Build tags to exclude postgresql engine

[anuraaga]

What do you want to change?

Would it be acceptable to add a build tag such as disable_postgresql to be able to exclude postgresql code from the build completely?

Currently, it is already stubbed out for windows

https://github.com/kyleconroy/sqlc/blob/58b0b6593fc665600619b0dfc69909c68ff2cda2/internal/engine/postgresql/parse_windows.go#L1

So the change would just be adding something like || disable_postgresl

The postgresl uses heavyweight cgo, resulting in issues like #1956, and likely the reason for the lack of windows support in the first place. Having a build tag would allow avoiding the scary looking warnings when using go run. Hopefully it's ok given the one-line nature of the change (could prefix experimental_ or something if not wanting to support indefinitely).

What database engines need to be changed?

PostgreSQL

What programming language backends need to be changed?

Go

[kyleconroy]

I'd like to keep our build tags tied to operating systems and architectures. In this case, I can also update the PostgreSQL tags to include cgo so that the PostgreSQL engine isn't build when cgo isn't enabled.

[anuraaga]

Thanks @kyleconroy! I could confirm that adding a cgo check and running with CGO_ENABLED=0 works fine for generating mysql stubs and does not generate log spam for mac os sdk warnings. Sent #2068 with the proposal