update linter config and fix issues

Selecting linters in the workflow file has the disadvantage that a manual
"golangci-lint run" invocation uses different settings. It's better to do it in
a configuration file.

Several of the selected linters were deprecated and thus get removed:

    WARN [runner] The linter 'structcheck' is deprecated (since v1.49.0) due to: The owner seems to have abandoned the linter. Replaced by unused.
    WARN [runner] The linter 'deadcode' is deprecated (since v1.49.0) due to: The owner seems to have abandoned the linter. Replaced by unused.
    WARN [runner] The linter 'varcheck' is deprecated (since v1.49.0) due to: The owner seems to have abandoned the linter. Replaced by unused.

Some issues were reported with this configuration by golangci-lint 1.52.2 and get fixed.

.github/workflows/lint.yaml

@@ -21,22 +21,3 @@ jobs:
           args:
                 -v
                 --max-same-issues 10
-                --disable-all
-                --exclude-use-default=false
-                -E asciicheck
-                -E deadcode
-                -E errcheck
-                -E forcetypeassert
-                -E gocritic
-                -E gofmt
-                -E goimports
-                -E gosimple
-                -E govet
-                -E ineffassign
-                -E misspell
-                -E revive
-                -E staticcheck
-                -E structcheck
-                -E typecheck
-                -E unused
-                -E varcheck

.golangci.yaml

@@ -0,0 +1,20 @@
+issues:
+  exclude-use-default: false
+
+linters:
+  disable-all: true
+  enable:
+  - asciicheck
+  - errcheck
+  - forcetypeassert
+  - gocritic
+  - gofmt
+  - goimports
+  - gosimple
+  - govet
+  - ineffassign
+  - misspell
+  - revive
+  - staticcheck
+  - typecheck
+  - unused

example/main.go

@@ -14,6 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+// This example shows how to instantiate a zap logger and what output
+// looks like.
 package main
 
 import (

internal/types/objectref.go

@@ -14,6 +14,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
+// Package types holds a copy of the ObjectRef type from klog for
+// use in the example.
 package types
 
 import (

zapr.go

@@ -31,14 +31,14 @@ limitations under the License.
 // Package zapr defines an implementation of the github.com/go-logr/logr
 // interfaces built on top of Zap (go.uber.org/zap).
 //
-// Usage
+// # Usage
 //
 // A new logr.Logger can be constructed from an existing zap.Logger using
 // the NewLogger function:
 //
-//  log := zapr.NewLogger(someZapLogger)
+//	log := zapr.NewLogger(someZapLogger)
 //
-// Implementation Details
+// # Implementation Details
 //
 // For the most part, concepts in Zap correspond directly with those in
 // logr.

zapr_test.go

@@ -45,7 +45,7 @@ func fixedTimeEncoder(_ time.Time, enc zapcore.PrimitiveArrayEncoder) {
 // discard is a replacement for io.Discard, needed for Go 1.14.
 type discard struct{}
 
-func (d discard) Write(p []byte) (n int, err error) { return n, nil }
+func (d discard) Write(_ []byte) (int, error) { return 0, nil }
 
 type marshaler struct {
 	msg string