dh-make-golang make: directly use the user preferred tag specified in "-git_revision" option

When a user specifies a valid tag when using

    dh-make-golang make -git_revision {some valid tag}

if there is another tag pointing to the same commit as the specified
tag, then dh-make-golang might use the other tag to determine the
package version.

This patch modifies the behavior of "dh-make-golang make" such that, if
the user specifies a valid tag in "-git_revision" option,
"dh-make-golang make" will always use the specified tag to determine the
upstream package version.

This patch also trivially changes the tests written in version_test.go
so that the tests adjusts to the new function signature of
version.go:pkgVersionFromGit().

Signed-off-by: William Lyu <William.Lyu@windriver.com>

Author: wlyu2

make.go

@@ -386,7 +386,7 @@ func makeUpstreamSourceTarball(repo, revision string, forcePrerelease bool) (*up
 
 	log.Printf("Determining upstream version number\n")
 
-	u.version, err = pkgVersionFromGit(repoDir, &u, forcePrerelease)
+	u.version, err = pkgVersionFromGit(repoDir, &u, revision, forcePrerelease)
 	if err != nil {
 		return nil, fmt.Errorf("get package version from Git: %w", err)
 	}

version.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"os/exec"
 	"regexp"
+	"slices"
 	"strconv"
 	"strings"
 	"time"
@@ -32,16 +33,33 @@ var (
 // Besides returning the Debian upstream version, the "upstream" struct
 // struct fields u.version, u.commitIsh, u.hasRelease and u.isRelease
 // are also set.
+// `preferredRev` should be empty if there are no user preferences.
 // TODO: also support other VCS
-func pkgVersionFromGit(gitdir string, u *upstream, forcePrerelease bool) (string, error) {
+func pkgVersionFromGit(gitdir string, u *upstream, preferredRev string, forcePrerelease bool) (string, error) {
 	var latestTag string
 	var commitsAhead int
 
-	// Find @latest version tag (whether annotated or not)
-	cmd := exec.Command("git", "describe", "--abbrev=0", "--tags", "--exclude", "*/v*")
-	cmd.Dir = gitdir
-	if out, err := cmd.Output(); err == nil {
-		latestTag = strings.TrimSpace(string(out))
+	var cmd *exec.Cmd // the temporary shell commands we execute
+
+	// If the user specifies a valid tag as the preferred revision, that tag should be used without additional heuristics.
+	if u.rr != nil {
+		if out, err := u.rr.VCS.Tags(gitdir); err == nil && slices.Contains(out, preferredRev) {
+			latestTag = preferredRev
+		}
+	}
+
+	// Find @latest version tag (whether annotated or not) when the user
+	// (1) does not specify a version tag, or
+	// (2) specifies an invalid version tag.
+	if len(latestTag) == 0 {
+		cmd = exec.Command("git", "describe", "--abbrev=0", "--tags", "--exclude", "*/v*")
+		cmd.Dir = gitdir
+		if out, err := cmd.Output(); err == nil {
+			latestTag = strings.TrimSpace(string(out))
+		}
+	}
+
+	if len(latestTag) > 0 {
 		u.hasRelease = true
 		u.tag = latestTag
 		log.Printf("Found latest tag %q", latestTag)

version_test.go

@@ -45,7 +45,7 @@ func TestSnapshotVersion(t *testing.T) {
 	}
 
 	var u upstream
-	got, err := pkgVersionFromGit(tempdir, &u, false)
+	got, err := pkgVersionFromGit(tempdir, &u, "", false)
 	if err != nil {
 		t.Fatalf("Determining package version from git failed: %v", err)
 	}
@@ -55,7 +55,7 @@ func TestSnapshotVersion(t *testing.T) {
 
 	gitCmdOrFatal(t, tempdir, "tag", "-a", "v1", "-m", "release v1")
 
-	got, err = pkgVersionFromGit(tempdir, &u, false)
+	got, err = pkgVersionFromGit(tempdir, &u, "", false)
 	if err != nil {
 		t.Fatalf("Determining package version from git failed: %v", err)
 	}
@@ -75,7 +75,7 @@ func TestSnapshotVersion(t *testing.T) {
 		t.Fatalf("Could not run %v: %v", cmd.Args, err)
 	}
 
-	got, err = pkgVersionFromGit(tempdir, &u, false)
+	got, err = pkgVersionFromGit(tempdir, &u, "", false)
 	if err != nil {
 		t.Fatalf("Determining package version from git failed: %v", err)
 	}
@@ -95,7 +95,7 @@ func TestSnapshotVersion(t *testing.T) {
 		t.Fatalf("Could not run %v: %v", cmd.Args, err)
 	}
 
-	got, err = pkgVersionFromGit(tempdir, &u, false)
+	got, err = pkgVersionFromGit(tempdir, &u, "", false)
 	if err != nil {
 		t.Fatalf("Determining package version from git failed: %v", err)
 	}