alphabetical order for type in trait definition also

[tisonkun]

I have code snippet below:

pub trait DataValue {
    type Value;
    type Mutation;
}

impl DataValue for Int64 {
    type Mutation = Int64Mutation;
    type Value = Int64Value;
}

where rustfmt will force types in the impl block in alphabetical order, but not for the trait block.

IntelliJ complains "Different impl member order from the trait" in this case.

[calebcartwright]

where rustfmt will force types in the impl block in alphabetical order, but not for the trait block.

Could you elaborate on what you mean by this? If I recall correctly the non-default reorder_impl_items will both regroup const and type items within an impl, which includes sorting within those groups, but that should never be "forced".

Are you requesting a new feature that's something of an analog of reorder_impl_items configuration that can be used for a similar non-default sorting of types in traits?

[tisonkun]

@calebcartwright rustfmt will change

impl DataValue for Int64 {
    type Value = Int64Value;
    type Mutation = Int64Mutation;
}

to

impl DataValue for Int64 {
    type Mutation = Int64Mutation;
    type Value = Int64Value;
}

but not applied on the trait. I'd like to apply this rule on trait which means

pub trait DataValue {
    type Value;
    type Mutation;
}

will be formatted to

pub trait DataValue {
    type Mutation;
    type Value;
}

[calebcartwright]

@calebcartwright rustfmt will change

No, rustfmt does not do this. The only way to force rustfmt to make this change in impl blocks is to change the default value of the reorder_impl_items configuration option. You can see this in action on this playground sample.

If you are convinced that the reordering is the default behavior of rustfmt it would be great if you could provide some steps to reproduce with a minimal example, as that would be a bug.

As such, I'd echo my earlier question to you on what specifically you are asking. Are you requesting:

• that when reorder_impl_items is overridden to true that it also reorder items beyond impls/in traits?
• that the rustfmt default behavior be modified to automatically reorder items in traits? if so, are you scoping your request to types or including the reshuffling of consts, macros, etc. too?
• that a new configuration option be added, e.g. reorder_trait_items
• something else?

[tisonkun]

@calebcartwright you're right that reorder_impl_items = true is configured.

Either of the below should resolve my request:

• [x] that when reorder_impl_items is overridden to true that it also reorder items beyond impls/in traits?
• [x] that a new configuration option be added, e.g. reorder_trait_items

reorder_trait_items may be better.

[tisonkun]

@calebcartwright any thoughts?

[calebcartwright]

@calebcartwright any thoughts?

I'd rather go with an explicit, new option (reorder_trait_items) as opposed to expanding the behavior of the existing option, especially given its name and age