diff --git a/ext/strscan/strscan.c b/ext/strscan/strscan.c
index 4746afd5178d7c..d63897dc61f35d 100644
--- a/ext/strscan/strscan.c
+++ b/ext/strscan/strscan.c
@@ -1278,6 +1278,7 @@ strscan_must_ascii_compat(VALUE str)
     rb_must_asciicompat(str);
 }
 
+/* :nodoc: */
 static VALUE
 strscan_scan_base10_integer(VALUE self)
 {
@@ -1315,6 +1316,7 @@ strscan_scan_base10_integer(VALUE self)
     return strscan_parse_integer(p, 10, len);
 }
 
+/* :nodoc: */
 static VALUE
 strscan_scan_base16_integer(VALUE self)
 {
@@ -2190,6 +2192,13 @@ strscan_named_captures(VALUE self)
                               Ruby Interface
    ======================================================================= */
 
+/*
+ * Document-class: StringScanner::Error
+ *
+ * The error class for StringScanner.
+ * See StringScanner#unscan.
+ */
+
 /*
  * Document-class: StringScanner
  *
@@ -2226,6 +2235,7 @@ Init_strscan(void)
     tmp = rb_str_new2("$Id$");
     rb_obj_freeze(tmp);
     rb_const_set(StringScanner, rb_intern("Id"), tmp);
+    rb_deprecate_constant(StringScanner, "Id");
 
     rb_define_alloc_func(StringScanner, strscan_s_allocate);
     rb_define_private_method(StringScanner, "initialize", strscan_initialize, -1);
diff --git a/test/strscan/test_stringscanner.rb b/test/strscan/test_stringscanner.rb
index 8218e5b6bebc85..dd3663ea6a2c90 100644
--- a/test/strscan/test_stringscanner.rb
+++ b/test/strscan/test_stringscanner.rb
@@ -107,11 +107,6 @@ def test_const_Version
     assert_equal(true, StringScanner::Version.frozen?)
   end
 
-  def test_const_Id
-    assert_instance_of(String, StringScanner::Id)
-    assert_equal(true, StringScanner::Id.frozen?)
-  end
-
   def test_inspect
     str = 'test string'.dup
     s = create_string_scanner(str, false)
diff --git a/tool/sync_default_gems.rb b/tool/sync_default_gems.rb
index 03f9625bfa5cd9..b2509f0062b0b5 100755
--- a/tool/sync_default_gems.rb
+++ b/tool/sync_default_gems.rb
@@ -381,7 +381,7 @@ def sync_default_gems(gem)
     end
 
     porcelain_status().each do |line|
-      /\A(?<x>.)(?<y>.) (?<path>.*)\z/ =~ line or raise
+      /\A(?:.)(?:.) (?<path>.*)\z/ =~ line or raise
       if config.excluded?(path)
         puts "Restoring excluded file: #{path}"
         IO.popen(%W"git checkout --" + [path], "rb", &:read)
@@ -553,7 +553,7 @@ def resolve_conflicts(gem, sha, edit)
   end
 
   def collect_cacheinfo(tree)
-    cacheinfo = pipe_readlines(%W"git ls-tree -r -t -z #{tree}").filter_map do |line|
+    pipe_readlines(%W"git ls-tree -r -t -z #{tree}").filter_map do |line|
       fields, path = line.split("\t", 2)
       mode, type, object = fields.split(" ", 3)
       next unless type == "blob"
@@ -640,12 +640,11 @@ def make_and_fixup_commit(gem, original_commit, cacheinfo, parent: nil, message:
   end
 
   def rewrite_commit(gem, sha)
-    config = REPOSITORIES[gem]
     author, message = make_commit_info(gem, sha)
     new_blobs = collect_cacheinfo("#{sha}")
     new_rewritten, new_ignored = rewrite_cacheinfo(gem, new_blobs)
 
-    headers, orig_message = IO.popen(%W[git cat-file commit #{sha}], "rb", &:read).split("\n\n", 2)
+    headers, _ = IO.popen(%W[git cat-file commit #{sha}], "rb", &:read).split("\n\n", 2)
     first_parent = headers[/^parent (.{40})$/, 1]
     unless first_parent
       # Root commit, first time to sync this repo
@@ -674,8 +673,6 @@ def rewrite_commit(gem, sha)
   end
 
   def pickup_commit(gem, sha, edit)
-    config = REPOSITORIES[gem]
-
     rewritten = rewrite_commit(gem, sha)
 
     # No changes remaining after rewriting