Clarify `aria-autocomplete` and `autocomplete` semantic equivalency

[tay1orjones]

Describe your concern

I've been reading through the specs regarding these two attributes and can't clearly identify if aria-autocomplete is semantically equivalent to HTML's autocomplete. I see a significant number of implementations of ComboBoxes using autocomplete="off" to instruct the browser to not use it's native autofill functionality (despite sometimes not being respected like in chrome). They additionally use aria-autocomplete="list" on the same element to convey the usage/presence of a custom listbox.

Is it an acceptable practice to use both aria-autocomplete and autocomplete on a ComboBox and other elements/widgets, or should only one of these be used?

Link to the version of the specification or documentation you were looking at at.

• https://www.w3.org/TR/wai-aria-1.2/#host_general_conflict
• https://www.w3.org/TR/wai-aria-1.2/#implicit_semantics
• https://www.w3.org/TR/core-aam-1.2/#ariaAutocompleteInlineListBoth

Does the issue exists in the editors draft (the editors draft is the most recent draft of the specification)?

Yes

Related: https://github.com/w3c/aria-practices/issues/639