Mass invoice validation with stock management : the user is not informed anymore to validate invoices manually

[glelarge]

Bug

Normally the mass invoice validation is not authorized due to the need to choose the warehouse where to increase/decrease the stock.
A message ErrorMassValidationNotAllowedWhenStockIncreaseOnAction is displayed to inform the user to do this validation manually one by one.
The invoices should not be validated.
Currently:

• no message is displayed
• the invoices are validated

Environment

• Version: 10.0.2 (second instance in parenthesis : 8.0.3)
• OS: Debian 7 (8)
• Web server: nginx (Apache)
• PHP: PHP 5.6 (7.3)
• Database: MariaDB (PostgreSQL)

Expected and actual behavior

The message ErrorMassValidationNotAllowedWhenStockIncreaseOnAction to inform the user should be displayed.
The invoices must not be validated.

Steps to reproduce the behavior

Activate the modules Invoices, Products and Stock.
In the Stock module options, set the STOCK_CALCULATE_ON_BILL option ("Decrease real stocks on validation of customer invoice/credit note") to true.
Create a product PR01.
Create a warehouse WH01 and set the quantity of PR01 in WH01.
Create a customer invoice with one line of 25 PR01. No need to create multiple invoices to reproduce the case.
Display the list of invoices and select the draft invoice(s) to be validated.
On the mass action drop list (top of the page), select the 'Validate' action.
Click on the 'Confirm' button.
No message is displayed.
The invoice is validated but the stock is not impacted.

Reason of the issue

Code references are based on the branch 10.0.

In the file core/actions_massactions.inc.php l.1087:

// Validate records
if (! $error && $massaction == 'validate' && $permtocreate)
{
	$objecttmp=new $objectclass($db);

	if ($objecttmp->element == 'invoice' && ! empty($conf->stock->enabled) && ! empty($conf->global->STOCK_CALCULATE_ON_BILL))
	{
		$langs->load("errors");
		setEventMessages($langs->trans('ErrorMassValidationNotAllowedWhenStockIncreaseOnAction'), null, 'errors');
		$error++;
	}

the test is always wrong as $objecttmp->element contains 'facture' and not 'invoice'.

The compta/facture/class/facture.class.php l.59 provides the correct value:

/**
 *	Class to manage invoices
 */
class Facture extends CommonInvoice
{
	/**
	 * @var string ID to identify managed object
	 */
	public $element='facture';

Proposed fix (based on branch 10.0)

Option 1

The basic fix would replace the tested value by 'invoice'.
Tested locally, it is working.

Option 2

Both 'invoice' and 'facture' values can be tested, like in core/class/discount.class.php l.557, 603, 648 :
if ($invoice->element == 'facture' || $invoice->element == 'invoice')

Option 3

Last option, probably stranger, would to do something like comm/action/class/actioncomm.class.php l.298 :

        // For backward compatibility
        if ($this->elementtype=='facture')  $this->elementtype='invoice';
        if ($this->elementtype=='commande') $this->elementtype='order';
        if ($this->elementtype=='contrat')  $this->elementtype='contract';

I will submit a PR following the option 2.