Simplify from_native and test corner case.

2 files changed, 20 insertions, 5 deletions

diff --git a/lib/ffi/enum.rb b/lib/ffi/enum.rb
index 903525e..83b6d89 100644
--- a/lib/ffi/enum.rb
+++ b/lib/ffi/enum.rb
@@ -280,15 +280,13 @@ module FFI
     # @param ctx unused
     # @return [Array<Symbol, Integer>] list of symbol names corresponding to val, plus an optional remainder if some bits don't match any constant
     def from_native(val, ctx)
-      list = @kv_map.select { |_, v| v & val != 0 }.keys
+      flags = @kv_map.select { |_, v| v & val != 0 }
+      list = flags.keys
       # If there are unmatch flags,
       # return them in an integer,
       # else information can be lost.
       # Similar to Enum behavior.
-      remainder = val ^ list.inject(0) do |tmp, o|
-        v = @kv_map[o]
-        if v then tmp |= v else tmp end
-      end
+      remainder = val ^ flags.values.reduce(0, :|)
       list.push remainder unless remainder == 0
       return list
     end
diff --git a/spec/ffi/bitmask_spec.rb b/spec/ffi/bitmask_spec.rb
index 4a404b0..0cbccfa 100644
--- a/spec/ffi/bitmask_spec.rb
+++ b/spec/ffi/bitmask_spec.rb
@@ -248,6 +248,23 @@ describe "A tagged typedef bitmask" do
     expect(TestBitmask4.test_tagged_nonint_bitmask6([1<<14,1<<42,1<<43])).to eq([:c26,:c28,1<<43])
   end
 
+  it "only remainder is given if only undefined mask are returned" do
+    expect(TestBitmask3.test_tagged_typedef_bitmask1(1<<4)).to eq([1<<4])
+    expect(TestBitmask3.test_tagged_typedef_bitmask1([1<<4])).to eq([1<<4])
+    expect(TestBitmask3.test_tagged_typedef_bitmask2(1<<6)).to eq([1<<6])
+    expect(TestBitmask3.test_tagged_typedef_bitmask2([1<<6])).to eq([1<<6])
+    expect(TestBitmask3.test_tagged_typedef_bitmask3(1<<7)).to eq([1<<7])
+    expect(TestBitmask3.test_tagged_typedef_bitmask3([1<<7])).to eq([1<<7])
+    expect(TestBitmask3.test_tagged_typedef_bitmask4(1<<9)).to eq([1<<9])
+    expect(TestBitmask3.test_tagged_typedef_bitmask4([1<<9])).to eq([1<<9])
+    expect(TestBitmask4.test_tagged_nonint_bitmask4(1<<10)).to eq([1<<10])
+    expect(TestBitmask4.test_tagged_nonint_bitmask4([1<<10])).to eq([1<<10])
+    expect(TestBitmask4.test_tagged_nonint_bitmask5(1<<16)).to eq([1<<16])
+    expect(TestBitmask4.test_tagged_nonint_bitmask5([1<<16])).to eq([1<<16])
+    expect(TestBitmask4.test_tagged_nonint_bitmask6(1<<43)).to eq([1<<43])
+    expect(TestBitmask4.test_tagged_nonint_bitmask6([1<<43])).to eq([1<<43])
+  end
+
   it "wrong constants rejected" do
     expect { TestBitmask3.test_tagged_typedef_bitmask1([:c2,:c4,:c5]) }.to raise_error(ArgumentError)
     expect { TestBitmask3.test_tagged_typedef_bitmask2([:c6,:c8,:c9]) }.to raise_error(ArgumentError)