cmd/go: go list all breaks in //go:build-only repos

[rsc]

cmd/go has its own //go:build evaluator, which is needed for
patterns like 'all'. The code is a modified copy of some unexported
routines from the go/build package. It doesn't know about //go:build.

This means that //go:build-only repos will not work with 'go list all'
under certain conditions.

Specifically:

% cat testdata/script/list_all_gobuild.txt
# go list all should work with //go:build-only modules
env GOOS=darwin
go list all
env GOOS=linux
go list all

-- go.mod --
module m

-- p/p.go --
package p

-- p/p_test.go --
//go:build linux

package p

import "m/q"

-- q/q_linux.go --
package q

-- r/r.go --
package r

-- r/r_test.go --
// +build linux

package r

import "m/s"

-- s/s_linux.go --
package s

% go test -run=Script/list_all_gobuild
go test proxy running at GOPROXY=http://127.0.0.1:55164/mod
--- FAIL: TestScript (0.01s)
    --- FAIL: TestScript/list_all_gobuild (0.04s)
        script_test.go:257: 
            # go list all should work with //go:build-only modules (0.016s)
            > env GOOS=darwin
            > go list all
            [stderr]
            package m/q: build constraints exclude all Go files in $WORK/gopath/src/q
            [exit status 1]
            FAIL: testdata/script/list_all_gobuild.txt:3: unexpected command failure
            
FAIL
exit status 1
FAIL	cmd/go	1.562s
% 

Note that r and s are fine, just not p and q.

This will need to be backported to Go 1.17.
Go 1.16 did not support //go:build lines, so it doesn't need the backport.

[rsc]

@gopherbot please backport 1.17

[gopherbot]

Change https://golang.org/cl/359355 mentions this issue: cmd/go: update for //go:build lines

[gopherbot]

Backport issue(s) opened: #49199 (for 1.17).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://golang.org/wiki/MinorReleases.

[gopherbot]

Change https://golang.org/cl/359404 mentions this issue: cmd/go: update for //go:build lines

[gopherbot]

Change https://golang.org/cl/359404 mentions this issue: [release-branch.go1.17] cmd/go: update for //go:build lines