feat: add untypedconst linter

Implements #3478.

Author: leonklingele

.golangci.next.reference.yml

@@ -2608,6 +2608,7 @@ linters:
     - typecheck
     - unconvert
     - unparam
+    - untypedconst
     - unused
     - usestdlibvars
     - varnamelen
@@ -2721,6 +2722,7 @@ linters:
     - typecheck
     - unconvert
     - unparam
+    - untypedconst
     - unused
     - usestdlibvars
     - varnamelen

go.mod

@@ -53,6 +53,7 @@ require (
 	github.com/hashicorp/go-version v1.6.0
 	github.com/hexops/gotextdiff v1.0.3
 	github.com/jgautheron/goconst v1.7.1
+	github.com/jiftechnify/untypedconst v0.1.0
 	github.com/jingyugao/rowserrcheck v1.1.1
 	github.com/jirfag/go-printf-func-name v0.0.0-20200119135958-7558a9eaa5af
 	github.com/jjti/go-spancheck v0.5.3

go.sum

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

pkg/golinters/untypedconst.go

@@ -645,6 +645,11 @@ func (b LinterBuilder) Build(cfg *config.Config) ([]*linter.Config, error) {
 			WithLoadForGoAnalysis().
 			WithURL("https://github.com/mvdan/unparam"),
 
+		linter.NewConfig(golinters.NewUntypedConst()).
+			WithSince("v1.58.0").
+			WithPresets(linter.PresetBugs).
+			WithURL("https://github.com/jiftechnify/untypedconst"),
+
 		linter.NewConfig(golinters.NewUnused(&cfg.LintersSettings.Unused, &cfg.LintersSettings.Staticcheck)).
 			WithEnabledByDefault().
 			WithSince("v1.20.0").

pkg/lint/lintersdb/builder_linter.go

@@ -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"`
+	}
+}