patch 7.4.2121

Problem:    No easy way to check if lambda and closure are supported.
Solution:   Add the +lambda feature.

src/evalfunc.c

@@ -5205,6 +5205,7 @@ f_has(typval_T *argvars, typval_T *rettv)
 #ifdef FEAT_KEYMAP
 	"keymap",
 #endif
+	"lambda", /* always with FEAT_EVAL, since 7.4.2120 with closure */
 #ifdef FEAT_LANGMAP
 	"langmap",
 #endif

src/testdir/test_lambda.vim

@@ -1,5 +1,9 @@
 " Test for lambda and closure
 
+function! Test_lambda_feature()
+  call assert_equal(1, has('lambda'))
+endfunction
+
 function! Test_lambda_with_filter()
   let s:x = 2
   call assert_equal([2, 3], filter([1, 2, 3], {i, v -> v >= s:x}))

src/version.c

@@ -304,6 +304,11 @@ static char *(features[]) =
 #else
 	"-keymap",
 #endif
+#ifdef FEAT_EVAL
+	"+lambda",
+#else
+	"-lambda",
+#endif
 #ifdef FEAT_LANGMAP
 	"+langmap",
 #else
@@ -758,6 +763,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2121,
 /**/
     2120,
 /**/