extended [allowRegex] parameter for unused-parameter and `unused-re…

…ceiver` rules #613

RULES_DESCRIPTIONS.md

@@ -735,13 +735,36 @@ _Configuration_: N/A
 
 _Description_: This rule warns on unused parameters. Functions or methods with unused parameters can be a symptom of an unfinished refactoring or a bug.
 
-_Configuration_: N/A
+_Configuration_: Supports arguments with single of `map[string]any` with option `allowRegex` to provide additional to `_` mask to allowed unused parameter names, for example:
+
+```toml
+[rule.unused-parameter]
+    Arguments = [ { allowRegex = "^_" } ]
+```
+
+allows any names started with `_`, not just `_` itself:
+
+```go
+func SomeFunc(_someObj *MyStruct) {} // matches rule
+```
 
 ## unused-receiver
 
 _Description_: This rule warns on unused method receivers. Methods with unused receivers can be a symptom of an unfinished refactoring or a bug.
 
-_Configuration_: N/A
+_Configuration_: Supports arguments with single of `map[string]any` with option `allowRegex` to provide additional to `_` mask to allowed unused receiver names, for example:
+
+```toml
+[rule.unused-receiver]
+    Arguments = [ { allowRegex = "^_" } ]
+```
+
+allows any names started with `_`, not just `_` itself:
+
+```go
+func (_my *MyStruct) SomeMethod() {} // matches rule
+```
+
 
 ## use-any
 

rule/unused-param.go

@@ -3,22 +3,62 @@ package rule
 import (
 	"fmt"
 	"go/ast"
+	"regexp"
+	"sync"
 
 	"github.com/mgechev/revive/lint"
 )
 
 // UnusedParamRule lints unused params in functions.
-type UnusedParamRule struct{}
+type UnusedParamRule struct {
+	configured bool
+	// regex to check if some name is valid for unused parameter, "^_$" by default
+	allowRegex *regexp.Regexp
+	sync.Mutex
+}
+
+func (r *UnusedParamRule) configure(args lint.Arguments) {
+	// optimistic pre-check
+	if r.configured {
+		return
+	}
+	r.Lock()
+	defer r.Unlock()
+	if r.configured {
+		return
+	}
+	r.configured = true
+	// while by default args is an array, i think it's good to provide structures inside it by default, not arrays or primitives
+	// it's more compatible to JSON nature of configurations
+	if len(args) == 0 {
+		return
+	}
+	// Arguments = [{}]
+	options := args[0].(map[string]interface{})
+	// Arguments = [{allowedRegex="^_"}]
+
+	if allowedRegexParam, ok := options["allowRegex"]; ok {
+		allowedRegexStr, ok := allowedRegexParam.(string)
+		if !ok {
+			panic(fmt.Errorf("error configuring [unused-parameter] rule: allowedRegex is not string but [%T]", allowedRegexParam))
+		}
+		var err error
+		r.allowRegex, err = regexp.Compile(allowedRegexStr)
+		if err != nil {
+			panic(fmt.Errorf("error configuring [unused-parameter] rule: allowedRegex is not valid regex [%s]: %v", allowedRegexStr, err))
+		}
+	}
+}
 
 // Apply applies the rule to given file.
-func (*UnusedParamRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
+func (r *UnusedParamRule) Apply(file *lint.File, args lint.Arguments) []lint.Failure {
+	r.configure(args)
 	var failures []lint.Failure
 
 	onFailure := func(failure lint.Failure) {
 		failures = append(failures, failure)
 	}
-
-	w := lintUnusedParamRule{onFailure: onFailure}
+	w := lintUnusedParamRule{onFailure: onFailure, allowRegex: r.allowRegex}
 
 	ast.Walk(w, file.AST)
 
@@ -31,7 +71,8 @@ func (*UnusedParamRule) Name() string {
 }
 
 type lintUnusedParamRule struct {
-	onFailure func(lint.Failure)
+	onFailure  func(lint.Failure)
+	allowRegex *regexp.Regexp
 }
 
 func (w lintUnusedParamRule) Visit(node ast.Node) ast.Visitor {
@@ -65,6 +106,10 @@ func (w lintUnusedParamRule) Visit(node ast.Node) ast.Visitor {
 
 		for _, p := range n.Type.Params.List {
 			for _, n := range p.Names {
+				// проверка на соответствие паттерну допустимых не используемых параметров
+				if w.allowRegex != nil && w.allowRegex.FindStringIndex(n.Name) != nil {
+					continue
+				}
 				if params[n.Obj] {
 					w.onFailure(lint.Failure{
 						Confidence: 1,

rule/unused-receiver.go

@@ -3,22 +3,63 @@ package rule
 import (
 	"fmt"
 	"go/ast"
+	"regexp"
+	"sync"
 
 	"github.com/mgechev/revive/lint"
 )
 
 // UnusedReceiverRule lints unused params in functions.
-type UnusedReceiverRule struct{}
+type UnusedReceiverRule struct {
+	configured bool
+	// regex to check if some name is valid for unused parameter, "^_$" by default
+	allowRegex *regexp.Regexp
+	sync.Mutex
+}
+
+func (r *UnusedReceiverRule) configure(args lint.Arguments) {
+	// optimistic pre-check
+	if r.configured {
+		return
+	}
+	r.Lock()
+	defer r.Unlock()
+	if r.configured {
+		return
+	}
+	r.configured = true
+	// while by default args is an array, i think it's good to provide structures inside it by default, not arrays or primitives
+	// it's more compatible to JSON nature of configurations
+	if len(args) == 0 {
+		return
+	}
+	// Arguments = [{}]
+	options := args[0].(map[string]interface{})
+	// Arguments = [{allowedRegex="^_"}]
+
+	if allowedRegexParam, ok := options["allowRegex"]; ok {
+		allowedRegexStr, ok := allowedRegexParam.(string)
+		if !ok {
+			panic(fmt.Errorf("error configuring [unused-receiver] rule: allowedRegex is not string but [%T]", allowedRegexParam))
+		}
+		var err error
+		r.allowRegex, err = regexp.Compile(allowedRegexStr)
+		if err != nil {
+			panic(fmt.Errorf("error configuring [unused-receiver] rule: allowedRegex is not valid regex [%s]: %v", allowedRegexStr, err))
+		}
+	}
+}
 
 // Apply applies the rule to given file.
-func (*UnusedReceiverRule) Apply(file *lint.File, _ lint.Arguments) []lint.Failure {
+func (r *UnusedReceiverRule) Apply(file *lint.File, args lint.Arguments) []lint.Failure {
+	r.configure(args)
 	var failures []lint.Failure
 
 	onFailure := func(failure lint.Failure) {
 		failures = append(failures, failure)
 	}
 
-	w := lintUnusedReceiverRule{onFailure: onFailure}
+	w := lintUnusedReceiverRule{onFailure: onFailure, allowRegex: r.allowRegex}
 
 	ast.Walk(w, file.AST)
 
@@ -31,7 +72,8 @@ func (*UnusedReceiverRule) Name() string {
 }
 
 type lintUnusedReceiverRule struct {
-	onFailure func(lint.Failure)
+	onFailure  func(lint.Failure)
+	allowRegex *regexp.Regexp
 }
 
 func (w lintUnusedReceiverRule) Visit(node ast.Node) ast.Visitor {
@@ -51,6 +93,10 @@ func (w lintUnusedReceiverRule) Visit(node ast.Node) ast.Visitor {
 			return nil // the receiver is already named _
 		}
 
+		if w.allowRegex != nil && w.allowRegex.FindStringIndex(recID.Name) != nil {
+			return nil
+		}
+
 		// inspect the func body looking for references to the receiver id
 		fselect := func(n ast.Node) bool {
 			ident, isAnID := n.(*ast.Ident)

test/unused-param_test.go

@@ -3,11 +3,15 @@ package test
 import (
 	"testing"
 
+	"github.com/mgechev/revive/lint"
 	"github.com/mgechev/revive/rule"
 )
 
 func TestUnusedParam(t *testing.T) {
 	testRule(t, "unused-param", &rule.UnusedParamRule{})
+	testRule(t, "unused-param-custom-regex", &rule.UnusedParamRule{}, &lint.RuleConfig{Arguments: []interface{}{
+		map[string]interface{}{"allowRegex": "^xxx"},
+	}})
 }
 
 func BenchmarkUnusedParam(b *testing.B) {

test/unused-receiver_test.go

@@ -3,9 +3,13 @@ package test
 import (
 	"testing"
 
+	"github.com/mgechev/revive/lint"
 	"github.com/mgechev/revive/rule"
 )
 
 func TestUnusedReceiver(t *testing.T) {
 	testRule(t, "unused-receiver", &rule.UnusedReceiverRule{})
+	testRule(t, "unused-receiver-custom-regex", &rule.UnusedReceiverRule{}, &lint.RuleConfig{Arguments: []interface{}{
+		map[string]interface{}{"allowRegex": "^xxx"},
+	}})
 }

testdata/unused-param-custom-regex.go

@@ -0,0 +1,12 @@
+package fixtures
+
+// all will ok with xxxParam if Arguments = [{allowRegex="^xxx"}]
+
+func f0(xxxParam int) {}
+
+// still works with _
+
+func f1(_ int) {}
+
+func f2(yyyParam int) { // MATCH /parameter 'yyyParam' seems to be unused, consider removing or renaming it as _/
+}

testdata/unused-receiver-custom-regex.go

@@ -0,0 +1,12 @@
+package fixtures
+
+// all will ok with xxxParam if Arguments = [{allowRegex="^xxx"}]
+
+func (xxxParam *SomeObj) f0() {}
+
+// still works with _
+
+func (_ *SomeObj) f1() {}
+
+func (yyyParam *SomeObj) f2() { // MATCH /method receiver 'yyyParam' is not referenced in method's body, consider removing or renaming it as _/
+}