formula: add fuzzy_search method

Library/Homebrew/brew.sh

@@ -583,14 +583,11 @@ then
 
   # Don't allow non-developers to customise Ruby warnings.
   unset HOMEBREW_RUBY_WARNINGS
-
-  # Disable Ruby options we don't need.
-  RUBY_DISABLE_OPTIONS="--disable=did_you_mean,rubyopt"
-else
-  # Don't disable did_you_mean for developers as it's useful.
-  RUBY_DISABLE_OPTIONS="--disable=rubyopt"
 fi
 
+# Disable Ruby options we don't need.
+RUBY_DISABLE_OPTIONS="--disable=rubyopt"
+
 if [[ -z "${HOMEBREW_RUBY_WARNINGS}" ]]
 then
   export HOMEBREW_RUBY_WARNINGS="-W1"

Library/Homebrew/formula.rb

@@ -2,6 +2,7 @@
 # frozen_string_literal: true
 
 require "cache_store"
+require "did_you_mean"
 require "formula_support"
 require "lock_file"
 require "formula_pin"
@@ -1671,6 +1672,13 @@ class Formula
     CoreTap.instance.alias_reverse_table
   end
 
+  # Returns a list of approximately matching formula names, but not the complete match
+  # @private
+  def self.fuzzy_search(name)
+    @spell_checker ||= DidYouMean::SpellChecker.new(dictionary: Set.new(names + full_names).to_a)
+    @spell_checker.correct(name)
+  end
+
   def self.[](name)
     Formulary.factory(name)
   end

Library/Homebrew/tap.rb

@@ -127,6 +127,7 @@ class Tap
     @style_exceptions = nil
     @pypi_formula_mappings = nil
     @config = nil
+    @spell_checker = nil
     remove_instance_variable(:@private) if instance_variable_defined?(:@private)
   end