chore: fix linter

.golangci.yml

@@ -0,0 +1,95 @@
+run:
+  tests: true
+  skip-dirs:
+    - _examples
+
+output:
+  print-issued-lines: false
+
+linters:
+  enable-all: true
+  disable:
+    - maligned
+    - megacheck
+    - lll
+    - gocyclo
+    - dupl
+    - gochecknoglobals
+    - funlen
+    - godox
+    - wsl
+    - gomnd
+    - gocognit
+    - goerr113
+    - nolintlint
+    - testpackage
+    - godot
+    - nestif
+    - paralleltest
+    - nlreturn
+    - cyclop
+    - exhaustivestruct
+    - gci
+    - gofumpt
+    - errorlint
+    - exhaustive
+    - ifshort
+    - wrapcheck
+    - stylecheck
+    - thelper
+    - nonamedreturns
+    - revive
+    - dupword
+    - exhaustruct
+    - varnamelen
+    - forcetypeassert
+    - ireturn
+    - maintidx
+    - govet
+    - nosnakecase
+    - testableexamples
+    - musttag
+    - depguard
+    - goconst
+    - perfsprint
+    - mnd
+    - predeclared
+    - nilnil
+
+linters-settings:
+  govet:
+    check-shadowing: true
+  gocyclo:
+    min-complexity: 10
+  dupl:
+    threshold: 100
+  goconst:
+    min-len: 8
+    min-occurrences: 3
+  forbidigo:
+    #forbid:
+    #  - (Must)?NewLexer$
+    exclude_godoc_examples: false
+
+issues:
+  max-per-linter: 0
+  max-same: 0
+  exclude-use-default: false
+  exclude:
+    # Captured by errcheck.
+    - "^(G104|G204):"
+    # Very commonly not checked.
+    - 'Error return value of .(.*\.Help|.*\.MarkFlagRequired|(os\.)?std(out|err)\..*|.*Close|.*Flush|os\.Remove(All)?|.*printf?|os\.(Un)?Setenv). is not checked'
+    - 'exported method (.*\.MarshalJSON|.*\.UnmarshalJSON|.*\.EntityURN|.*\.GoString|.*\.Pos) should have comment or be unexported'
+    - "composite literal uses unkeyed fields"
+    - 'declaration of "err" shadows declaration'
+    - "should not use dot imports"
+    - "Potential file inclusion via variable"
+    - "should have comment or be unexported"
+    - "comment on exported var .* should be of the form"
+    - "at least one file in a package should have a package comment"
+    - "string literal contains the Unicode"
+    - "methods on the same type should have the same receiver name"
+    - "_TokenType_name should be _TokenTypeName"
+    - "`_TokenType_map` should be `_TokenTypeMap`"
+    - "rewrite if-else to switch statement"

bin/golangci-lint

@@ -1 +1 @@
-.golangci-lint-1.51.2.pkg
+.golangci-lint-1.61.0.pkg

check.go

@@ -29,7 +29,7 @@ func (e inexhaustiveError) Error() string {
 // Names returns a sorted list of names corresponding to the missing variant
 // cases.
 func (e inexhaustiveError) Names() []string {
-	var list []string
+	list := make([]string, 0, len(e.Missing))
 	for _, o := range e.Missing {
 		list = append(list, o.Name())
 	}
@@ -103,7 +103,7 @@ func missingVariantsInSwitch(
 		// A catch-all case defeats all exhaustiveness checks.
 		return def, nil
 	}
-	var variantTypes []types.Type
+	variantTypes := make([]types.Type, 0, len(variantExprs))
 	for _, expr := range variantExprs {
 		variantTypes = append(variantTypes, pkg.TypesInfo.TypeOf(expr))
 	}

def.go

@@ -71,7 +71,7 @@ type sumTypeDef struct {
 // sum type declarations. If no such sum type definition could be found for
 // any of the given declarations, then an error is returned.
 func findSumTypeDefs(decls []sumTypeDecl) ([]sumTypeDef, []error) {
-	var defs []sumTypeDef
+	defs := make([]sumTypeDef, 0, len(decls))
 	var errs []error
 	for _, decl := range decls {
 		def, err := newSumTypeDef(decl.Package.Types, decl)
@@ -104,7 +104,7 @@ func newSumTypeDef(pkg *types.Package, decl sumTypeDecl) (*sumTypeDef, error) {
 		return nil, notInterfaceError{decl}
 	}
 	hasUnexported := false
-	for i := 0; i < iface.NumMethods(); i++ {
+	for i := range iface.NumMethods() {
 		if !iface.Method(i).Exported() {
 			hasUnexported = true
 			break

go.mod

@@ -1,6 +1,6 @@
 module github.com/alecthomas/go-check-sumtype
 
-go 1.22.0
+go 1.23.0
 
 toolchain go1.23.3
 

help_test.go

@@ -15,7 +15,7 @@ func setupPackages(t *testing.T, code string) (string, []*packages.Package) {
 		t.Fatal(err)
 	}
 	srcPath := filepath.Join(tmpdir, "src.go")
-	if err := ioutil.WriteFile(srcPath, []byte(code), 0666); err != nil {
+	if err := ioutil.WriteFile(srcPath, []byte(code), 0600); err != nil {
 		t.Fatal(err)
 	}
 	pkgs, err := tycheckAll([]string{srcPath})