From b254ccf03d2714192af2ced5c73530415bc5d71e Mon Sep 17 00:00:00 2001
From: Gus Eggert <gus@gus.dev>
Date: Wed, 31 Aug 2022 12:56:23 -0400
Subject: [PATCH] fix: iterate over BlueMap in deterministic order

This is so that outputs are deterministic, which is important for
e.g. to check in CI that the 'go generate' output has not changed.
---
 codegen/blueprint.go | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/codegen/blueprint.go b/codegen/blueprint.go
index 479f93a..e1250d0 100644
--- a/codegen/blueprint.go
+++ b/codegen/blueprint.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"sort"
 	"text/template"
 
 	"github.com/ipld/edelweiss/util/indent"
@@ -48,9 +49,19 @@ type T struct {
 
 type BlueMap map[string]Blueprint
 
+// SortedKeys returns a deterministically-ordered set of keys
+func (x BlueMap) SortedKeys() []string {
+	var keys []string
+	for k := range x {
+		keys = append(keys, k)
+	}
+	sort.Stable(sort.StringSlice(keys))
+	return keys
+}
+
 func (x BlueMap) Write(ctx GoFileContext, w io.Writer) error {
-	for _, b := range x {
-		if err := b.Write(ctx, w); err != nil {
+	for _, k := range x.SortedKeys() {
+		if err := x[k].Write(ctx, w); err != nil {
 			return nil
 		}
 	}
@@ -107,7 +118,8 @@ func flattenBlueprint(ctx GoFileContext, b Blueprint) (Blueprint, error) {
 
 func flattenBlueMap(ctx GoFileContext, bm BlueMap) (BlueMap, error) {
 	r := BlueMap{}
-	for k, v := range bm {
+	for _, k := range bm.SortedKeys() {
+		v := bm[k]
 		f, err := flattenBlueprint(ctx, v)
 		if err != nil {
 			return nil, err