patch 8.2.2322: Vim9: closure nested limiting to one level

Problem:    Vim9: closure nested limiting to one level.
Solution:   Add outer_T.  Also make STOREOUTER work.

Author: brammool

src/structs.h

@@ -1965,6 +1965,14 @@ typedef struct funcstack_S
     int		fs_copyID;	// for garray_T collection
 } funcstack_T;
 
+typedef struct outer_S outer_T;
+struct outer_S {
+    garray_T	*out_stack;	    // stack from outer scope
+    int		out_frame_idx;	    // index of stack frame in out_stack
+    outer_T	*out_up;	    // outer scope of outer scope or NULL
+    int		out_up_is_copy;	    // don't free out_up
+};
+
 struct partial_S
 {
     int		pt_refcount;	// reference count
@@ -1975,13 +1983,11 @@ struct partial_S
     int		pt_auto;	// when TRUE the partial was created for using
 				// dict.member in handle_subscript()
 
-    // For a compiled closure: the arguments and local variables.
-    garray_T	*pt_ectx_stack;	    // where to find local vars
-    int		pt_ectx_frame;	    // index of function frame in uf_ectx_stack
-    garray_T	*pt_outer_stack;    // pt_ectx_stack one level up
-    int		pt_outer_frame;	    // pt_ectx_frame one level up.
-    funcstack_T	*pt_funcstack;	    // copy of stack, used after context
-				    // function returns
+    // For a compiled closure: the arguments and local variables scope
+    outer_T	pt_outer;
+
+    funcstack_T	*pt_funcstack;	// copy of stack, used after context
+				// function returns
 
     int		pt_argc;	// number of arguments
     typval_T	*pt_argv;	// arguments in allocated array

src/testdir/test_vim9_func.vim

@@ -1822,6 +1822,13 @@ def Test_nested_closure_using_argument()
   assert_equal(['x', 'x2'], DoFilterThis('x'))
 enddef
 
+def Test_triple_nested_closure()
+  var what = 'x'
+  var Match = (val: string, cmp: string): bool => stridx(val, cmp) == 0
+  var Filter = (l) => filter(l, (_, v) => Match(v, what))
+  assert_equal(['x', 'x2'], ['x', 'y', 'a', 'x2', 'c']->Filter())
+enddef
+
 func Test_silent_echo()
   CheckScreendump
 

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2322,
 /**/
     2321,
 /**/

src/vim9.h

@@ -307,7 +307,7 @@ typedef struct {
 typedef struct {
     int		outer_idx;	// index
     int		outer_depth;	// nesting level, stack frames to go up
-} outer_T;
+} isn_outer_T;
 
 /*
  * Instruction
@@ -348,7 +348,7 @@ struct isn_S {
 	put_T		    put;
 	cmod_T		    cmdmod;
 	unpack_T	    unpack;
-	outer_T		    outer;
+	isn_outer_T	    outer;
     } isn_arg;
 };
 
@@ -375,10 +375,13 @@ struct dfunc_S {
 // Number of entries used by stack frame for a function call.
 // - ec_dfunc_idx:   function index
 // - ec_iidx:        instruction index
-// - ec_outer_stack: stack used for closures  TODO: can we avoid this?
-// - ec_outer_frame: stack frame for closures
+// - ec_outer:	     stack used for closures
 // - ec_frame_idx:   previous frame index
-#define STACK_FRAME_SIZE 5
+#define STACK_FRAME_FUNC_OFF 0
+#define STACK_FRAME_IIDX_OFF 1
+#define STACK_FRAME_OUTER_OFF 2
+#define STACK_FRAME_IDX_OFF 3
+#define STACK_FRAME_SIZE 4
 
 
 #ifdef DEFINE_VIM9_GLOBALS