linters/errcheck: add support for ignore/exclude flags

Add support for the exclude and ignore flags of errcheck.
Note that, this commit depends on golangci/errcheck#1. We need
to merge it first, update vendors and only then merge this one.

Gopkg.toml

@@ -22,6 +22,10 @@
   name = "github.com/spf13/viper"
   version = "1.0.2"
 
+[[constraint]]
+  branch = "master"
+  name = "github.com/spf13/pflag"
+
 [[constraint]]
   branch = "master"
   name = "github.com/mitchellh/go-ps"

pkg/commands/run.go

@@ -75,16 +75,20 @@ func initFlagSet(fs *pflag.FlagSet, cfg *config.Config, m *lintersdb.Manager) {
 	lsc := &cfg.LintersSettings
 
 	// Hide all linters settings flags: they were initially visible,
-	// but when number of linters started to grow it became ovious that
+	// but when number of linters started to grow it became obvious that
 	// we can't fill 90% of flags by linters settings: common flags became hard to find.
 	// New linters settings should be done only through config file.
 	fs.BoolVar(&lsc.Errcheck.CheckTypeAssertions, "errcheck.check-type-assertions",
 		false, "Errcheck: check for ignored type assertion results")
 	hideFlag("errcheck.check-type-assertions")
-
 	fs.BoolVar(&lsc.Errcheck.CheckAssignToBlank, "errcheck.check-blank", false,
 		"Errcheck: check for errors assigned to blank identifier: _ = errFunc()")
 	hideFlag("errcheck.check-blank")
+	fs.StringVar(&lsc.Errcheck.Exclude, "errcheck.exclude", "", "errcheck.exclude")
+	hideFlag("errcheck.exclude")
+	lsc.Errcheck.Ignore = config.IgnoreFlag{}
+	fs.Var(&lsc.Errcheck.Ignore, "errcheck.ignore", "errcheck.ignore")
+	hideFlag("errcheck.ignore")
 
 	fs.BoolVar(&lsc.Govet.CheckShadowing, "govet.check-shadowing", false,
 		"Govet: check for shadowed variables")

pkg/config/config.go

@@ -1,6 +1,9 @@
 package config
 
 import (
+	"fmt"
+	"regexp"
+	"strings"
 	"time"
 )
 
@@ -115,10 +118,6 @@ type Run struct {
 }
 
 type LintersSettings struct {
-	Errcheck struct {
-		CheckTypeAssertions bool `mapstructure:"check-type-assertions"`
-		CheckAssignToBlank  bool `mapstructure:"check-blank"`
-	}
 	Govet struct {
 		CheckShadowing       bool `mapstructure:"check-shadowing"`
 		UseInstalledPackages bool `mapstructure:"use-installed-packages"`
@@ -164,6 +163,14 @@ type LintersSettings struct {
 	Unparam  UnparamSettings
 	Nakedret NakedretSettings
 	Prealloc PreallocSettings
+	Errcheck ErrcheckSettings
+}
+
+type ErrcheckSettings struct {
+	CheckTypeAssertions bool       `mapstructure:"check-type-assertions"`
+	CheckAssignToBlank  bool       `mapstructure:"check-blank"`
+	Ignore              IgnoreFlag `mapstructure:"ignore"`
+	Exclude             string     `mapstructure:"exclude"`
 }
 
 type LllSettings struct {
@@ -248,3 +255,47 @@ func NewDefault() *Config {
 		LintersSettings: defaultLintersSettings,
 	}
 }
+
+// IgnoreFlags was taken from errcheck in order to keep the API identical.
+// https://github.com/kisielk/errcheck/blob/1787c4bee836470bf45018cfbc783650db3c6501/main.go#L25-L60
+type IgnoreFlag map[string]*regexp.Regexp
+
+func (f IgnoreFlag) String() string {
+	pairs := make([]string, 0, len(f))
+	for pkg, re := range f {
+		prefix := ""
+		if pkg != "" {
+			prefix = pkg + ":"
+		}
+		pairs = append(pairs, prefix+re.String())
+	}
+	return fmt.Sprintf("%q", strings.Join(pairs, ","))
+}
+
+func (f IgnoreFlag) Set(s string) error {
+	if s == "" {
+		return nil
+	}
+	for _, pair := range strings.Split(s, ",") {
+		colonIndex := strings.Index(pair, ":")
+		var pkg, re string
+		if colonIndex == -1 {
+			pkg = ""
+			re = pair
+		} else {
+			pkg = pair[:colonIndex]
+			re = pair[colonIndex+1:]
+		}
+		regex, err := regexp.Compile(re)
+		if err != nil {
+			return err
+		}
+		f[pkg] = regex
+	}
+	return nil
+}
+
+// Type returns the type of the flag follow the pflag format.
+func (IgnoreFlag) Type() string {
+	return "stringToRegexp"
+}

pkg/golinters/errcheck.go

@@ -1,12 +1,16 @@
 package golinters
 
 import (
+	"bufio"
 	"context"
 	"fmt"
+	"os"
 
 	errcheckAPI "github.com/golangci/errcheck/golangci"
+	"github.com/golangci/golangci-lint/pkg/config"
 	"github.com/golangci/golangci-lint/pkg/lint/linter"
 	"github.com/golangci/golangci-lint/pkg/result"
+	"github.com/pkg/errors"
 )
 
 type Errcheck struct{}
@@ -21,8 +25,11 @@ func (Errcheck) Desc() string {
 }
 
 func (e Errcheck) Run(ctx context.Context, lintCtx *linter.Context) ([]result.Issue, error) {
-	errCfg := &lintCtx.Settings().Errcheck
-	issues, err := errcheckAPI.Run(lintCtx.Program, errCfg.CheckAssignToBlank, errCfg.CheckTypeAssertions)
+	errCfg, err := genConfig(&lintCtx.Settings().Errcheck)
+	if err != nil {
+		return nil, err
+	}
+	issues, err := errcheckAPI.RunWithConfig(lintCtx.Program, errCfg)
 	if err != nil {
 		return nil, err
 	}
@@ -48,3 +55,36 @@ func (e Errcheck) Run(ctx context.Context, lintCtx *linter.Context) ([]result.Is
 
 	return res, nil
 }
+
+func genConfig(errCfg *config.ErrcheckSettings) (*errcheckAPI.Config, error) {
+	c := &errcheckAPI.Config{
+		Ignore:  errCfg.Ignore,
+		Blank:   errCfg.CheckAssignToBlank,
+		Asserts: errCfg.CheckTypeAssertions,
+	}
+	if errCfg.Exclude != "" {
+		exclude, err := readExcludeFile(errCfg.Exclude)
+		if err != nil {
+			return nil, err
+		}
+		c.Exclude = exclude
+	}
+	return c, nil
+}
+
+func readExcludeFile(name string) (map[string]bool, error) {
+	exclude := make(map[string]bool)
+	fh, err := os.Open(name)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed reading exclude file: %s", name)
+	}
+	scanner := bufio.NewScanner(fh)
+	for scanner.Scan() {
+		name := scanner.Text()
+		exclude[name] = true
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, errors.Wrapf(err, "failed scanning file: %s", name)
+	}
+	return exclude, nil
+}