Add a function to narrow an IInstruction to have a given program address

[mcintyre94]

This is another function that is helpful for using generated clients.

The generated client includes a function to parse an IInstruction:

export function parseTransferSolInstruction<
  TProgram extends string,
  TAccountMetas extends readonly IAccountMeta[]
>(
  instruction: IInstruction<TProgram> & <snip>
): ParsedTransferSolInstruction<TProgram, TAccountMetas>

The problem is that if we pass an IInstruction from a deserialized transaction to this parse function, then it has TProgram = string, and we end up with ParsedTransferSolInstruction<TProgram = string>, ie we lose the known program address in the type. This can cause issues when we use this type and expect it to include a more specific type.

This PR adds a function to narrow an instruction type to include a known program address as TProgram. If we do this before calling eg this parse function, then we can maintain the program address in the type correctly.

Eg:

const instruction: IInstruction<string> // from eg a deserialized transaction
const address = '1234' as Address

if(instruction.programAddress === address) {
  const parsed = parseInstruction(instruction); // ParsedInstruction<string>
}

if(isInstructionWithKnownProgramAddress(instruction, address)) {
  const parsed = parseInstruction(instruction); // ParsedInstruction<'1234'>
}

[steveluscher]

I sort of prefer something like isInstructionForProgram rather than isInstructionWithKnownProgramAddress, but no big deal either way! I just think it's less clear what it means to be ‘with’ a program address.

[github-actions]

🎉 This PR is included in version 1.91.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[github-actions]

Because there has been no activity on this PR for 14 days since it was merged, it has been automatically locked. Please open a new issue if it requires a follow up.