feat: add untypedconst linter

Implements #3478.

Author: leonklingele

.golangci.next.reference.yml

@@ -111,6 +111,7 @@ linters:
     - tparallel
     - unconvert
     - unparam
+    - untypedconst
     - unused
     - usestdlibvars
     - usetesting
@@ -227,6 +228,7 @@ linters:
     - tparallel
     - unconvert
     - unparam
+    - untypedconst
     - unused
     - usestdlibvars
     - usetesting

go.mod

@@ -55,6 +55,7 @@ require (
 	github.com/gostaticanalysis/nilerr v0.1.1
 	github.com/hashicorp/go-version v1.7.0
 	github.com/jgautheron/goconst v1.7.1
+	github.com/jiftechnify/untypedconst v0.1.0
 	github.com/jingyugao/rowserrcheck v1.1.1
 	github.com/jjti/go-spancheck v0.6.4
 	github.com/julz/importas v0.2.0

go.sum

@@ -0,0 +1,67 @@
+//golangcitest:args -Euntypedconst
+package testdata
+
+import (
+	"fmt"
+)
+
+type ExString string
+
+func retExString() ExString {
+	if true {
+		return ExString("hoge")
+	} else {
+		fmt.Println("This should never happen")
+		return "hoge" // want `returning untyped constant as defined type "command-line-arguments.ExString"`
+	}
+}
+
+type ExInt int
+
+func retExInt() ExInt {
+	if true {
+		return ExInt(1)
+	} else {
+		return 1 // want `returning untyped constant as defined type "command-line-arguments.ExInt"`
+	}
+}
+
+type ExFloat float64
+
+func retExFloat() ExFloat {
+	if true {
+		return ExFloat(0.5)
+	} else {
+		return 0.5 // want `returning untyped constant as defined type "command-line-arguments.ExFloat"`
+	}
+}
+
+type ExComplex complex128
+
+func retExComplex() ExComplex {
+	if true {
+		return ExComplex(1.0 + 0.5i)
+	} else {
+		return 1.0 + 0.5i // want `returning untyped constant as defined type "command-line-arguments.ExComplex"`
+	}
+}
+
+type ExRune rune
+
+func retExRune() ExRune {
+	if true {
+		return ExRune('a')
+	} else {
+		return 'a' // want `returning untyped constant as defined type "command-line-arguments.ExRune"`
+	}
+}
+
+type ExBool bool
+
+func retExBool() ExBool {
+	if true {
+		return ExBool(true)
+	} else {
+		return true // want `returning untyped constant as defined type "command-line-arguments.ExBool"`
+	}
+}

pkg/golinters/untypedconst/testdata/untypedconst.go

@@ -0,0 +1,19 @@
+package untypedconst
+
+import (
+	"github.com/jiftechnify/untypedconst"
+	"golang.org/x/tools/go/analysis"
+
+	"github.com/golangci/golangci-lint/pkg/goanalysis"
+)
+
+func New() *goanalysis.Linter {
+	a := untypedconst.Analyzer
+
+	return goanalysis.NewLinter(
+		a.Name,
+		a.Doc,
+		[]*analysis.Analyzer{a},
+		nil,
+	).WithLoadMode(goanalysis.LoadModeTypesInfo)
+}

pkg/golinters/untypedconst/untypedconst.go

@@ -104,6 +104,7 @@ import (
 	"github.com/golangci/golangci-lint/pkg/golinters/tparallel"
 	"github.com/golangci/golangci-lint/pkg/golinters/unconvert"
 	"github.com/golangci/golangci-lint/pkg/golinters/unparam"
+	"github.com/golangci/golangci-lint/pkg/golinters/untypedconst"
 	"github.com/golangci/golangci-lint/pkg/golinters/unused"
 	"github.com/golangci/golangci-lint/pkg/golinters/usestdlibvars"
 	"github.com/golangci/golangci-lint/pkg/golinters/usetesting"
@@ -817,6 +818,12 @@ func (LinterBuilder) Build(cfg *config.Config) ([]*linter.Config, error) {
 			WithLoadForGoAnalysis().
 			WithURL("https://github.com/mvdan/unparam"),
 
+		linter.NewConfig(untypedconst.New()).
+			WithSince("v1.65.0").
+			WithPresets(linter.PresetBugs).
+			WithLoadForGoAnalysis().
+			WithURL("https://github.com/jiftechnify/untypedconst"),
+
 		linter.NewConfig(unused.New(&cfg.LintersSettings.Unused)).
 			WithEnabledByDefault().
 			WithSince("v1.20.0").