From 5e03e9be65f3568c1ec1278a2fe395a8fb644ab1 Mon Sep 17 00:00:00 2001
From: Bill Ruddock <bill.ruddock@gmail.com>
Date: Mon, 6 Jul 2020 05:27:29 +0100
Subject: [PATCH] Allow top-level const in MutableConst

Allow top-level `::ENV`, `::Struct` in Style/MutableConstant cop.
---
 lib/rubocop/cop/style/mutable_constant.rb       | 8 ++++----
 spec/rubocop/cop/style/mutable_constant_spec.rb | 8 ++++++++
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/lib/rubocop/cop/style/mutable_constant.rb b/lib/rubocop/cop/style/mutable_constant.rb
index e3e512859ee..d4c310e38c9 100644
--- a/lib/rubocop/cop/style/mutable_constant.rb
+++ b/lib/rubocop/cop/style/mutable_constant.rb
@@ -150,14 +150,14 @@ def correct_splat_expansion(corrector, expr, splat_value)
         def_node_matcher :operation_produces_immutable_object?, <<~PATTERN
           {
             (const _ _)
-            (send (const nil? :Struct) :new ...)
-            (block (send (const nil? :Struct) :new ...) ...)
+            (send (const {nil? cbase} :Struct) :new ...)
+            (block (send (const {nil? cbase} :Struct) :new ...) ...)
             (send _ :freeze)
             (send {float int} {:+ :- :* :** :/ :% :<<} _)
             (send _ {:+ :- :* :** :/ :%} {float int})
             (send _ {:== :=== :!= :<= :>= :< :>} _)
-            (send (const nil? :ENV) :[] _)
-            (or (send (const nil? :ENV) :[] _) _)
+            (send (const {nil? cbase} :ENV) :[] _)
+            (or (send (const {nil? cbase} :ENV) :[] _) _)
             (send _ {:count :length :size} ...)
             (block (send _ {:count :length :size} ...) ...)
           }
diff --git a/spec/rubocop/cop/style/mutable_constant_spec.rb b/spec/rubocop/cop/style/mutable_constant_spec.rb
index ca503ffae45..eb372db00ec 100644
--- a/spec/rubocop/cop/style/mutable_constant_spec.rb
+++ b/spec/rubocop/cop/style/mutable_constant_spec.rb
@@ -61,6 +61,7 @@
     it_behaves_like 'immutable objects', 'FOO - BAR'
     it_behaves_like 'immutable objects', "'foo' + 'bar'"
     it_behaves_like 'immutable objects', "ENV['foo']"
+    it_behaves_like 'immutable objects', "::ENV['foo']"
 
     it 'allows method call assignments' do
       expect_no_offenses('TOP_TEST = Something.new')
@@ -192,9 +193,13 @@
     it_behaves_like 'immutable objects', '1.5'
     it_behaves_like 'immutable objects', ':sym'
     it_behaves_like 'immutable objects', "ENV['foo']"
+    it_behaves_like 'immutable objects', "::ENV['foo']"
     it_behaves_like 'immutable objects', 'OTHER_CONST'
+    it_behaves_like 'immutable objects', '::OTHER_CONST'
     it_behaves_like 'immutable objects', 'Namespace::OTHER_CONST'
+    it_behaves_like 'immutable objects', '::Namespace::OTHER_CONST'
     it_behaves_like 'immutable objects', 'Struct.new'
+    it_behaves_like 'immutable objects', '::Struct.new'
     it_behaves_like 'immutable objects', 'Struct.new(:a, :b)'
     it_behaves_like 'immutable objects', <<~RUBY
       Struct.new(:node) do
@@ -303,6 +308,9 @@ def assignment?
         expect_no_offenses(<<~RUBY)
           CONST = ENV['foo'] || 'foo'
         RUBY
+        expect_no_offenses(<<~RUBY)
+          CONST = ::ENV['foo'] || 'foo'
+        RUBY
       end
 
       it 'accepts operating on a constant and an interger' do