Check others major versions of packages in estimate

Instead of immediately checking that the repo root path is in the
list of packages in Debian, use the full import path (including the
potential major version suffix), then check for other major versions
if applicable, and finally, check for the repo root.

This allows to display that another major version is currently packaged
in Debian, and prevents hiding necessary major upgrades to already
packaged Go modules with a mismatched version.

Author: n-peugnet

estimate.go

@@ -7,11 +7,16 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
+	"strconv"
 	"strings"
 
 	"golang.org/x/tools/go/vcs"
 )
 
+// majorVersionRegexp checks if an import path contains a major version suffix.
+var majorVersionRegexp = regexp.MustCompile(`([/.])v([0-9]+)$`)
+
 func clone(srcdir, repo string) error {
 	done := make(chan struct{})
 	defer close(done)
@@ -64,6 +69,24 @@ func removeVendor(gopath string) (found bool, _ error) {
 	return found, err
 }
 
+// otherVersions guesses the import paths of potential other major version
+// of the given module import path, based on [majorVersionRegex].
+func otherVersions(mod string) (mods []string) {
+	matches := majorVersionRegexp.FindStringSubmatch(mod)
+	if matches == nil {
+		return
+	}
+	matchFull, matchSep, matchVer := matches[0], matches[1], matches[2]
+	matchIndex := len(mod) - len(matchFull)
+	prefix := mod[:matchIndex]
+	version, _ := strconv.Atoi(matchVer)
+	for v := version - 1; v > 1; v-- {
+		mods = append(mods, prefix+matchSep+"v"+strconv.Itoa(v))
+	}
+	mods = append(mods, prefix)
+	return
+}
+
 func estimate(importpath string) error {
 	removeTemp := func(path string) {
 		if err := forceRemoveAll(path); err != nil {
@@ -167,7 +190,6 @@ func estimate(importpath string) error {
 	// Analyse the dependency graph
 	var lines []string
 	seen := make(map[string]bool)
-	rrseen := make(map[string]bool)
 	var visit func(n *Node, indent int)
 	visit = func(n *Node, indent int) {
 		// Get the module name without its version, as go mod graph
@@ -183,19 +205,36 @@ func estimate(importpath string) error {
 		if mod == "go" || mod == "toolchain" {
 			return
 		}
-		rr, err := vcs.RepoRootForImportPath(mod, false)
-		if err != nil {
-			log.Printf("Could not determine repo path for import path %q: %v\n", mod, err)
-			return
+		if _, ok := golangBinaries[mod]; ok {
+			return // already packaged in Debian
 		}
-		if rrseen[rr.Root] {
-			return
+		var debianVersion string
+		// Check for potential other major versions already in Debian.
+		for _, otherVersion := range otherVersions(mod) {
+			if _, ok := golangBinaries[otherVersion]; ok {
+				debianVersion = otherVersion
+				break
+			}
 		}
-		rrseen[rr.Root] = true
-		if _, ok := golangBinaries[rr.Root]; ok {
-			return // already packaged in Debian
+		if debianVersion == "" {
+			// When multiple modules are developped in the same repo,
+			// the repo root is often used as the import path metadata
+			// in Debian, so we do a last try with that.
+			rr, err := vcs.RepoRootForImportPath(mod, false)
+			if err != nil {
+				log.Printf("Could not determine repo path for import path %q: %v\n", mod, err)
+			} else if _, ok := golangBinaries[rr.Root]; ok {
+				// Log info to indicate that it is an approximate match
+				// but consider that it is packaged and skip the children.
+				log.Printf("%s is packaged as %s in Debian", mod, rr.Root)
+				return
+			}
+		}
+		if debianVersion != "" {
+			lines = append(lines, fmt.Sprintf("%s%s\t(%s in Debian)", strings.Repeat("  ", indent), mod, debianVersion))
+		} else {
+			lines = append(lines, fmt.Sprintf("%s%s", strings.Repeat("  ", indent), mod))
 		}
-		lines = append(lines, fmt.Sprintf("%s%s", strings.Repeat("  ", indent), rr.Root))
 		for _, n := range n.children {
 			visit(n, indent+1)
 		}