refactor: linkage between journal as payment and gain/loss journal

erpnext/accounts/doctype/gl_entry/gl_entry.py

@@ -58,6 +58,13 @@ class GLEntry(Document):
 			validate_balance_type(self.account, adv_adj)
 			validate_frozen_account(self.account, adv_adj)
 
+			if (
+				self.voucher_type == "Journal Entry"
+				and frappe.get_cached_value("Journal Entry", self.voucher_no, "voucher_type")
+				== "Exchange Gain Or Loss"
+			):
+				return
+
 			if frappe.get_cached_value("Account", self.account, "account_type") not in [
 				"Receivable",
 				"Payable",

erpnext/accounts/doctype/journal_entry/journal_entry.py

@@ -499,6 +499,7 @@ class JournalEntry(AccountsController):
 				)
 
 				if not against_entries:
+					if self.voucher_type != "Exchange Gain Or Loss":
 						frappe.throw(
 							_(
 								"Journal Entry {0} does not have account {1} or already matched against other voucher"

erpnext/controllers/accounts_controller.py

@@ -1039,9 +1039,9 @@ class AccountsController(TransactionBase):
 									"cost_center": erpnext.get_default_cost_center(self.company),
 									# TODO: figure out a way to pass reference
 									# throws 'Journal Entry doesn't have {account} or doesn't have matched account'
-									# "reference_type": self.doctype,
-									# "reference_name": self.name,
-									# "reference_detail_no": arg.idx,
+									"reference_type": self.doctype,
+									"reference_name": self.name,
+									"reference_detail_no": arg.idx,
 									reverse_dr_or_cr: abs(arg.get("difference_amount")),
 									reverse_dr_or_cr + "_in_account_currency": 0,
 								}