new nlreturn linter (#1267)

* new nlreturn linter

* fix: import order

Co-authored-by: Sergey Vilgelm <sergey.vilgelm@ibm.com>

Author: ssgreg

go.mod

@@ -48,6 +48,7 @@ require (
 	github.com/spf13/cobra v1.0.0
 	github.com/spf13/pflag v1.0.5
 	github.com/spf13/viper v1.7.0
+	github.com/ssgreg/nlreturn/v2 v2.0.1
 	github.com/stretchr/testify v1.6.1
 	github.com/tdakkota/asciicheck v0.0.0-20200416190851-d7f85be797a2
 	github.com/tetafro/godot v0.4.8

go.sum

@@ -359,6 +359,8 @@ github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An
 github.com/spf13/viper v1.4.0/go.mod h1:PTJ7Z/lr49W6bUbkmS1V3by4uWynFiR9p7+dSq/yZzE=
 github.com/spf13/viper v1.7.0 h1:xVKxvI7ouOI5I+U9s2eeiUfMaWBVoXA3AWskkrqK0VM=
 github.com/spf13/viper v1.7.0/go.mod h1:8WkrPz2fc9jxqZNCJI/76HCieCp4Q8HaLFoCha5qpdg=
+github.com/ssgreg/nlreturn/v2 v2.0.1 h1:+lm6xFjVuNw/9t/Fh5sIwfNWefiD5bddzc6vwJ1TvRI=
+github.com/ssgreg/nlreturn/v2 v2.0.1/go.mod h1:E/iiPB78hV7Szg2YfRgyIrk1AD6JVMTRkkxBiELzh2I=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.1.1 h1:2vfRuCMp5sSVIDSqO8oNnWJq7mPa6KVP3iPIwFBuy8A=
 github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

pkg/golinters/nlreturn.go

@@ -0,0 +1,19 @@
+package golinters
+
+import (
+	"github.com/ssgreg/nlreturn/v2/pkg/nlreturn"
+	"golang.org/x/tools/go/analysis"
+
+	"github.com/golangci/golangci-lint/pkg/golinters/goanalysis"
+)
+
+func NewNLReturn() *goanalysis.Linter {
+	return goanalysis.NewLinter(
+		"nlreturn",
+		"nlreturn checks for a new line before return and branch statements to increase code clarity",
+		[]*analysis.Analyzer{
+			nlreturn.NewAnalyzer(),
+		},
+		nil,
+	).WithLoadMode(goanalysis.LoadModeSyntax)
+}

pkg/lint/lintersdb/manager.go

@@ -301,6 +301,10 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 			WithPresets(linter.PresetBugs).
 			WithLoadForGoAnalysis().
 			WithURL("https://github.com/ryanrolds/sqlclosecheck"),
+		linter.NewConfig(golinters.NewNLReturn()).
+			WithPresets(linter.PresetStyle).
+			WithLoadForGoAnalysis().
+			WithURL("https://github.com/ssgreg/nlreturn"),
 		// nolintlint must be last because it looks at the results of all the previous linters for unused nolint directives
 		linter.NewConfig(golinters.NewNoLintLint()).
 			WithPresets(linter.PresetStyle).

test/testdata/nlreturn.go

@@ -0,0 +1,161 @@
+//args: -Enlreturn
+package testdata
+
+func cha() {
+	ch := make(chan interface{})
+	ch1 := make(chan interface{})
+	ch2 := make(chan interface{})
+
+	select {
+	case <-ch:
+		return
+
+	case <-ch1:
+		{
+			a := 1
+			_ = a
+			{
+				a := 1
+				_ = a
+				return // ERROR "return with no blank line before"
+			}
+
+			return
+		}
+
+		return
+
+	case <-ch2:
+		{
+			a := 1
+			_ = a
+			return // ERROR "return with no blank line before"
+		}
+		return // ERROR "return with no blank line before"
+	}
+}
+
+func baz() {
+	switch 0 {
+	case 0:
+		a := 1
+		_ = a
+		fallthrough // ERROR "fallthrough with no blank line before"
+	case 1:
+		a := 1
+		_ = a
+		break // ERROR "break with no blank line before"
+	case 2:
+		break
+	}
+}
+
+func foo() int {
+	v := []int{}
+	for range v {
+		return 0
+	}
+
+	for range v {
+		for range v {
+			return 0
+		}
+		return 0 // ERROR "return with no blank line before"
+	}
+
+	o := []int{
+		0, 1,
+	}
+
+	return o[0]
+}
+
+func bar() int {
+	o := 1
+	if o == 1 {
+		if o == 0 {
+			return 1
+		}
+		return 0 // ERROR "return with no blank line before"
+	}
+
+	return o
+}
+
+func main() {
+	return
+}
+
+func bugNoAssignSmthHandling() string {
+	switch 0 {
+	case 0:
+		o := struct {
+			foo string
+		}{
+			"foo",
+		}
+		return o.foo // ERROR "return with no blank line before"
+
+	case 1:
+		o := struct {
+			foo string
+		}{
+			"foo",
+		}
+
+		return o.foo
+	}
+
+	return ""
+}
+
+func bugNoExprSmthHandling(string) {
+	switch 0 {
+	case 0:
+		bugNoExprSmthHandling(
+			"",
+		)
+		return // ERROR "return with no blank line before"
+
+	case 1:
+		bugNoExprSmthHandling(
+			"",
+		)
+
+		return
+	}
+}
+
+func bugNoDeferSmthHandling(string) {
+	switch 0 {
+	case 0:
+		defer bugNoDeferSmthHandling(
+			"",
+		)
+		return // ERROR "return with no blank line before"
+
+	case 1:
+		defer bugNoDeferSmthHandling(
+			"",
+		)
+
+		return
+	}
+}
+
+func bugNoGoSmthHandling(string) {
+	switch 0 {
+	case 0:
+		go bugNoGoSmthHandling(
+			"",
+		)
+		return // ERROR "return with no blank line before"
+
+	case 1:
+		go bugNoGoSmthHandling(
+			"",
+		)
+
+		return
+	}
+}