[Bug]: Ineffective overflow protection in CmdIncreaseLoan

[James103]

Version of OpenTTD

0355299

Expected result

When taking out a loan, if the total bank balance would exceed the maximum possible bank balance, the command should error.

Actual result

When taking out a loan, if the total bank balance would exceed the maximum possible bank balance, you lose some of your 'Own Funds', just enough to bring your total bank balance at or under the maximum.

Steps to reproduce

1. Somehow acquire £ 2⁶³-1 in your 'Own Funds' or load this save: Gronnway Transport, 363576-09-15.zip
2. Try to take out a loan.
3. The command succeeds, but you lose some of your 'Own Funds'.

Caused by the following:

OpenTTD/src/misc_cmd.cpp

Lines 63 to 64 in 0355299

	/* Overflow protection */
	if (c->money + c->current_loan + loan < c->money) return CMD_ERROR;