diff --git a/Library/Homebrew/Gemfile b/Library/Homebrew/Gemfile
index f13e5f3bbf..80ff8819be 100644
--- a/Library/Homebrew/Gemfile
+++ b/Library/Homebrew/Gemfile
@@ -21,6 +21,7 @@ gem "simplecov", require: false
 gem "sorbet", require: false
 gem "sorbet-runtime", require: false
 gem "tapioca", require: false
+gem "warning", require: false
 
 # vendored gems
 gem "activesupport"
diff --git a/Library/Homebrew/Gemfile.lock b/Library/Homebrew/Gemfile.lock
index e2573ae3a2..841e67d3aa 100644
--- a/Library/Homebrew/Gemfile.lock
+++ b/Library/Homebrew/Gemfile.lock
@@ -163,6 +163,7 @@ GEM
       unf_ext
     unf_ext (0.0.7.7)
     unicode-display_width (2.0.0)
+    warning (1.1.0)
     webrick (1.7.0)
     webrobots (0.1.2)
     zeitwerk (2.4.2)
@@ -200,6 +201,7 @@ DEPENDENCIES
   sorbet-runtime
   sorbet-runtime-stub
   tapioca
+  warning
 
 BUNDLED WITH
    1.17.3
diff --git a/Library/Homebrew/style.rb b/Library/Homebrew/style.rb
index 4e3b80942f..32a46a3471 100644
--- a/Library/Homebrew/style.rb
+++ b/Library/Homebrew/style.rb
@@ -72,6 +72,8 @@ module Homebrew
       end
     end
 
+    RUBOCOP = (HOMEBREW_LIBRARY_PATH/"utils/rubocop.rb").freeze
+
     def run_rubocop(files, output_type,
                     fix: false, except_cops: nil, only_cops: nil, display_cop_names: false, reset_cache: false,
                     debug: false, verbose: false)
@@ -134,11 +136,6 @@ module Homebrew
 
       FileUtils.rm_rf cache_env["XDG_CACHE_HOME"] if reset_cache
 
-      ruby_args = [
-        "-S",
-        "rubocop",
-      ].compact.freeze
-
       case output_type
       when :print
         args << "--debug" if debug
@@ -149,11 +146,11 @@ module Homebrew
 
         args << "--color" if Tty.color?
 
-        system cache_env, RUBY_PATH, *ruby_args, *args
+        system cache_env, RUBY_PATH, RUBOCOP, *args
         $CHILD_STATUS.success?
       when :json
         result = system_command RUBY_PATH,
-                                args: [*ruby_args, "--format", "json", *args],
+                                args: [RUBOCOP, "--format", "json", *args],
                                 env:  cache_env
         json = json_result!(result)
         json["files"]
diff --git a/Library/Homebrew/utils/rubocop.rb b/Library/Homebrew/utils/rubocop.rb
new file mode 100755
index 0000000000..92479fc410
--- /dev/null
+++ b/Library/Homebrew/utils/rubocop.rb
@@ -0,0 +1,19 @@
+#!/usr/bin/env ruby
+# typed: false
+# frozen_string_literal: true
+
+require "warning"
+
+warnings = [
+  "warning: parser/current is loading parser/ruby26, which recognizes",
+  "warning: 2.6.6-compliant syntax, but you are running 2.6.3.",
+  "warning: please see https://github.com/whitequark/parser#compatibility-with-ruby-mri.",
+]
+
+warnings.each do |warning|
+  Warning.ignore Regexp.new(warning)
+end
+
+require "rubocop"
+
+exit RuboCop::CLI.new.run
diff --git a/Library/Homebrew/vendor/bundle/ruby/2.6.0/gems/warning-1.1.0/lib/warning.rb b/Library/Homebrew/vendor/bundle/ruby/2.6.0/gems/warning-1.1.0/lib/warning.rb
new file mode 100644
index 0000000000..52177b3c5d
--- /dev/null
+++ b/Library/Homebrew/vendor/bundle/ruby/2.6.0/gems/warning-1.1.0/lib/warning.rb
@@ -0,0 +1,248 @@
+require 'monitor'
+
+module Warning
+  module Processor
+    # Map of symbols to regexps for warning messages to ignore.
+    IGNORE_MAP = {
+      ambiguous_slash: /: warning: ambiguous first argument; put parentheses or a space even after `\/' operator\n\z/,
+      arg_prefix: /: warning: `[&\*]' interpreted as argument prefix\n\z/,
+      bignum: /: warning: constant ::Bignum is deprecated\n\z/,
+      fixnum: /: warning: constant ::Fixnum is deprecated\n\z/,
+      method_redefined: /: warning: method redefined; discarding old .+\n\z|: warning: previous definition of .+ was here\n\z/,
+      missing_gvar: /: warning: global variable `\$.+' not initialized\n\z/,
+      missing_ivar: /: warning: instance variable @.+ not initialized\n\z/,
+      not_reached: /: warning: statement not reached\n\z/,
+      shadow: /: warning: shadowing outer local variable - \w+\n\z/,
+      unused_var: /: warning: assigned but unused variable - \w+\n\z/,
+      useless_operator: /: warning: possibly useless use of [><!=]+ in void context\n\z/,
+      keyword_separation: /: warning: (?:Using the last argument (?:for `.+' )?as keyword parameters is deprecated; maybe \*\* should be added to the call|Passing the keyword argument (?:for `.+' )?as the last hash parameter is deprecated|Splitting the last argument (?:for `.+' )?into positional and keyword parameters is deprecated|The called method (?:`.+' )?is defined here)\n\z/,
+      safe: /: warning: (?:rb_safe_level_2_warning|rb_safe_level|rb_set_safe_level_force|rb_set_safe_level|rb_secure|rb_insecure_operation|rb_check_safe_obj|\$SAFE) will (?:be removed|become a normal global variable) in Ruby 3\.0\n\z/,
+      taint: /: warning: (?:rb_error_untrusted|rb_check_trusted|Pathname#taint|Pathname#untaint|rb_env_path_tainted|Object#tainted\?|Object#taint|Object#untaint|Object#untrusted\?|Object#untrust|Object#trust|rb_obj_infect|rb_tainted_str_new|rb_tainted_str_new_cstr) is deprecated and will be removed in Ruby 3\.2\.\n\z/,
+      mismatched_indentations: /: warning: mismatched indentations at '.+' with '.+' at \d+\n\z/,
+    }
+
+    # Map of action symbols to procs that return the symbol
+    ACTION_PROC_MAP = {
+      default: proc{|_| :default},
+      backtrace: proc{|_| :backtrace},
+      raise: proc{|_| :raise},
+    }
+    private_constant :ACTION_PROC_MAP
+
+    # Clear all current ignored warnings, warning processors, and duplicate check cache.
+    # Also disables deduplicating warnings if that is currently enabled.
+    def clear
+      synchronize do
+        @ignore.clear
+        @process.clear
+        @dedup = false
+      end
+    end
+
+    # Deduplicate warnings, supress warning messages if the same warning message
+    # has already occurred.  Note that this can lead to unbounded memory use
+    # if unique warnings are generated.
+    def dedup
+      @dedup = {}
+    end
+
+    def freeze
+      @ignore.freeze
+      @process.freeze
+      super
+    end
+    
+    # Ignore any warning messages matching the given regexp, if they
+    # start with the given path.
+    # The regexp can also be one of the following symbols (or an array including them), which will
+    # use an appropriate regexp for the given warning:
+    #
+    # :arg_prefix :: Ignore warnings when using * or & as an argument prefix
+    # :ambiguous_slash :: Ignore warnings for things like <tt>method /regexp/</tt>
+    # :bignum :: Ignore warnings when referencing the ::Bignum constant.
+    # :fixnum :: Ignore warnings when referencing the ::Fixnum constant.
+    # :keyword_separation :: Ignore warnings related to keyword argument separation.
+    # :method_redefined :: Ignore warnings when defining a method in a class/module where a
+    #                      method of the same name was already defined in that class/module.
+    # :missing_gvar :: Ignore warnings for accesses to global variables
+    #                  that have not yet been initialized
+    # :missing_ivar :: Ignore warnings for accesses to instance variables
+    #                  that have not yet been initialized
+    # :not_reached :: Ignore statement not reached warnings.
+    # :safe :: Ignore warnings related to $SAFE and related C-API functions.
+    # :shadow :: Ignore warnings related to shadowing outer local variables.
+    # :taint :: Ignore warnings related to taint and related methods and C-API functions.
+    # :unused_var :: Ignore warnings for unused variables.
+    # :useless_operator :: Ignore warnings when using operators such as == and > when the
+    #                      result is not used.
+    #
+    # Examples:
+    #
+    #   # Ignore all uninitialized instance variable warnings
+    #   Warning.ignore(/instance variable @\w+ not initialized/)
+    #
+    #   # Ignore all uninitialized instance variable warnings in current file
+    #   Warning.ignore(/instance variable @\w+ not initialized/, __FILE__)
+    #
+    #   # Ignore all uninitialized instance variable warnings in current file
+    #   Warning.ignore(:missing_ivar, __FILE__)
+    #
+    #   # Ignore all uninitialized instance variable and method redefined warnings in current file
+    #   Warning.ignore([:missing_ivar, :method_redefined],  __FILE__)
+    def ignore(regexp, path='')
+      unless regexp = convert_regexp(regexp)
+        raise TypeError, "first argument to Warning.ignore should be Regexp, Symbol, or Array of Symbols, got #{regexp.inspect}"
+      end
+
+      synchronize do 
+        @ignore << [path, regexp]
+      end
+      nil
+    end
+
+    # Handle all warnings starting with the given path, instead of
+    # the default behavior of printing them to $stderr. Examples:
+    #
+    #   # Write warning to LOGGER at level warning
+    #   Warning.process do |warning|
+    #     LOGGER.warning(warning)
+    #   end
+    #
+    #   # Write warnings in the current file to LOGGER at level error level
+    #   Warning.process(__FILE__) do |warning|
+    #     LOGGER.error(warning)
+    #   end
+    #
+    # The block can return one of the following symbols:
+    #
+    # :default :: Take the default action (call super, printing to $stderr).
+    # :backtrace :: Take the default action (call super, printing to $stderr),
+    #               and also print the backtrace.
+    # :raise :: Raise a RuntimeError with the warning as the message.
+    #
+    # If the block returns anything else, it is assumed the block completely handled
+    # the warning and takes no other action.
+    #
+    # Instead of passing a block, you can pass a hash of actions to take for specific
+    # warnings, using regexp as keys and a callable objects as values:
+    #
+    #   Warning.ignore(__FILE__,
+    #     /instance variable @\w+ not initialized/ => proc do |warning|
+    #       LOGGER.warning(warning)
+    #     end,
+    #     /global variable `\$\w+' not initialized/ => proc do |warning|
+    #       LOGGER.error(warning)
+    #     end
+    #   )
+    #
+    # Instead of passing a regexp as a key, you can pass a symbol that is recognized
+    # by Warning.ignore.  Instead of passing a callable object as a value, you can
+    # pass a symbol, which will be treated as a callable object that returns that symbol:
+    #
+    #   Warning.process(__FILE__, :missing_ivar=>:backtrace, :keyword_separation=>:raise)
+    def process(path='', actions=nil, &block)
+      if block
+        if actions
+          raise ArgumentError, "cannot pass both actions and block to Warning.process"
+        end
+      elsif actions
+        block = {}
+        actions.each do |regexp, value|
+          unless regexp = convert_regexp(regexp)
+            raise TypeError, "action provided to Warning.process should be Regexp, Symbol, or Array of Symbols, got #{regexp.inspect}"
+          end
+
+          block[regexp] = ACTION_PROC_MAP[value] || value
+        end
+      else
+        raise ArgumentError, "must pass either actions or block to Warning.process"
+      end
+
+      synchronize do
+        @process << [path, block]
+        @process.sort_by!(&:first)
+        @process.reverse!
+      end
+      nil
+    end
+
+    # Handle ignored warnings and warning processors.  If the warning is
+    # not ignored, is not a duplicate warning (if checking for duplicates)
+    # and there is no warning processor setup for the warning
+    # string, then use the default behavior of writing to $stderr.
+    def warn(str)
+      synchronize{@ignore.dup}.each do |path, regexp|
+        if str.start_with?(path) && str =~ regexp
+          return
+        end
+      end
+
+      if @dedup
+        if synchronize{@dedup[str]}
+          return
+        end
+
+        synchronize{@dedup[str] = true}
+      end
+
+      action = catch(:action) do
+        synchronize{@process.dup}.each do |path, block|
+          if str.start_with?(path)
+            if block.is_a?(Hash)
+              block.each do |regexp, blk|
+                if str =~ regexp
+                  throw :action, blk.call(str)
+                end
+              end
+            else
+              throw :action, block.call(str)
+            end
+          end
+        end
+
+        :default
+      end
+
+      case action
+      when :default
+        super
+      when :backtrace
+        super
+        $stderr.puts caller
+      when :raise
+        raise str
+      else
+        # nothing
+      end
+
+      nil
+    end
+
+    private
+
+    # Convert the given Regexp, Symbol, or Array of Symbols into a Regexp.
+    def convert_regexp(regexp)
+      case regexp
+      when Regexp
+        regexp
+      when Symbol
+        IGNORE_MAP.fetch(regexp)
+      when Array
+        Regexp.union(regexp.map{|re| IGNORE_MAP.fetch(re)})
+      else
+        # nothing
+      end
+    end
+
+    def synchronize(&block)
+      @monitor.synchronize(&block)
+    end
+  end
+
+  @ignore = []
+  @process = []
+  @dedup = false
+  @monitor = Monitor.new
+
+  extend Processor
+end