Add suggested fix

Author: uudashr

unused/testdata/src/a/a.go.golden

@@ -0,0 +1,38 @@
+package user
+
+import "database/sql"
+
+type User struct {
+	ID   string
+	Name string
+}
+
+type UserRepositorySQL struct {
+	DB *sql.DB
+}
+
+func (r *UserRepositorySQL) UserOf(id string) (*User, error) {
+	var u User
+	err := r.DB.QueryRow("SELECT id, name FROM users WHERE id = ?", id).Scan(u.ID, u.Name)
+	if err != nil {
+		return nil, err
+	}
+
+	return &u, nil
+}
+
+type Granter interface {
+	Grant(permission string) error
+}
+
+func AllowAll(g Granter) error {
+	return g.Grant("all")
+}
+
+type Allower interface {
+	Allow(permission string) error
+}
+
+func Allow(x interface{}) {
+	_ = x.(Allower)
+}

unused/testdata/src/agroup/agroup.go

@@ -0,0 +1,44 @@
+package user
+
+import "database/sql"
+
+type (
+	User struct {
+		ID   string
+		Name string
+	}
+
+	UserRepository interface { // want "interface UserRepository is declared but not used within the package"
+		UserOf(id string) (*User, error)
+	}
+
+	UserRepositorySQL struct {
+		DB *sql.DB
+	}
+)
+
+func (r *UserRepositorySQL) UserOf(id string) (*User, error) {
+	var u User
+	err := r.DB.QueryRow("SELECT id, name FROM users WHERE id = ?", id).Scan(u.ID, u.Name)
+	if err != nil {
+		return nil, err
+	}
+
+	return &u, nil
+}
+
+type Granter interface {
+	Grant(permission string) error
+}
+
+func AllowAll(g Granter) error {
+	return g.Grant("all")
+}
+
+type Allower interface {
+	Allow(permission string) error
+}
+
+func Allow(x interface{}) {
+	_ = x.(Allower)
+}

unused/testdata/src/agroup/agroup.go.golden

@@ -0,0 +1,40 @@
+package user
+
+import "database/sql"
+
+type (
+	User struct {
+		ID   string
+		Name string
+	}
+
+	UserRepositorySQL struct {
+		DB *sql.DB
+	}
+)
+
+func (r *UserRepositorySQL) UserOf(id string) (*User, error) {
+	var u User
+	err := r.DB.QueryRow("SELECT id, name FROM users WHERE id = ?", id).Scan(u.ID, u.Name)
+	if err != nil {
+		return nil, err
+	}
+
+	return &u, nil
+}
+
+type Granter interface {
+	Grant(permission string) error
+}
+
+func AllowAll(g Granter) error {
+	return g.Grant("all")
+}
+
+type Allower interface {
+	Allow(permission string) error
+}
+
+func Allow(x interface{}) {
+	_ = x.(Allower)
+}

unused/testdata/src/d/d.go.golden

@@ -0,0 +1,20 @@
+package actor
+
+// Doer performs some work.
+//
+//iface:ignore
+type Doer interface {
+	Do() error
+}
+
+//iface:ignore=unused
+type Runner interface {
+	Run() error
+}
+
+//iface:ignore=other
+
+//iface:ignore=other,unused
+type Server interface {
+	Serve() error
+}

unused/unused.go

@@ -48,7 +48,8 @@ func (r *runner) run(pass *analysis.Pass) (interface{}, error) {
 	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
 
 	// Collect all interface type declarations
-	ifaceDecls := make(map[string]token.Pos)
+	ifaceDecls := make(map[string]*ast.TypeSpec)
+	genDecls := make(map[string]*ast.GenDecl) // ifaceName -> GenDecl
 
 	nodeFilter := []ast.Node{
 		(*ast.GenDecl)(nil),
@@ -80,7 +81,7 @@ func (r *runner) run(pass *analysis.Pass) (interface{}, error) {
 
 			_, ok = ts.Type.(*ast.InterfaceType)
 			if !ok {
-				return
+				continue
 			}
 
 			if r.debug {
@@ -93,7 +94,8 @@ func (r *runner) run(pass *analysis.Pass) (interface{}, error) {
 				continue
 			}
 
-			ifaceDecls[ts.Name.Name] = ts.Pos()
+			ifaceDecls[ts.Name.Name] = ts
+			genDecls[ts.Name.Name] = decl
 		}
 	})
 
@@ -117,21 +119,51 @@ func (r *runner) run(pass *analysis.Pass) (interface{}, error) {
 			return
 		}
 
-		pos := ifaceDecls[ident.Name]
-		if pos == ident.Pos() {
+		ts, ok := ifaceDecls[ident.Name]
+		if !ok {
+			return
+		}
+
+		if ts.Pos() == ident.Pos() {
 			// The identifier is the interface type declaration
 			return
 		}
 
 		delete(ifaceDecls, ident.Name)
+		delete(genDecls, ident.Name)
 	})
 
 	if r.debug {
 		fmt.Printf("Package %s %s\n", pass.Pkg.Path(), pass.Pkg.Name())
 	}
 
-	for name, pos := range ifaceDecls {
-		pass.Reportf(pos, "interface %s is declared but not used within the package", name)
+	for name, ts := range ifaceDecls {
+		decl := genDecls[name]
+
+		var node ast.Node
+		if len(decl.Specs) == 1 {
+			node = decl
+		} else {
+			node = ts
+		}
+
+		msg := fmt.Sprintf("interface %s is declared but not used within the package", name)
+		pass.Report(analysis.Diagnostic{
+			Pos:     ts.Pos(),
+			Message: msg,
+			SuggestedFixes: []analysis.SuggestedFix{
+				{
+					Message: "Remove the unused interface declaration",
+					TextEdits: []analysis.TextEdit{
+						{
+							Pos:     node.Pos(),
+							End:     node.End(),
+							NewText: []byte{},
+						},
+					},
+				},
+			},
+		})
 	}
 
 	return nil, nil

unused/unused_test.go

@@ -14,8 +14,9 @@ func TestAnalyzer(t *testing.T) {
 	}
 
 	testdata := analysistest.TestData()
-	analysistest.Run(t, testdata, unused.Analyzer, "a")
-	analysistest.Run(t, testdata, unused.Analyzer, "b")
-	analysistest.Run(t, testdata, unused.Analyzer, "c")
-	analysistest.Run(t, testdata, unused.Analyzer, "d")
+	analysistest.RunWithSuggestedFixes(t, testdata, unused.Analyzer, "a")
+	analysistest.RunWithSuggestedFixes(t, testdata, unused.Analyzer, "agroup")
+	analysistest.RunWithSuggestedFixes(t, testdata, unused.Analyzer, "b")
+	analysistest.RunWithSuggestedFixes(t, testdata, unused.Analyzer, "c")
+	analysistest.RunWithSuggestedFixes(t, testdata, unused.Analyzer, "d")
 }