chore: address remaining golangci-lint findings and enforce them

Expand the enabled linter set in .golangci.yml (err113, goconst,
gocritic, intrange, modernize, perfsprint, thelper, unconvert, unparam,
wastedassign, whitespace) and address every new finding:

- wastedassign: collapse ExecInit's 8 dead var = "" initializations and
  one in parser.go where regexpValue was assigned and immediately
  reassigned.
- gocritic (assignOp / ifElseChain / typeSwitchVar): use x += y, rewrite
  if-else chains to switch, switch on typed values.
- intrange: for range b.N in benchmarks, for i := range len(portValue)
  in the port prefix check; keep escape.go as-is (i needed after loop)
  with a //nolint rationale.
- modernize: replace interface{} with any in tests, use slices.Contains.
- perfsprint: fmt.Sprintf("%d", i) -> strconv.Itoa(i) in test names.
- unconvert: drop redundant int() around p.componentStart.
- unparam: consumeRequiredToken no longer returns its *token since
  every caller discarded it.
- whitespace: trim a stray trailing newline in buildExpected and a
  leading one in newExpectedResult.
- err113: hoist "invalid hostname" to errInvalidHostname at package
  level, add two test-only sentinels for the WPT harness.
- goconst: extract "pattern"/"url" into initTypePattern / initTypeURL.
- thelper: t.Helper() in the three WPT test helpers.
- Drop the dead commented //p.result.Hash/Search lines in the
  constructor parser and refactor the surrounding if/else into a switch.

All 365 WPT cases + the regression tests still pass; golangci-lint
reports 0 issues with the widened configuration.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: dunglas

.golangci.yml

@@ -1,6 +1,18 @@
 version: "2"
 
 linters:
+  enable:
+    - err113
+    - goconst
+    - gocritic
+    - intrange
+    - modernize
+    - perfsprint
+    - thelper
+    - unconvert
+    - unparam
+    - wastedassign
+    - whitespace
   settings:
     staticcheck:
       checks:

benchmark_test.go

@@ -40,7 +40,7 @@ func BenchmarkNew(b *testing.B) {
 			b.ReportAllocs()
 			var p *urlpattern.URLPattern
 			var err error
-			for i := 0; i < b.N; i++ {
+			for range b.N {
 				p, err = urlpattern.New(bc.pattern, bc.baseURL, nil)
 				if err != nil {
 					b.Fatal(err)
@@ -60,7 +60,7 @@ func BenchmarkTest(b *testing.B) {
 		b.Run(bc.name, func(b *testing.B) {
 			b.ReportAllocs()
 			var ok bool
-			for i := 0; i < b.N; i++ {
+			for range b.N {
 				ok = p.Test(bc.input, "")
 			}
 			benchBoolSink = ok
@@ -77,7 +77,7 @@ func BenchmarkExec(b *testing.B) {
 		b.Run(bc.name, func(b *testing.B) {
 			b.ReportAllocs()
 			var r *urlpattern.URLPatternResult
-			for i := 0; i < b.N; i++ {
+			for range b.N {
 				r = p.Exec(bc.input, "")
 			}
 			benchResultSink = r

constructor_type_parser.go

@@ -68,15 +68,13 @@ func parseConstructorString(input string) (*URLPatternInit, error) {
 			if p.state == stateInit {
 				p.rewind()
 
-				if p.isHashPrefix() {
+				switch {
+				case p.isHashPrefix():
 					p.changeState(stateHash, 1)
-				} else if p.isSearchPrefix() {
+				case p.isSearchPrefix():
 					p.changeState(stateSearch, 1)
-					//p.result.Hash = ""
-				} else {
+				default:
 					p.changeState(statePathname, 0)
-					//p.result.Hash = ""
-					//p.result.Search = ""
 				}
 
 				p.tokenIndex += p.tokenIncrement
@@ -160,26 +158,28 @@ func parseConstructorString(input string) (*URLPatternInit, error) {
 			}
 
 		case stateHostname:
-			if p.isIPV6Open() {
+			switch {
+			case p.isIPV6Open():
 				p.hostnameIPv6BracketDepth++
-			} else if p.isIPV6Close() {
+			case p.isIPV6Close():
 				p.hostnameIPv6BracketDepth--
-			} else if p.isPortPrefix() && p.hostnameIPv6BracketDepth == 0 {
+			case p.isPortPrefix() && p.hostnameIPv6BracketDepth == 0:
 				p.changeState(statePort, 1)
-			} else if p.isPathnameStart() {
+			case p.isPathnameStart():
 				p.changeState(statePathname, 0)
-			} else if p.isSearchPrefix() {
+			case p.isSearchPrefix():
 				p.changeState(stateSearch, 1)
-			} else if p.isHashPrefix() {
+			case p.isHashPrefix():
 				p.changeState(stateHash, 1)
 			}
 
 		case statePort:
-			if p.isPathnameStart() {
+			switch {
+			case p.isPathnameStart():
 				p.changeState(statePathname, 0)
-			} else if p.isSearchPrefix() {
+			case p.isSearchPrefix():
 				p.changeState(stateSearch, 1)
-			} else if p.isHashPrefix() {
+			case p.isHashPrefix():
 				p.changeState(stateHash, 1)
 			}
 
@@ -351,15 +351,15 @@ func (p *constructorTypeParser) changeState(newState state, skip int) {
 	}
 
 	p.state = newState
-	p.tokenIndex = p.tokenIndex + skip
+	p.tokenIndex += skip
 	p.componentStart = p.tokenIndex
 	p.tokenIncrement = 0
 }
 
 // https://urlpattern.spec.whatwg.org/#make-a-component-string
 func (p *constructorTypeParser) makeComponentString() string {
 	token := p.tokenList[p.tokenIndex]
-	componentStartToken := p.getSafeToken(int(p.componentStart))
+	componentStartToken := p.getSafeToken(p.componentStart)
 	componentStartInputIndex := componentStartToken.index
 	endIndex := token.index
 

escape.go

@@ -35,7 +35,7 @@ func init() {
 func escapeRegexpString(s string) string {
 	// A byte loop is correct because all metacharacters are ASCII.
 	var i int
-	for i = 0; i < len(s); i++ {
+	for i = 0; i < len(s); i++ { //nolint:intrange // i is reused below
 		if specialRegexp(s[i]) {
 			break
 		}
@@ -63,7 +63,7 @@ func escapeRegexpString(s string) string {
 func escapePatternString(s string) string {
 	// A byte loop is correct because all metacharacters are ASCII.
 	var i int
-	for i = 0; i < len(s); i++ {
+	for i = 0; i < len(s); i++ { //nolint:intrange // i is reused below
 		if specialPattern(s[i]) {
 			break
 		}

parser.go

@@ -47,6 +47,8 @@ var (
 	ErrInvalidPort         = errors.New("invalid port")
 )
 
+var errInvalidHostname = errors.New("invalid hostname")
+
 // https://urlpattern.spec.whatwg.org/#encoding-callback
 type encodingCallback func(string) (string, error)
 
@@ -88,7 +90,7 @@ func parsePatternString(input string, options options, encodingCallback encoding
 			}
 
 			if prefix != "" && prefix != string(options.prefixCodePoint) {
-				p.pendingFixedValue = p.pendingFixedValue + prefix
+				p.pendingFixedValue += prefix
 				prefix = ""
 			}
 
@@ -115,7 +117,7 @@ func parsePatternString(input string, options options, encodingCallback encoding
 			}
 		}
 		if fixedToken != nil {
-			p.pendingFixedValue = p.pendingFixedValue + fixedToken.value
+			p.pendingFixedValue += fixedToken.value
 
 			continue
 		}
@@ -146,7 +148,7 @@ func parsePatternString(input string, options options, encodingCallback encoding
 				return nil, err
 			}
 
-			if _, err := p.consumeRequiredToken(tokenClose); err != nil {
+			if err := p.consumeRequiredToken(tokenClose); err != nil {
 				return nil, fmt.Errorf("missing close token: %w", err)
 			}
 
@@ -166,7 +168,7 @@ func parsePatternString(input string, options options, encodingCallback encoding
 			return nil, err
 		}
 
-		if _, err := p.consumeRequiredToken(tokenEnd); err != nil {
+		if err := p.consumeRequiredToken(tokenEnd); err != nil {
 			return nil, fmt.Errorf("missing end token: %w", err)
 		}
 	}
@@ -265,7 +267,7 @@ func (p *patternParser) addPart(prefix string, nameToken *token, regexpOrWildcar
 	}
 
 	if nameToken == nil && regexpOrWildcardToken == nil && modifier == partModifierNone {
-		p.pendingFixedValue = p.pendingFixedValue + prefix
+		p.pendingFixedValue += prefix
 
 		return nil
 	}
@@ -295,12 +297,13 @@ func (p *patternParser) addPart(prefix string, nameToken *token, regexpOrWildcar
 		return nil
 	}
 
-	regexpValue := ""
-	if regexpOrWildcardToken == nil {
+	var regexpValue string
+	switch {
+	case regexpOrWildcardToken == nil:
 		regexpValue = p.segmentWildcardRegexp
-	} else if regexpOrWildcardToken.tType == tokenAsterisk {
+	case regexpOrWildcardToken.tType == tokenAsterisk:
 		regexpValue = fullWildcardRegexpValue
-	} else {
+	default:
 		regexpValue = regexpOrWildcardToken.value
 	}
 
@@ -312,7 +315,6 @@ func (p *patternParser) addPart(prefix string, nameToken *token, regexpOrWildcar
 	case fullWildcardRegexpValue:
 		pType = partFullWildcard
 		regexpValue = ""
-
 	}
 
 	name := ""
@@ -373,16 +375,16 @@ func (p *patternParser) consumeText() (string, error) {
 }
 
 // https://urlpattern.spec.whatwg.org/#consume-a-required-token
-func (p *patternParser) consumeRequiredToken(tokenType tokenType) (*token, error) {
+func (p *patternParser) consumeRequiredToken(tokenType tokenType) error {
 	result, err := p.tryConsumeToken(tokenType)
 	if err != nil {
-		return nil, err
+		return err
 	}
 	if result == nil {
-		return nil, ErrRequiredToken
+		return ErrRequiredToken
 	}
 
-	return result, nil
+	return nil
 }
 
 // https://urlpattern.spec.whatwg.org/#generate-a-segment-wildcard-regexp
@@ -435,7 +437,7 @@ func canonicalizeHostname(hostnameValue, protocolValue string) (string, error) {
 	if hostnameValue[0] != '[' {
 		for _, c := range hostnameValue {
 			if c == ':' {
-				return "", errors.New("invalid hostname")
+				return "", errInvalidHostname
 			}
 		}
 	}
@@ -478,12 +480,13 @@ func canonicalizePort(portValue, protocolValue string) (string, error) {
 	// an ASCII digit (e.g. "invalid80"). Without this the URL library returns
 	// an empty port instead of failing.
 	firstDigit := false
-	for i := 0; i < len(portValue); i++ {
+	for i := range len(portValue) {
 		c := portValue[i]
 		if c == '\t' || c == '\n' || c == '\r' {
 			continue
 		}
 		firstDigit = c >= '0' && c <= '9'
+
 		break
 	}
 	if !firstDigit {