1 files changed, 63 insertions, 0 deletions
diff --git a/config/initializers/sprockets_patch.rb b/config/initializers/sprockets_patch.rb
new file mode 100644
index 00000000000..76474b370be
--- /dev/null
+++ b/config/initializers/sprockets_patch.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+# This backports https://github.com/rails/sprockets/pull/759 to Sprockets v3.7.2 to
+# fix thread-safety issues with compiling SASS.
+#
+# This pull request has already been merged in Sprockets v4.2.0, but we
+# don't plan on upgrading: https://gitlab.com/gitlab-org/gitlab/-/issues/373997#note_1360248557
+
+require 'sprockets/utils'
+
+unless Gem::Version.new(Sprockets::VERSION) == Gem::Version.new('3.7.2')
+  raise 'New version of Sprockets detected. This patch can likely be removed.'
+end
+
+# rubocop:disable Style/CombinableLoops -- Keep the format consistent with upstream project
+# rubocop:disable Cop/LineBreakAroundConditionalBlock -- Keep the format consistent with upstream project
+# rubocop:disable Style/IfUnlessModifier -- Keep the format consistent with upstream project
+# rubocop:disable Style/SoleNestedConditional -- Keep the format consistent with upstream project
+module Sprockets
+  module Utils
+    extend self
+
+    MODULE_INCLUDE_MUTEX = Mutex.new
+    private_constant :MODULE_INCLUDE_MUTEX
+
+    # Internal: Inject into target module for the duration of the block.
+    #
+    # mod - Module
+    #
+    # Returns result of block.
+    def module_include(base, mod)
+      MODULE_INCLUDE_MUTEX.synchronize do
+        old_methods = {}
+
+        mod.instance_methods.each do |sym|
+          old_methods[sym] = base.instance_method(sym) if base.method_defined?(sym)
+        end
+
+        unless UNBOUND_METHODS_BIND_TO_ANY_OBJECT
+          base.send(:include, mod) unless base < mod
+        end
+
+        mod.instance_methods.each do |sym|
+          method = mod.instance_method(sym)
+          base.send(:define_method, sym, method)
+        end
+
+        yield
+      ensure
+        mod.instance_methods.each do |sym|
+          base.send(:undef_method, sym) if base.method_defined?(sym)
+        end
+        old_methods.each do |sym, method|
+          base.send(:define_method, sym, method)
+        end
+      end
+    end
+  end
+end
+# rubocop:enable Style/CombinableLoops
+# rubocop:enable Cop/LineBreakAroundConditionalBlock
+# rubocop:enable Style/IfUnlessModifier
+# rubocop:enable Style/SoleNestedConditional