Prevent None and All members in flags enums (#4395)

RX14 · Martin Verzilli · commit 0e78159eff91 · 2017-05-14T10:42:01.000-03:00
* Prevent None and All members in flags enums Fixes #1251
diff --git a/spec/compiler/codegen/enum_spec.cr b/spec/compiler/codegen/enum_spec.cr
@@ -106,25 +106,29 @@ describe "Code gen: enum" do
 
   it "codegens enum None redefined" do
     run(%(
-      @[Flags]
-      enum Foo
-        A
-        None = 10
+      lib Lib
+        @[Flags]
+        enum Foo
+          A
+          None = 10
+        end
       end
 
-      Foo::None
+      Lib::Foo::None
       )).to_i.should eq(10)
   end
 
   it "codegens enum All redefined" do
     run(%(
-      @[Flags]
-      enum Foo
-        A
-        All = 10
+      lib Lib
+        @[Flags]
+        enum Foo
+          A
+          All = 10
+        end
       end
 
-      Foo::All
+      Lib::Foo::All
       )).to_i.should eq(10)
   end
 
diff --git a/spec/compiler/semantic/enum_spec.cr b/spec/compiler/semantic/enum_spec.cr
@@ -183,6 +183,51 @@ describe "Semantic: enum" do
       )) { int32 }
   end
 
+  it "disallows None value when defined with @[Flags]" do
+    assert_error %(
+      @[Flags]
+      enum Foo
+        None
+      end
+      ),
+      "flags enum can't contain None or All members"
+  end
+
+  it "disallows All value when defined with @[Flags]" do
+    assert_error %(
+      @[Flags]
+      enum Foo
+        All = 50
+      end
+      ),
+      "flags enum can't contain None or All members"
+  end
+
+  it "doesn't error when defining a non-flags enum with None or All" do
+    assert_type(%(
+      enum Foo
+        None
+        All = 50
+      end
+
+      Foo::None.value
+      )) { int32 }
+  end
+
+  it "doesn't error when defining a flags enum in a lib with None or All" do
+    assert_type(%(
+      lib Lib
+        @[Flags]
+        enum Foo
+          None
+          All = 50
+        end
+      end
+
+      Lib::Foo::None.value
+      )) { int32 }
+  end
+
   it "doesn't error when defining a method for an enum with flags" do
     assert_type(%(
       @[Flags]
diff --git a/src/compiler/crystal/semantic/top_level_visitor.cr b/src/compiler/crystal/semantic/top_level_visitor.cr
@@ -550,6 +550,10 @@ class Crystal::TopLevelVisitor < Crystal::SemanticVisitor
         node.raise "can't reopen enum and add more constants to it"
       end
 
+      if is_flags && !@in_lib && {"None", "All"}.includes?(member.name)
+        member.raise "flags enum can't contain None or All members, they are autogenerated"
+      end
+
       if default_value = member.default_value
         counter = interpret_enum_value(default_value, base_type)
       end
diff --git a/src/llvm/enums.cr b/src/llvm/enums.cr
@@ -2,7 +2,6 @@ module LLVM
   {% if LibLLVM.has_constant?(:AttributeRef) %}
     @[Flags]
     enum Attribute : UInt64
-      None = 0
       Alignment = 1 << 0
       AllocSize = 1 << 1
       AlwaysInline = 1 << 2
