')
+  call assert_fails('eval [1, 2, 3]-> sort ()', 'E260:')
+endfunc

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1828,
 /**/
     1827,
 /**/