What version of Go are you using (go version)?

Go 1.8.3

What did you do?

I have implemented an instance of an sql/driver with a Conn instance that satisfies the ExecerContext interface. But unless the Conn also satisfies the Execer interfaces respectfully, the *Context versions are never called.

(Note, the same issue exists with respect to QueryerContext and Queryer, but for simplicity I will only discuss Execer/Context)

Further, when both Execer and ExecerContext are satisfied, or both Queryer and QueryerContext are satisfied, the non-Context version is never called, meaning all drivers that wish to satisfy the Context version must also define a useless non-Context version (example).

What did you expect to see?

I expected that implementing an ExecerContext would be sufficient to satisfy the documented "optional" nature of the interface.

What did you see instead?

I was required to also satisify the Execer interface, even though this requirement is not to my knowledge documented, nor should it be functionally necessary.

Suggestion:

Re-factor the database/sql package to require only one of the interfaces to be satisfied, not both.