diff --git a/lib/bundler/definition.rb b/lib/bundler/definition.rb
index 4fca763bcc..2e0f23a402 100644
--- a/lib/bundler/definition.rb
+++ b/lib/bundler/definition.rb
@@ -255,20 +255,18 @@ module Bundler
     #
     # @return [SpecSet] resolved dependencies
     def resolve
-      @resolve ||= begin
-        if Bundler.frozen_bundle?
-          Bundler.ui.debug "Frozen, using resolution from the lockfile"
-          @locked_specs
-        elsif !unlocking? && nothing_changed?
-          Bundler.ui.debug("Found no changes, using resolution from the lockfile")
-          SpecSet.new(filter_specs(@locked_specs, @dependencies.select {|dep| @locked_specs[dep].any? }))
-        else
-          last_resolve = converge_locked_specs
-          # Run a resolve against the locally available gems
-          Bundler.ui.debug("Found changes from the lockfile, re-resolving dependencies because #{change_reason}")
-          expanded_dependencies = expand_dependencies(dependencies + metadata_dependencies, true)
-          Resolver.resolve(expanded_dependencies, source_requirements, last_resolve, gem_version_promoter, additional_base_requirements_for_resolve, platforms)
-        end
+      @resolve ||= if Bundler.frozen_bundle?
+        Bundler.ui.debug "Frozen, using resolution from the lockfile"
+        @locked_specs
+      elsif !unlocking? && nothing_changed?
+        Bundler.ui.debug("Found no changes, using resolution from the lockfile")
+        SpecSet.new(filter_specs(@locked_specs, @dependencies.select {|dep| @locked_specs[dep].any? }))
+      else
+        last_resolve = converge_locked_specs
+        # Run a resolve against the locally available gems
+        Bundler.ui.debug("Found changes from the lockfile, re-resolving dependencies because #{change_reason}")
+        expanded_dependencies = expand_dependencies(dependencies + metadata_dependencies, true)
+        Resolver.resolve(expanded_dependencies, source_requirements, last_resolve, gem_version_promoter, additional_base_requirements_for_resolve, platforms)
       end
     end
 
@@ -735,12 +733,10 @@ module Bundler
     end
 
     def metadata_dependencies
-      @metadata_dependencies ||= begin
-        [
-          Dependency.new("Ruby\0", RubyVersion.system.gem_version),
-          Dependency.new("RubyGems\0", Gem::VERSION),
-        ]
-      end
+      @metadata_dependencies ||= [
+        Dependency.new("Ruby\0", RubyVersion.system.gem_version),
+        Dependency.new("RubyGems\0", Gem::VERSION),
+      ]
     end
 
     def expand_dependencies(dependencies, remote = false)
diff --git a/lib/bundler/dependency.rb b/lib/bundler/dependency.rb
index d12b120bba..018a3182b9 100644
--- a/lib/bundler/dependency.rb
+++ b/lib/bundler/dependency.rb
@@ -9,6 +9,7 @@ module Bundler
     attr_reader :autorequire
     attr_reader :groups, :platforms, :gemfile, :git, :github, :branch, :ref
 
+    # rubocop:disable Naming/VariableNumber
     PLATFORM_MAP = {
       :ruby     => Gem::Platform::RUBY,
       :ruby_18  => Gem::Platform::RUBY,
@@ -91,6 +92,7 @@ module Bundler
       :x64_mingw_30 => Gem::Platform::X64_MINGW,
       :x64_mingw_31 => Gem::Platform::X64_MINGW,
     }.freeze
+    # rubocop:enable Naming/VariableNumber
 
     def initialize(name, version, options = {}, &blk)
       type = options["type"] || :runtime
diff --git a/lib/bundler/dsl.rb b/lib/bundler/dsl.rb
index 1ae19a46e9..bfa078046c 100644
--- a/lib/bundler/dsl.rb
+++ b/lib/bundler/dsl.rb
@@ -511,9 +511,7 @@ module Bundler
       #         be raised.
       #
       def contents
-        @contents ||= begin
-          dsl_path && File.exist?(dsl_path) && File.read(dsl_path)
-        end
+        @contents ||= dsl_path && File.exist?(dsl_path) && File.read(dsl_path)
       end
 
       # The message of the exception reports the content of podspec for the
diff --git a/lib/bundler/errors.rb b/lib/bundler/errors.rb
index 0bc1a860df..f10b6cc68f 100644
--- a/lib/bundler/errors.rb
+++ b/lib/bundler/errors.rb
@@ -41,12 +41,14 @@ module Bundler
   class GemspecError < BundlerError; status_code(14); end
   class InvalidOption < BundlerError; status_code(15); end
   class ProductionError < BundlerError; status_code(16); end
+
   class HTTPError < BundlerError
     status_code(17)
     def filter_uri(uri)
       URICredentialsFilter.credential_filtered_uri(uri)
     end
   end
+
   class RubyVersionMismatch < BundlerError; status_code(18); end
   class SecurityError < BundlerError; status_code(19); end
   class LockfileError < BundlerError; status_code(20); end
diff --git a/lib/bundler/fetcher.rb b/lib/bundler/fetcher.rb
index 6fe047568f..e9d5dd505c 100644
--- a/lib/bundler/fetcher.rb
+++ b/lib/bundler/fetcher.rb
@@ -20,6 +20,7 @@ module Bundler
     class TooManyRequestsError < HTTPError; end
     # This error is raised if the API returns a 413 (only printed in verbose)
     class FallbackError < HTTPError; end
+
     # This is the error raised if OpenSSL fails the cert verification
     class CertificateFailureError < HTTPError
       def initialize(remote_uri)
@@ -33,6 +34,7 @@ module Bundler
           " sources and change 'https' to 'http'."
       end
     end
+
     # This is the error raised when a source is HTTPS and OpenSSL didn't load
     class SSLError < HTTPError
       def initialize(msg = nil)
@@ -42,6 +44,7 @@ module Bundler
             "using RVM are available at rvm.io/packages/openssl."
       end
     end
+
     # This error is raised if HTTP authentication is required, but not provided.
     class AuthenticationRequiredError < HTTPError
       def initialize(remote_uri)
@@ -52,6 +55,7 @@ module Bundler
           "or by storing the credentials in the `#{Settings.key_for(remote_uri)}` environment variable"
       end
     end
+
     # This error is raised if HTTP authentication is provided, but incorrect.
     class BadAuthenticationError < HTTPError
       def initialize(remote_uri)
diff --git a/lib/bundler/fetcher/base.rb b/lib/bundler/fetcher/base.rb
index 16cc98273a..62cc75add8 100644
--- a/lib/bundler/fetcher/base.rb
+++ b/lib/bundler/fetcher/base.rb
@@ -19,14 +19,12 @@ module Bundler
       end
 
       def fetch_uri
-        @fetch_uri ||= begin
-          if remote_uri.host == "rubygems.org"
-            uri = remote_uri.dup
-            uri.host = "index.rubygems.org"
-            uri
-          else
-            remote_uri
-          end
+        @fetch_uri ||= if remote_uri.host == "rubygems.org"
+          uri = remote_uri.dup
+          uri.host = "index.rubygems.org"
+          uri
+        else
+          remote_uri
         end
       end
 
diff --git a/lib/bundler/plugin/api/source.rb b/lib/bundler/plugin/api/source.rb
index a6ae08237c..67c45bd204 100644
--- a/lib/bundler/plugin/api/source.rb
+++ b/lib/bundler/plugin/api/source.rb
@@ -258,7 +258,7 @@ module Bundler
           @dependencies |= Array(names)
         end
 
-        # Note: Do not override if you don't know what you are doing.
+        # NOTE: Do not override if you don't know what you are doing.
         def can_lock?(spec)
           spec.source == self
         end
@@ -285,7 +285,7 @@ module Bundler
         end
         alias_method :identifier, :to_s
 
-        # Note: Do not override if you don't know what you are doing.
+        # NOTE: Do not override if you don't know what you are doing.
         def include?(other)
           other == self
         end
@@ -294,7 +294,7 @@ module Bundler
           SharedHelpers.digest(:SHA1).hexdigest(uri)
         end
 
-        # Note: Do not override if you don't know what you are doing.
+        # NOTE: Do not override if you don't know what you are doing.
         def gem_install_dir
           Bundler.install_path
         end
diff --git a/lib/bundler/resolver.rb b/lib/bundler/resolver.rb
index d749694952..18eb18160d 100644
--- a/lib/bundler/resolver.rb
+++ b/lib/bundler/resolver.rb
@@ -233,19 +233,17 @@ module Bundler
     # before dependencies that are unconstrained
     def amount_constrained(dependency)
       @amount_constrained ||= {}
-      @amount_constrained[dependency.name] ||= begin
-        if (base = @base[dependency.name]) && !base.empty?
-          dependency.requirement.satisfied_by?(base.first.version) ? 0 : 1
-        else
-          all = index_for(dependency).search(dependency.name).size
+      @amount_constrained[dependency.name] ||= if (base = @base[dependency.name]) && !base.empty?
+        dependency.requirement.satisfied_by?(base.first.version) ? 0 : 1
+      else
+        all = index_for(dependency).search(dependency.name).size
 
-          if all <= 1
-            all - 1_000_000
-          else
-            search = search_for(dependency)
-            search = @prerelease_specified[dependency.name] ? search.count : search.count {|s| !s.version.prerelease? }
-            search - all
-          end
+        if all <= 1
+          all - 1_000_000
+        else
+          search = search_for(dependency)
+          search = @prerelease_specified[dependency.name] ? search.count : search.count {|s| !s.version.prerelease? }
+          search - all
         end
       end
     end
diff --git a/lib/bundler/source/git.rb b/lib/bundler/source/git.rb
index eb82544b86..ed66dcdc12 100644
--- a/lib/bundler/source/git.rb
+++ b/lib/bundler/source/git.rb
@@ -219,13 +219,11 @@ module Bundler
       # across different projects, this cache will be shared.
       # When using local git repos, this is set to the local repo.
       def cache_path
-        @cache_path ||= begin
-          if Bundler.requires_sudo? || Bundler.feature_flag.global_gem_cache?
-            Bundler.user_cache
-          else
-            Bundler.bundle_path.join("cache", "bundler")
-          end.join("git", git_scope)
-        end
+        @cache_path ||= if Bundler.requires_sudo? || Bundler.feature_flag.global_gem_cache?
+          Bundler.user_cache
+        else
+          Bundler.bundle_path.join("cache", "bundler")
+        end.join("git", git_scope)
       end
 
       def app_cache_dirname
diff --git a/lib/rubygems.rb b/lib/rubygems.rb
index 4eb67c7a16..add4034837 100644
--- a/lib/rubygems.rb
+++ b/lib/rubygems.rb
@@ -607,7 +607,6 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
     return if @yaml_loaded
 
     require 'psych'
-    require_relative 'rubygems/psych_additions'
     require_relative 'rubygems/psych_tree'
 
     require_relative 'rubygems/safe_yaml'
@@ -1018,7 +1017,6 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
 
   def self.load_plugin_files(plugins) # :nodoc:
     plugins.each do |plugin|
-
       # Skip older versions of the GemCutter plugin: Its commands are in
       # RubyGems proper now.
 
diff --git a/lib/rubygems/commands/install_command.rb b/lib/rubygems/commands/install_command.rb
index adf2cdba84..87563accb0 100644
--- a/lib/rubygems/commands/install_command.rb
+++ b/lib/rubygems/commands/install_command.rb
@@ -261,7 +261,7 @@ You can use `i` command instead of `install`.
       return unless Gem::SourceFetchProblem === x
 
       require_relative "../uri"
-      msg = "Unable to pull data from '#{Gem::Uri.new(x.source.uri).redacted}': #{x.error.message}"
+      msg = "Unable to pull data from '#{Gem::Uri.redact(x.source.uri)}': #{x.error.message}"
 
       alert_warning msg
     end
diff --git a/lib/rubygems/commands/sources_command.rb b/lib/rubygems/commands/sources_command.rb
index 9e74f3c47d..35fba1bd04 100644
--- a/lib/rubygems/commands/sources_command.rb
+++ b/lib/rubygems/commands/sources_command.rb
@@ -62,7 +62,7 @@ class Gem::Commands::SourcesCommand < Gem::Command
       say "#{source_uri} is not a URI"
       terminate_interaction 1
     rescue Gem::RemoteFetcher::FetchError => e
-      say "Error fetching #{source_uri}:\n\t#{e.message}"
+      say "Error fetching #{Gem::Uri.redact(source.uri)}:\n\t#{e.message}"
       terminate_interaction 1
     end
   end
diff --git a/lib/rubygems/core_ext/kernel_require.rb b/lib/rubygems/core_ext/kernel_require.rb
index 4b867c55e9..23badd75d2 100644
--- a/lib/rubygems/core_ext/kernel_require.rb
+++ b/lib/rubygems/core_ext/kernel_require.rb
@@ -18,7 +18,7 @@ module Kernel
   end
 
   file = Gem::KERNEL_WARN_IGNORES_INTERNAL_ENTRIES ? "<internal:#{__FILE__}>" : __FILE__
-  module_eval <<'RUBY', file, __LINE__ + 1
+  module_eval <<'RUBY', file, __LINE__ + 1 # rubocop:disable Style/EvalWithLocation
   ##
   # When RubyGems is required, Kernel#require is replaced with our own which
   # is capable of loading gems on demand.
diff --git a/lib/rubygems/errors.rb b/lib/rubygems/errors.rb
index f115ce23d0..e6e222033d 100644
--- a/lib/rubygems/errors.rb
+++ b/lib/rubygems/errors.rb
@@ -168,7 +168,7 @@ module Gem
     # An English description of the error.
 
     def wordy
-      "Unable to download data from #{Gem::Uri.new(@source.uri).redacted} - #{@error.message}"
+      "Unable to download data from #{Gem::Uri.redact(@source.uri)} - #{@error.message}"
     end
 
     ##
diff --git a/lib/rubygems/ext/builder.rb b/lib/rubygems/ext/builder.rb
index c98ff643fc..99dd2c162c 100644
--- a/lib/rubygems/ext/builder.rb
+++ b/lib/rubygems/ext/builder.rb
@@ -55,7 +55,7 @@ class Gem::Ext::Builder
     end
   end
 
-  def self.run(command, results, command_name = nil, dir = Dir.pwd)
+  def self.run(command, results, command_name = nil, dir = Dir.pwd, env = {})
     verbose = Gem.configuration.really_verbose
 
     begin
@@ -70,9 +70,9 @@ class Gem::Ext::Builder
 
       require "open3"
       # Set $SOURCE_DATE_EPOCH for the subprocess.
-      env = { 'SOURCE_DATE_EPOCH' => Gem.source_date_epoch_string }
+      build_env = { 'SOURCE_DATE_EPOCH' => Gem.source_date_epoch_string }.merge(env)
       output, status = begin
-                         Open3.capture2e(env, *command, :chdir => dir)
+                         Open3.capture2e(build_env, *command, :chdir => dir)
                        rescue => error
                          raise Gem::InstallError, "#{command_name || class_name} failed#{error.message}"
                        end
diff --git a/lib/rubygems/ext/cargo_builder.rb b/lib/rubygems/ext/cargo_builder.rb
index eedc950bec..232c0a313d 100644
--- a/lib/rubygems/ext/cargo_builder.rb
+++ b/lib/rubygems/ext/cargo_builder.rb
@@ -4,48 +4,67 @@
 # over the `cargo rustc` command which takes care of building Rust code in a way
 # that Ruby can use.
 class Gem::Ext::CargoBuilder < Gem::Ext::Builder
-  attr_reader :spec
+  attr_accessor :spec, :runner, :profile
 
   def initialize(spec)
+    require_relative "../command"
+    require_relative "cargo_builder/link_flag_converter"
+
     @spec = spec
+    @runner = self.class.method(:run)
+    @profile = :release
   end
 
   def build(_extension, dest_path, results, args = [], lib_dir = nil, cargo_dir = Dir.pwd)
-    require "rubygems/command"
     require "fileutils"
     require "shellwords"
 
     build_crate(dest_path, results, args, cargo_dir)
-    ext_path = rename_cdylib_for_ruby_compatibility(dest_path)
-    finalize_directory(ext_path, dest_path, lib_dir, cargo_dir)
+    validate_cargo_build!(dest_path)
+    rename_cdylib_for_ruby_compatibility(dest_path)
+    finalize_directory(dest_path, lib_dir, cargo_dir)
     results
   end
 
-  private
-
   def build_crate(dest_path, results, args, cargo_dir)
+    env = build_env
+    cmd = cargo_command(cargo_dir, dest_path, args)
+    runner.call cmd, results, 'cargo', cargo_dir, env
+
+    results
+  end
+
+  def build_env
+    build_env = rb_config_env
+    build_env["RUBY_STATIC"] = "true" if ruby_static? && ENV.key?('RUBY_STATIC')
+    build_env
+  end
+
+  def cargo_command(cargo_dir, dest_path, args = [])
     manifest = File.join(cargo_dir, "Cargo.toml")
-
-    given_ruby_static = ENV["RUBY_STATIC"]
-
-    ENV["RUBY_STATIC"] = "true" if ruby_static? && !given_ruby_static
-
     cargo = ENV.fetch("CARGO", "cargo")
 
     cmd = []
     cmd += [cargo, "rustc"]
+    cmd += ["--target", ENV['CARGO_BUILD_TARGET']] if ENV['CARGO_BUILD_TARGET']
     cmd += ["--target-dir", dest_path]
     cmd += ["--manifest-path", manifest]
-    cmd += ["--lib", "--release", "--locked"]
-    cmd += ["--"]
-    cmd += [*cargo_rustc_args(dest_path)]
+    cmd += ["--lib"]
+    cmd += ["--profile", profile.to_s]
+    cmd += ["--locked"] if profile == :release
     cmd += Gem::Command.build_args
     cmd += args
+    cmd += ["--"]
+    cmd += [*cargo_rustc_args(dest_path)]
+    cmd
+  end
 
-    self.class.run cmd, results, self.class.class_name, cargo_dir
-    results
-  ensure
-    ENV["RUBY_STATIC"] = given_ruby_static
+  private
+
+  def rb_config_env
+    result = {}
+    RbConfig::CONFIG.each {|k, v| result["RBCONFIG_#{k}"] = v }
+    result
   end
 
   def cargo_rustc_args(dest_dir)
@@ -92,7 +111,7 @@ class Gem::Ext::CargoBuilder < Gem::Ext::Builder
   def libruby_args(dest_dir)
     libs = makefile_config(ruby_static? ? "LIBRUBYARG_STATIC" : "LIBRUBYARG_SHARED")
     raw_libs = Shellwords.split(libs)
-    raw_libs.flat_map {|l| ldflag_to_link_modifier(l, dest_dir) }
+    raw_libs.flat_map {|l| ldflag_to_link_modifier(l) }
   end
 
   def ruby_static?
@@ -103,22 +122,33 @@ class Gem::Ext::CargoBuilder < Gem::Ext::Builder
 
   # Ruby expects the dylib to follow a file name convention for loading
   def rename_cdylib_for_ruby_compatibility(dest_path)
-    dylib_path = validate_cargo_build!(dest_path)
-    dlext_name = "#{spec.name}.#{makefile_config("DLEXT")}"
-    new_name = dylib_path.gsub(File.basename(dylib_path), dlext_name)
-    FileUtils.cp(dylib_path, new_name)
-    new_name
+    new_path = final_extension_path(dest_path)
+    FileUtils.cp(cargo_dylib_path(dest_path), new_path)
+    new_path
   end
 
   def validate_cargo_build!(dir)
-    prefix = so_ext == "dll" ? "" : "lib"
-    dylib_path = File.join(dir, "release", "#{prefix}#{cargo_crate_name}.#{so_ext}")
+    dylib_path = cargo_dylib_path(dir)
 
     raise DylibNotFoundError, dir unless File.exist?(dylib_path)
 
     dylib_path
   end
 
+  def final_extension_path(dest_path)
+    dylib_path = cargo_dylib_path(dest_path)
+    dlext_name = "#{spec.name}.#{makefile_config("DLEXT")}"
+    dylib_path.gsub(File.basename(dylib_path), dlext_name)
+  end
+
+  def cargo_dylib_path(dest_path)
+    prefix = so_ext == "dll" ? "" : "lib"
+    path_parts = [dest_path]
+    path_parts << ENV['CARGO_BUILD_TARGET'] if ENV['CARGO_BUILD_TARGET']
+    path_parts += [profile_target_directory, "#{prefix}#{cargo_crate_name}.#{so_ext}"]
+    File.join(*path_parts)
+  end
+
   def cargo_crate_name
     spec.metadata.fetch('cargo_crate_name', spec.name).tr('-', '_')
   end
@@ -127,42 +157,19 @@ class Gem::Ext::CargoBuilder < Gem::Ext::Builder
     split_flags("DLDFLAGS")
       .map {|arg| maybe_resolve_ldflag_variable(arg, dest_dir) }
       .compact
-      .flat_map {|arg| ldflag_to_link_modifier(arg, dest_dir) }
+      .flat_map {|arg| ldflag_to_link_modifier(arg) }
   end
 
   def rustc_lib_flags(dest_dir)
-    split_flags("LIBS").flat_map {|arg| ldflag_to_link_modifier(arg, dest_dir) }
+    split_flags("LIBS").flat_map {|arg| ldflag_to_link_modifier(arg) }
   end
 
   def split_flags(var)
     Shellwords.split(RbConfig::CONFIG.fetch(var, ""))
   end
 
-  def ldflag_to_link_modifier(arg, dest_dir)
-    flag = arg[0..1]
-    val = arg[2..-1]
-
-    case flag
-    when "-L" then ["-L", "native=#{val}"]
-    when "-l" then ["-l", val.to_s]
-    when "-F" then ["-l", "framework=#{val}"]
-    else ["-C", "link_arg=#{arg}"]
-    end
-  end
-
-  def link_flag(link_name)
-    # These are provided by the CRT with MSVC
-    # @see https://github.com/rust-lang/pkg-config-rs/blob/49a4ac189aafa365167c72e8e503565a7c2697c2/src/lib.rs#L622
-    return [] if msvc_target? && ["m", "c", "pthread"].include?(link_name)
-
-    if link_name.include?("ruby")
-      # Specify the lib kind and give it the name "ruby" for linking
-      kind = ruby_static? ? "static" : "dylib"
-
-      ["-l", "#{kind}=ruby:#{link_name}"]
-    else
-      ["-l", link_name]
-    end
+  def ldflag_to_link_modifier(arg)
+    LinkFlagConverter.convert(arg)
   end
 
   def msvc_target?
@@ -182,20 +189,24 @@ class Gem::Ext::CargoBuilder < Gem::Ext::Builder
     !!Gem::WIN_PATTERNS.find {|r| target_platform =~ r }
   end
 
-  # Intepolate substition vars in the arg (i.e. $(DEFFILE))
+  # Interpolate substition vars in the arg (i.e. $(DEFFILE))
   def maybe_resolve_ldflag_variable(input_arg, dest_dir)
-    str = input_arg.gsub(/\$\((\w+)\)/) do |var_name|
-      case var_name
-      # On windows, it is assumed that mkmf has setup an exports file for the
-      # extension, so we have to to create one ourselves.
-      when "DEFFILE"
-        write_deffile(dest_dir)
-      else
-        RbConfig::CONFIG[var_name]
-      end
-    end.strip
+    var_matches = input_arg.match(/\$\((\w+)\)/)
 
-    str == "" ? nil : str
+    return input_arg unless var_matches
+
+    var_name = var_matches[1]
+
+    return input_arg if var_name.nil? || var_name.chomp.empty?
+
+    case var_name
+    # On windows, it is assumed that mkmf has setup an exports file for the
+    # extension, so we have to to create one ourselves.
+    when "DEFFILE"
+      write_deffile(dest_dir)
+    else
+      RbConfig::CONFIG[var_name]
+    end
   end
 
   def write_deffile(dest_dir)
@@ -241,14 +252,18 @@ class Gem::Ext::CargoBuilder < Gem::Ext::Builder
 
   # Good balance between binary size and debugability
   def debug_flags
+    return [] if profile == :dev
+
     ["-C", "debuginfo=1"]
   end
 
   # Copied from ExtConfBuilder
-  def finalize_directory(ext_path, dest_path, lib_dir, extension_dir)
+  def finalize_directory(dest_path, lib_dir, extension_dir)
     require "fileutils"
     require "tempfile"
 
+    ext_path = final_extension_path(dest_path)
+
     begin
       tmp_dest = Dir.mktmpdir(".gem.", extension_dir)
 
@@ -280,6 +295,14 @@ class Gem::Ext::CargoBuilder < Gem::Ext::Builder
     path
   end
 
+  def profile_target_directory
+    case profile
+    when :release then 'release'
+    when :dev     then 'debug'
+    else          raise "unknown target directory for profile: #{profile}"
+    end
+  end
+
   # Error raised when no cdylib artifact was created
   class DylibNotFoundError < StandardError
     def initialize(dir)
diff --git a/lib/rubygems/ext/cargo_builder/link_flag_converter.rb b/lib/rubygems/ext/cargo_builder/link_flag_converter.rb
new file mode 100644
index 0000000000..111bb05492
--- /dev/null
+++ b/lib/rubygems/ext/cargo_builder/link_flag_converter.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+class Gem::Ext::CargoBuilder < Gem::Ext::Builder
+  # Converts Ruby link flags into something cargo understands
+  class LinkFlagConverter
+    def self.convert(arg)
+      case arg.chomp
+      when /^-L\s*(.+)$/
+        ["-L", "native=#{$1}"]
+      when /^--library=(\w+\S+)$/, /^-l\s*(\w+\S+)$/
+        ["-l", $1]
+      when /^-l\s*:lib(\S+).a$/
+        ["-l", "static=#{$1}"]
+      when /^-l\s*:lib(\S+).(so|dylib|dll)$/
+        ["-l", "dylib=#{$1}"]
+      when /^-F\s*(.*)$/
+        ["-l", "framework=#{$1}"]
+      else
+        ["-C", "link_arg=#{arg}"]
+      end
+    end
+  end
+end
diff --git a/lib/rubygems/local_remote_options.rb b/lib/rubygems/local_remote_options.rb
index 9811c8f948..6b5e08bf1c 100644
--- a/lib/rubygems/local_remote_options.rb
+++ b/lib/rubygems/local_remote_options.rb
@@ -78,7 +78,6 @@ module Gem::LocalRemoteOptions
   def add_clear_sources_option
     add_option(:"Local/Remote", '--clear-sources',
                'Clear the gem sources') do |value, options|
-
       Gem.sources = nil
       options[:sources_cleared] = true
     end
@@ -105,7 +104,6 @@ module Gem::LocalRemoteOptions
 
     add_option(:"Local/Remote", '-s', '--source URL', URI::HTTP,
                'Append URL to list of remote gem sources') do |source, options|
-
       source << '/' if source !~ /\/\z/
 
       if options.delete :sources_cleared
diff --git a/lib/rubygems/psych_additions.rb b/lib/rubygems/psych_additions.rb
deleted file mode 100644
index a13c1ec676..0000000000
--- a/lib/rubygems/psych_additions.rb
+++ /dev/null
@@ -1,10 +0,0 @@
-# frozen_string_literal: true
-# This exists just to satisfy bugs in marshal'd gemspecs that
-# contain a reference to Psych::PrivateType. We prune these out
-# in Specification._load, but if we don't have the constant, Marshal
-# blows up.
-
-module Psych # :nodoc:
-  class PrivateType # :nodoc:
-  end
-end
diff --git a/lib/rubygems/request.rb b/lib/rubygems/request.rb
index 136b154bee..6d6c2d8de8 100644
--- a/lib/rubygems/request.rb
+++ b/lib/rubygems/request.rb
@@ -193,7 +193,7 @@ class Gem::Request
     begin
       @requests[connection.object_id] += 1
 
-      verbose "#{request.method} #{Gem::Uri.new(@uri).redacted}"
+      verbose "#{request.method} #{Gem::Uri.redact(@uri)}"
 
       file_name = File.basename(@uri.path)
       # perform download progress reporter only for gems
diff --git a/lib/rubygems/source.rb b/lib/rubygems/source.rb
index 85c300a8f8..5f49a0d216 100644
--- a/lib/rubygems/source.rb
+++ b/lib/rubygems/source.rb
@@ -26,15 +26,8 @@ class Gem::Source
   # Creates a new Source which will use the index located at +uri+.
 
   def initialize(uri)
-    begin
-      unless uri.kind_of? URI
-        uri = URI.parse(uri.to_s)
-      end
-    rescue URI::InvalidURIError
-      raise if Gem::Source == self.class
-    end
-
-    @uri = uri
+    require_relative "uri"
+    @uri = Gem::Uri.parse!(uri)
     @update_cache = nil
   end
 
diff --git a/lib/rubygems/source/git.rb b/lib/rubygems/source/git.rb
index 8d5dc1f69d..1d964eb59a 100644
--- a/lib/rubygems/source/git.rb
+++ b/lib/rubygems/source/git.rb
@@ -49,8 +49,8 @@ class Gem::Source::Git < Gem::Source
   # will be checked out when the gem is installed.
 
   def initialize(name, repository, reference, submodules = false)
-    super repository
-
+    require_relative "../uri"
+    @uri = Gem::Uri.parse(repository)
     @name            = name
     @repository      = repository
     @reference       = reference
diff --git a/lib/rubygems/source_list.rb b/lib/rubygems/source_list.rb
index 16e90e1ef7..7abe796409 100644
--- a/lib/rubygems/source_list.rb
+++ b/lib/rubygems/source_list.rb
@@ -48,15 +48,11 @@ class Gem::SourceList
   # String.
 
   def <<(obj)
-    require "uri"
-
     src = case obj
-    when URI
-      Gem::Source.new(obj)
     when Gem::Source
       obj
     else
-      Gem::Source.new(URI.parse(obj))
+      Gem::Source.new(obj)
     end
 
     @sources << src unless @sources.include?(src)
diff --git a/lib/rubygems/specification.rb b/lib/rubygems/specification.rb
index d8a212a04a..56db0945eb 100644
--- a/lib/rubygems/specification.rb
+++ b/lib/rubygems/specification.rb
@@ -1272,10 +1272,26 @@ class Gem::Specification < Gem::BasicSpecification
     array = begin
       Marshal.load str
     rescue ArgumentError => e
-      raise unless e.message.include?("YAML")
+      #
+      # Some very old marshaled specs included references to `YAML::PrivateType`
+      # and `YAML::Syck::DefaultKey` constants due to bugs in the old emitter
+      # that generated them. Workaround the issue by defining the necessary
+      # constants and retrying.
+      #
+      message = e.message
+      raise unless message.include?("YAML::")
 
-      Object.const_set "YAML", Psych
-      Marshal.load str
+      Object.const_set "YAML", Psych unless Object.const_defined?(:YAML)
+
+      if message.include?("YAML::Syck::")
+        YAML.const_set "Syck", YAML unless YAML.const_defined?(:Syck)
+
+        YAML::Syck.const_set "DefaultKey", Class.new if message.include?("YAML::Syck::DefaultKey")
+      elsif message.include?("YAML::PrivateType")
+        YAML.const_set "PrivateType", Class.new
+      end
+
+      retry
     end
 
     spec = Gem::Specification.new
diff --git a/lib/rubygems/uri.rb b/lib/rubygems/uri.rb
index ba30fac2f5..6acb9041f9 100644
--- a/lib/rubygems/uri.rb
+++ b/lib/rubygems/uri.rb
@@ -5,6 +5,44 @@
 #
 
 class Gem::Uri
+  ##
+  # Parses and redacts uri
+
+  def self.redact(uri)
+    new(uri).redacted
+  end
+
+  ##
+  # Parses uri, raising if it's invalid
+
+  def self.parse!(uri)
+    require "uri"
+
+    raise URI::InvalidURIError unless uri
+
+    return uri unless uri.is_a?(String)
+
+    # Always escape URI's to deal with potential spaces and such
+    # It should also be considered that source_uri may already be
+    # a valid URI with escaped characters. e.g. "{DESede}" is encoded
+    # as "%7BDESede%7D". If this is escaped again the percentage
+    # symbols will be escaped.
+    begin
+      URI.parse(uri)
+    rescue URI::InvalidURIError
+      URI.parse(URI::DEFAULT_PARSER.escape(uri))
+    end
+  end
+
+  ##
+  # Parses uri, returning the original uri if it's invalid
+
+  def self.parse(uri)
+    parse!(uri)
+  rescue URI::InvalidURIError
+    uri
+  end
+
   def initialize(source_uri)
     @parsed_uri = parse(source_uri)
   end
@@ -26,7 +64,7 @@ class Gem::Uri
   end
 
   def redact_credentials_from(text)
-    return text unless valid_uri? && password?
+    return text unless valid_uri? && password? && text.include?(to_s)
 
     text.sub(password, 'REDACTED')
   end
@@ -50,35 +88,12 @@ class Gem::Uri
 
   private
 
-  ##
-  # Parses the #uri, raising if it's invalid
-
   def parse!(uri)
-    require "uri"
-
-    raise URI::InvalidURIError unless uri
-
-    # Always escape URI's to deal with potential spaces and such
-    # It should also be considered that source_uri may already be
-    # a valid URI with escaped characters. e.g. "{DESede}" is encoded
-    # as "%7BDESede%7D". If this is escaped again the percentage
-    # symbols will be escaped.
-    begin
-      URI.parse(uri)
-    rescue URI::InvalidURIError
-      URI.parse(URI::DEFAULT_PARSER.escape(uri))
-    end
+    self.class.parse!(uri)
   end
 
-  ##
-  # Parses the #uri, returning the original uri if it's invalid
-
   def parse(uri)
-    return uri unless uri.is_a?(String)
-
-    parse!(uri)
-  rescue URI::InvalidURIError
-    uri
+    self.class.parse(uri)
   end
 
   def with_redacted_user
diff --git a/spec/bundler/bundler/dsl_spec.rb b/spec/bundler/bundler/dsl_spec.rb
index 4802b62a58..19c8f2e889 100644
--- a/spec/bundler/bundler/dsl_spec.rb
+++ b/spec/bundler/bundler/dsl_spec.rb
@@ -137,6 +137,7 @@ RSpec.describe Bundler::Dsl do
   end
 
   describe "#gem" do
+    # rubocop:disable Naming/VariableNumber
     [:ruby, :ruby_18, :ruby_19, :ruby_20, :ruby_21, :ruby_22, :ruby_23, :ruby_24, :ruby_25, :ruby_26, :ruby_27,
      :ruby_30, :ruby_31, :mri, :mri_18, :mri_19, :mri_20, :mri_21, :mri_22, :mri_23, :mri_24, :mri_25, :mri_26,
      :mri_27, :mri_30, :mri_31, :jruby, :rbx, :truffleruby].each do |platform|
@@ -144,6 +145,7 @@ RSpec.describe Bundler::Dsl do
         subject.gem("foo", :platform => platform)
       end
     end
+    # rubocop:enable Naming/VariableNumber
 
     it "rejects invalid platforms" do
       expect { subject.gem("foo", :platform => :bogus) }.
diff --git a/spec/bundler/bundler/plugin_spec.rb b/spec/bundler/bundler/plugin_spec.rb
index 8a1a6cd97a..d28479cf31 100644
--- a/spec/bundler/bundler/plugin_spec.rb
+++ b/spec/bundler/bundler/plugin_spec.rb
@@ -280,12 +280,12 @@ RSpec.describe Bundler::Plugin do
       end
 
       Bundler::Plugin::Events.send(:reset)
-      Bundler::Plugin::Events.send(:define, :EVENT_1, "event-1")
-      Bundler::Plugin::Events.send(:define, :EVENT_2, "event-2")
+      Bundler::Plugin::Events.send(:define, :EVENT1, "event-1")
+      Bundler::Plugin::Events.send(:define, :EVENT2, "event-2")
 
-      allow(index).to receive(:hook_plugins).with(Bundler::Plugin::Events::EVENT_1).
+      allow(index).to receive(:hook_plugins).with(Bundler::Plugin::Events::EVENT1).
         and_return(["foo-plugin", "", nil])
-      allow(index).to receive(:hook_plugins).with(Bundler::Plugin::Events::EVENT_2).
+      allow(index).to receive(:hook_plugins).with(Bundler::Plugin::Events::EVENT2).
         and_return(["foo-plugin"])
       allow(index).to receive(:plugin_path).with("foo-plugin").and_return(path)
       allow(index).to receive(:load_paths).with("foo-plugin").and_return([])
@@ -303,33 +303,33 @@ RSpec.describe Bundler::Plugin do
 
     it "executes the hook" do
       expect do
-        Plugin.hook(Bundler::Plugin::Events::EVENT_1)
+        Plugin.hook(Bundler::Plugin::Events::EVENT1)
       end.to output("hook for event 1\n").to_stdout
     end
 
     context "single plugin declaring more than one hook" do
       let(:code) { <<-RUBY }
-        Bundler::Plugin::API.hook(Bundler::Plugin::Events::EVENT_1) {}
-        Bundler::Plugin::API.hook(Bundler::Plugin::Events::EVENT_2) {}
+        Bundler::Plugin::API.hook(Bundler::Plugin::Events::EVENT1) {}
+        Bundler::Plugin::API.hook(Bundler::Plugin::Events::EVENT2) {}
         puts "loaded"
       RUBY
 
       it "evals plugins.rb once" do
         expect do
-          Plugin.hook(Bundler::Plugin::Events::EVENT_1)
-          Plugin.hook(Bundler::Plugin::Events::EVENT_2)
+          Plugin.hook(Bundler::Plugin::Events::EVENT1)
+          Plugin.hook(Bundler::Plugin::Events::EVENT2)
         end.to output("loaded\n").to_stdout
       end
     end
 
     context "a block is passed" do
       let(:code) { <<-RUBY }
-        Bundler::Plugin::API.hook(Bundler::Plugin::Events::EVENT_1) { |&blk| blk.call }
+        Bundler::Plugin::API.hook(Bundler::Plugin::Events::EVENT1) { |&blk| blk.call }
       RUBY
 
       it "is passed to the hook" do
         expect do
-          Plugin.hook(Bundler::Plugin::Events::EVENT_1) { puts "win" }
+          Plugin.hook(Bundler::Plugin::Events::EVENT1) { puts "win" }
         end.to output("win\n").to_stdout
       end
     end
diff --git a/spec/bundler/install/gemfile/platform_spec.rb b/spec/bundler/install/gemfile/platform_spec.rb
index cf80844b02..68d794ed84 100644
--- a/spec/bundler/install/gemfile/platform_spec.rb
+++ b/spec/bundler/install/gemfile/platform_spec.rb
@@ -466,11 +466,9 @@ RSpec.describe "bundle install with platform conditionals" do
 
   it "does not attempt to install gems from other rubies when using --local" do
     bundle "config set --local force_ruby_platform true"
-    other_ruby_version_tag = RUBY_VERSION =~ /^1\.8/ ? :ruby_19 : :ruby_18
-
     gemfile <<-G
       source "#{file_uri_for(gem_repo1)}"
-      gem "some_gem", platform: :#{other_ruby_version_tag}
+      gem "some_gem", platform: :ruby_22
     G
 
     bundle "install --local"
diff --git a/test/rubygems/data/excon-0.7.7.gemspec.rz b/test/rubygems/data/excon-0.7.7.gemspec.rz
new file mode 100644
index 0000000000..159bd4bb1c
Binary files /dev/null and b/test/rubygems/data/excon-0.7.7.gemspec.rz differ
diff --git a/test/rubygems/data/null-type.gemspec.rz b/test/rubygems/data/pry-0.4.7.gemspec.rz
similarity index 100%
rename from test/rubygems/data/null-type.gemspec.rz
rename to test/rubygems/data/pry-0.4.7.gemspec.rz
diff --git a/test/rubygems/helper.rb b/test/rubygems/helper.rb
index c03ce7e6c6..75eed7be6b 100644
--- a/test/rubygems/helper.rb
+++ b/test/rubygems/helper.rb
@@ -1191,7 +1191,7 @@ Also, a list:
   # Is this test being run on a ruby/ruby repository?
   #
 
-  def testing_ruby_repo?
+  def ruby_repo?
     !ENV["GEM_COMMAND"].nil?
   end
 
diff --git a/test/rubygems/test_gem_commands_cert_command.rb b/test/rubygems/test_gem_commands_cert_command.rb
index 901bf5aed6..95b2fdf0ee 100644
--- a/test/rubygems/test_gem_commands_cert_command.rb
+++ b/test/rubygems/test_gem_commands_cert_command.rb
@@ -188,7 +188,6 @@ Added '/CN=alternate/DC=example'
     @build_ui = Gem::MockGemUi.new "#{passphrase}\n#{passphrase}"
 
     use_ui @build_ui do
-
       e = assert_raise Gem::CommandLineError do
         @cmd.execute
       end
@@ -266,7 +265,6 @@ Added '/CN=alternate/DC=example'
 
       assert_equal "Passphrase and passphrase confirmation don't match",
                    e.message
-
     end
 
     assert_path_not_exist File.join(@tempdir, 'gem-private_key.pem')
diff --git a/test/rubygems/test_gem_commands_sources_command.rb b/test/rubygems/test_gem_commands_sources_command.rb
index 7bca0f3803..f10347a6dc 100644
--- a/test/rubygems/test_gem_commands_sources_command.rb
+++ b/test/rubygems/test_gem_commands_sources_command.rb
@@ -161,7 +161,6 @@ class TestGemCommandsSourcesCommand < Gem::TestCase
     ui = Gem::MockGemUi.new("n")
 
     use_ui ui do
-
       assert_raise Gem::MockGemUi::TermError do
         @cmd.execute
       end
@@ -202,6 +201,56 @@ Error fetching http://beta-gems.example.com:
     assert_equal '', @ui.error
   end
 
+  def test_execute_add_existent_source_invalid_uri
+    spec_fetcher
+
+    uri = "https://u:p@example.com/specs.#{@marshal_version}.gz"
+
+    @cmd.handle_options %w[--add https://u:p@example.com]
+    @fetcher.data[uri] = proc do
+      raise Gem::RemoteFetcher::FetchError.new('it died', uri)
+    end
+
+    use_ui @ui do
+      assert_raise Gem::MockGemUi::TermError do
+        @cmd.execute
+      end
+    end
+
+    expected = <<-EOF
+Error fetching https://u:REDACTED@example.com:
+\tit died (https://u:REDACTED@example.com/specs.#{@marshal_version}.gz)
+    EOF
+
+    assert_equal expected, @ui.output
+    assert_equal '', @ui.error
+  end
+
+  def test_execute_add_existent_source_invalid_uri_with_error_by_chance_including_the_uri_password
+    spec_fetcher
+
+    uri = "https://u:secret@example.com/specs.#{@marshal_version}.gz"
+
+    @cmd.handle_options %w[--add https://u:secret@example.com]
+    @fetcher.data[uri] = proc do
+      raise Gem::RemoteFetcher::FetchError.new('it secretly died', uri)
+    end
+
+    use_ui @ui do
+      assert_raise Gem::MockGemUi::TermError do
+        @cmd.execute
+      end
+    end
+
+    expected = <<-EOF
+Error fetching https://u:REDACTED@example.com:
+\tit secretly died (https://u:REDACTED@example.com/specs.#{@marshal_version}.gz)
+    EOF
+
+    assert_equal expected, @ui.output
+    assert_equal '', @ui.error
+  end
+
   def test_execute_add_redundant_source
     spec_fetcher
 
diff --git a/test/rubygems/test_gem_ext_cargo_builder.rb b/test/rubygems/test_gem_ext_cargo_builder.rb
index 559a31f5ad..2da98c03e2 100644
--- a/test/rubygems/test_gem_ext_cargo_builder.rb
+++ b/test/rubygems/test_gem_ext_cargo_builder.rb
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 require_relative 'helper'
 require 'rubygems/ext'
 
@@ -7,12 +8,9 @@ class TestGemExtCargoBuilder < Gem::TestCase
     super
 
     @rust_envs = {
-      'CARGO_HOME' => File.join(@orig_env['HOME'], '.cargo'),
-      'RUSTUP_HOME' => File.join(@orig_env['HOME'], '.rustup'),
+      'CARGO_HOME' => ENV.fetch('CARGO_HOME', File.join(@orig_env['HOME'], '.cargo')),
+      'RUSTUP_HOME' => ENV.fetch('RUSTUP_HOME', File.join(@orig_env['HOME'], '.rustup')),
     }
-
-    system(@rust_envs, 'cargo', '-V', out: IO::NULL, err: [:child, :out])
-    pend 'cargo not present' unless $?.success?
   end
 
   def setup_rust_gem(name)
@@ -57,15 +55,35 @@ class TestGemExtCargoBuilder < Gem::TestCase
     end
 
     output = output.join "\n"
-
     bundle = File.join(@dest_path, "release/rust_ruby_example.#{RbConfig::CONFIG['DLEXT']}")
 
-    require(bundle)
-
-    assert_match RustRubyExample.reverse('hello'), 'olleh'
-
-    assert_match "Compiling rust_ruby_example v0.1.0", output
     assert_match "Finished release [optimized] target(s)", output
+    assert_ffi_handle bundle, 'Init_rust_ruby_example'
+  rescue Exception => e
+    pp output if output
+
+    raise(e)
+  end
+
+  def test_build_dev_profile
+    skip_unsupported_platforms!
+    setup_rust_gem "rust_ruby_example"
+
+    output = []
+
+    Dir.chdir @ext do
+      ENV.update(@rust_envs)
+      spec = Gem::Specification.new 'rust_ruby_example', '0.1.0'
+      builder = Gem::Ext::CargoBuilder.new(spec)
+      builder.profile = :dev
+      builder.build nil, @dest_path, output
+    end
+
+    output = output.join "\n"
+    bundle = File.join(@dest_path, "debug/rust_ruby_example.#{RbConfig::CONFIG['DLEXT']}")
+
+    assert_match "Finished dev [unoptimized + debuginfo] target(s)", output
+    assert_ffi_handle bundle, 'Init_rust_ruby_example'
   rescue Exception => e
     pp output if output
 
@@ -98,21 +116,23 @@ class TestGemExtCargoBuilder < Gem::TestCase
     skip_unsupported_platforms!
     setup_rust_gem "rust_ruby_example"
 
+    require 'open3'
+
     Dir.chdir @ext do
       require 'tmpdir'
 
-      gem = [@rust_envs, *ruby_with_rubygems_in_load_path, File.expand_path('../../bin/gem', __dir__)]
+      env_for_subprocess = @rust_envs.merge("GEM_HOME" => Gem.paths.home)
+      gem = [env_for_subprocess, *ruby_with_rubygems_in_load_path, File.expand_path('../../bin/gem', __dir__)]
 
       Dir.mktmpdir("rust_ruby_example") do |dir|
         built_gem = File.expand_path(File.join(dir, "rust_ruby_example.gem"))
         Open3.capture2e(*gem, "build", "rust_ruby_example.gemspec", "--output", built_gem)
         Open3.capture2e(*gem, "install", "--verbose", "--local", built_gem, *ARGV)
+
+        stdout_and_stderr_str, status = Open3.capture2e(env_for_subprocess, *ruby_with_rubygems_in_load_path, "-rrust_ruby_example", "-e", "puts 'Result: ' + RustRubyExample.reverse('hello world')")
+        assert status.success?, stdout_and_stderr_str
+        assert_match "Result: #{"hello world".reverse}", stdout_and_stderr_str
       end
-
-      stdout_and_stderr_str, status = Open3.capture2e(@rust_envs, *ruby_with_rubygems_in_load_path, "-rrust_ruby_example", "-e", "puts 'Result: ' + RustRubyExample.reverse('hello world')")
-
-      assert status.success?, stdout_and_stderr_str
-      assert_match "Result: #{"hello world".reverse}", stdout_and_stderr_str
     end
   end
 
@@ -123,7 +143,8 @@ class TestGemExtCargoBuilder < Gem::TestCase
     Dir.chdir @ext do
       require 'tmpdir'
 
-      gem = [@rust_envs, *ruby_with_rubygems_in_load_path, File.expand_path('../../bin/gem', __dir__)]
+      env_for_subprocess = @rust_envs.merge("GEM_HOME" => Gem.paths.home)
+      gem = [env_for_subprocess, *ruby_with_rubygems_in_load_path, File.expand_path('../../bin/gem', __dir__)]
 
       Dir.mktmpdir("custom_name") do |dir|
         built_gem = File.expand_path(File.join(dir, "custom_name.gem"))
@@ -131,17 +152,27 @@ class TestGemExtCargoBuilder < Gem::TestCase
         Open3.capture2e(*gem, "install", "--verbose", "--local", built_gem, *ARGV)
       end
 
-      stdout_and_stderr_str, status = Open3.capture2e(@rust_envs, *ruby_with_rubygems_in_load_path, "-rcustom_name", "-e", "puts 'Result: ' + CustomName.say_hello")
+      stdout_and_stderr_str, status = Open3.capture2e(env_for_subprocess, *ruby_with_rubygems_in_load_path, "-rcustom_name", "-e", "puts 'Result: ' + CustomName.say_hello")
 
       assert status.success?, stdout_and_stderr_str
       assert_match "Result: Hello world!", stdout_and_stderr_str
     end
   end
 
+  private
+
   def skip_unsupported_platforms!
     pend "jruby not supported" if java_platform?
     pend "truffleruby not supported (yet)" if RUBY_ENGINE == 'truffleruby'
     pend "mswin not supported (yet)" if /mswin/ =~ RUBY_PLATFORM && ENV.key?('GITHUB_ACTIONS')
-    pend "ruby.h is not provided by ruby repo" if testing_ruby_repo?
+    system(@rust_envs, 'cargo', '-V', out: IO::NULL, err: [:child, :out])
+    pend 'cargo not present' unless $?.success?
+    pend "ruby.h is not provided by ruby repo" if ruby_repo?
+  end
+
+  def assert_ffi_handle(bundle, name)
+    require 'fiddle'
+    dylib_handle = Fiddle.dlopen bundle
+    assert_nothing_raised { dylib_handle[name] }
   end
 end
diff --git a/test/rubygems/test_gem_ext_cargo_builder/custom_name/Cargo.lock b/test/rubygems/test_gem_ext_cargo_builder/custom_name/Cargo.lock
index d4499f08ff..cb1bdb3c61 100644
--- a/test/rubygems/test_gem_ext_cargo_builder/custom_name/Cargo.lock
+++ b/test/rubygems/test_gem_ext_cargo_builder/custom_name/Cargo.lock
@@ -83,9 +83,9 @@ checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
 [[package]]
 name = "clang-sys"
-version = "1.3.1"
+version = "1.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4cc00842eed744b858222c4c9faf7243aafc6d33f92f96935263ef4d8a41ce21"
+checksum = "5a050e2153c5be08febd6734e29298e844fdb0fa21aeddd63b4eb7baa106c69b"
 dependencies = [
  "glob",
  "libc",
@@ -193,18 +193,18 @@ dependencies = [
 
 [[package]]
 name = "log"
-version = "0.4.14"
+version = "0.4.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "51b9bbe6c47d51fc3e1a9b945965946b4c44142ab8792c50835a980d362c2710"
+checksum = "abb12e687cfb44aa40f41fc3978ef76448f9b6038cad6aef4259d3c095a2382e"
 dependencies = [
  "cfg-if",
 ]
 
 [[package]]
 name = "memchr"
-version = "2.4.1"
+version = "2.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "308cc39be01b73d0d18f82a0e7b2a3df85245f84af96fdddc5d202d27e47b86a"
+checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
 
 [[package]]
 name = "minimal-lexical"
@@ -214,13 +214,12 @@ checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
 
 [[package]]
 name = "nom"
-version = "7.1.0"
+version = "7.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1b1d11e1ef389c76fe5b81bcaf2ea32cf88b62bc494e19f493d0b30e7a930109"
+checksum = "a8903e5a29a317527874d0402f867152a3d21c908bb0b933e416c65e301d4c36"
 dependencies = [
  "memchr",
  "minimal-lexical",
- "version_check",
 ]
 
 [[package]]
@@ -231,37 +230,37 @@ checksum = "19b17cddbe7ec3f8bc800887bab5e717348c95ea2ca0b1bf0837fb964dc67099"
 
 [[package]]
 name = "pkg-config"
-version = "0.3.24"
+version = "0.3.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "58893f751c9b0412871a09abd62ecd2a00298c6c83befa223ef98c52aef40cbe"
+checksum = "1df8c4ec4b0627e53bdf214615ad287367e482558cf84b109250b37464dc03ae"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.36"
+version = "1.0.39"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c7342d5883fbccae1cc37a2353b09c87c9b0f3afd73f5fb9bba687a1f733b029"
+checksum = "c54b25569025b7fc9651de43004ae593a75ad88543b17178aa5e1b9c4f15f56f"
 dependencies = [
- "unicode-xid",
+ "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.15"
+version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "864d3e96a899863136fc6e99f3d7cae289dafe43bf2c5ac19b70df7210c0a145"
+checksum = "a1feb54ed693b93a84e14094943b84b7c4eae204c512b7ccb95ab0c66d278ad1"
 dependencies = [
  "proc-macro2",
 ]
 
 [[package]]
 name = "rb-sys"
-version = "0.9.0"
-source = "git+https://github.com/ianks/rb-sys?tag=v0.9.0#e4f00b9761af818d069a35d3802afdb15f5da5c3"
+version = "0.9.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f5465c5bd695ef70959b91b4ca9cfd515e9af012f6d9f0ae46f09fa4bcc3b722"
 dependencies = [
  "bindgen",
  "cc",
  "lazy_static",
- "libc",
  "linkify",
  "pkg-config",
  "shell-words",
@@ -269,9 +268,9 @@ dependencies = [
 
 [[package]]
 name = "regex"
-version = "1.5.5"
+version = "1.5.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1a11647b6b25ff05a515cb92c365cec08801e83423a235b51e231e1808747286"
+checksum = "d83f127d94bdbcda4c8cc2e50f6f84f4b611f69c902699ca385a39c3a75f9ff1"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -280,9 +279,9 @@ dependencies = [
 
 [[package]]
 name = "regex-syntax"
-version = "0.6.25"
+version = "0.6.26"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f497285884f3fcff424ffc933e56d7cbca511def0c9831a7f9b5f6153e3cc89b"
+checksum = "49b3de9ec5dc0a3417da371aab17d729997c15010e7fd24ff707773a33bddb64"
 
 [[package]]
 name = "rustc-hash"
@@ -326,35 +325,29 @@ dependencies = [
  "unicode-width",
 ]
 
+[[package]]
+name = "unicode-ident"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d22af068fba1eb5edcb4aea19d382b2a3deb4c8f9d475c589b6ada9e0fd493ee"
+
 [[package]]
 name = "unicode-width"
 version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3ed742d4ea2bd1176e236172c8429aaf54486e7ac098db29ffe6529e0ce50973"
 
-[[package]]
-name = "unicode-xid"
-version = "0.2.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8ccb82d61f80a663efe1f787a51b16b5a51e3314d6ac365b08639f52387b33f3"
-
 [[package]]
 name = "vec_map"
 version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f1bddf1187be692e79c5ffeab891132dfb0f236ed36a43c7ed39f1165ee20191"
 
-[[package]]
-name = "version_check"
-version = "0.9.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
-
 [[package]]
 name = "which"
-version = "4.2.4"
+version = "4.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2a5a7e487e921cf220206864a94a89b6c6905bfc19f1057fa26a4cb360e5c1d2"
+checksum = "5c4fb54e6113b6a8772ee41c3404fb0301ac79604489467e0a9ce1f3e97c24ae"
 dependencies = [
  "either",
  "lazy_static",
diff --git a/test/rubygems/test_gem_ext_cargo_builder/custom_name/Cargo.toml b/test/rubygems/test_gem_ext_cargo_builder/custom_name/Cargo.toml
index d2f56869f1..cbc9225140 100644
--- a/test/rubygems/test_gem_ext_cargo_builder/custom_name/Cargo.toml
+++ b/test/rubygems/test_gem_ext_cargo_builder/custom_name/Cargo.toml
@@ -6,5 +6,4 @@ version = "0.1.0"
 crate-type = ["cdylib"]
 
 [dependencies]
-# Needed until bindgen has the `allowlist_file` feature
-rb-sys = { git = "https://github.com/ianks/rb-sys", tag = "v0.9.0" }
+rb-sys = "0.9.4" 
diff --git a/test/rubygems/test_gem_ext_cargo_builder/custom_name/build.rb b/test/rubygems/test_gem_ext_cargo_builder/custom_name/build.rb
index 63ac2e5ce6..4d2f8488a4 100644
--- a/test/rubygems/test_gem_ext_cargo_builder/custom_name/build.rb
+++ b/test/rubygems/test_gem_ext_cargo_builder/custom_name/build.rb
@@ -15,7 +15,7 @@ gemspec = File.expand_path('custom_name.gemspec', __dir__)
 
 Dir.mktmpdir("custom_name") do |dir|
   built_gem = File.expand_path(File.join(dir, "custom_name.gem"))
-  system(*gem, "build", gemspec, "--output", built_gem)
-  system(*gem, "install", "--verbose", "--local", built_gem, *ARGV)
+  system *gem, "build", gemspec, "--output", built_gem
+  system *gem, "install", "--verbose", "--local", built_gem, *ARGV
   system %q(ruby -rcustom_name -e "puts 'Result: ' + CustomName.say_hello")
 end
diff --git a/test/rubygems/test_gem_ext_cargo_builder/rust_ruby_example/Cargo.lock b/test/rubygems/test_gem_ext_cargo_builder/rust_ruby_example/Cargo.lock
index 568a01ddbd..edbeda8420 100644
--- a/test/rubygems/test_gem_ext_cargo_builder/rust_ruby_example/Cargo.lock
+++ b/test/rubygems/test_gem_ext_cargo_builder/rust_ruby_example/Cargo.lock
@@ -83,9 +83,9 @@ checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
 [[package]]
 name = "clang-sys"
-version = "1.3.1"
+version = "1.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4cc00842eed744b858222c4c9faf7243aafc6d33f92f96935263ef4d8a41ce21"
+checksum = "5a050e2153c5be08febd6734e29298e844fdb0fa21aeddd63b4eb7baa106c69b"
 dependencies = [
  "glob",
  "libc",
@@ -186,18 +186,18 @@ dependencies = [
 
 [[package]]
 name = "log"
-version = "0.4.14"
+version = "0.4.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "51b9bbe6c47d51fc3e1a9b945965946b4c44142ab8792c50835a980d362c2710"
+checksum = "abb12e687cfb44aa40f41fc3978ef76448f9b6038cad6aef4259d3c095a2382e"
 dependencies = [
  "cfg-if",
 ]
 
 [[package]]
 name = "memchr"
-version = "2.4.1"
+version = "2.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "308cc39be01b73d0d18f82a0e7b2a3df85245f84af96fdddc5d202d27e47b86a"
+checksum = "2dffe52ecf27772e601905b7522cb4ef790d2cc203488bbd0e2fe85fcb74566d"
 
 [[package]]
 name = "minimal-lexical"
@@ -207,13 +207,12 @@ checksum = "68354c5c6bd36d73ff3feceb05efa59b6acb7626617f4962be322a825e61f79a"
 
 [[package]]
 name = "nom"
-version = "7.1.0"
+version = "7.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1b1d11e1ef389c76fe5b81bcaf2ea32cf88b62bc494e19f493d0b30e7a930109"
+checksum = "a8903e5a29a317527874d0402f867152a3d21c908bb0b933e416c65e301d4c36"
 dependencies = [
  "memchr",
  "minimal-lexical",
- "version_check",
 ]
 
 [[package]]
@@ -224,37 +223,37 @@ checksum = "19b17cddbe7ec3f8bc800887bab5e717348c95ea2ca0b1bf0837fb964dc67099"
 
 [[package]]
 name = "pkg-config"
-version = "0.3.24"
+version = "0.3.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "58893f751c9b0412871a09abd62ecd2a00298c6c83befa223ef98c52aef40cbe"
+checksum = "1df8c4ec4b0627e53bdf214615ad287367e482558cf84b109250b37464dc03ae"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.36"
+version = "1.0.39"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c7342d5883fbccae1cc37a2353b09c87c9b0f3afd73f5fb9bba687a1f733b029"
+checksum = "c54b25569025b7fc9651de43004ae593a75ad88543b17178aa5e1b9c4f15f56f"
 dependencies = [
- "unicode-xid",
+ "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.15"
+version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "864d3e96a899863136fc6e99f3d7cae289dafe43bf2c5ac19b70df7210c0a145"
+checksum = "a1feb54ed693b93a84e14094943b84b7c4eae204c512b7ccb95ab0c66d278ad1"
 dependencies = [
  "proc-macro2",
 ]
 
 [[package]]
 name = "rb-sys"
-version = "0.9.0"
-source = "git+https://github.com/ianks/rb-sys?tag=v0.9.0#e4f00b9761af818d069a35d3802afdb15f5da5c3"
+version = "0.9.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f5465c5bd695ef70959b91b4ca9cfd515e9af012f6d9f0ae46f09fa4bcc3b722"
 dependencies = [
  "bindgen",
  "cc",
  "lazy_static",
- "libc",
  "linkify",
  "pkg-config",
  "shell-words",
@@ -262,9 +261,9 @@ dependencies = [
 
 [[package]]
 name = "regex"
-version = "1.5.5"
+version = "1.5.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1a11647b6b25ff05a515cb92c365cec08801e83423a235b51e231e1808747286"
+checksum = "d83f127d94bdbcda4c8cc2e50f6f84f4b611f69c902699ca385a39c3a75f9ff1"
 dependencies = [
  "aho-corasick",
  "memchr",
@@ -273,9 +272,9 @@ dependencies = [
 
 [[package]]
 name = "regex-syntax"
-version = "0.6.25"
+version = "0.6.26"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f497285884f3fcff424ffc933e56d7cbca511def0c9831a7f9b5f6153e3cc89b"
+checksum = "49b3de9ec5dc0a3417da371aab17d729997c15010e7fd24ff707773a33bddb64"
 
 [[package]]
 name = "rust_ruby_example"
@@ -326,35 +325,29 @@ dependencies = [
  "unicode-width",
 ]
 
+[[package]]
+name = "unicode-ident"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d22af068fba1eb5edcb4aea19d382b2a3deb4c8f9d475c589b6ada9e0fd493ee"
+
 [[package]]
 name = "unicode-width"
 version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3ed742d4ea2bd1176e236172c8429aaf54486e7ac098db29ffe6529e0ce50973"
 
-[[package]]
-name = "unicode-xid"
-version = "0.2.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8ccb82d61f80a663efe1f787a51b16b5a51e3314d6ac365b08639f52387b33f3"
-
 [[package]]
 name = "vec_map"
 version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f1bddf1187be692e79c5ffeab891132dfb0f236ed36a43c7ed39f1165ee20191"
 
-[[package]]
-name = "version_check"
-version = "0.9.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
-
 [[package]]
 name = "which"
-version = "4.2.4"
+version = "4.2.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2a5a7e487e921cf220206864a94a89b6c6905bfc19f1057fa26a4cb360e5c1d2"
+checksum = "5c4fb54e6113b6a8772ee41c3404fb0301ac79604489467e0a9ce1f3e97c24ae"
 dependencies = [
  "either",
  "lazy_static",
diff --git a/test/rubygems/test_gem_ext_cargo_builder/rust_ruby_example/Cargo.toml b/test/rubygems/test_gem_ext_cargo_builder/rust_ruby_example/Cargo.toml
index 4d1337bd7b..3aec0690b0 100644
--- a/test/rubygems/test_gem_ext_cargo_builder/rust_ruby_example/Cargo.toml
+++ b/test/rubygems/test_gem_ext_cargo_builder/rust_ruby_example/Cargo.toml
@@ -6,5 +6,4 @@ version = "0.1.0"
 crate-type = ["cdylib"]
 
 [dependencies]
-# Needed until bindgen has the `allowlist_file` feature
-rb-sys = { git = "https://github.com/ianks/rb-sys", tag = "v0.9.0" }
+rb-sys = "0.9.4"
diff --git a/test/rubygems/test_gem_ext_cargo_builder_link_flag_converter.rb b/test/rubygems/test_gem_ext_cargo_builder_link_flag_converter.rb
new file mode 100644
index 0000000000..3abcb83fa9
--- /dev/null
+++ b/test/rubygems/test_gem_ext_cargo_builder_link_flag_converter.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+require_relative 'helper'
+require 'rubygems/ext'
+require 'rubygems/ext/cargo_builder/link_flag_converter'
+
+class TestGemExtCargoBuilderLinkFlagConverter < Gem::TestCase
+  CASES = {
+    test_search_path_basic:             ["-L/usr/local/lib", ["-L", "native=/usr/local/lib"]],
+    test_search_path_space:             ["-L /usr/local/lib", ["-L", "native=/usr/local/lib"]],
+    test_search_path_space_in_path:     ["-L/usr/local/my\ lib", ["-L", "native=/usr/local/my\ lib"]],
+    test_simple_lib:                    ["-lfoo", ["-l", "foo"]],
+    test_lib_with_nonascii:             ["-lws2_32", ["-l", "ws2_32"]],
+    test_simple_lib_space:              ["-l foo", ["-l", "foo"]],
+    test_verbose_lib_space:             ["--library=foo", ["-l", "foo"]],
+    test_libstatic_with_colon:          ["-l:libssp.a", ["-l", "static=ssp"]],
+    test_libstatic_with_colon_space:    ["-l :libssp.a", ["-l", "static=ssp"]],
+    test_unconventional_lib_with_colon: ["-l:ssp.a", ["-C", "link_arg=-l:ssp.a"]],
+    test_dylib_with_colon_space:        ["-l :libssp.dylib", ["-l", "dylib=ssp"]],
+    test_so_with_colon_space:           ["-l :libssp.so", ["-l", "dylib=ssp"]],
+    test_dll_with_colon_space:          ["-l :libssp.dll", ["-l", "dylib=ssp"]],
+    test_framework:                     ["-F/some/path", ["-l", "framework=/some/path"]],
+    test_framework_space:               ["-F /some/path", ["-l", "framework=/some/path"]],
+    test_non_lib_dash_l:                ["test_rubygems_20220413-976-lemgf9/prefix", ["-C", "link_arg=test_rubygems_20220413-976-lemgf9/prefix"]],
+  }.freeze
+
+  CASES.each do |test_name, (arg, expected)|
+    raise "duplicate test name" if instance_methods.include?(test_name)
+
+    define_method(test_name) do
+      assert_equal(expected, Gem::Ext::CargoBuilder::LinkFlagConverter.convert(arg))
+    end
+  end
+end
diff --git a/test/rubygems/test_gem_ext_cargo_builder_unit.rb b/test/rubygems/test_gem_ext_cargo_builder_unit.rb
new file mode 100644
index 0000000000..f6712e44a1
--- /dev/null
+++ b/test/rubygems/test_gem_ext_cargo_builder_unit.rb
@@ -0,0 +1,75 @@
+# frozen_string_literal: true
+
+require_relative 'helper'
+require 'rubygems/ext'
+
+class TestGemExtCargoBuilderUnit < Gem::TestCase
+  def test_cargo_command_passes_args
+    skip_unsupported_platforms!
+    spec = Gem::Specification.new 'rust_ruby_example', '0.1.0'
+    builder = Gem::Ext::CargoBuilder.new(spec)
+    command = builder.cargo_command(Dir.pwd, @tempdir, ['--all-features'])
+
+    assert_includes command, '--all-features'
+  end
+
+  def test_cargo_command_locks_in_release_profile
+    skip_unsupported_platforms!
+    spec = Gem::Specification.new 'rust_ruby_example', '0.1.0'
+    builder = Gem::Ext::CargoBuilder.new(spec)
+    builder.profile = :release
+    command = builder.cargo_command(Dir.pwd, @tempdir)
+
+    assert_includes command, '--locked'
+  end
+
+  def test_cargo_command_does_not_lock_in_dev_profile
+    skip_unsupported_platforms!
+    spec = Gem::Specification.new 'rust_ruby_example', '0.1.0'
+    builder = Gem::Ext::CargoBuilder.new(spec)
+    builder.profile = :dev
+    command = builder.cargo_command(Dir.pwd, @tempdir)
+
+    assert_not_includes command, '--locked'
+  end
+
+  def test_cargo_command_passes_respects_cargo_env_var
+    skip_unsupported_platforms!
+    old_cargo = ENV['CARGO']
+    ENV['CARGO'] = 'mycargo'
+    spec = Gem::Specification.new 'rust_ruby_example', '0.1.0'
+    builder = Gem::Ext::CargoBuilder.new(spec)
+    command = builder.cargo_command(Dir.pwd, @tempdir)
+
+    assert_includes command, 'mycargo'
+  ensure
+    ENV['CARGO'] = old_cargo
+  end
+
+  def test_build_env_includes_rbconfig
+    skip_unsupported_platforms!
+    spec = Gem::Specification.new 'rust_ruby_example', '0.1.0'
+    builder = Gem::Ext::CargoBuilder.new(spec)
+    env = builder.build_env
+
+    assert_equal env.fetch('RBCONFIG_RUBY_SO_NAME'), RbConfig::CONFIG['RUBY_SO_NAME']
+  end
+
+  def test_cargo_command_passes_respects_cargo_build_target
+    skip_unsupported_platforms!
+    old_cargo = ENV['CARGO_BUILD_TARGET']
+    ENV['CARGO_BUILD_TARGET'] = 'x86_64-unknown-linux-gnu'
+    spec = Gem::Specification.new 'rust_ruby_example', '0.1.0'
+    builder = Gem::Ext::CargoBuilder.new(spec)
+    command = builder.cargo_command(Dir.pwd, @tempdir, ['--locked'])
+
+    assert_includes command, '--target'
+    assert_includes command, 'x86_64-unknown-linux-gnu'
+  ensure
+    ENV['CARGO_BUILD_TARGET'] = old_cargo
+  end
+
+  def skip_unsupported_platforms!
+    pend "jruby not supported" if java_platform?
+  end
+end
diff --git a/test/rubygems/test_gem_ext_ext_conf_builder.rb b/test/rubygems/test_gem_ext_ext_conf_builder.rb
index 10a544cbbc..38d07aa52b 100644
--- a/test/rubygems/test_gem_ext_ext_conf_builder.rb
+++ b/test/rubygems/test_gem_ext_ext_conf_builder.rb
@@ -50,7 +50,6 @@ class TestGemExtExtConfBuilder < Gem::TestCase
     end
 
     configure_args do
-
       File.open File.join(@ext, 'extconf.rb'), 'w' do |extconf|
         extconf.puts "require 'mkmf'\ncreate_makefile 'foo'"
       end
diff --git a/test/rubygems/test_gem_request_set_gem_dependency_api.rb b/test/rubygems/test_gem_request_set_gem_dependency_api.rb
index cc4f99df91..14f51575e4 100644
--- a/test/rubygems/test_gem_request_set_gem_dependency_api.rb
+++ b/test/rubygems/test_gem_request_set_gem_dependency_api.rb
@@ -758,13 +758,11 @@ end
     with_engine_version 'jruby', '1.7.6' do
       assert @gda.ruby RUBY_VERSION,
                :engine => 'jruby', :engine_version => '1.7.6'
-
     end
 
     with_engine_version 'truffleruby', '1.0.0-rc11' do
       assert @gda.ruby RUBY_VERSION,
                :engine => 'truffleruby', :engine_version => '1.0.0-rc11'
-
     end
   end
 
diff --git a/test/rubygems/test_gem_specification.rb b/test/rubygems/test_gem_specification.rb
index 8591957245..928fd571ed 100644
--- a/test/rubygems/test_gem_specification.rb
+++ b/test/rubygems/test_gem_specification.rb
@@ -1068,7 +1068,15 @@ dependencies: []
   end
 
   def test_handles_private_null_type
-    path = File.expand_path 'data/null-type.gemspec.rz', __dir__
+    path = File.expand_path 'data/pry-0.4.7.gemspec.rz', __dir__
+
+    data = Marshal.load Gem::Util.inflate(Gem.read_binary(path))
+
+    assert_instance_of Gem::Specification, data
+  end
+
+  def test_handles_dependencies_with_syck_requirements_bug
+    path = File.expand_path 'data/excon-0.7.7.gemspec.rz', __dir__
 
     data = Marshal.load Gem::Util.inflate(Gem.read_binary(path))
 
@@ -3006,7 +3014,6 @@ Please report a bug if this causes problems.
 
       @a1.homepage = 'https://rubygems.org'
       assert_equal true, @a1.validate
-
     end
   end
 
diff --git a/test/rubygems/test_require.rb b/test/rubygems/test_require.rb
index 2b63bc600a..3e393a4df3 100644
--- a/test/rubygems/test_require.rb
+++ b/test/rubygems/test_require.rb
@@ -444,7 +444,7 @@ class TestGemRequire < Gem::TestCase
   end
 
   def test_realworld_default_gem
-    omit "this test can't work under ruby-core setup" if testing_ruby_repo?
+    omit "this test can't work under ruby-core setup" if ruby_repo?
 
     cmd = <<-RUBY
       $stderr = $stdout
@@ -457,7 +457,7 @@ class TestGemRequire < Gem::TestCase
   end
 
   def test_realworld_upgraded_default_gem
-    omit "this test can't work under ruby-core setup" if testing_ruby_repo?
+    omit "this test can't work under ruby-core setup" if ruby_repo?
 
     newer_json = util_spec("json", "999.99.9", nil, ["lib/json.rb"])
     install_gem newer_json
diff --git a/tool/bundler/dev_gems.rb b/tool/bundler/dev_gems.rb
index 8a858c1e67..0e5e681f73 100644
--- a/tool/bundler/dev_gems.rb
+++ b/tool/bundler/dev_gems.rb
@@ -6,11 +6,6 @@ gem "rdoc", "6.2.0" # 6.2.1 is required > Ruby 2.3
 gem "test-unit", "~> 3.0"
 gem "rake", "~> 13.0"
 
-group :lint do
-  gem "rubocop", "~> 0.80.1"
-  gem "rubocop-performance", "~> 1.5.2"
-end
-
 gem "webrick", "~> 1.6"
 gem "parallel_tests", "~> 2.29"
 gem "parallel", "1.19.2" # 1.20+ is required > Ruby 2.3
diff --git a/tool/bundler/dev_gems.rb.lock b/tool/bundler/dev_gems.rb.lock
index 3cb74d83f4..4b9ca32fa5 100644
--- a/tool/bundler/dev_gems.rb.lock
+++ b/tool/bundler/dev_gems.rb.lock
@@ -1,23 +1,16 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    ast (2.4.2)
     diff-lcs (1.5.0)
     hpricot (0.8.6)
-    jaro_winkler (1.5.4)
-    jaro_winkler (1.5.4-java)
     mustache (1.1.1)
     parallel (1.19.2)
     parallel_tests (2.32.0)
       parallel
-    parser (3.1.0.0)
-      ast (~> 2.4.1)
     power_assert (2.0.1)
-    rainbow (3.1.1)
     rake (13.0.6)
     rdiscount (2.2.0.2)
     rdoc (6.2.0)
-    rexml (3.2.5)
     ronn (0.7.3)
       hpricot (>= 0.8.2)
       mustache (>= 0.7.0)
@@ -31,20 +24,8 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.11.0)
     rspec-support (3.11.0)
-    rubocop (0.80.1)
-      jaro_winkler (~> 1.5.1)
-      parallel (~> 1.10)
-      parser (>= 2.7.0.1)
-      rainbow (>= 2.2.2, < 4.0)
-      rexml
-      ruby-progressbar (~> 1.7)
-      unicode-display_width (>= 1.4.0, < 1.7)
-    rubocop-performance (1.5.2)
-      rubocop (>= 0.71.0)
-    ruby-progressbar (1.11.0)
     test-unit (3.5.3)
       power_assert
-    unicode-display_width (1.6.1)
     uri (0.10.1)
     webrick (1.7.0)
 
@@ -65,8 +46,6 @@ DEPENDENCIES
   rspec-core (~> 3.8)
   rspec-expectations (~> 3.8)
   rspec-mocks (~> 3.11.1)
-  rubocop (~> 0.80.1)
-  rubocop-performance (~> 1.5.2)
   test-unit (~> 3.0)
   uri (~> 0.10.1)
   webrick (~> 1.6)