Found in

• 118.0a1

Affected versions

• 118.0a1

Tested platforms

• Affected platforms: Windows 10

Preconditions

• browser.search.region = CA
• Have at least one Address already saved

Steps to reproduce

1. Reach the Address form on https://www.newegg.ca
2. Click on the Full Name field
3. Click on the Address field
4. Click on the City field and select an address entry from the dropdown

Expected result

• The address dropdown should be displayed for all the eligible fields and all the fields should be autofilled.

Actual result

• The address dropdown is not displayed for the Full Name and Address fields and the autofill is also not working for those fields. The full address is autofilled in the Apartment, suite, unit, etc. field. Also the Province field (dropdown) is not autofilled.

Regression range

• N/A

Aditional Notes

• In Chrome the Name field is working as expected. The Address field is not autofilled there as well.
• Fathom Fox Sample

Some notes:

• the name field has the name 'ContactWith' and doesn't match as a name field. There is a label just before the <input> that contains the text 'Full Name' but this label is not directly associated with the input element (it should either have a for attribute or be nested inside the label). We could add 'contact' to HeuristicsRegExp.sys.mjs to fix this issue, although the word contact is currently used for phone numbers.
• there are two address fields on the form. The first has autocomplete="new-password" so gets ignored as an address. The second
  one has a placeholder of 'Apartment, ...' and gets treated as the first address field. Chrome autofills the address in this unexpected way as well.
• the province appears to be filled in correctly, but it does not get displayed during the preview.

(In reply to Neil Deakin from comment #1)

Some notes:

• the name field has the name 'ContactWith' and doesn't match as a name field. There is a label just before the <input> that contains the text 'Full Name' but this label is not directly associated with the input element (it should either have a for attribute or be nested inside the label). We could add 'contact' to HeuristicsRegExp.sys.mjs to fix this issue, although the word contact is currently used for phone numbers.

Another solution is finding this "label" in
https://searchfox.org/mozilla-central/rev/47a0a01e1f7ad0451c6ba6c790d5c6855df512c1/toolkit/components/formautofill/shared/FormAutofillHeuristics.sys.mjs#962-976

We do have this heuristic in NewPasswordModel
https://searchfox.org/mozilla-central/rev/47a0a01e1f7ad0451c6ba6c790d5c6855df512c1/toolkit/components/passwordmgr/NewPasswordModel.sys.mjs#186-193

The issue with Address Line 1 persists in the Nightly 138.0a1 when tested on macOS 13. The autofill dropdown is not displayed, and no saved address is populated when triggering autofill in other fields. Additionally, the full address is autofilled in Address Line 2, as mentioned in Comment 0.
The Province is not being previewed, as noted in Comment 1. Please let me know if this should be filed as a separate issue.

I think there are no more issues here to fix:

1. The address field incorrectly has autocomplete="new-password" so we don't treat it as an address field. Instead we fill into address-line2. This is either an error on the page or some attempt to disable autocomplete on that field.
2. The province is filled correctly but the button label doesn't have a preview because the site is displaying a custom label instead of the normal dropdown button.

Chrome does the same thing in both cases.