version.c: last commit title

* version.c (ruby_show_version): show last commit title, if
  different than the trunk.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49638 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

tool/file2lastrev.rb

@@ -47,7 +47,7 @@ rescue VCS::NotFoundError => e
   abort "#{File.basename(Program)}: #{e.message}" unless @suppress_not_found
 else
   begin
-    last, changed, modified, branch = vcs.get_revisions(ARGV.shift)
+    last, changed, modified, branch, title = vcs.get_revisions(ARGV.shift)
   rescue => e
     abort "#{File.basename(Program)}: #{e.message}" unless @suppress_not_found
     exit false
@@ -65,6 +65,9 @@ when :revision_h
     name = branch.sub(/\A(.{#{limit-e.size}}).{#{e.size+1},}/o) {$1+e}
     puts "#define RUBY_BRANCH_NAME #{name.dump}"
   end
+  if title
+    puts "#define RUBY_LAST_COMMIT_TITLE #{title.dump}"
+  end
 when :doxygen
   puts "r#{changed}/r#{last}"
 when :modified

tool/vcs.rb

@@ -260,6 +260,7 @@ class VCS
       logcmd << "--grep=^ *git-svn-id: .*@[0-9][0-9]*"
       idpat = /git-svn-id: .*?@(\d+) \S+\Z/
       log = IO.pread(logcmd)
+      commit = log[/\Acommit (\w+)/, 1]
       last = log[idpat, 1]
       if path
         cmd = logcmd
@@ -271,7 +272,9 @@ class VCS
       end
       modified = log[/^Date:\s+(.*)/, 1]
       branch = IO.pread(gitcmd + %W[symbolic-ref HEAD])[%r'\A(?:refs/heads/)?(.+)', 1]
-      [last, changed, modified, branch]
+      title = IO.pread(gitcmd + ["log", "--format=%s", "-n1", "#{commit}..HEAD"])
+      title = nil if title.empty?
+      [last, changed, modified, branch, title]
     end
 
     Branch = Struct.new(:to_str)

version.c

@@ -78,6 +78,9 @@ void
 ruby_show_version(void)
 {
     PRINT(description);
+#ifdef RUBY_LAST_COMMIT_TITLE
+    fputs("last_commit=" RUBY_LAST_COMMIT_TITLE, stdout);
+#endif
 #ifdef HAVE_MALLOC_CONF
     if (malloc_conf) printf("malloc_conf=%s\n", malloc_conf);
 #endif