Drop support for Ruby 2.3

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 Get upgrade notes from Sprockets 3.x to 4.x at https://github.com/rails/sprockets/blob/master/UPGRADING.md
 
+## Master
+
+- Remove remaining support for Ruby < 2.4.[#672](https://github.com/rails/sprockets/pull/672)
+
 ## 4.0.2
 
 - Fix `etag` and digest path compilation that were generating string with invalid digest since 4.0.1.

lib/sprockets/digest_utils.rb

@@ -68,18 +68,8 @@ def detect_digest_class(bytes)
       Encoding => ->(val, digest) {
         digest << 'Encoding'.freeze
         digest << val.name
-      },
-    }
-    if 0.class != Integer # Ruby < 2.4
-      ADD_VALUE_TO_DIGEST[Fixnum] = ->(val, digest) {
-        digest << 'Integer'.freeze
-        digest << val.to_s
       }
-      ADD_VALUE_TO_DIGEST[Bignum] = ->(val, digest) {
-        digest << 'Integer'.freeze
-        digest << val.to_s
-      }
-    end
+    }
 
     ADD_VALUE_TO_DIGEST.compare_by_identity.rehash
 

lib/sprockets/loader.rb

@@ -291,7 +291,7 @@ def resolve_dependencies(uris)
       # Internal: Retrieves an asset based on its digest
       #
       # unloaded - An UnloadedAsset
-      # limit    - A Fixnum which sets the maximum number of versions of "histories"
+      # limit    - An Integer which sets the maximum number of versions of "histories"
       #            stored in the cache
       #
       # This method attempts to retrieve the last `limit` number of histories of an asset

lib/sprockets/processor_utils.rb

@@ -118,8 +118,9 @@ def processors_cache_keys(processors)
       Symbol,
       TrueClass,
       FalseClass,
-      NilClass
-    ] + (0.class == Integer ? [Integer] : [Bignum, Fixnum])).freeze
+      NilClass,
+      Integer
+    ]).freeze
 
     # Internal: Set of all nested compound metadata types that can nest values.
     VALID_METADATA_COMPOUND_TYPES = Set.new([