patch 9.0.0502: a closure in a nested loop in a :def function does not work

Problem:    A closure in a nested loop in a :def function does not work.
Solution:   Use an array of loopvars, one per loop level.

src/errors.h

@@ -3329,3 +3329,7 @@ EXTERN char e_cannot_use_type_with_this_variable_str[]
 EXTERN char e_cannot_use_length_endcol_and_endlnum_with_text[]
 	INIT(= N_("E1305: Cannot use \"length\", \"end_col\" and \"end_lnum\" with \"text\""));
 #endif
+#ifdef FEAT_EVAL
+EXTERN char e_loop_nesting_too_deep[]
+	INIT(= N_("E1306: Loop nesting too deep"));
+#endif

src/eval.c

@@ -4807,10 +4807,11 @@ partial_free(partial_T *pt)
 	funcstack_check_refcount(pt->pt_funcstack);
     }
     // Similarly for loop variables.
-    if (pt->pt_loopvars != NULL)
+    for (i = 0; i < MAX_LOOP_DEPTH; ++i)
+	if (pt->pt_loopvars[i] != NULL)
 	{
-	--pt->pt_loopvars->lvs_refcount;
+	    --pt->pt_loopvars[i]->lvs_refcount;
-	loopvars_check_refcount(pt->pt_loopvars);
+	    loopvars_check_refcount(pt->pt_loopvars[i]);
 	}
 
     vim_free(pt);
@@ -4839,8 +4840,15 @@ partial_unref(partial_T *pt)
 	    if (pt->pt_funcstack != NULL)
 		done = funcstack_check_refcount(pt->pt_funcstack);
 
-	    if (!done && pt->pt_loopvars != NULL)
+	    if (!done)
-		loopvars_check_refcount(pt->pt_loopvars);
+	    {
+		int	depth;
+
+		for (depth = 0; depth < MAX_LOOP_DEPTH; ++depth)
+		    if (pt->pt_loopvars[depth] != NULL
+			    && loopvars_check_refcount(pt->pt_loopvars[depth]))
+		    break;
+	    }
 	}
     }
 }

src/proto/userfunc.pro

@@ -16,7 +16,7 @@ int func_is_global(ufunc_T *ufunc);
 int func_requires_g_prefix(ufunc_T *ufunc);
 int func_name_refcount(char_u *name);
 void func_clear_free(ufunc_T *fp, int force);
-int copy_lambda_to_global_func(char_u *lambda, char_u *global, short loop_var_idx, short loop_var_count, ectx_T *ectx);
+int copy_lambda_to_global_func(char_u *lambda, char_u *global, loopvarinfo_T *loopvarinfo, ectx_T *ectx);
 int funcdepth_increment(void);
 void funcdepth_decrement(void);
 int funcdepth_get(void);

src/proto/vim9cmds.pro

@@ -11,8 +11,8 @@ char_u *compile_for(char_u *arg_start, cctx_T *cctx);
 char_u *compile_endfor(char_u *arg, cctx_T *cctx);
 char_u *compile_while(char_u *arg, cctx_T *cctx);
 char_u *compile_endwhile(char_u *arg, cctx_T *cctx);
-short get_loop_var_info(cctx_T *cctx, short *loop_var_idx);
+int get_loop_var_info(cctx_T *cctx, loopvarinfo_T *lvi);
-int get_loop_var_idx(cctx_T *cctx);
+void get_loop_var_idx(cctx_T *cctx, int idx, lvar_T *lvar);
 char_u *compile_continue(char_u *arg, cctx_T *cctx);
 char_u *compile_break(char_u *arg, cctx_T *cctx);
 char_u *compile_block(char_u *arg, cctx_T *cctx);

src/proto/vim9execute.pro

@@ -9,11 +9,11 @@ void restore_current_ectx(ectx_T *ectx);
 int add_defer_function(char_u *name, int argcount, typval_T *argvars);
 char_u *char_from_string(char_u *str, varnumber_T index);
 char_u *string_slice(char_u *str, varnumber_T first, varnumber_T last, int exclusive);
-int fill_partial_and_closure(partial_T *pt, ufunc_T *ufunc, short loop_var_idx, short loop_var_count, ectx_T *ectx);
+int fill_partial_and_closure(partial_T *pt, ufunc_T *ufunc, loopvarinfo_T *loopvarinfo, ectx_T *ectx);
 int may_load_script(int sid, int *loaded);
 typval_T *lookup_debug_var(char_u *name);
 int may_break_in_function(ufunc_T *ufunc);
-void loopvars_check_refcount(loopvars_T *loopvars);
+int loopvars_check_refcount(loopvars_T *loopvars);
 int set_ref_in_loopvars(int copyID);
 int exe_typval_instr(typval_T *tv, typval_T *rettv);
 char_u *exe_substitute_instr(void);

src/proto/vim9instr.pro

@@ -31,7 +31,7 @@ int generate_CHECKLEN(cctx_T *cctx, int min_len, int more_OK);
 int generate_STORE(cctx_T *cctx, isntype_T isn_type, int idx, char_u *name);
 int generate_STORENR(cctx_T *cctx, int idx, varnumber_T value);
 int generate_LOAD(cctx_T *cctx, isntype_T isn_type, int idx, char_u *name, type_T *type);
-int generate_LOADOUTER(cctx_T *cctx, int idx, int nesting, int loop_idx, type_T *type);
+int generate_LOADOUTER(cctx_T *cctx, int idx, int nesting, int loop_depth, int loop_idx, type_T *type);
 int generate_LOADV(cctx_T *cctx, char_u *name);
 int generate_UNLET(cctx_T *cctx, isntype_T isn_type, char_u *name, int forceit);
 int generate_LOCKCONST(cctx_T *cctx);
@@ -40,13 +40,13 @@ int generate_VIM9SCRIPT(cctx_T *cctx, isntype_T isn_type, int sid, int idx, type
 int generate_NEWLIST(cctx_T *cctx, int count, int use_null);
 int generate_NEWDICT(cctx_T *cctx, int count, int use_null);
 int generate_FUNCREF(cctx_T *cctx, ufunc_T *ufunc, isn_T **isnp);
-int generate_NEWFUNC(cctx_T *cctx, char_u *lambda_name, char_u *func_name, short loop_var_idx, short loop_var_count);
+int generate_NEWFUNC(cctx_T *cctx, char_u *lambda_name, char_u *func_name);
 int generate_DEF(cctx_T *cctx, char_u *name, size_t len);
 int generate_JUMP(cctx_T *cctx, jumpwhen_T when, int where);
 int generate_WHILE(cctx_T *cctx, int funcref_idx);
 int generate_JUMP_IF_ARG_SET(cctx_T *cctx, int arg_off);
 int generate_FOR(cctx_T *cctx, int loop_idx);
-int generate_ENDLOOP(cctx_T *cctx, int funcref_idx, int prev_local_count);
+int generate_ENDLOOP(cctx_T *cctx, loop_info_T *loop_info);
 int generate_TRYCONT(cctx_T *cctx, int levels, int where);
 int check_internal_func_args(cctx_T *cctx, int func_idx, int argcount, int method_call, type2_T **argtypes, type2_T *shuffled_argtypes);
 int generate_BCALL(cctx_T *cctx, int func_idx, int argcount, int method_call);

src/structs.h

@@ -2108,6 +2108,9 @@ struct loopvars_S
     int		lvs_copyID;	// for garbage collection
 };
 
+// maximum nesting of :while and :for loops in a :def function
+#define MAX_LOOP_DEPTH 10
+
 typedef struct outer_S outer_T;
 struct outer_S {
     garray_T	*out_stack;	    // stack from outer scope, or a copy
@@ -2116,11 +2119,13 @@ struct outer_S {
     outer_T	*out_up;	    // outer scope of outer scope or NULL
     partial_T	*out_up_partial;    // partial owning out_up or NULL
 
-    garray_T	*out_loop_stack;    // stack from outer scope, or a copy
+    struct {
+	garray_T *stack;	    // stack from outer scope, or a copy
 				    // containing only vars inside the loop
-    short	out_loop_var_idx;   // first variable defined in a loop
+	short	 var_idx;	    // first variable defined in a loop in
-				    // in out_loop_stack
+				    // out_loop_stack
-    short	out_loop_var_count; // number of variables defined in a loop
+	short	 var_count;	    // number of variables defined in a loop
+    } out_loop[MAX_LOOP_DEPTH];
 };
 
 struct partial_S
@@ -2141,7 +2146,8 @@ struct partial_S
 
     funcstack_T	*pt_funcstack;	// copy of stack, used after context
 				// function returns
-    loopvars_T	*pt_loopvars;	// copy of loop variables, used after loop
+    loopvars_T	*(pt_loopvars[MAX_LOOP_DEPTH]);
+				// copy of loop variables, used after loop
 				// block ends
 
     typval_T	*pt_argv;	// arguments in allocated array
@@ -2151,6 +2157,14 @@ struct partial_S
     dict_T	*pt_dict;	// dict for "self"
 };
 
+typedef struct {
+    short	lvi_depth;	    // current nested loop depth
+    struct {
+	short	var_idx;	    // index of first variable inside loop
+	short	var_count;	    // number of variables inside loop
+    } lvi_loop[MAX_LOOP_DEPTH];
+} loopvarinfo_T;
+
 typedef struct AutoPatCmd_S AutoPatCmd_T;
 
 /*

src/testdir/test_vim9_disassemble.vim

@@ -1023,15 +1023,15 @@ def Test_disassemble_closure_in_loop()
 
         'endif\_s*' ..
         'g:Ref = () => ii\_s*' ..
-        '\d\+ FUNCREF <lambda>4 var $3 - $3\_s*' ..
+        '\d\+ FUNCREF <lambda>4 vars  $3-$3\_s*' ..
         '\d\+ STOREG g:Ref\_s*' ..
 
         'continue\_s*' ..
-        '\d\+ ENDLOOP $1 save $3 - $3\_s*' ..
+        '\d\+ ENDLOOP ref $1 save $3-$3 depth 0\_s*' ..
         '\d\+ JUMP -> \d\+\_s*' ..
 
         'break\_s*' ..
-        '\d\+ ENDLOOP $1 save $3 - $3\_s*' ..
+        '\d\+ ENDLOOP ref $1 save $3-$3 depth 0\_s*' ..
         '\d\+ JUMP -> \d\+\_s*' ..
 
          'if g:val\_s*' ..
@@ -1041,12 +1041,12 @@ def Test_disassemble_closure_in_loop()
 
         '  return\_s*' ..
         '\d\+ PUSHNR 0\_s*' ..
-        '\d\+ ENDLOOP $1 save $3 - $3\_s*' ..
+        '\d\+ ENDLOOP ref $1 save $3-$3 depth 0\_s*' ..
         '\d\+ RETURN\_s*' ..
 
         'endif\_s*' ..
         'endfor\_s*' ..
-        '\d\+ ENDLOOP $1 save $3 - $3\_s*' ..
+        '\d\+ ENDLOOP ref $1 save $3-$3 depth 0\_s*' ..
         '\d\+ JUMP -> \d\+\_s*' ..
         '\d\+ DROP\_s*' ..
         '\d\+ RETURN void',

src/testdir/test_vim9_script.vim

@@ -2322,10 +2322,46 @@ def Test_for_loop_with_closure()
         endfor
       endfor
   END
-  v9.CheckScriptSuccess(['vim9script'] + lines)
+  v9.CheckDefAndScriptSuccess(lines)
-  # FIXME: not yet right for :def
+enddef
-  lines[14] = 'assert_equal(2 .. a, flist[n]())'
+
-  v9.CheckDefSuccess(lines)
+def Test_define_global_closure_in_loops()
+  var lines =<< trim END
+      vim9script
+
+      def Func()
+        for i in range(3)
+          var ii = i
+          for a in ['a', 'b', 'c']
+            var aa = a
+            if ii == 0 && aa == 'a'
+              def g:Global_0a(): string
+                return ii .. aa
+              enddef
+            endif
+            if ii == 1 && aa == 'b'
+              def g:Global_1b(): string
+                return ii .. aa
+              enddef
+            endif
+            if ii == 2 && aa == 'c'
+              def g:Global_2c(): string
+                return ii .. aa
+              enddef
+            endif
+          endfor
+        endfor
+      enddef
+      Func()
+  END
+  v9.CheckScriptSuccess(lines)
+  assert_equal("0a", g:Global_0a())
+  assert_equal("1b", g:Global_1b())
+  assert_equal("2c", g:Global_2c())
+
+  delfunc g:Global_0a
+  delfunc g:Global_1b
+  delfunc g:Global_2c
 enddef
 
 def Test_for_loop_fails()
@@ -2418,6 +2454,32 @@ def Test_for_loop_fails()
       endfor
   END
   v9.CheckDefExecAndScriptFailure(lines, 'E1013: Argument 2: type mismatch, expected dict<number> but got dict<string>')
+
+  lines =<< trim END
+      for a in range(3)
+        while a > 3
+          for b in range(2)
+            while b < 0
+              for c in range(5)
+                while c > 6
+                  while c < 0
+                    for d in range(1)
+                      for e in range(3)
+                        while e > 3
+                        endwhile
+                      endfor
+                    endfor
+                  endwhile
+                endwhile
+              endfor
+            endwhile
+          endfor
+        endwhile
+      endfor
+  END
+  v9.CheckDefSuccess(lines)
+
+  v9.CheckDefFailure(['for x in range(3)'] + lines + ['endfor'], 'E1306:')
 enddef
 
 def Test_for_loop_script_var()

src/userfunc.c

@@ -2455,8 +2455,7 @@ func_clear_free(ufunc_T *fp, int force)
 copy_lambda_to_global_func(
 	char_u		*lambda,
 	char_u		*global,
-	short	loop_var_idx,
+	loopvarinfo_T	*loopvarinfo,
-	short	loop_var_count,
 	ectx_T		*ectx)
 {
     ufunc_T *ufunc = find_func_even_dead(lambda, FFED_IS_GLOBAL);
@@ -2524,14 +2523,12 @@ copy_lambda_to_global_func(
 
 	if (pt == NULL)
 	    goto failed;
-	if (fill_partial_and_closure(pt, ufunc, loop_var_idx, loop_var_count,
+	if (fill_partial_and_closure(pt, ufunc, loopvarinfo, ectx) == FAIL)
-								 ectx) == FAIL)
 	{
 	    vim_free(pt);
 	    goto failed;
 	}
 	ufunc->uf_partial = pt;
-	--pt->pt_refcount;  // not actually referenced here
     }
 
     return OK;

src/version.c

@@ -699,6 +699,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    502,
 /**/
     501,
 /**/

src/vim9.h

@@ -263,19 +263,20 @@ typedef struct {
 
 // arguments to ISN_FOR
 typedef struct {
-    int	    for_idx;	    // loop variable index
+    short	for_loop_idx;	// loop variable index
     int		for_end;	// position to jump to after done
 } forloop_T;
 
 // arguments to ISN_WHILE
 typedef struct {
-    int	    while_funcref_idx;  // variable index for funcref count
+    short	while_funcref_idx;  // variable index for funcref count
     int		while_end;	    // position to jump to after done
 } whileloop_T;
 
 // arguments to ISN_ENDLOOP
 typedef struct {
     short    end_funcref_idx;	// variable index of funcrefs.ga_len
+    short    end_depth;		// nested loop depth
     short    end_var_idx;	// first variable declared in the loop
     short    end_var_count;	// number of variables declared in the loop
 } endloop_T;
@@ -357,8 +358,7 @@ typedef struct {
 // extra arguments for funcref_T
 typedef struct {
     char_u	  *fre_func_name;	// function name for legacy function
-    short	fre_loop_var_idx;   // index of first variable inside loop
+    loopvarinfo_T fre_loopvar_info;	// info about variables inside loops
-    short	fre_loop_var_count; // number of variables inside loop
 } funcref_extra_T;
 
 // arguments to ISN_FUNCREF
@@ -371,8 +371,7 @@ typedef struct {
 typedef struct {
     char_u	  *nfa_lambda;	    // name of the lambda already defined
     char_u	  *nfa_global;	    // name of the global function to be created
-    short	nfa_loop_var_idx;    // index of first variable inside loop
+    loopvarinfo_T nfa_loopvar_info; // ifno about variables inside loops
-    short	nfa_loop_var_count;  // number of variables inside loop
 } newfuncarg_T;
 
 typedef struct {
@@ -628,6 +627,7 @@ typedef struct {
     int	    li_local_count;	    // ctx_locals.ga_len at loop start
     int	    li_closure_count;	    // ctx_closure_count at loop start
     int	    li_funcref_idx;	    // index of var that holds funcref count
+    int	    li_depth;		    // nested loop depth
 } loop_info_T;
 
 /*
@@ -678,6 +678,7 @@ struct scope_S {
     scopetype_T se_type;
     int		se_local_count;	    // ctx_locals.ga_len before scope
     skip_T	se_skip_save;	    // ctx_skip before the block
+    int		se_loop_depth;	    // number of loop scopes, including this
     union {
 	ifscope_T	se_if;
 	whilescope_T	se_while;
@@ -693,6 +694,7 @@ typedef struct {
     char_u	*lv_name;
     type_T	*lv_type;
     int		lv_idx;		// index of the variable on the stack
+    int		lv_loop_depth;	// depth for variable inside a loop or -1
     int		lv_loop_idx;	// index of first variable inside a loop or -1
     int		lv_from_outer;	// nesting level, using ctx_outer scope
     int		lv_const;	// when TRUE cannot be assigned to

src/vim9cmds.c

@@ -347,6 +347,8 @@ new_scope(cctx_T *cctx, scopetype_T type)
     cctx->ctx_scope = scope;
     scope->se_type = type;
     scope->se_local_count = cctx->ctx_locals.ga_len;
+    if (scope->se_outer != NULL)
+	scope->se_loop_depth = scope->se_outer->se_loop_depth;
     return scope;
 }
 
@@ -823,7 +825,9 @@ compile_for(char_u *arg_start, cctx_T *cctx)
     scope_T	*scope;
     forscope_T	*forscope;
     lvar_T	*loop_lvar;	// loop iteration variable
+    int		loop_lvar_idx;
     lvar_T	*funcref_lvar;
+    int		funcref_lvar_idx;
     lvar_T	*var_lvar;	// variable for "var"
     type_T	*vartype;
     type_T	*item_type = &t_any;
@@ -867,6 +871,12 @@ compile_for(char_u *arg_start, cctx_T *cctx)
     scope = new_scope(cctx, FOR_SCOPE);
     if (scope == NULL)
 	return NULL;
+    if (scope->se_loop_depth == MAX_LOOP_DEPTH)
+    {
+	emsg(_(e_loop_nesting_too_deep));
+	return NULL;
+    }
+    ++scope->se_loop_depth;
     forscope = &scope->se_u.se_for;
 
     // Reserve a variable to store the loop iteration counter and initialize it
@@ -877,7 +887,9 @@ compile_for(char_u *arg_start, cctx_T *cctx)
 	drop_scope(cctx);
 	return NULL;  // out of memory
     }
-    generate_STORENR(cctx, loop_lvar->lv_idx, -1);
+    // get the index before a following reserve_local() makes the lval invalid
+    loop_lvar_idx = loop_lvar->lv_idx;
+    generate_STORENR(cctx, loop_lvar_idx, -1);
 
     // Reserve a variable to store ec_funcrefs.ga_len, used in ISN_ENDLOOP.
     // The variable index is always the loop var index plus one.
@@ -888,6 +900,8 @@ compile_for(char_u *arg_start, cctx_T *cctx)
 	drop_scope(cctx);
 	return NULL;  // out of memory
     }
+    // get the index before a following reserve_local() makes the lval invalid
+    funcref_lvar_idx = funcref_lvar->lv_idx;
 
     // compile "expr", it remains on the stack until "endfor"
     arg = p;
@@ -951,7 +965,7 @@ compile_for(char_u *arg_start, cctx_T *cctx)
 	    cctx->ctx_prev_lnum = save_prev_lnum;
 	}
 
-	generate_FOR(cctx, loop_lvar->lv_idx);
+	generate_FOR(cctx, loop_lvar_idx);
 
 	arg = arg_start;
 	if (var_list)
@@ -1053,8 +1067,8 @@ compile_for(char_u *arg_start, cctx_T *cctx)
 	}
 
 	// remember the number of variables and closures, used for ENDLOOP
-	compile_fill_loop_info(&forscope->fs_loop_info,
+	compile_fill_loop_info(&forscope->fs_loop_info, funcref_lvar_idx, cctx);
-						   funcref_lvar->lv_idx, cctx);
+	forscope->fs_loop_info.li_depth = scope->se_loop_depth - 1;
     }
 
     return arg_end;
@@ -1075,8 +1089,7 @@ compile_loop_end(loop_info_T *loop_info, cctx_T *cctx)
 {
     if (cctx->ctx_locals.ga_len > loop_info->li_local_count
 	    && cctx->ctx_closure_count > loop_info->li_closure_count)
-	return generate_ENDLOOP(cctx, loop_info->li_funcref_idx,
+	return generate_ENDLOOP(cctx, loop_info);
-						    loop_info->li_local_count);
     return OK;
 }
 
@@ -1151,10 +1164,17 @@ compile_while(char_u *arg, cctx_T *cctx)
     scope_T	    *scope;
     whilescope_T    *whilescope;
     lvar_T	    *funcref_lvar;
+    int		    funcref_lvar_idx;
 
     scope = new_scope(cctx, WHILE_SCOPE);
     if (scope == NULL)
 	return NULL;
+    if (scope->se_loop_depth == MAX_LOOP_DEPTH)
+    {
+	emsg(_(e_loop_nesting_too_deep));
+	return NULL;
+    }
+    ++scope->se_loop_depth;
     whilescope = &scope->se_u.se_while;
 
     // "endwhile" jumps back here, one before when profiling or using cmdmods
@@ -1168,10 +1188,12 @@ compile_while(char_u *arg, cctx_T *cctx)
 	drop_scope(cctx);
 	return NULL;  // out of memory
     }
+    // get the index before a following reserve_local() makes the lval invalid
+    funcref_lvar_idx = funcref_lvar->lv_idx;
 
     // remember the number of variables and closures, used for ENDLOOP
-    compile_fill_loop_info(&whilescope->ws_loop_info,
+    compile_fill_loop_info(&whilescope->ws_loop_info, funcref_lvar_idx, cctx);
-						   funcref_lvar->lv_idx, cctx);
+    whilescope->ws_loop_info.li_depth = scope->se_loop_depth - 1;
 
     // compile "expr"
     if (compile_expr0(&p, cctx) == FAIL)
@@ -1193,7 +1215,7 @@ compile_while(char_u *arg, cctx_T *cctx)
 
 	// "while_end" is set when ":endwhile" is found
 	if (compile_jump_to_end(&whilescope->ws_end_label,
-			 JUMP_WHILE_FALSE, funcref_lvar->lv_idx, cctx) == FAIL)
+			     JUMP_WHILE_FALSE, funcref_lvar_idx, cctx) == FAIL)
 	    return FAIL;
     }
 
@@ -1249,45 +1271,83 @@ compile_endwhile(char_u *arg, cctx_T *cctx)
 
 /*
  * Get the current information about variables declared inside a loop.
- * Returns zero if there are none, otherwise the count.
+ * Returns TRUE if there are any and fills "lvi".
- * "loop_var_idx" is then set to the index of the first variable.
  */
-    short
+    int
-get_loop_var_info(cctx_T *cctx, short *loop_var_idx)
+get_loop_var_info(cctx_T *cctx, loopvarinfo_T *lvi)
 {
     scope_T	*scope = cctx->ctx_scope;
+    int		prev_local_count = 0;
+
+    CLEAR_POINTER(lvi);
+    for (;;)
+    {
+	loop_info_T	*loopinfo;
+	int		cur_local_last;
 	int		start_local_count;
 
 	while (scope != NULL && scope->se_type != WHILE_SCOPE
 						&& scope->se_type != FOR_SCOPE)
 	    scope = scope->se_outer;
 	if (scope == NULL)
-	return 0;
+	    break;
 
 	if (scope->se_type == WHILE_SCOPE)
-	start_local_count = scope->se_u.se_while.ws_loop_info.li_local_count;
+	{
+	    loopinfo = &scope->se_u.se_while.ws_loop_info;
+	    // :while reserves one variable for funcref count
+	    cur_local_last = loopinfo->li_local_count - 1;
+	}
 	else
-	start_local_count = scope->se_u.se_for.fs_loop_info.li_local_count;
+	{
+	    loopinfo = &scope->se_u.se_for.fs_loop_info;
+	    // :for reserves three variable: loop count, funcref count and loop
+	    // var
+	    cur_local_last = loopinfo->li_local_count - 3;
+	}
+
+	start_local_count = loopinfo->li_local_count;
 	if (cctx->ctx_locals.ga_len > start_local_count)
 	{
-	*loop_var_idx = (short)start_local_count;
+	    lvi->lvi_loop[loopinfo->li_depth].var_idx =
-	return (short)(cctx->ctx_locals.ga_len - start_local_count);
+						      (short)start_local_count;
+	    lvi->lvi_loop[loopinfo->li_depth].var_count =
+			  (short)(cctx->ctx_locals.ga_len - start_local_count
+							   - prev_local_count);
+	    if (lvi->lvi_depth == 0)
+		lvi->lvi_depth = loopinfo->li_depth + 1;
 	}
-    return 0;
+
+	scope = scope->se_outer;
+	prev_local_count = cctx->ctx_locals.ga_len - cur_local_last;
+    }
+    return lvi->lvi_depth > 0;
 }
 
 /*
- * Get the index of the first variable in a loop, if any.
+ * Get the index of the variable "idx" in a loop, if any.
- * Returns -1 if none.
  */
-    int
+    void
-get_loop_var_idx(cctx_T *cctx)
+get_loop_var_idx(cctx_T *cctx, int idx, lvar_T *lvar)
 {
-    short loop_var_idx;
+    loopvarinfo_T lvi;
 
-    if (get_loop_var_info(cctx, &loop_var_idx) > 0)
+    lvar->lv_loop_depth = -1;
-	return loop_var_idx;
+    lvar->lv_loop_idx = -1;
-    return -1;
+    if (get_loop_var_info(cctx, &lvi))
+    {
+	int depth;
+
+	for (depth = lvi.lvi_depth - 1; depth >= 0; --depth)
+	    if (idx >= lvi.lvi_loop[depth].var_idx
+		    && idx < lvi.lvi_loop[depth].var_idx
+					       + lvi.lvi_loop[depth].var_count)
+	    {
+		lvar->lv_loop_depth = depth;
+		lvar->lv_loop_idx = lvi.lvi_loop[depth].var_idx;
+		return;
+	    }
+    }
 }
 
 /*

src/vim9execute.c

@@ -1827,8 +1827,7 @@ call_eval_func(
 fill_partial_and_closure(
 	partial_T	*pt,
 	ufunc_T		*ufunc,
-	short	    loop_var_idx,
+	loopvarinfo_T	*lvi,
-	short	    loop_var_count,
 	ectx_T		*ectx)
 {
     pt->pt_func = ufunc;
@@ -1854,13 +1853,22 @@ fill_partial_and_closure(
 	    }
 	}
 
-	// The closure may need to find variables defined inside a loop.  A
+	if (lvi != NULL)
-	// new reference is made every time, ISN_ENDLOOP will check if they
+	{
-	// are actually used.
+	    int	depth;
-	pt->pt_outer.out_loop_stack = &ectx->ec_stack;
+
-	pt->pt_outer.out_loop_var_idx = ectx->ec_frame_idx + STACK_FRAME_SIZE
+	    // The closure may need to find variables defined inside a loop,
-								+ loop_var_idx;
+	    // for every nested loop.  A new reference is made every time,
-	pt->pt_outer.out_loop_var_count = loop_var_count;
+	    // ISN_ENDLOOP will check if they are actually used.
+	    for (depth = 0; depth < lvi->lvi_depth; ++depth)
+	    {
+		pt->pt_outer.out_loop[depth].stack = &ectx->ec_stack;
+		pt->pt_outer.out_loop[depth].var_idx = ectx->ec_frame_idx
+			 + STACK_FRAME_SIZE + lvi->lvi_loop[depth].var_idx;
+		pt->pt_outer.out_loop[depth].var_count =
+					    lvi->lvi_loop[depth].var_count;
+	    }
+	}
 
 	// If the function currently executing returns and the closure is still
 	// being referenced, we need to make a copy of the context (arguments
@@ -2507,7 +2515,7 @@ execute_for(isn_T *iptr, ectx_T *ectx)
     int		jump = FALSE;
     typval_T	*ltv = STACK_TV_BOT(-1);
     typval_T	*idxtv =
-		   STACK_TV_VAR(iptr->isn_arg.forloop.for_idx);
+		   STACK_TV_VAR(iptr->isn_arg.forloop.for_loop_idx);
 
     if (GA_GROW_FAILS(&ectx->ec_stack, 1))
 	return FAIL;
@@ -2613,7 +2621,7 @@ execute_for(isn_T *iptr, ectx_T *ectx)
 	// Store the current number of funcrefs, this may be used in
 	// ISN_LOOPEND.  The variable index is always one more than the loop
 	// variable index.
-	tv = STACK_TV_VAR(iptr->isn_arg.forloop.for_idx + 1);
+	tv = STACK_TV_VAR(iptr->isn_arg.forloop.for_loop_idx + 1);
 	tv->vval.v_number = ectx->ec_funcrefs.ga_len;
     }
 
@@ -2661,18 +2669,20 @@ execute_endloop(isn_T *iptr, ectx_T *ectx)
     endloop_T	*endloop = &iptr->isn_arg.endloop;
     typval_T	*tv_refcount = STACK_TV_VAR(endloop->end_funcref_idx);
     int		prev_closure_count = tv_refcount->vval.v_number;
+    int		depth = endloop->end_depth;
     garray_T	*gap = &ectx->ec_funcrefs;
     int		closure_in_use = FALSE;
     loopvars_T  *loopvars;
     typval_T    *stack;
     int		idx;
 
-    // Check if any created closure is still being referenced.
+    // Check if any created closure is still being referenced and loopvars have
+    // not been saved yet for the current depth.
     for (idx = prev_closure_count; idx < gap->ga_len; ++idx)
     {
 	partial_T   *pt = ((partial_T **)gap->ga_data)[idx];
 
-	if (pt->pt_refcount > 1 && pt->pt_loopvars == NULL)
+	if (pt->pt_refcount > 1 && pt->pt_loopvars[depth] == NULL)
 	{
 	    int refcount = pt->pt_refcount;
 	    int i;
@@ -2728,14 +2738,14 @@ execute_endloop(isn_T *iptr, ectx_T *ectx)
     {
 	partial_T   *pt = ((partial_T **)gap->ga_data)[idx];
 
-	if (pt->pt_refcount > 1 && pt->pt_loopvars == NULL)
+	if (pt->pt_refcount > 1 && pt->pt_loopvars[depth] == NULL)
 	{
 	    ++loopvars->lvs_refcount;
-	    pt->pt_loopvars = loopvars;
+	    pt->pt_loopvars[depth] = loopvars;
 
-	    pt->pt_outer.out_loop_stack = &loopvars->lvs_ga;
+	    pt->pt_outer.out_loop[depth].stack = &loopvars->lvs_ga;
-	    pt->pt_outer.out_loop_var_idx -= ectx->ec_frame_idx
+	    pt->pt_outer.out_loop[depth].var_idx -=
-				     + STACK_FRAME_SIZE + endloop->end_var_idx;
+		  ectx->ec_frame_idx + STACK_FRAME_SIZE + endloop->end_var_idx;
 	}
     }
 
@@ -2747,37 +2757,44 @@ execute_endloop(isn_T *iptr, ectx_T *ectx)
  * loopvars may be the only reference to the partials in the local variables.
  * Go over all of them, the funcref and can be freed if all partials
  * referencing the loopvars have a reference count of one.
+ * Return TRUE if it was freed.
  */
-    void
+    int
 loopvars_check_refcount(loopvars_T *loopvars)
 {
     int		    i;
     garray_T	    *gap = &loopvars->lvs_ga;
     int		    done = 0;
+	typval_T	*stack = gap->ga_data;
 
     if (loopvars->lvs_refcount > loopvars->lvs_min_refcount)
-	return;
+	return FALSE;
     for (i = 0; i < gap->ga_len; ++i)
     {
 	typval_T    *tv = ((typval_T *)gap->ga_data) + i;
 
 	if (tv->v_type == VAR_PARTIAL && tv->vval.v_partial != NULL
-		&& tv->vval.v_partial->pt_loopvars == loopvars
 		&& tv->vval.v_partial->pt_refcount == 1)
+	{
+	    int	    depth;
+
+	    for (depth = 0; depth < MAX_LOOP_DEPTH; ++depth)
+		if (tv->vval.v_partial->pt_loopvars[depth] == loopvars)
 		    ++done;
 	}
-    if (done == loopvars->lvs_min_refcount)
+    }
-    {
+    if (done != loopvars->lvs_min_refcount)
-	typval_T	*stack = gap->ga_data;
+	return FALSE;
 
     // All partials referencing the loopvars have a reference count of
     // one, thus the loopvars is no longer of use.
+    stack = gap->ga_data;
     for (i = 0; i < gap->ga_len; ++i)
 	clear_tv(stack + i);
     vim_free(stack);
     remove_loopvars_from_list(loopvars);
     vim_free(loopvars);
-    }
+    return TRUE;
 }
 
 /*
@@ -3804,11 +3821,12 @@ exec_instructions(ectx_T *ectx)
 			    iemsg("LOADOUTER depth more than scope levels");
 			goto theend;
 		    }
-		    if (depth == OUTER_LOOP_DEPTH)
+		    if (depth < 0)
 			// Variable declared in loop.  May be copied if the
 			// loop block has already ended.
-			tv = ((typval_T *)outer->out_loop_stack->ga_data)
+			tv = ((typval_T *)outer->out_loop[-depth - 1]
-					    + outer->out_loop_var_idx
+							       .stack->ga_data)
+					  + outer->out_loop[-depth - 1].var_idx
 					  + iptr->isn_arg.outer.outer_idx;
 		    else
 			// Variable declared in a function.  May be copied if
@@ -4142,8 +4160,7 @@ exec_instructions(ectx_T *ectx)
 			goto theend;
 		    }
 		    if (fill_partial_and_closure(pt, ufunc,
-				extra == NULL ? 0 : extra->fre_loop_var_idx,
+			       extra == NULL ? NULL : &extra->fre_loopvar_info,
-				extra == NULL ? 0 : extra->fre_loop_var_count,
 								 ectx) == FAIL)
 			goto theend;
 		    tv = STACK_TV_BOT(0);
@@ -4160,8 +4177,8 @@ exec_instructions(ectx_T *ectx)
 		    newfuncarg_T    *arg = iptr->isn_arg.newfunc.nf_arg;
 
 		    if (copy_lambda_to_global_func(arg->nfa_lambda,
-					arg->nfa_global, arg->nfa_loop_var_idx,
+				       arg->nfa_global, &arg->nfa_loopvar_info,
-					arg->nfa_loop_var_count, ectx) == FAIL)
+				       ectx) == FAIL)
 			goto theend;
 		}
 		break;
@@ -4236,7 +4253,7 @@ exec_instructions(ectx_T *ectx)
 			ectx->ec_iidx = iptr->isn_arg.whileloop.while_end;
 
 		    // Store the current funccal count, may be used by
-		    // ISN_LOOPEND later
+		    // ISN_ENDLOOP later
 		    tv = STACK_TV_VAR(
 				    iptr->isn_arg.whileloop.while_funcref_idx);
 		    tv->vval.v_number = ectx->ec_funcrefs.ga_len;
@@ -5581,6 +5598,11 @@ call_def_function(
 	// Check the function was really compiled.
 	dfunc_T	*dfunc = ((dfunc_T *)def_functions.ga_data)
 							 + ufunc->uf_dfunc_idx;
+	if (dfunc->df_ufunc == NULL)
+	{
+	    semsg(_(e_function_was_deleted_str), printable_func_name(ufunc));
+	    return FAIL;
+	}
 	if (INSTRUCTIONS(dfunc) == NULL)
 	{
 	    iemsg("using call_def_function() on not compiled function");
@@ -5717,8 +5739,13 @@ call_def_function(
 	    if (partial != NULL)
 	    {
 		outer_T *outer = get_pt_outer(partial);
+		int	depth;
+		void	*ptr = outer->out_stack;
 
-		if (outer->out_stack == NULL && outer->out_loop_stack == NULL)
+		// see if any stack was set
+		for (depth = 0; ptr == NULL && depth < MAX_LOOP_DEPTH; ++depth)
+		    ptr = outer->out_loop[depth].stack;
+		if (ptr == NULL)
 		{
 		    if (current_ectx != NULL)
 		    {
@@ -5767,6 +5794,8 @@ call_def_function(
 	ectx.ec_stack.ga_len += dfunc->df_varcount;
 	if (dfunc->df_has_closure)
 	{
+	    // Initialize the variable that counts how many closures were
+	    // created.  This is used in handle_closure_in_use().
 	    STACK_TV_VAR(idx)->v_type = VAR_NUMBER;
 	    STACK_TV_VAR(idx)->vval.v_number = 0;
 	    ++ectx.ec_stack.ga_len;
@@ -5911,6 +5940,32 @@ may_invoke_defer_funcs(ectx_T *ectx)
 	invoke_defer_funcs(ectx);
 }
 
+/*
+ * Return loopvarinfo in a printable form in allocated memory.
+ */
+    static char_u *
+printable_loopvarinfo(loopvarinfo_T *lvi)
+{
+    garray_T	ga;
+    int		depth;
+
+    ga_init2(&ga, 1, 100);
+    for (depth = 0; depth < lvi->lvi_depth; ++depth)
+    {
+	if (ga_grow(&ga, 50) == FAIL)
+	    break;
+	if (lvi->lvi_loop[depth].var_idx == 0)
+	    STRCPY(ga.ga_data + ga.ga_len, " -");
+	else
+	    vim_snprintf(ga.ga_data + ga.ga_len, 50, " $%d-$%d",
+			    lvi->lvi_loop[depth].var_idx,
+			    lvi->lvi_loop[depth].var_idx
+					 + lvi->lvi_loop[depth].var_count - 1);
+	ga.ga_len = STRLEN(ga.ga_data);
+    }
+    return ga.ga_data;
+}
+
 /*
  * List instructions "instr" up to "instr_count" or until ISN_FINISH.
  * "ufunc" has the source lines, NULL for the instructions of ISN_SUBSTITUTE.
@@ -6073,11 +6128,12 @@ list_instructions(char *pfx, isn_T *instr, int instr_count, ufunc_T *ufunc)
 		    if (outer->outer_idx < 0)
 			smsg("%s%4d LOADOUTER level %d arg[%d]", pfx, current,
 					outer->outer_depth,
-				outer->outer_idx
+					outer->outer_idx + STACK_FRAME_SIZE);
-							  + STACK_FRAME_SIZE);
+		    else if (outer->outer_depth < 0)
-		    else if (outer->outer_depth == OUTER_LOOP_DEPTH)
+			smsg("%s%4d LOADOUTER $%d in loop level %d",
-			smsg("%s%4d LOADOUTER level 1 $%d in loop",
+					       pfx, current,
-					       pfx, current, outer->outer_idx);
+					       outer->outer_idx,
+					       -outer->outer_depth);
 		    else
 			smsg("%s%4d LOADOUTER level %d $%d", pfx, current,
 					      outer->outer_depth,
@@ -6400,14 +6456,17 @@ list_instructions(char *pfx, isn_T *instr, int instr_count, ufunc_T *ufunc)
 		    }
 		    else
 			name = extra->fre_func_name;
-		    if (extra == NULL || extra->fre_loop_var_count == 0)
+		    if (extra == NULL || extra->fre_loopvar_info.lvi_depth == 0)
 			smsg("%s%4d FUNCREF %s", pfx, current, name);
 		    else
-			smsg("%s%4d FUNCREF %s var $%d - $%d", pfx, current,
+		    {
-				name,
+			char_u	*info = printable_loopvarinfo(
-				extra->fre_loop_var_idx,
+						     &extra->fre_loopvar_info);
-				extra->fre_loop_var_idx
+
-					      + extra->fre_loop_var_count - 1);
+			smsg("%s%4d FUNCREF %s vars %s", pfx, current,
+								   name, info);
+			vim_free(info);
+		    }
 		}
 		break;
 
@@ -6415,14 +6474,18 @@ list_instructions(char *pfx, isn_T *instr, int instr_count, ufunc_T *ufunc)
 		{
 		    newfuncarg_T    *arg = iptr->isn_arg.newfunc.nf_arg;
 
-		    if (arg->nfa_loop_var_count == 0)
+		    if (arg->nfa_loopvar_info.lvi_depth == 0)
 			smsg("%s%4d NEWFUNC %s %s", pfx, current,
 					     arg->nfa_lambda, arg->nfa_global);
 		    else
-			smsg("%s%4d NEWFUNC %s %s var $%d - $%d", pfx, current,
+		    {
-			  arg->nfa_lambda, arg->nfa_global,
+			char_u	*info = printable_loopvarinfo(
-			  arg->nfa_loop_var_idx,
+						       &arg->nfa_loopvar_info);
-			  arg->nfa_loop_var_idx + arg->nfa_loop_var_count - 1);
+
+			smsg("%s%4d NEWFUNC %s %s vars %s", pfx, current,
+				       arg->nfa_lambda, arg->nfa_global, info);
+			vim_free(info);
+		    }
 		}
 		break;
 
@@ -6479,7 +6542,7 @@ list_instructions(char *pfx, isn_T *instr, int instr_count, ufunc_T *ufunc)
 		    forloop_T *forloop = &iptr->isn_arg.forloop;
 
 		    smsg("%s%4d FOR $%d -> %d", pfx, current,
-					   forloop->for_idx, forloop->for_end);
+				      forloop->for_loop_idx, forloop->for_end);
 		}
 		break;
 
@@ -6487,10 +6550,12 @@ list_instructions(char *pfx, isn_T *instr, int instr_count, ufunc_T *ufunc)
 		{
 		    endloop_T *endloop = &iptr->isn_arg.endloop;
 
-		    smsg("%s%4d ENDLOOP $%d save $%d - $%d", pfx, current,
+		    smsg("%s%4d ENDLOOP ref $%d save $%d-$%d depth %d",
+								  pfx, current,
 			    endloop->end_funcref_idx,
 			    endloop->end_var_idx,
-			    endloop->end_var_idx + endloop->end_var_count - 1);
+			    endloop->end_var_idx + endloop->end_var_count - 1,
+			    endloop->end_depth);
 		}
 		break;
 

src/vim9instr.c

@@ -997,6 +997,7 @@ generate_LOADOUTER(
 	cctx_T	    *cctx,
 	int	    idx,
 	int	    nesting,
+	int	    loop_depth,
 	int	    loop_idx,
 	type_T	    *type)
 {
@@ -1008,9 +1009,9 @@ generate_LOADOUTER(
     if (nesting == 1 && loop_idx >= 0 && idx >= loop_idx)
     {
 	// Load a variable defined in a loop.  A copy will be made at the end
-	// of the loop.  TODO: how about deeper nesting?
+	// of the loop.
 	isn->isn_arg.outer.outer_idx = idx - loop_idx;
-	isn->isn_arg.outer.outer_depth = OUTER_LOOP_DEPTH;
+	isn->isn_arg.outer.outer_depth = -loop_depth - 1;
     }
     else
     {
@@ -1207,8 +1208,8 @@ generate_FUNCREF(
     isn_T	    *isn;
     type_T	    *type;
     funcref_extra_T *extra;
-    short	    loop_var_idx;
+    loopvarinfo_T   loopinfo;
-    short	    loop_var_count;
+    int		    has_vars;
 
     RETURN_OK_IF_SKIP(cctx);
     if ((isn = generate_instr(cctx, ISN_FUNCREF)) == NULL)
@@ -1216,20 +1217,22 @@ generate_FUNCREF(
     if (isnp != NULL)
 	*isnp = isn;
 
-    loop_var_count = get_loop_var_info(cctx, &loop_var_idx);
+    has_vars = get_loop_var_info(cctx, &loopinfo);
-    if (ufunc->uf_def_status == UF_NOT_COMPILED || loop_var_count > 0)
+    if (ufunc->uf_def_status == UF_NOT_COMPILED || has_vars)
     {
 	extra = ALLOC_CLEAR_ONE(funcref_extra_T);
 	if (extra == NULL)
 	    return FAIL;
 	isn->isn_arg.funcref.fr_extra = extra;
-	extra->fre_loop_var_idx = loop_var_idx;
+	extra->fre_loopvar_info = loopinfo;
-	extra->fre_loop_var_count = loop_var_count;
     }
     if (ufunc->uf_def_status == UF_NOT_COMPILED)
 	extra->fre_func_name = vim_strsave(ufunc->uf_name);
     else
 	isn->isn_arg.funcref.fr_dfunc_idx = ufunc->uf_dfunc_idx;
+
+    // Reserve an extra variable to keep track of the number of closures
+    // created.
     cctx->ctx_has_closure = 1;
 
     // If the referenced function is a closure, it may use items further up in
@@ -1252,9 +1255,7 @@ generate_FUNCREF(
 generate_NEWFUNC(
 	cctx_T	*cctx,
 	char_u	*lambda_name,
-	char_u	*func_name,
+	char_u	*func_name)
-	short	loop_var_idx,
-	short	loop_var_count)
 {
     isn_T	*isn;
     int		ret = OK;
@@ -1271,11 +1272,14 @@ generate_NEWFUNC(
 		ret = FAIL;
 	    else
 	    {
+		// Reserve an extra variable to keep track of the number of
+		// closures created.
+		cctx->ctx_has_closure = 1;
+
 		isn->isn_arg.newfunc.nf_arg = arg;
 		arg->nfa_lambda = lambda_name;
 		arg->nfa_global = func_name;
-		arg->nfa_loop_var_idx = loop_var_idx;
+		(void)get_loop_var_info(cctx, &arg->nfa_loopvar_info);
-		arg->nfa_loop_var_count = loop_var_count;
 		return OK;
 	    }
 	}
@@ -1371,27 +1375,25 @@ generate_FOR(cctx_T *cctx, int loop_idx)
     RETURN_OK_IF_SKIP(cctx);
     if ((isn = generate_instr(cctx, ISN_FOR)) == NULL)
 	return FAIL;
-    isn->isn_arg.forloop.for_idx = loop_idx;
+    isn->isn_arg.forloop.for_loop_idx = loop_idx;
 
     // type doesn't matter, will be stored next
     return push_type_stack(cctx, &t_any);
 }
 
     int
-generate_ENDLOOP(
+generate_ENDLOOP(cctx_T *cctx, loop_info_T *loop_info)
-	cctx_T	*cctx,
-	int	funcref_idx,
-	int	prev_local_count)
 {
     isn_T	*isn;
 
     RETURN_OK_IF_SKIP(cctx);
     if ((isn = generate_instr(cctx, ISN_ENDLOOP)) == NULL)
 	return FAIL;
-    isn->isn_arg.endloop.end_funcref_idx = funcref_idx;
+    isn->isn_arg.endloop.end_depth = loop_info->li_depth;
-    isn->isn_arg.endloop.end_var_idx = prev_local_count;
+    isn->isn_arg.endloop.end_funcref_idx = loop_info->li_funcref_idx;
+    isn->isn_arg.endloop.end_var_idx = loop_info->li_local_count;
     isn->isn_arg.endloop.end_var_count =
-				    cctx->ctx_locals.ga_len - prev_local_count;
+			   cctx->ctx_locals.ga_len - loop_info->li_local_count;
     return OK;
 }