patch 8.2.1026: Vim9: cannot break the line after "->"

Problem:    Vim9: cannot break the line after "->".
Solution:   Check for a continuation line after "->", "[" and ".".  Ignore
            trailing white space.

src/testdir/test_vim9_expr.vim

@@ -1029,6 +1029,21 @@ def Test_expr7_trailing()
   assert_equal(123, d.key)
 enddef
 
+def Test_expr7_subscript_linebreak()
+  let range = range(
+  		3)
+  let l = range->
+  	map('string(v:key)')
+  assert_equal(['0', '1', '2'], l)
+
+  assert_equal('1', l[
+	1])
+
+  let d = #{one: 33}
+  assert_equal(33, d.
+	one)
+enddef
+
 
 func Test_expr7_trailing_fails()
   call CheckDefFailure(['let l = [2]', 'l->{l -> add(l, 8)}'], 'E107')

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1026,
 /**/
     1025,
 /**/

src/vim9compile.c

@@ -3538,7 +3538,10 @@ compile_subscript(
 		return FAIL;
 	    *start_leader = end_leader;   // don't apply again later
 
-	    *arg = skipwhite(*arg + 2);
+	    p = *arg + 2;
+	    *arg = skipwhite(p);
+	    if (may_get_next_line(p, arg, cctx) == FAIL)
+		return FAIL;
 	    if (**arg == '{')
 	    {
 		// lambda call:  list->{lambda}
@@ -3567,6 +3570,7 @@ compile_subscript(
 	{
 	    garray_T	*stack = &cctx->ctx_type_stack;
 	    type_T	**typep;
+	    char_u	*p;
 
 	    // list index: list[123]
 	    // dict member: dict[key]
@@ -3576,7 +3580,10 @@ compile_subscript(
 	    if (generate_ppconst(cctx, ppconst) == FAIL)
 		return FAIL;
 
-	    *arg = skipwhite(*arg + 1);
+	    p = *arg + 1;
+	    *arg = skipwhite(p);
+	    if (may_get_next_line(p, arg, cctx) == FAIL)
+		return FAIL;
 	    if (compile_expr0(arg, cctx) == FAIL)
 		return FAIL;
 
@@ -3617,8 +3624,10 @@ compile_subscript(
 		return FAIL;
 
 	    ++*arg;
-	    p = *arg;
+	    if (may_get_next_line(*arg, arg, cctx) == FAIL)
+		return FAIL;
 	    // dictionary member: dict.name
+	    p = *arg;
 	    if (eval_isnamec1(*p))
 		while (eval_isnamec(*p))
 		    MB_PTR_ADV(p);
@@ -6664,7 +6673,7 @@ compile_def_function(ufunc_T *ufunc, int set_return_type, cctx_T *outer_cctx)
 	if (line != NULL && *line == '|')
 	    // the line continues after a '|'
 	    ++line;
-	else if (line != NULL && *line != NUL
+	else if (line != NULL && *skipwhite(line) != NUL
 		&& !(*line == '#' && (line == cctx.ctx_line_start
 						    || VIM_ISWHITE(line[-1]))))
 	{