errcheck: allow exclude config without extra file

.golangci.example.yml

@@ -117,6 +117,14 @@ linters-settings:
     # see https://github.com/kisielk/errcheck#excluding-functions for details
     exclude: /path/to/file.txt
 
+    # list of functions to exclude from checking, where each entry is a single
+    # function to exclude.
+    # see https://github.com/kisielk/errcheck#excluding-functions for details
+    exclude-functions:
+      - io/ioutil.ReadFile
+      - io.Copy(*bytes.Buffer)
+      - io.Copy(os.Stdout)
+
   errorlint:
     # Check whether fmt.Errorf uses the %w verb for formatting errors. See the readme for caveats
     errorf: true

pkg/commands/run.go

@@ -133,6 +133,9 @@ func initFlagSet(fs *pflag.FlagSet, cfg *config.Config, m *lintersdb.Manager, is
 	fs.StringVar(&lsc.Errcheck.Exclude, "errcheck.exclude", "",
 		"Path to a file containing a list of functions to exclude from checking")
 	hideFlag("errcheck.exclude")
+	fs.StringSliceVar(&lsc.Errcheck.ExcludeFunctions, "errcheck.exclude-functions", nil,
+		"List of functions to exclude from checking")
+	hideFlag("errcheck.exclude-functions")
 	fs.StringVar(&lsc.Errcheck.Ignore, "errcheck.ignore", "fmt:.*",
 		`Comma-separated list of pairs of the form pkg:regex. The regex is used to ignore names within pkg`)
 	hideFlag("errcheck.ignore")

pkg/config/linters_settings.go

@@ -161,10 +161,11 @@ type DuplSettings struct {
 }
 
 type ErrcheckSettings struct {
-	CheckTypeAssertions bool   `mapstructure:"check-type-assertions"`
-	CheckAssignToBlank  bool   `mapstructure:"check-blank"`
-	Ignore              string `mapstructure:"ignore"`
-	Exclude             string `mapstructure:"exclude"`
+	CheckTypeAssertions bool     `mapstructure:"check-type-assertions"`
+	CheckAssignToBlank  bool     `mapstructure:"check-blank"`
+	Ignore              string   `mapstructure:"ignore"`
+	Exclude             string   `mapstructure:"exclude"`
+	ExcludeFunctions    []string `mapstructure:"exclude-functions"`
 }
 
 type ErrorLintSettings struct {

pkg/golinters/errcheck.go

@@ -152,6 +152,8 @@ func getChecker(errCfg *config.ErrcheckSettings) (*errcheck.Checker, error) {
 		checker.Exclusions.Symbols = append(checker.Exclusions.Symbols, exclude...)
 	}
 
+	checker.Exclusions.Symbols = append(checker.Exclusions.Symbols, errCfg.ExcludeFunctions...)
+
 	return &checker, nil
 }
 

test/testdata/errcheck_exclude_functions.go

@@ -0,0 +1,19 @@
+//args: -Eerrcheck
+//config: linters-settings.errcheck.check-blank=true
+//config: linters-settings.errcheck.exclude-functions=io/ioutil.ReadFile,io/ioutil.ReadDir
+package testdata
+
+import (
+	"io/ioutil"
+)
+
+func TestErrcheckExclude() []byte {
+	ret, _ := ioutil.ReadFile("f.txt")
+	_, _ = ioutil.ReadDir("dir")
+	return ret
+}
+
+func TestErrcheckNoExclude() []byte {
+	ret, _ := ioutil.ReadAll(nil) // ERROR "Error return value of `ioutil.ReadAll` is not checked"
+	return ret
+}