From ed39d2b22d406bc1ab10b51fffe4e7a3fea06c06 Mon Sep 17 00:00:00 2001
From: Daniel Vandersluis <daniel.vandersluis@gmail.com>
Date: Wed, 29 Sep 2021 00:19:42 -0400
Subject: [PATCH] [Fix #10134] Update `Style/MutableConstant` to not consider
 multiline uninterpolated strings as unfrozen in ruby 3.0.

---
 .../fix_update_stylemutableconstant_to_not.md |  1 +
 .../cop/mixin/frozen_string_literal.rb        |  6 +++-
 lib/rubocop/cop/style/mutable_constant.rb     |  5 ++--
 .../cop/style/mutable_constant_spec.rb        | 28 +++++++++++++++++++
 4 files changed, 37 insertions(+), 3 deletions(-)
 create mode 100644 changelog/fix_update_stylemutableconstant_to_not.md

diff --git a/changelog/fix_update_stylemutableconstant_to_not.md b/changelog/fix_update_stylemutableconstant_to_not.md
new file mode 100644
index 00000000000..ba18e164c0d
--- /dev/null
+++ b/changelog/fix_update_stylemutableconstant_to_not.md
@@ -0,0 +1 @@
+* [#10134](https://github.com/rubocop/rubocop/issues/10134): Update `Style/MutableConstant` to not consider multiline uninterpolated strings as unfrozen in ruby 3.0. ([@dvandersluis][])
diff --git a/lib/rubocop/cop/mixin/frozen_string_literal.rb b/lib/rubocop/cop/mixin/frozen_string_literal.rb
index 56b93a328dd..6f58a9adf57 100644
--- a/lib/rubocop/cop/mixin/frozen_string_literal.rb
+++ b/lib/rubocop/cop/mixin/frozen_string_literal.rb
@@ -20,7 +20,7 @@ def frozen_string_literal_comment_exists?
 
       def frozen_string_literal?(node)
         frozen_string = if target_ruby_version >= 3.0
-                          node.str_type? || frozen_heredoc?(node)
+                          uninterpolated_string?(node) || frozen_heredoc?(node)
                         else
                           FROZEN_STRING_LITERAL_TYPES_RUBY27.include?(node.type)
                         end
@@ -28,6 +28,10 @@ def frozen_string_literal?(node)
         frozen_string && frozen_string_literals_enabled?
       end
 
+      def uninterpolated_string?(node)
+        node.str_type? || (node.dstr_type? && node.each_descendant(:begin).none?)
+      end
+
       def frozen_heredoc?(node)
         return false unless node.dstr_type? && node.heredoc?
 
diff --git a/lib/rubocop/cop/style/mutable_constant.rb b/lib/rubocop/cop/style/mutable_constant.rb
index fd16a40285f..6382eb8a875 100644
--- a/lib/rubocop/cop/style/mutable_constant.rb
+++ b/lib/rubocop/cop/style/mutable_constant.rb
@@ -21,8 +21,9 @@ module Style
       #
       # NOTE: Regexp and Range literals are frozen objects since Ruby 3.0.
       #
-      # NOTE: From Ruby 3.0, this cop allows explicit freezing of interpolated
-      # string literals when `# frozen-string-literal: true` is used.
+      # NOTE: From Ruby 3.0, interpolated strings are not frozen when
+      # `# frozen-string-literal: true` is used, so this cop enforces explicit
+      # freezing for such strings.
       #
       # NOTE: From Ruby 3.0, this cop allows explicit freezing of constants when
       # the `shareable_constant_value` directive is used.
diff --git a/spec/rubocop/cop/style/mutable_constant_spec.rb b/spec/rubocop/cop/style/mutable_constant_spec.rb
index 04151a41711..b65a5c7cdaa 100644
--- a/spec/rubocop/cop/style/mutable_constant_spec.rb
+++ b/spec/rubocop/cop/style/mutable_constant_spec.rb
@@ -132,6 +132,25 @@
             HERE
           RUBY
         end
+
+        it 'does not register an offense when using a multiline string' do
+          expect_no_offenses(<<~RUBY)
+            # frozen_string_literal: true
+
+            CONST = 'foo' \
+                    'bar'
+          RUBY
+        end
+
+        it 'registers an offense when using a multiline string with interpolation' do
+          expect_offense(<<~'RUBY')
+            # frozen_string_literal: true
+
+            CONST = "#{foo}" \
+                    ^^^^^^^^^^ Freeze mutable objects assigned to constants.
+                    'bar'
+          RUBY
+        end
       end
 
       context 'when the frozen string literal comment is false' do
@@ -166,6 +185,15 @@
             HERE
           RUBY
         end
+
+        it 'does not register an offense when using a multiline string' do
+          expect_no_offenses(<<~RUBY)
+            # frozen_string_literal: true
+
+            CONST = 'foo' \
+                    'bar'
+          RUBY
+        end
       end
 
       context 'when the frozen string literal comment is false' do