Hi :)

I may be wrong, but documentation (Symfony 5.x) says thatNumberType's optionrounding_mode defaults to\NumberFormatter::ROUND_HALFUP :https://symfony.com/doc/5.x/reference/forms/types/number.html#rounding-mode

In my project, one of my form's fields is aNumberType, with norounding_mode norscale configured:

publicfunction buildForm(FormBuilderInterface$builder,array$options)    {$builder            ->add('altitude',                NumberType::class,                ['label' =>'common.label.altimetric_reference.altitude','attr' => ['class' =>'altitude-field'],'required' =>false,'help' =>'common.help.value_in_m',                ]            )[...]

But because of how\Symfony\Component\Form\Extension\Core\DataTransformer\NumberToLocalizedStringTransformer::getNumberFormatter has been implemented, I think the documentation is not accurate:

protectedfunctiongetNumberFormatter()    {$formatter =new \NumberFormatter($this->locale ?? \Locale::getDefault(), \NumberFormatter::DECIMAL);if (null !==$this->scale) {$formatter->setAttribute(\NumberFormatter::FRACTION_DIGITS,$this->scale);$formatter->setAttribute(\NumberFormatter::ROUNDING_MODE,$this->roundingMode);        }$formatter->setAttribute(\NumberFormatter::GROUPING_USED,$this->grouping);return$formatter;    }

As shown above, the number formatter is not configured with any rounding when no scale is defined (even if one is configured in the form I reckon). Because of that, in our project (with French locale), the effective rounding mode used is\NumberFormatter::ROUND_HALFEVEN (and scale seems to default to3). Instead of the advertised\NumberFormatter::ROUND_HALFUP.

This gives us an unexpected and weird behavior when users type in numbers like485,3485, as it gets rounded to485,348 instead of485,349.

In all honesty, I'm not sure if this is a documentation issue, a bug inNumberToLocalizedStringTransformer::getNumberFormatter or if I'm missing something?

Thanks for your insights :)