add exhaustive linter (#1166)

* wip

more

add new files

run command fixes

more

* go.mod

* order

* same package

* review comment

* enable linter in .golangci.yml

* add testcase for default-signifies-exhaustive: true

* adjust runGoErrchk instead

* disable the linter

* cleanup

* more cleanup

* cleanup

.golangci.example.yml

@@ -98,6 +98,11 @@ linters-settings:
     # path to a file containing a list of functions to exclude from checking
     # see https://github.com/kisielk/errcheck#excluding-functions for details
     exclude: /path/to/file.txt
+  exhaustive:
+    # indicates that switch statements are to be considered exhaustive if a
+    # 'default' case is present, even if all enum members aren't listed in the
+    # switch
+    default-signifies-exhaustive: false
   funlen:
     lines: 60
     statements: 40
@@ -174,7 +179,7 @@ linters-settings:
       modules:                                                        # List of blocked modules
         # - github.com/uudashr/go-module:                             # Blocked module
         #     recommendations:                                        # Recommended modules that should be used instead (Optional)
-        #       - golang.org/x/mod                           
+        #       - golang.org/x/mod
         #     reason: "`mod` is the official go.mod parser library."  # Reason why the recommended module should be used (Optional)
       versions:                                                       # List of blocked module version constraints
         # - github.com/mitchellh/go-homedir:                          # Blocked module with version constraint

.golangci.yml

@@ -9,6 +9,8 @@ linters-settings:
       - github.com/sirupsen/logrus: "logging is allowed only by logutils.Log"
   dupl:
     threshold: 100
+  exhaustive:
+    default-signifies-exhaustive: false
   funlen:
     lines: 100
     statements: 50
@@ -104,6 +106,7 @@ linters:
 
   # don't enable:
   # - asciicheck
+  # - exhaustive (TODO: enable after next release; current release at time of writing is v1.27)
   # - gochecknoglobals
   # - gocognit
   # - godot

go.mod

@@ -34,6 +34,7 @@ require (
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/mitchellh/go-ps v1.0.0
 	github.com/nakabonne/nestif v0.3.0
+	github.com/nishanths/exhaustive v0.0.0-20200525081945-8e46705b6132
 	github.com/pkg/errors v0.9.1
 	github.com/ryancurrah/gomodguard v1.1.0
 	github.com/securego/gosec/v2 v2.3.0
@@ -52,7 +53,7 @@ require (
 	github.com/ultraware/whitespace v0.0.4
 	github.com/uudashr/gocognit v1.0.1
 	github.com/valyala/quicktemplate v1.5.0
-	golang.org/x/tools v0.0.0-20200502202811-ed308ab3e770
+	golang.org/x/tools v0.0.0-20200519015757-0d0afa43d58a
 	gopkg.in/yaml.v2 v2.3.0
 	honnef.co/go/tools v0.0.1-2020.1.4
 	mvdan.cc/interfacer v0.0.0-20180901003855-c20040233aed

go.sum

@@ -267,6 +267,8 @@ github.com/nbutton23/zxcvbn-go v0.0.0-20180912185939-ae427f1e4c1d h1:AREM5mwr4u1
 github.com/nbutton23/zxcvbn-go v0.0.0-20180912185939-ae427f1e4c1d/go.mod h1:o96djdrsSGy3AWPyBgZMAGfxZNfgntdJG+11KU4QvbU=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e h1:fD57ERR4JtEqsWbfPhv4DMiApHyliiK5xCTNVSPiaAs=
 github.com/niemeyer/pretty v0.0.0-20200227124842-a10e7caefd8e/go.mod h1:zD1mROLANZcx1PVRCS0qkT7pwLkGfwJo4zjcN/Tysno=
+github.com/nishanths/exhaustive v0.0.0-20200525081945-8e46705b6132 h1:NjznefjSrral0MiR4KlB41io/d3OklvhcgQUdfZTqJE=
+github.com/nishanths/exhaustive v0.0.0-20200525081945-8e46705b6132/go.mod h1:wBEpHwM2OdmeNpdCvRPUlkEbBuaFmcK4Wv8Q7FuGW3c=
 github.com/oklog/ulid v1.3.1/go.mod h1:CirwcVhetQ6Lv90oh/F+FBtV6XMibvdAFo93nm5qn4U=
 github.com/onsi/ginkgo v1.6.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
 github.com/onsi/ginkgo v1.12.0 h1:Iw5WCbBcaAAd0fpRb1c9r5YCylv4XDoCSigm1zLevwU=
@@ -511,6 +513,8 @@ golang.org/x/tools v0.0.0-20200502202811-ed308ab3e770 h1:M9Fif0OxNji8w+HvmhVQ8KJ
 golang.org/x/tools v0.0.0-20200502202811-ed308ab3e770 h1:M9Fif0OxNji8w+HvmhVQ8KJtiZOsjU9RgslJGhn95XE=
 golang.org/x/tools v0.0.0-20200502202811-ed308ab3e770 h1:M9Fif0OxNji8w+HvmhVQ8KJtiZOsjU9RgslJGhn95XE=
 golang.org/x/tools v0.0.0-20200502202811-ed308ab3e770/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
+golang.org/x/tools v0.0.0-20200519015757-0d0afa43d58a h1:gILuVKC+ZPD6g/tj6zBOdnOH1ZHI0zZ86+KLMogc6/s=
+golang.org/x/tools v0.0.0-20200519015757-0d0afa43d58a/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7 h1:9zdDQZ7Thm29KFXgAX/+yaf3eVbP7djjWp/dXAppNCc=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898 h1:/atklqdjdhuosWIl6AIbOeHJjicWYPqR9bpxqxYG2pA=

pkg/config/config.go

@@ -242,6 +242,7 @@ type LintersSettings struct {
 	Testpackage TestpackageSettings
 	Nestif      NestifSettings
 	NoLintLint  NoLintLintSettings
+	Exhaustive  ExhaustiveSettings
 
 	Custom map[string]CustomLinterSettings
 }
@@ -339,6 +340,10 @@ type NestifSettings struct {
 	MinComplexity int `mapstructure:"min-complexity"`
 }
 
+type ExhaustiveSettings struct {
+	DefaultSignifiesExhaustive bool `mapstructure:"default-signifies-exhaustive"`
+}
+
 var defaultLintersSettings = LintersSettings{
 	Lll: LllSettings{
 		LineLength: 120,
@@ -389,6 +394,9 @@ var defaultLintersSettings = LintersSettings{
 	Nestif: NestifSettings{
 		MinComplexity: 5,
 	},
+	Exhaustive: ExhaustiveSettings{
+		DefaultSignifiesExhaustive: false,
+	},
 }
 
 type CustomLinterSettings struct {

pkg/golinters/exhaustive.go

@@ -0,0 +1,25 @@
+package golinters
+
+import (
+	"github.com/nishanths/exhaustive"
+	"golang.org/x/tools/go/analysis"
+
+	"github.com/golangci/golangci-lint/pkg/config"
+	"github.com/golangci/golangci-lint/pkg/golinters/goanalysis"
+)
+
+func NewExhaustive(settings *config.ExhaustiveSettings) *goanalysis.Linter {
+	a := exhaustive.Analyzer
+
+	var cfg map[string]map[string]interface{}
+	if settings != nil {
+		cfg = map[string]map[string]interface{}{
+			a.Name: {
+				exhaustive.DefaultSignifiesExhaustiveFlag: settings.DefaultSignifiesExhaustive,
+			},
+		}
+	}
+
+	return goanalysis.NewLinter(a.Name, a.Doc, []*analysis.Analyzer{a}, cfg).
+		WithLoadMode(goanalysis.LoadModeTypesInfo)
+}

pkg/golinters/goanalysis/runner.go

@@ -935,7 +935,8 @@ func sizeOfReflectValueTreeBytes(rv reflect.Value, visitedPtrs map[uintptr]struc
 		return rv.Len()
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
 		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
-		reflect.Uintptr, reflect.Bool, reflect.Float32, reflect.Float64, reflect.UnsafePointer:
+		reflect.Uintptr, reflect.Bool, reflect.Float32, reflect.Float64,
+		reflect.Complex64, reflect.Complex128, reflect.Func, reflect.UnsafePointer:
 		return int(rv.Type().Size())
 	case reflect.Invalid:
 		return 0

pkg/lint/lintersdb/manager.go

@@ -87,9 +87,11 @@ func enableLinterConfigs(lcs []*linter.Config, isEnabled func(lc *linter.Config)
 func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 	var govetCfg *config.GovetSettings
 	var testpackageCfg *config.TestpackageSettings
+	var exhaustiveCfg *config.ExhaustiveSettings
 	if m.cfg != nil {
 		govetCfg = &m.cfg.LintersSettings.Govet
 		testpackageCfg = &m.cfg.LintersSettings.Testpackage
+		exhaustiveCfg = &m.cfg.LintersSettings.Exhaustive
 	}
 	const megacheckName = "megacheck"
 	lcs := []*linter.Config{
@@ -275,6 +277,10 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 		linter.NewConfig(golinters.NewExportLoopRef()).
 			WithPresets(linter.PresetBugs).
 			WithURL("https://github.com/kyoh86/exportloopref"),
+		linter.NewConfig(golinters.NewExhaustive(exhaustiveCfg)).
+			WithPresets(linter.PresetBugs).
+			WithLoadForGoAnalysis().
+			WithURL("https://github.com/nishanths/exhaustive"),
 		// 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/linters_test.go

@@ -17,9 +17,13 @@ import (
 
 func runGoErrchk(c *exec.Cmd, files []string, t *testing.T) {
 	output, err := c.CombinedOutput()
-	assert.Error(t, err)
-	_, ok := err.(*exec.ExitError)
-	assert.True(t, ok, err)
+	// The returned error will be nil if the test file does not have any issues
+	// and thus the linter exits with exit code 0. So perform the additional
+	// assertions only if the error is non-nil.
+	if err != nil {
+		_, ok := err.(*exec.ExitError)
+		assert.True(t, ok, err)
+	}
 
 	// TODO: uncomment after deprecating go1.11
 	// assert.Equal(t, exitcodes.IssuesFound, exitErr.ExitCode())

test/testdata/configs/exhaustive.yml

@@ -0,0 +1,3 @@
+linters-settings:
+  exhaustive:
+    default-signifies-exhaustive: true

test/testdata/exhaustive.go

@@ -0,0 +1,17 @@
+//args: -Eexhaustive
+package testdata
+
+type Direction int
+
+const (
+	North Direction = iota
+	East
+	South
+	West
+)
+
+func processDirection(d Direction) {
+	switch d { // ERROR "missing cases in switch of type Direction: East, West"
+	case North, South:
+	}
+}

test/testdata/exhaustive_default.go

@@ -0,0 +1,19 @@
+//args: -Eexhaustive
+//config_path: testdata/configs/exhaustive.yml
+package testdata
+
+type Direction int
+
+const (
+	North Direction = iota
+	East
+	South
+	West
+)
+
+func processDirectionDefault(d Direction) {
+	switch d {
+	case North, South:
+	default:
+	}
+}