v.debug: fix $dbg with @[heap] structs (fix #23979) (#23989)

vlib/v/debug/tests/struct_heap.expect

@@ -0,0 +1,10 @@
+#!/usr/bin/env expect
+source "common.tcl"
+
+expect "Break on * main in ${test_file}:8"
+expect "${test_file}:8 vdbg> "
+send "p st\n"
+expect "st = AStruct{\r\n    a: 1\r\n} (main.AStruct)"
+expect "${test_file}:8 vdbg> "
+send "q\n"
+expect eof

vlib/v/debug/tests/struct_heap.vv

@@ -0,0 +1,10 @@
+@[heap]
+struct AStruct {
+	a int
+}
+
+fn main() {
+	st := AStruct{1}
+	$dbg;
+	dump(st)
+}

vlib/v/gen/c/cgen.v

@@ -4527,6 +4527,8 @@ fn (mut g Gen) debugger_stmt(node ast.DebuggerStmt) {
 							'&'
 						} else if !str_method_expects_ptr && obj.typ.is_ptr() {
 							'*'.repeat(obj.typ.nr_muls())
+						} else if !str_method_expects_ptr && obj_sym.is_heap() {
+							'*'
 						} else if obj.is_auto_heap && var_typ.is_ptr() && str_method_expects_ptr {
 							'*'
 						} else if !obj.is_auto_heap && var_typ.is_ptr() && str_method_expects_ptr {