authors: Enable auto updates (#5074)

Removes the manual handling of the AUTHORS file, giving every committer automatic credit for their contribution.

Manual tweaks to the file are still accepted and retained by the scripts.

script/authors.go

@@ -32,12 +32,18 @@ var (
 )
 
 const authorsHeader = `# This is the official list of Syncthing authors for copyright purposes.
-# The format is:
+#
+# THIS FILE IS MOSTLY AUTO GENERATED. IF YOU'VE MADE A COMMIT TO THE
+# REPOSITORY YOU WILL BE ADDED HERE AUTOMATICALLY WITHOUT THE NEED FOR
+# ANY MANUAL ACTION.
+#
+# That said, you are welcome to correct your name or add a nickname / GitHub
+# user name as appropriate. The format is:
 #
 #    Name Name Name (nickname) <email1@example.com> <email2@example.com>
 #
-# After changing this list, run "go run script/authors.go" to sort and update
-# the GUI HTML.
+# The in-GUI authors list is periodically automatically updated from the
+# contents of this file.
 #
 `
 
@@ -50,8 +56,42 @@ type author struct {
 }
 
 func main() {
+	// Read authors from the AUTHORS file
 	authors := getAuthors()
 
+	// Grab the set of thus known email addresses
+	listed := make(stringSet)
+	names := make(map[string]int)
+	for i, a := range authors {
+		names[a.name] = i
+		for _, e := range a.emails {
+			listed.add(e)
+		}
+	}
+
+	// Grab the set of all known authors based on the git log, and add any
+	// missing ones to the authors list.
+	all := allAuthors()
+	for email, name := range all {
+		if listed.has(email) {
+			continue
+		}
+
+		if _, ok := names[name]; ok && name != "" {
+			// We found a match on name
+			authors[names[name]].emails = append(authors[names[name]].emails, email)
+			listed.add(email)
+			continue
+		}
+
+		authors = append(authors, author{
+			name:   name,
+			emails: []string{email},
+		})
+		names[name] = len(authors) - 1
+		listed.add(email)
+	}
+
 	// Write author names in GUI about modal
 
 	getContributions(authors)
@@ -167,6 +207,46 @@ next:
 	}
 }
 
+// list of commits that we don't include in our author file; because they
+// are legacy things that don't affect code, are committed with incorrect
+// address, or for other reasons.
+var excludeCommits = stringSetFromStrings([]string{
+	"a9339d0627fff439879d157c75077f02c9fac61b",
+	"254c63763a3ad42fd82259f1767db526cff94a14",
+	"32a76901a91ff0f663db6f0830e0aedec946e4d0",
+	"bc7639b0ffcea52b2197efb1c0bb68b338d1c915",
+})
+
+// allAuthors returns the set of authors in the git commit log, except those
+// in excluded commits.
+func allAuthors() map[string]string {
+	args := append([]string{"log", "--format=%H %ae %an"})
+	cmd := exec.Command("git", args...)
+	bs, err := cmd.Output()
+	if err != nil {
+		log.Fatal("git:", err)
+	}
+
+	names := make(map[string]string)
+	for _, line := range bytes.Split(bs, []byte{'\n'}) {
+		fields := strings.SplitN(string(line), " ", 3)
+		if len(fields) != 3 {
+			continue
+		}
+		hash, email, name := fields[0], fields[1], fields[2]
+
+		if excludeCommits.has(hash) {
+			continue
+		}
+
+		if names[email] == "" {
+			names[email] = name
+		}
+	}
+
+	return names
+}
+
 type byContributions []author
 
 func (l byContributions) Len() int { return len(l) }
@@ -194,3 +274,34 @@ func (l byName) Less(a, b int) bool {
 }
 
 func (l byName) Swap(a, b int) { l[a], l[b] = l[b], l[a] }
+
+// A simple string set type
+
+type stringSet map[string]struct{}
+
+func stringSetFromStrings(ss []string) stringSet {
+	s := make(stringSet)
+	for _, e := range ss {
+		s.add(e)
+	}
+	return s
+}
+
+func (s stringSet) add(e string) {
+	s[e] = struct{}{}
+}
+
+func (s stringSet) has(e string) bool {
+	_, ok := s[e]
+	return ok
+}
+
+func (s stringSet) except(other stringSet) stringSet {
+	diff := make(stringSet)
+	for e := range s {
+		if !other.has(e) {
+			diff.add(e)
+		}
+	}
+	return diff
+}