x/build, cmd/go: extend main Go repo's "every vet check is forcibly made high-confidence" behavior to golang.org/x packages that are vendored (or exclude vendored packages from it)

[dmitshur]

The go test command normally runs a select subset of vet checks, and fails the test if any of them fail.

In the main Go repo, to aid development, that behavior is forcibly modified to have all vet checks be treated as strict and included in go test:

// In GOROOT, we enable all the vet tests during 'go test',
// not just the high-confidence subset. This gets us extra
// checking for the standard library (at some compliance cost)
// and helps us gain experience about how well the checks
// work, to help decide which should be turned on by default.

(https://cs.opensource.google/go/go/+/master:src/cmd/go/internal/work/exec.go;l=1256-1260;drc=2b3794e3e8a0ecf9d0ff7d8689ca9cdaea974e08)

This causes some unnecessary friction when it comes to golang.org/x packages that are vendored into the main Go repo. For example, a self-assignment finding that was introduced in CL 663756 (but not reported because that was in x/arch) started being reported a week or two later (in CL 678556 and CL 677257).

We can avoid this friction by either extending this behavior to apply to all golang.org/x packages that are vendored (or all golang.org/x repos?), or by having it not apply to vendored packages at all.

CC @golang/release, @golang/command-line, @adonovan.

[seankhliao]

I'm surprised there isn't already enforcement that go vet passes on all golang.org/x repos?

[gabyhelp]

Related Issues

• cmd/go/internal/test: -vet accepts bad input #47309 (closed)

Related Code Changes

• all: update vendored dependencies [generated]
• cmd/vet: honor analyzer flags when running vet outside $GOROOT/src
• cmd/vet: new rule to call out testing functions that are never tested
• cmd/vet: add a vet build tag so compiler test files can be excluded
• cmd/vet: include the errors.As check from upstream x/tools
• cmd/go: run vet automatically during go test
• cmd/dist: vet non-test packages in short mode
• cmd/vet: switch to x/tools/go/analysis implementation
• cmd/go: diagnose go.mod and vendor out of sync in std and cmd

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