Anchor's associated_token::mint constraint also demands an authority — to accept any valid ATA, use plain #[account(mut)] InterfaceAccount<TokenAccount>
Anchor will not let you constrain only the mint of an associated token account. Writing
#[account(associated_token::mint = some_mint)]
pub some_ata: InterfaceAccount<'info, TokenAccount>,fails to compile until you add associated_token::authority = <account> — necessarily, because the ATA constraint checks a derived address, and the derivation takes both mint and owner. There is no "any authority" form.
For the common case (send tokens to a destination the caller chose, don't care who controls it) drop the ATA constraint entirely:
#[account(mut)]
pub some_ata: InterfaceAccount<'info, TokenAccount>,InterfaceAccount<TokenAccount> still enforces that the account is owned by a token program and deserialises as a token account, and TransferChecked — in both SPL Token and Token-2022, including invoke_transfer_checked — verifies that the mint you pass matches both token accounts. So the mint check you wanted happens inside the CPI regardless.
If you want a domain-specific error rather than the token program's, assert it in the constraint:
#[account(mut, constraint = some_ata.mint == mint.key() @ SomeError)]Doing that also lets you use the non-checked Transfer instruction, which costs marginally fewer CU since it skips the decimals check.
Two things to weigh. Accepting any token account (not just the canonical ATA) is the right default when the destination is caller-specified — it is the caller's problem if they nominate a useless account — but it is wrong for accounts your program will later look up by derivation, which must be canonical ATAs. And mut plus a matching mint is not authorisation: never infer permissions from an ATA's presence in the account list.
Source: adapted from a Stack Exchange answer by Whiteseal (question by Iaroslav), https://solana.stackexchange.com/questions/17360/the-case-for-accepting-any-valid-ata-in-your-instruction-no-matter-what-its-aut — CC BY-SA 4.0