feature: initial release for generics support (#42)

* feature: initial release for generics support
* chores: bump go version for CI pipelines
* chores: rename test file for generics
* refactor: issues diagnostics improvments

.github/workflows/main.yaml

@@ -16,9 +16,9 @@ jobs:
       fail-fast: true
       matrix:
         go:
-          - "1.17"
-          - "1.16"
-          - "1.15"
+          - "1.19"
+          - "1.20"
+
     steps:
 
       - uses: actions/checkout@v2
@@ -41,11 +41,11 @@ jobs:
 
       - name: Install goveralls
         env: { GO111MODULE: "off" }
-        if: matrix.go == '1.17'
+        if: matrix.go == '1.20'
         run: go get github.com/mattn/goveralls
 
       - name: Coverage - Sending Report to Coveral
-        if: matrix.go == '1.17'
+        if: matrix.go == '1.20'
         env:
           COVERALLS_TOKEN: ${{ secrets.github_token }}
         run: goveralls -coverprofile=coverage.cov -service=github

.github/workflows/release.yaml

@@ -6,7 +6,7 @@ on:
       - v*
 
 env:
-  GO_VERSION: 1.17
+  GO_VERSION: 1.20
 
 jobs:
 

analyzer/analyzer.go

@@ -2,7 +2,6 @@ package analyzer
 
 import (
 	"flag"
-	"fmt"
 	"go/ast"
 	gotypes "go/types"
 	"strings"
@@ -41,7 +40,7 @@ func (a *analyzer) run(pass *analysis.Pass) (interface{}, error) {
 
 	ins, _ := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
 
-	// 00. does file have dot-imported stadard packages?
+	// 00. does file have dot-imported standard packages?
 	dotImportedStd := make(map[string]struct{})
 	ins.Preorder([]ast.Node{(*ast.ImportSpec)(nil)}, func(node ast.Node) {
 		i, _ := node.(*ast.ImportSpec)
@@ -66,17 +65,25 @@ func (a *analyzer) run(pass *analysis.Pass) (interface{}, error) {
 			return
 		}
 
+		seen := make(map[string]bool, 4)
+
 		// 004. Filtering Results.
-		for _, i := range filterInterfaces(pass, f.Type.Results, dotImportedStd) {
+		for _, issue := range filterInterfaces(pass, f.Type, dotImportedStd) {
+
+			if a.handler.IsValid(issue) {
+				continue
+			}
 
-			if a.handler.IsValid(i) {
+			issue.Enrich(f)
+
+			key := issue.HashString()
+
+			if ok := seen[key]; ok {
 				continue
 			}
+			seen[key] = true
 
-			a.found = append(a.found, analysis.Diagnostic{ //nolint: exhaustivestruct
-				Pos:     f.Pos(),
-				Message: fmt.Sprintf("%s returns interface (%s)", f.Name.Name, i.Name),
-			})
+			a.found = append(a.found, issue.ExportDiagnostic())
 		}
 	})
 
@@ -122,20 +129,26 @@ func flags() flag.FlagSet {
 	return *set
 }
 
-func filterInterfaces(p *analysis.Pass, fl *ast.FieldList, di map[string]struct{}) []types.IFace {
+func filterInterfaces(p *analysis.Pass, ft *ast.FuncType, di map[string]struct{}) []types.IFace {
 	var results []types.IFace
 
-	for pos, el := range fl.List {
+	if ft.Results == nil { // this can't happen, but double checking.
+		return results
+	}
+
+	tp := newTypeParams(ft.TypeParams)
+
+	for _, el := range ft.Results.List {
 		switch v := el.Type.(type) {
 		// ----- empty or anonymous interfaces
 		case *ast.InterfaceType:
 
 			if len(v.Methods.List) == 0 {
-				results = append(results, issue("interface{}", pos, types.EmptyInterface))
+				results = append(results, types.NewIssue("interface{}", types.EmptyInterface))
 				continue
 			}
 
-			results = append(results, issue("anonymous interface", pos, types.AnonInterface))
+			results = append(results, types.NewIssue("anonymous interface", types.AnonInterface))
 
 		// ------ Errors and interfaces from same package
 		case *ast.Ident:
@@ -148,24 +161,28 @@ func filterInterfaces(p *analysis.Pass, fl *ast.FieldList, di map[string]struct{
 			word := t1.String()
 			// only build in interface is error
 			if obj := gotypes.Universe.Lookup(word); obj != nil {
-				results = append(results, issue(obj.Name(), pos, types.ErrorInterface))
+				results = append(results, types.NewIssue(obj.Name(), types.ErrorInterface))
+				continue
+			}
 
+			// found in type params
+			if tp.In(word) {
+				results = append(results, types.NewIssue(word, types.Generic))
 				continue
 			}
 
 			// is it dot-imported package?
 			// handling cases when stdlib package imported via "." dot-import
-			//
 			if len(di) > 0 {
 				name := stdPkgInterface(word)
 				if _, ok := di[name]; ok {
-					results = append(results, issue(word, pos, types.NamedStdInterface))
+					results = append(results, types.NewIssue(word, types.NamedStdInterface))
 
 					continue
 				}
 			}
 
-			results = append(results, issue(word, pos, types.NamedInterface))
+			results = append(results, types.NewIssue(word, types.NamedInterface))
 
 		// ------- standard library and 3rd party interfaces
 		case *ast.SelectorExpr:
@@ -177,12 +194,11 @@ func filterInterfaces(p *analysis.Pass, fl *ast.FieldList, di map[string]struct{
 
 			word := t1.String()
 			if isStdPkgInterface(word) {
-				results = append(results, issue(word, pos, types.NamedStdInterface))
-
+				results = append(results, types.NewIssue(word, types.NamedStdInterface))
 				continue
 			}
 
-			results = append(results, issue(word, pos, types.NamedInterface))
+			results = append(results, types.NewIssue(word, types.NamedInterface))
 		}
 	}
 
@@ -214,12 +230,3 @@ func stdPkg(pkg string) string {
 
 	return ""
 }
-
-// issue is shortcut that creates issue for next filtering.
-func issue(name string, pos int, interfaceType types.IType) types.IFace {
-	return types.IFace{
-		Name: name,
-		Pos:  pos,
-		Type: interfaceType,
-	}
-}

analyzer/analyzer_test.go

@@ -13,7 +13,6 @@ import (
 	"testing"
 
 	"github.com/butuzov/ireturn/analyzer/internal/types"
-
 	"github.com/stretchr/testify/assert"
 	"golang.org/x/tools/go/analysis/analysistest"
 )
@@ -43,6 +42,13 @@ func TestAll(t *testing.T) {
 		want: []string{},
 	})
 
+	// tests = append(tests, testCase{
+	// 	name: "Generic Interface",
+	// 	mask: []string{"generic.go", "go.*"},
+	// 	meta: map[string]string{},
+	// 	want: []string{},
+	// })
+
 	tests = append(tests, testCase{
 		name: "interface{}/allow",
 		mask: []string{"empty_interface.go", "go.*"},
@@ -204,6 +210,7 @@ func TestAll(t *testing.T) {
 		},
 	})
 
+	// was already commented
 	// tests = append(tests, testCase{
 	// 	name: "Named/allow/(stdmimic)",
 	// 	mask: []string{"internal/io/*"},
@@ -234,10 +241,16 @@ func TestAll(t *testing.T) {
 	})
 
 	tests = append(tests, testCase{
-		name: "default/all/non_std/reject_all_but_named",
+		name: "defaults",
 		mask: []string{"*.go", "github.com/foo/bar/*", "internal/sample/*"},
 		meta: map[string]string{}, // skipping any configuration to run default one.
 		want: []string{
+			"Min returns generic interface (T)",
+			"MixedReturnParameters returns generic interface (T)",
+			"MixedReturnParameters returns generic interface (K)",
+			"Max returns generic interface (foobar)",
+			"Foo returns generic interface (GENERIC)",
+			"SumIntsOrFloats returns generic interface (V)",
 			"s returns interface (github.com/foo/bar.Buzzer)",
 			"New returns interface (github.com/foo/bar.Buzzer)",
 			"NewDeclared returns interface (internal/sample.Doer)",
@@ -252,6 +265,51 @@ func TestAll(t *testing.T) {
 		meta: map[string]string{
 			"allow": types.NameStdLib, // allow only interfaces from standard library
 		},
+		want: []string{
+			"NewanonymousInterface returns interface (anonymous interface)",
+			"dissAllowDirective2 returns interface (interface{})",
+			"dissAllowDirective6 returns interface (interface{})",
+			"fooInterface returns interface (interface{})",
+			"errorReturn returns interface (error)",
+			"errorAliasReturn returns interface (error)",
+			"errorTypeReturn returns interface (error)",
+			"newErrorInterface returns interface (error)",
+			"Min returns generic interface (T)",
+			"MixedReturnParameters returns generic interface (T)",
+			"MixedReturnParameters returns generic interface (K)",
+			"Max returns generic interface (foobar)",
+			"Foo returns generic interface (GENERIC)",
+			"SumIntsOrFloats returns generic interface (V)",
+			"s returns interface (github.com/foo/bar.Buzzer)",
+			"New returns interface (github.com/foo/bar.Buzzer)",
+			"NewDeclared returns interface (internal/sample.Doer)",
+			"newIDoer returns interface (example.iDoer)",
+			"NewNamedStruct returns interface (example.FooerBarer)",
+		},
+	})
+
+	tests = append(tests, testCase{
+		name: "generic/reject",
+		mask: []string{"*.go", "github.com/foo/bar/*", "internal/sample/*"},
+		meta: map[string]string{
+			"reject": types.NameGeneric, // allow only generic interfaces
+		},
+		want: []string{
+			"Min returns generic interface (T)",
+			"MixedReturnParameters returns generic interface (T)",
+			"MixedReturnParameters returns generic interface (K)",
+			"Max returns generic interface (foobar)",
+			"Foo returns generic interface (GENERIC)",
+			"SumIntsOrFloats returns generic interface (V)",
+		},
+	})
+
+	tests = append(tests, testCase{
+		name: "generic/allow",
+		mask: []string{"*.go", "github.com/foo/bar/*", "internal/sample/*"},
+		meta: map[string]string{
+			"allow": types.NameGeneric, // allow only generic interfaces
+		},
 		want: []string{
 			"NewanonymousInterface returns interface (anonymous interface)",
 			"dissAllowDirective2 returns interface (interface{})",
@@ -266,6 +324,9 @@ func TestAll(t *testing.T) {
 			"NewDeclared returns interface (internal/sample.Doer)",
 			"newIDoer returns interface (example.iDoer)",
 			"NewNamedStruct returns interface (example.FooerBarer)",
+			"NamedContext returns interface (context.Context)",
+			"NamedBytes returns interface (io.Writer)",
+			"NamedStdFile returns interface (go/types.Importer)",
 		},
 	})
 
@@ -350,7 +411,7 @@ func directory(t *testing.T) (goroot, srcdir string, err error) {
 	goroot = t.TempDir()
 	srcdir = filepath.Join(goroot, "src")
 
-	if err := os.MkdirAll(srcdir, 0777); err != nil {
+	if err := os.MkdirAll(srcdir, 0o777); err != nil {
 		return "", "", err
 	}
 
@@ -375,7 +436,7 @@ func (tc testCase) xerox(root string) error {
 			}
 
 			// create if no exists
-			if err := os.MkdirAll(filepath.Join(root, directory), 0777); err != nil {
+			if err := os.MkdirAll(filepath.Join(root, directory), 0o777); err != nil {
 				return err
 			}
 
@@ -394,7 +455,7 @@ func cp(src, dst string) error {
 		return err
 	} else if data, err := ioutil.ReadFile(location); err != nil {
 		return err
-	} else if err := ioutil.WriteFile(filepath.Join(dst, filepath.Base(src)), data, 0600); err != nil {
+	} else if err := ioutil.WriteFile(filepath.Join(dst, filepath.Base(src)), data, 0o600); err != nil {
 		return err
 	}
 

analyzer/internal/config/config.go

@@ -55,6 +55,8 @@ func (config *defaultConfig) compileList() {
 			config.quick |= uint8(types.AnonInterface)
 		case types.NameStdLib:
 			config.quick |= uint8(types.NamedStdInterface)
+		case types.NameGeneric:
+			config.quick |= uint8(types.Generic)
 		}
 
 		// allow to parse regular expressions

analyzer/internal/config/new.go

@@ -10,7 +10,7 @@ import (
 
 var ErrCollisionOfInterests = errors.New("can't have both `-accept` and `-reject` specified at same time")
 
-//nolint: exhaustivestruct
+// nolint: exhaustivestruct
 func DefaultValidatorConfig() *allowConfig {
 	return allowAll([]string{
 		types.NameEmpty,  // "empty": empty interfaces (interface{})
@@ -40,7 +40,7 @@ func New(fs *flag.FlagSet) (interface{}, error) {
 		return rejectAll(rejectList), nil
 	}
 
-	// can have none at same time.
+	// can have none (defaults are used) at same time.
 	return nil, nil
 }
 

analyzer/internal/types/iface.go

@@ -1,7 +1,49 @@
 package types
 
+import (
+	"fmt"
+	"go/ast"
+	"go/token"
+
+	"golang.org/x/tools/go/analysis"
+)
+
 type IFace struct {
-	Name string // Preserved for named interfaces
-	Pos  int    // Position in return tuple
+	Name string // Interface name
 	Type IType  // Type of the interface
+
+	Pos      token.Pos // Token Position
+	FuncName string    //
+}
+
+func NewIssue(name string, interfaceType IType) IFace {
+	return IFace{
+		Name: name,
+		// Pos:  pos,
+		Type: interfaceType,
+	}
+}
+
+func (i *IFace) Enrich(f *ast.FuncDecl) {
+	i.FuncName = f.Name.Name
+	i.Pos = f.Pos()
+}
+
+func (i IFace) String() string {
+	if i.Type == Generic {
+		return fmt.Sprintf("%s returns generic interface (%s)", i.FuncName, i.Name)
+	}
+
+	return fmt.Sprintf("%s returns interface (%s)", i.FuncName, i.Name)
+}
+
+func (i IFace) HashString() string {
+	return fmt.Sprintf("%v-%s", i.Pos, i.String())
+}
+
+func (i IFace) ExportDiagnostic() analysis.Diagnostic {
+	return analysis.Diagnostic{ //nolint: exhaustivestruct
+		Pos:     i.Pos,
+		Message: i.String(),
+	}
 }