False negative with `defer` and `golang.org/x/tools v0.22.0+`

[maratori]

We use the nilerr as part of golangci-lint. It uses a newer version of golang.org/x/tools library, producing false negative results. The problem appears starting from golang.org/x/tools v0.22.0. Now, you use an outdated version of the library:

nilerr/go.mod

Line 7 in e68fdc0

golang.org/x/tools v0.0.0-20201023174141-c8cfbd0f21e6

Here is the minimal test that passes with golang.org/x/tools v0.21.0 and fails with golang.org/x/tools v0.22.0 (or greater):

package a

func issue() error {
	defer func() {}()

	err := do()
	if err != nil {
		return nil // want "error is not nil \\(line 6\\) but it returns nil"
	}

	return nil
}

$ go get golang.org/x/tools@v0.21.0
go: upgraded golang.org/x/tools v0.0.0-20201023174141-c8cfbd0f21e6 => v0.21.0
$ go mod tidy
$ go test    
PASS
ok      github.com/gostaticanalysis/nilerr      0.391s
$ go get golang.org/x/tools@v0.22.0
go: upgraded golang.org/x/tools v0.21.0 => v0.22.0
$ go mod tidy
$ go test                          
--- FAIL: Test (0.57s)
    analysistest.go:604: a/a.go:192: no diagnostic was reported matching `error is not nil \(lines \[178 181\]\) but it returns nil`
    analysistest.go:604: a/b.go:8: no diagnostic was reported matching `error is not nil \(line 6\) but it returns nil`
FAIL
exit status 1
FAIL    github.com/gostaticanalysis/nilerr      0.778s