go: Prefer the longest keywords (#404)

Some langauges have two different step keywords starting with the same
characters. In cases like these, we need to ensure that if a user types
out the longer of these keywords, that is what gets matched.

This is done by sorting the keywords for each dialect.

As well as this, I've added handling to make sure that the sorting is
only done once per dialect to make it inline with other fixes. This
required a couple of fields to be added to the `Dialect` struct, so I've
updated the `builtin_dialects.go.jq` file to built the `Dialect` struct
in a way that allows zero base instantiation.

Author: tigh-latte

CHANGELOG.md

@@ -13,6 +13,7 @@ This document is formatted according to the principles of [Keep A CHANGELOG](htt
 - [Java] Prefer the longest step keyword ([#401](https://github.com/cucumber/gherkin/pull/401))
 - [.NET] Prefer the longest step keyword ([#405](https://github.com/cucumber/gherkin/pull/405))
 - [PHP] Prefer the longest step keyword ([#403](https://github.com/cucumber/gherkin/pull/403))
+- [Go] Prefer the longest step keyword ([#403](https://github.com/cucumber/gherkin/pull/404))
 
 ## [32.1.1] - 2025-04-11
 ### Fixed

go/dialect.go

@@ -1,13 +1,34 @@
 package gherkin
 
-import messages "github.com/cucumber/messages/go/v24"
+import (
+	"sort"
+
+	messages "github.com/cucumber/messages/go/v24"
+)
+
+func init() {
+	// only needs to be calcuated one, on startup
+	for _, d := range builtinDialects {
+		d.stepKeywords = []string{}
+		d.stepKeywords = append(d.stepKeywords, d.Keywords[given]...)
+		d.stepKeywords = append(d.stepKeywords, d.Keywords[when]...)
+		d.stepKeywords = append(d.stepKeywords, d.Keywords[then]...)
+		d.stepKeywords = append(d.stepKeywords, d.Keywords[and]...)
+		d.stepKeywords = append(d.stepKeywords, d.Keywords[but]...)
+		sort.Slice(d.stepKeywords, func(i, j int) bool {
+			return d.stepKeywords[i] > d.stepKeywords[j]
+		})
+	}
+}
 
 type Dialect struct {
 	Language     string
 	Name         string
 	Native       string
 	Keywords     map[string][]string
 	KeywordTypes map[string]messages.StepKeywordType
+
+	stepKeywords []string
 }
 
 func (g *Dialect) FeatureKeywords() []string {
@@ -23,12 +44,7 @@ func (g *Dialect) ScenarioKeywords() []string {
 }
 
 func (g *Dialect) StepKeywords() []string {
-	result := g.Keywords["given"]
-	result = append(result, g.Keywords["when"]...)
-	result = append(result, g.Keywords["then"]...)
-	result = append(result, g.Keywords["and"]...)
-	result = append(result, g.Keywords["but"]...)
-	return result
+	return g.stepKeywords
 }
 
 func (g *Dialect) BackgroundKeywords() []string {