Introduce `VCS::Null` for fallback

tool/file2lastrev.rb

@@ -32,8 +32,8 @@ OptionParser.new {|opts|
     rescue VCS::NotFoundError => e
       abort "#{File.basename(Program)}: #{e.message}" unless @suppress_not_found
       opts.remove
+      nil
     end
-    nil
   end
   opts.new
   opts.on("--srcdir=PATH", "use PATH as source directory") do |path|
@@ -62,15 +62,11 @@ OptionParser.new {|opts|
   opts.order! rescue abort "#{File.basename(Program)}: #{$!}\n#{opts}"
   if vcs
     vcs.set_options(vcs_options) # options after --srcdir
-  else
-    new_vcs["."]
+  elsif new_vcs["."]
+  else @suppress_not_found
+    (vcs = VCS::Null.new(nil)).set_options(vcs_options)
   end
 }
-unless vcs
-  # Output only release_date when .git is missing
-  puts VCS.release_date if @output == :revision_h
-  exit
-end
 
 output =
   case @output
@@ -99,10 +95,6 @@ ok = true
   begin
     puts output[*vcs.get_revisions(arg)]
   rescue => e
-    if @suppress_not_found and VCS::NotFoundError === e
-      puts VCS.release_date if @output == :revision_h
-      next
-    end
     warn "#{File.basename(Program)}: #{e.message}"
     ok = false
   end

tool/lib/vcs.rb

@@ -98,7 +98,7 @@ class VCS
     opts
   end
 
-  def self.release_date(time = Time.now - 10) # the same default as make-snapshot
+  def release_date(time)
     t = time.utc
     [
       t.strftime('#define RUBY_RELEASE_YEAR %Y'),
@@ -246,7 +246,7 @@ class VCS
       t = release_datetime.utc
       code << t.strftime('#define RUBY_RELEASE_DATETIME "%FT%TZ"')
     end
-    code += VCS.release_date(release_date)
+    code += self.release_date(release_date)
     code
   end
 
@@ -775,4 +775,15 @@ class VCS
       true
     end
   end
+
+  class Null < self
+    def get_revisions(path, srcdir = nil)
+      @modified ||= Time.now - 10
+      return nil, nil, @modified
+    end
+
+    def revision_header(last, release_date, release_datetime = nil, branch = nil, title = nil, limit: 20)
+      self.release_date(release_date)
+    end
+  end
 end

tool/make-snapshot

@@ -295,7 +295,7 @@ def package(vcs, rev, destdir, tmp = nil)
   if info = vcs.get_revisions(url)
     modified = info[2]
   else
-    modified = Time.now - 10
+    _, _, modified = VCS::Null.new(nil).get_revisions(url)
   end
   if !revision and info
     revision = info