errcheck: allow exclude config without extra file (#2110)

Co-authored-by: Fernandez Ludovic <ldez@users.noreply.github.com>

.golangci.example.yml

@@ -113,10 +113,18 @@ linters-settings:
     # see https://github.com/kisielk/errcheck#the-deprecated-method for details
     ignore: fmt:.*,io/ioutil:^Read.*
 
+    # [deprecated] use exclude-functions instead.
     # 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
 
+    # 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

.golangci.yml

@@ -122,6 +122,12 @@ issues:
     - path: _test\.go
       linters:
         - gomnd
+
+    - path: pkg/golinters/errcheck.go
+      text: "SA1019: errCfg.Exclude is deprecated: use ExcludeFunctions instead"
+    - path: pkg/commands/run.go
+      text: "SA1019: lsc.Errcheck.Exclude is deprecated: use ExcludeFunctions instead"
+
     # TODO must be removed after the release of the next version (v1.41.0)
     - path: pkg/commands/run.go
       linters:

pkg/config/linters_settings.go

@@ -161,10 +161,13 @@ 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"`
+	ExcludeFunctions    []string `mapstructure:"exclude-functions"`
+
+	// Deprecated: use ExcludeFunctions instead
+	Exclude string `mapstructure:"exclude"`
 }
 
 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.yml

@@ -0,0 +1,6 @@
+linters-settings:
+  errcheck:
+    check-blank: true
+    exclude-functions:
+      - io/ioutil.ReadFile
+      - io/ioutil.ReadDir

test/testdata/errcheck_exclude_functions.go

@@ -0,0 +1,18 @@
+//args: -Eerrcheck
+//config_path: testdata/errcheck/exclude_functions.yml
+package testdata
+
+import (
+	"io/ioutil"
+)
+
+func TestErrcheckExcludeFunctions() []byte {
+	ret, _ := ioutil.ReadFile("f.txt")
+	ioutil.ReadDir("dir")
+	return ret
+}
+
+func TestErrcheckNoExcludeFunctions() []byte {
+	ret, _ := ioutil.ReadAll(nil) // ERROR "Error return value of `ioutil.ReadAll` is not checked"
+	return ret
+}