Use each_with_object

Library/Homebrew/extend/enumerable.rbi

@@ -1,16 +1,5 @@
 # typed: strict
 
-module Enumerable
-  requires_ancestor { Object }
-
-  sig {
-    type_parameters(:key).params(
-      block: T.nilable(T.proc.params(o: Enumerable::Elem).returns(T.type_parameter(:key))),
-    ).returns(T::Hash[T.type_parameter(:key), Enumerable::Elem])
-  }
-  def index_by(&block); end
-end
-
 class Hash
   sig { returns(T::Hash[Hash::K, Hash::V]) }
   def compact_blank; end

Library/Homebrew/formula_installer.rb

@@ -565,8 +565,8 @@ def runtime_requirements(formula)
   def expand_requirements
     unsatisfied_reqs = Hash.new { |h, k| h[k] = [] }
     formulae = [formula]
-    formula_deps_map = {}
-    formula.recursive_dependencies.each { |dep| formula_deps_map[dep.name] = dep }
+    formula_deps_map = formula.recursive_dependencies
+                              .each_with_object({}) { |dep, h| h[dep.name] = dep }
 
     while (f = formulae.pop)
       runtime_requirements = runtime_requirements(f)
@@ -1206,11 +1206,10 @@ def previously_fetched_formula
   def fetch_bottle_tab
     @fetch_bottle_tab ||= begin
       formula.fetch_bottle_tab
-      @bottle_tab_runtime_dependencies = {}
-      formula.bottle_tab_attributes
-             .fetch("runtime_dependencies", [])
-             .each { |dep| @bottle_tab_runtime_dependencies[dep["full_name"]] = dep }
-      @bottle_tab_runtime_dependencies.freeze
+      @bottle_tab_runtime_dependencies = formula.bottle_tab_attributes
+                                                .fetch("runtime_dependencies", [])
+                                                .each_with_object({}) { |dep, h| h[dep["full_name"]] = dep }
+                                                .freeze
       true
     rescue DownloadError, ArgumentError
       @fetch_bottle_tab = true