why "Transaction references a signature that is unnecessary" warning, and value of 'isSigner' is false in IDL?

Question

I was playing with counter program in program-example repo.

When run test, I got warning: Transaction references a signature that is unnecessary, only the fee payer and instruction signer accounts should sign a transaction., even though the contract method executed as expected.

The on-chain code is:

#[program]
pub mod counter_anchor {
    use super::*;
        ...
        
    pub fn increment(ctx: Context<Increment>) -> Result<()> {
        msg!(" call increment +  ...");        
        ctx.accounts.counter.count = ctx.accounts.counter.count.checked_add(1).unwrap();
        Ok(())
    }
    ....
}

    ...
#[derive(Accounts)]
pub struct Increment<'info> {
    #[account(mut)]
    pub counter: Account<'info, Counter>,
}

#[account]
#[derive(InitSpace)]
pub struct Counter {
    count: u64,
}

And my client js code is:

async function test_call_increase() {

  let tx = await program.methods
    .increment()
    .accounts({
      counter: counterKeypair.publicKey,
    })
    // .signers([payer.payer, counterKeypair])    
    .transaction();

    let txHash = await sendAndConfirmTransaction(
      provider.connection,
      tx,
      [wallet.payer, counterKeypair],  // <== Here, two signer, first one for pay gas.
      { skipPreflight: true }
      );

}

Also , in target/types/counter_anchor.ts , its isSigner is false.

    {
      "name": "increment",
      "accounts": [
        {
          "name": "counter",
          "isMut": true,
          "isSigner": false
        }
      ],
      "args": []
    },

AFAIK, I should let counter account to participate signing as to change its account data.

Why it say that counter shouldn't appear in signer list? How to fix it?

Thanks.

Answer 1

I found the reason is: account was declared with ' #[account(init,...)]' macro. so this account's owner is my own program, though it isn't PDA.

But, as to program owned accounts(non-PDAs) and PDAs, which one should choose? I know when to choose PDAs, but don't know when to use program owned accounts(non-PDAs).

What's your opinion?