merge revision(s) 8d04260acd8b6fba98867acc1a7e786495813fa0,2fbd8dca18a102cb3ffc5e7e6235c09fd0d04ba3,4165ec91d87ff1fcb41e312d896bea8a678c9bab,4d21134f3f1645ae2042d836e750ad267ee1551f,70da92cdf7ac75e071353c4551419ad02c284497,ea321a654d4b4fd6d56a1cdd6e117c62075898ee,ae68a8df586e9f3b3211e9c174b7001e57ee6aee,af67ced3b0945e8ea67434f8e66ef1e602656438,e77c766b7ab17e801c5cfa881754c392f8c13f0b:

	[ruby/net-http] turn on frozen strings for net/http/header

	https://github.com/ruby/net-http/commit/a5203c9f92
	---
	 lib/net/http/header.rb | 2 +-
	 1 file changed, 1 insertion(+), 1 deletion(-)

	[ruby/net-http] turn on frozen strings for net/http/generic_request

	https://github.com/ruby/net-http/commit/b92ade088d
	---
	 lib/net/http/generic_request.rb | 6 +++---
	 1 file changed, 3 insertions(+), 3 deletions(-)

	[ruby/net-http] update net/http/response to be frozen string literal

	https://github.com/ruby/net-http/commit/dc3b4a75ca
	---
	 lib/net/http/response.rb | 6 +++---
	 1 file changed, 3 insertions(+), 3 deletions(-)

	[ruby/net-http] freeze rest of lib

	https://github.com/ruby/net-http/commit/455a74734a
	---
	 lib/net/http.rb             | 2 +-
	 lib/net/http/backward.rb    | 2 +-
	 lib/net/http/exceptions.rb  | 2 +-
	 lib/net/http/proxy_delta.rb | 2 +-
	 lib/net/http/request.rb     | 2 +-
	 lib/net/http/requests.rb    | 2 +-
	 lib/net/https.rb            | 2 +-
	 7 files changed, 7 insertions(+), 7 deletions(-)

	[ruby/net-http] Fix on 2.7

	https://github.com/ruby/net-http/commit/5194fd541e
	---
	 lib/net/http.rb | 2 +-
	 1 file changed, 1 insertion(+), 1 deletion(-)

	[ruby/net-http] use +'' everywhere

	https://github.com/ruby/net-http/commit/1077427152
	---
	 lib/net/http/generic_request.rb | 4 ++--
	 lib/net/http/response.rb        | 2 +-
	 2 files changed, 3 insertions(+), 3 deletions(-)

	[ruby/net-http] Update lib/net/http/response.rb

	@natematykiewicz's suggestion to avoid a string allocation

	https://github.com/ruby/net-http/commit/925630f227

	Co-authored-by: Nate Matykiewicz <natematykiewicz@gmail.com>
	---
	 lib/net/http/response.rb | 2 +-
	 1 file changed, 1 insertion(+), 1 deletion(-)

	[ruby/net-http] Update lib/net/http.rb

	@natematykiewicz's suggestion to avoid another string allocation

	https://github.com/ruby/net-http/commit/4a22c42338

	Co-authored-by: Nate Matykiewicz <natematykiewicz@gmail.com>
	---
	 lib/net/http.rb | 4 ++--
	 1 file changed, 2 insertions(+), 2 deletions(-)

	[ruby/net-http] No longer neccessary to call `String#freeze` on
	 string literals.

	See #144

	https://github.com/ruby/net-http/commit/5a986c13d3
	---
	 lib/net/http.rb                 | 2 +-
	 lib/net/http/generic_request.rb | 8 ++++----
	 2 files changed, 5 insertions(+), 5 deletions(-)

10 files changed, 21 insertions, 21 deletions

diff --git a/lib/net/http.rb b/lib/net/http.rb
index 89277ca49d..82ab6ab574 100644
--- a/lib/net/http.rb
+++ b/lib/net/http.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #
 # = net/http.rb
 #
@@ -1615,8 +1615,8 @@ module Net   #:nodoc:
                                       write_timeout: @write_timeout,
                                       continue_timeout: @continue_timeout,
                                       debug_output: @debug_output)
-          buf = "CONNECT #{conn_address}:#{@port} HTTP/#{HTTPVersion}\r\n"
-          buf << "Host: #{@address}:#{@port}\r\n"
+          buf = +"CONNECT #{conn_address}:#{@port} HTTP/#{HTTPVersion}\r\n" \
+            "Host: #{@address}:#{@port}\r\n"
           if proxy_user
             credential = ["#{proxy_user}:#{proxy_pass}"].pack('m0')
             buf << "Proxy-Authorization: Basic #{credential}\r\n"
@@ -1798,7 +1798,7 @@ module Net   #:nodoc:
     def proxy_uri # :nodoc:
       return if @proxy_uri == false
       @proxy_uri ||= URI::HTTP.new(
-        "http".freeze, nil, address, port, nil, nil, nil, nil, nil
+        "http", nil, address, port, nil, nil, nil, nil, nil
       ).find_proxy || false
       @proxy_uri || nil
     end
diff --git a/lib/net/http/backward.rb b/lib/net/http/backward.rb
index 691e41e4f1..b44577edbd 100644
--- a/lib/net/http/backward.rb
+++ b/lib/net/http/backward.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 # for backward compatibility
 
 # :enddoc:
diff --git a/lib/net/http/exceptions.rb b/lib/net/http/exceptions.rb
index 9c425cae16..ceec8f7b0a 100644
--- a/lib/net/http/exceptions.rb
+++ b/lib/net/http/exceptions.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Net
   # Net::HTTP exception class.
   # You cannot use Net::HTTPExceptions directly; instead, you must use
diff --git a/lib/net/http/generic_request.rb b/lib/net/http/generic_request.rb
index 8877cd04ae..44e329a0c8 100644
--- a/lib/net/http/generic_request.rb
+++ b/lib/net/http/generic_request.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #
 # \HTTPGenericRequest is the parent of the Net::HTTPRequest class.
 #
@@ -23,7 +23,7 @@ class Net::HTTPGenericRequest
       raise ArgumentError, "no host component for URI" unless (hostname && hostname.length > 0)
       @uri = uri_or_path.dup
       host = @uri.hostname.dup
-      host << ":".freeze << @uri.port.to_s if @uri.port != @uri.default_port
+      host << ":" << @uri.port.to_s if @uri.port != @uri.default_port
       @path = uri_or_path.request_uri
       raise ArgumentError, "no HTTP request path given" unless @path
     else
@@ -212,15 +212,15 @@ class Net::HTTPGenericRequest
     return unless @uri
 
     if ssl
-      scheme = 'https'.freeze
+      scheme = 'https'
       klass = URI::HTTPS
     else
-      scheme = 'http'.freeze
+      scheme = 'http'
       klass = URI::HTTP
     end
 
     if host = self['host']
-      host.sub!(/:.*/m, ''.freeze)
+      host.sub!(/:.*/m, '')
     elsif host = @uri.host
     else
      host = addr
@@ -316,7 +316,7 @@ class Net::HTTPGenericRequest
     boundary ||= SecureRandom.urlsafe_base64(40)
     chunked_p = chunked?
 
-    buf = ''
+    buf = +''
     params.each do |key, value, h={}|
       key = quote_string(key, charset)
       filename =
@@ -401,7 +401,7 @@ class Net::HTTPGenericRequest
     if /[\r\n]/ =~ reqline
       raise ArgumentError, "A Request-Line must not contain CR or LF"
     end
-    buf = ""
+    buf = +''
     buf << reqline << "\r\n"
     each_capitalized do |k,v|
       buf << "#{k}: #{v}\r\n"
diff --git a/lib/net/http/header.rb b/lib/net/http/header.rb
index ec5552f04d..6660c8075a 100644
--- a/lib/net/http/header.rb
+++ b/lib/net/http/header.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 #
 # The \HTTPHeader module provides access to \HTTP headers.
 #
diff --git a/lib/net/http/proxy_delta.rb b/lib/net/http/proxy_delta.rb
index a2f770ebdb..e7d30def64 100644
--- a/lib/net/http/proxy_delta.rb
+++ b/lib/net/http/proxy_delta.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 module Net::HTTP::ProxyDelta   #:nodoc: internal use only
   private
 
diff --git a/lib/net/http/request.rb b/lib/net/http/request.rb
index e900b8a17a..4a138572e9 100644
--- a/lib/net/http/request.rb
+++ b/lib/net/http/request.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 
 # This class is the base class for \Net::HTTP request classes.
 # The class should not be used directly;
diff --git a/lib/net/http/requests.rb b/lib/net/http/requests.rb
index 96cedcabcc..5724164205 100644
--- a/lib/net/http/requests.rb
+++ b/lib/net/http/requests.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 
 # HTTP/1.1 methods --- RFC2616
 
diff --git a/lib/net/http/response.rb b/lib/net/http/response.rb
index 1d83935c10..192fa2c749 100644
--- a/lib/net/http/response.rb
+++ b/lib/net/http/response.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 
 # This class is the base class for \Net::HTTP response classes.
 #
@@ -273,7 +273,7 @@ class Net::HTTPResponse
 
   def error!   #:nodoc:
     message = @code
-    message += ' ' + @message.dump if @message
+    message = "#{message} #{@message.dump}" if @message
     raise error_type().new(message, self)
   end
 
@@ -648,7 +648,7 @@ class Net::HTTPResponse
     if block
       Net::ReadAdapter.new(block)
     else
-      dest || ''
+      dest || +''
     end
   end
 
diff --git a/lib/net/https.rb b/lib/net/https.rb
index d46721c82a..0f23e1fb13 100644
--- a/lib/net/https.rb
+++ b/lib/net/https.rb
@@ -1,4 +1,4 @@
-# frozen_string_literal: false
+# frozen_string_literal: true
 =begin
 
 = net/https -- SSL/TLS enhancement for Net::HTTP.