feat: add support for enforce-map-style rule (#895)

Co-authored-by: chavacava <salvadorcavadini+github@gmail.com>

README.md

@@ -535,6 +535,7 @@ List of all available rules. The rules ported from `golint` are left unchanged a
 | [`comment-spacings`](./RULES_DESCRIPTIONS.md#comment-spacings)          |  []string   |  Warns on malformed comments |    no    |  no   |
 | [`redundant-import-alias`](./RULES_DESCRIPTIONS.md#redundant-import-alias)          |  n/a   |  Warns on import aliases matching the imported package name |    no    |  no   |
 | [`import-alias-naming`](./RULES_DESCRIPTIONS.md#import-alias-naming)         | string (defaults to ^[a-z][a-z0-9]{0,}$) | Conventions around the naming of import aliases.                              |    no    |  no   |
+| [`enforce-map-style`](./RULES_DESCRIPTIONS.md#enforce-map-style) |  string (defaults to "any")  |  Enforces consistent usage of `make(map[type]type)` or `map[type]type{}` for map initialization. Does not affect `make(map[type]type, size)` constructions. |    no    |  no   |
 
 
 ## Configurable rules

RULES_DESCRIPTIONS.md

@@ -333,6 +333,22 @@ _Description_: Sometimes `gofmt` is not enough to enforce a common formatting of
 
 _Configuration_: N/A
 
+## enforce-map-style
+
+_Description_: This rule enforces consistent usage of `make(map[type]type)` or `map[type]type{}` for map initialization. It does not affect `make(map[type]type, size)` constructions as well as `map[type]type{k1: v1}`.
+
+_Configuration_: (string) Specifies the enforced style for map initialization. The options are:
+- "any": No enforcement (default).
+- "make": Enforces the usage of `make(map[type]type)`.
+- "literal": Enforces the usage of `map[type]type{}`.
+
+Example:
+
+```toml
+[rule.enforce-map-style]
+  arguments = ["make"]
+```
+
 ## error-naming
 
 _Description_: By convention, for the sake of readability, variables of type `error` must be named with the prefix `err`.

config/config.go

@@ -90,6 +90,7 @@ var allRules = append([]lint.Rule{
 	&rule.IfReturnRule{},
 	&rule.RedundantImportAlias{},
 	&rule.ImportAliasNamingRule{},
+	&rule.EnforceMapStyleRule{},
 }, defaultRules...)
 
 var allFormatters = []lint.Formatter{

rule/enforce-map-style.go

@@ -0,0 +1,164 @@
+package rule
+
+import (
+	"fmt"
+	"go/ast"
+	"sync"
+
+	"github.com/mgechev/revive/lint"
+)
+
+type enforceMapStyleType string
+
+const (
+	enforceMapStyleTypeAny     enforceMapStyleType = "any"
+	enforceMapStyleTypeMake    enforceMapStyleType = "make"
+	enforceMapStyleTypeLiteral enforceMapStyleType = "literal"
+)
+
+func mapStyleFromString(s string) (enforceMapStyleType, error) {
+	switch s {
+	case string(enforceMapStyleTypeAny), "":
+		return enforceMapStyleTypeAny, nil
+	case string(enforceMapStyleTypeMake):
+		return enforceMapStyleTypeMake, nil
+	case string(enforceMapStyleTypeLiteral):
+		return enforceMapStyleTypeLiteral, nil
+	default:
+		return enforceMapStyleTypeAny, fmt.Errorf(
+			"invalid map style: %s (expecting one of %v)",
+			s,
+			[]enforceMapStyleType{
+				enforceMapStyleTypeAny,
+				enforceMapStyleTypeMake,
+				enforceMapStyleTypeLiteral,
+			},
+		)
+	}
+}
+
+// EnforceMapStyleRule implements a rule to enforce `make(map[type]type)` over `map[type]type{}`.
+type EnforceMapStyleRule struct {
+	configured      bool
+	enforceMapStyle enforceMapStyleType
+	sync.Mutex
+}
+
+func (r *EnforceMapStyleRule) configure(arguments lint.Arguments) {
+	r.Lock()
+	defer r.Unlock()
+	
+	if r.configured {
+		return
+	}
+	r.configured = true
+
+	if len(arguments) < 1 {
+		r.enforceMapStyle = enforceMapStyleTypeAny
+		return
+	}
+
+	enforceMapStyle, ok := arguments[0].(string) 
+	if !ok {
+		panic(fmt.Sprintf("Invalid argument '%v' for 'enforce-map-style' rule. Expecting string, got %T", arguments[0], arguments[0]))
+	}
+
+	var err error
+	r.enforceMapStyle, err = mapStyleFromString(enforceMapStyle)
+
+	if err != nil {
+		panic(fmt.Sprintf("Invalid argument to the enforce-map-style rule: %v", err))
+	}
+}
+
+// Apply applies the rule to given file.
+func (r *EnforceMapStyleRule) Apply(file *lint.File, arguments lint.Arguments) []lint.Failure {
+	r.configure(arguments)
+
+	if r.enforceMapStyle == enforceMapStyleTypeAny {
+		// this linter is not configured
+		return nil
+	}
+
+	var failures []lint.Failure
+
+	astFile := file.AST
+	ast.Inspect(astFile, func(n ast.Node) bool {
+		switch v := n.(type) {
+		case *ast.CompositeLit:
+			if r.enforceMapStyle != enforceMapStyleTypeMake {
+				return true
+			}
+
+			if !r.isMapType(v.Type) {
+				return true
+			}
+
+			if len(v.Elts) > 0 {
+				// not an empty map
+				return true
+			}
+
+			failures = append(failures, lint.Failure{
+				Confidence: 1,
+				Node:       v,
+				Category:   "style",
+				Failure:    "use make(map[type]type) instead of map[type]type{}",
+			})
+		case *ast.CallExpr:
+			if r.enforceMapStyle != enforceMapStyleTypeLiteral {
+				// skip any function calls, even if it's make(map[type]type)
+				// we don't want to report it if literals are not enforced
+				return true
+			}
+
+			ident, ok := v.Fun.(*ast.Ident)
+			if !ok || ident.Name != "make" {
+				return true
+			}
+
+			if len(v.Args) != 1 {
+				// skip make(map[type]type, size) and invalid empty declarations
+				return true
+			}
+
+			if !r.isMapType(v.Args[0]) {
+				// not a map type
+				return true
+			}
+
+			failures = append(failures, lint.Failure{
+				Confidence: 1,
+				Node:       v.Args[0],
+				Category:   "style",
+				Failure:    "use map[type]type{} instead of make(map[type]type)",
+			})
+		}
+		return true
+	})
+
+	return failures
+}
+
+// Name returns the rule name.
+func (r *EnforceMapStyleRule) Name() string {
+	return "enforce-map-style"
+}
+
+func (r *EnforceMapStyleRule) isMapType(v ast.Expr) bool {
+	switch t := v.(type) {
+	case *ast.MapType:
+		return true
+	case *ast.Ident:
+		if t.Obj == nil {
+			return false
+		}
+		typeSpec, ok := t.Obj.Decl.(*ast.TypeSpec)
+		if !ok {
+			return false
+		}
+		return r.isMapType(typeSpec.Type)
+	default:
+		return false
+	}
+}

test/enforce-map-style_test.go

@@ -0,0 +1,24 @@
+package test
+
+import (
+	"testing"
+
+	"github.com/mgechev/revive/lint"
+	"github.com/mgechev/revive/rule"
+)
+
+func TestEnforceMapStyle_any(t *testing.T) {
+	testRule(t, "enforce-map-style-any", &rule.EnforceMapStyleRule{})
+}
+
+func TestEnforceMapStyle_make(t *testing.T) {
+	testRule(t, "enforce-map-style-make", &rule.EnforceMapStyleRule{}, &lint.RuleConfig{
+		Arguments: []interface{}{"make"},
+	})
+}
+
+func TestEnforceMapStyle_literal(t *testing.T) {
+	testRule(t, "enforce-map-style-literal", &rule.EnforceMapStyleRule{}, &lint.RuleConfig{
+		Arguments: []interface{}{"literal"},
+	})
+}

testdata/enforce-map-style-any.go

@@ -0,0 +1,13 @@
+package fixtures
+
+func somefn() {
+	m1 := make(map[string]string)
+	m2 := map[string]string{}
+	m3 := make(map[string]string, 10)
+	m4 := map[string]string{"k1": "v1"}
+
+	_ = m1
+	_ = m2
+	_ = m3
+	_ = m4
+}

testdata/enforce-map-style-literal.go

@@ -0,0 +1,51 @@
+package fixtures
+
+func somefn() {
+	m0 := make(map[string]string, 10)
+	m1 := make(map[string]string) // MATCH /use map[type]type{} instead of make(map[type]type)/
+	m2 := map[string]string{}
+	m3 := map[string]string{"k1": "v1", "k2": "v2"}
+
+	_ = m0
+	_ = m1
+	_ = m2
+	_ = m3
+}
+
+type Map map[string]string
+
+func somefn2() {
+	m0 := make(Map, 10)
+	m1 := make(Map) // MATCH /use map[type]type{} instead of make(map[type]type)/
+	m2 := Map{}
+	m3 := Map{"k1": "v1", "k2": "v2"}
+
+	_ = m0
+	_ = m1
+	_ = m2
+	_ = m3
+}
+
+type MapMap Map
+
+func somefn3() {
+	m0 := make(MapMap, 10)
+	m1 := make(MapMap) // MATCH /use map[type]type{} instead of make(map[type]type)/
+	m2 := MapMap{}
+	m3 := MapMap{"k1": "v1", "k2": "v2"}
+
+	_ = m0
+	_ = m1
+	_ = m2
+	_ = m3
+}
+
+func somefn4() {
+	m1 := map[string]map[string]string{}
+	m1["el0"] = make(map[string]string, 10)
+	m1["el1"] = make(map[string]string) // MATCH /use map[type]type{} instead of make(map[type]type)/
+	m1["el2"] = map[string]string{}
+	m1["el3"] = map[string]string{"k1": "v1", "k2": "v2"}
+
+	_ = m1
+}

testdata/enforce-map-style-make.go

@@ -0,0 +1,51 @@
+package fixtures
+
+func somefn() {
+	m0 := make(map[string]string, 10)
+	m1 := make(map[string]string)
+	m2 := map[string]string{} // MATCH /use make(map[type]type) instead of map[type]type{}/
+	m3 := map[string]string{"k1": "v1", "k2": "v2"}
+
+	_ = m0
+	_ = m1
+	_ = m2
+	_ = m3
+}
+
+type Map map[string]string
+
+func somefn2() {
+	m0 := make(Map, 10)
+	m1 := make(Map)
+	m2 := Map{} // MATCH /use make(map[type]type) instead of map[type]type{}/
+	m3 := Map{"k1": "v1", "k2": "v2"}
+
+	_ = m0
+	_ = m1
+	_ = m2
+	_ = m3
+}
+
+type MapMap Map
+
+func somefn3() {
+	m0 := make(MapMap, 10)
+	m1 := make(MapMap)
+	m2 := MapMap{} // MATCH /use make(map[type]type) instead of map[type]type{}/
+	m3 := MapMap{"k1": "v1", "k2": "v2"}
+
+	_ = m0
+	_ = m1
+	_ = m2
+	_ = m3
+}
+
+func somefn4() {
+	m1 := map[string]map[string]string{} // MATCH /use make(map[type]type) instead of map[type]type{}/
+	m1["el0"] = make(map[string]string, 10)
+	m1["el1"] = make(map[string]string)
+	m1["el2"] = map[string]string{} // MATCH /use make(map[type]type) instead of map[type]type{}/
+	m1["el3"] = map[string]string{"k1": "v1", "k2": "v2"}
+
+	_ = m1
+}