cmd/go: go install / go.mod / go:embed / build tags don't play well together.

[james-lawrence]

have a program where I have three files:

workspace_16.go which contains // +build go1.16 and a go:embed
workspace_15.go // +build !go1.16
workspace.go

and a go.mod with
go 1.14

cmd/bw/workspace_16.go:64:3: go:embed requires go1.16 or later (-lang was set to go1.14; check go.mod)

expect it to build properly.

[jayconrod]

The go directive in go.mod is the problem here. It needs to be go 1.16 or higher.

Closing since this seems like it's working as intended. Your +build tags look like they should work.

But #30791 is related. The go directive is not all that well-documented or understood.

[james-lawrence]

@jayconrod I believe you misunderstood the problem. it doesn't build, the source code with the build tags should build properly for both go 1.14, 1.15, and 1.16. 1.16 isn't the minimum version. changing go.mod to use version 1.16 would prevent it from building with go 1.14.

edit: waiting on results from CI, I believe i may have made an erroneous assumption on the build failure based on local builds. =)

[james-lawrence]

@jayconrod nm then, I stand corrected. the error in CI was from an import that didn't get autoremoved during save. sigh