Migrate RUBY_VERSION/RUBY_DESCRIPTION to Git

from Subversion.

This behavior is tentative and not discussed well. The point of
discussion will be just the length of commit hash, and I thought we
should include this kind of change in 2.7.0-preview1 release even before
the length is fixed yet.

Let's discuss that afterwards and fix it later as needed. Naruse
suggested that length=10 is very unlikely to cause conflict, and thus
it's used by email notification and rubyci now. This behavior is in
favor of that for now.

NEWS

@@ -134,4 +134,11 @@ GC::
 === Miscellaneous changes
 
 * Require compilers to support C99 [Misc #15347]
+
   * Details of our dialect: https://bugs.ruby-lang.org/projects/ruby-trunk/wiki/C99
+
+* Upstream repository is changed from Subversion to Git.
+
+  * RUBY_REVISION class is changed from Integer to String.
+
+  * RUBY_DESCRIPTION includes Git revision instead of Subversion's one.

tool/file2lastrev.rb

@@ -54,7 +54,7 @@ parser.parse! rescue abort "#{File.basename(Program)}: #{$!}\n#{parser}"
   when :revision_h
     Proc.new {|last, changed, modified, branch, title|
       [
-        "#define RUBY_REVISION #{changed || 0}",
+        "#define RUBY_REVISION \"#{changed[0...10]}\"",
         if branch
           e = '..'
           limit = 16

tool/vcs.rb

@@ -374,27 +374,16 @@ class VCS
 
     def self.get_revisions(path, srcdir = nil)
       gitcmd = [COMMAND]
-      desc = cmd_read_at(srcdir, [gitcmd + %w[describe --tags --match REV_*]])
-      if /\AREV_(\d+)(?:-(\d+)-g\h+)?\Z/ =~ desc
-        last = ($1.to_i + $2.to_i).to_s
-      end
-      logcmd = gitcmd + %W[log -n1 --date=iso]
-      logcmd << "--grep=^ *git-svn-id: .*@[0-9][0-9]*" unless last
-      idpat = /git-svn-id: .*?@(\d+) \S+\Z/
-      log = cmd_read_at(srcdir, [logcmd])
-      commit = log[/\Acommit (\w+)/, 1]
-      last ||= log[idpat, 1]
+      last = cmd_read_at(srcdir, [[*gitcmd, 'rev-parse', 'HEAD']]).rstrip
       if path
-        cmd = logcmd
-        cmd += [path] unless path == '.'
-        log = cmd_read_at(srcdir, [cmd])
-        changed = log[idpat, 1] || last
+        log = cmd_read_at(srcdir, [[*gitcmd, 'log', '-n1', '--date=iso', path]])
       else
-        changed = last
+        log = cmd_read_at(srcdir, [[*gitcmd, 'log', '-n1', '--date=iso']])
       end
+      changed = log[/\Acommit (\h+)/, 1]
       modified = log[/^Date:\s+(.*)/, 1]
       branch = cmd_read_at(srcdir, [gitcmd + %W[symbolic-ref HEAD]])[%r'\A(?:refs/heads/)?(.+)', 1]
-      title = cmd_read_at(srcdir, [gitcmd + %W[log --format=%s -n1 #{commit}..HEAD]])
+      title = cmd_read_at(srcdir, [gitcmd + %W[log --format=%s -n1 HEAD]])
       title = nil if title.empty?
       [last, changed, modified, branch, title]
     end

version.c

@@ -33,6 +33,7 @@ const int ruby_api_version[] = {
     STRINGIZE(RUBY_VERSION_MINOR) "." \
     STRINGIZE(RUBY_VERSION_TEENY) ""
 const char ruby_version[] = RUBY_VERSION;
+const char ruby_revision[] = RUBY_REVISION;
 const char ruby_release_date[] = RUBY_RELEASE_DATE;
 const char ruby_platform[] = RUBY_PLATFORM;
 const int ruby_patchlevel = RUBY_PATCHLEVEL;
@@ -46,7 +47,6 @@ void
 Init_version(void)
 {
     enum {ruby_patchlevel = RUBY_PATCHLEVEL};
-    enum {ruby_revision = RUBY_REVISION};
     VALUE version;
     VALUE ruby_engine_name;
     /*
@@ -69,7 +69,7 @@ Init_version(void)
     /*
      * The SVN revision for this ruby.
      */
-    rb_define_global_const("RUBY_REVISION", MKINT(revision));
+    rb_define_global_const("RUBY_REVISION", MKSTR(revision));
     /*
      * The copyright string for ruby
      */

version.h

@@ -45,20 +45,18 @@
 #ifndef RUBY_REVISION
 # include "revision.h"
 #endif
-#ifndef RUBY_REVISION
-# define RUBY_REVISION 0
-#endif
 
-#if RUBY_REVISION
+#ifdef RUBY_REVISION
 # if RUBY_PATCHLEVEL == -1
 #  ifndef RUBY_BRANCH_NAME
 #   define RUBY_BRANCH_NAME "trunk"
 #  endif
-#  define RUBY_REVISION_STR " "RUBY_BRANCH_NAME" "STRINGIZE(RUBY_REVISION)
+#  define RUBY_REVISION_STR " "RUBY_BRANCH_NAME" "RUBY_REVISION
 # else
-#  define RUBY_REVISION_STR " revision "STRINGIZE(RUBY_REVISION)
+#  define RUBY_REVISION_STR " revision "RUBY_REVISION
 # endif
 #else
+# define RUBY_REVISION "HEAD"
 # define RUBY_REVISION_STR ""
 #endif