Turn class variable warnings into exceptions

This changes the following warnings:

* warning: class variable access from toplevel
* warning: class variable @foo of D is overtaken by C

into RuntimeErrors.  Handle defined?(@@foo) at toplevel
by returning nil instead of raising an exception (the previous
behavior warned before returning nil when defined? was used).

Refactor the specs to avoid the warnings even in older versions.
The specs were checking for the warnings, but the purpose of
the related specs as evidenced from their description is to
test for behavior, not for warnings.

Fixes [Bug #14541]

3 files changed, 17 insertions, 21 deletions

diff --git a/spec/ruby/core/exception/name_spec.rb b/spec/ruby/core/exception/name_spec.rb
index d1def51f24..c8a49b40e2 100644
--- a/spec/ruby/core/exception/name_spec.rb
+++ b/spec/ruby/core/exception/name_spec.rb
@@ -21,9 +21,7 @@ describe "NameError#name" do
 
   it "returns a class variable name as a symbol" do
     -> {
-      -> {
-        @@doesnt_exist
-      }.should complain(/class variable access from toplevel/)
+      eval("class singleton_class::A; @@doesnt_exist end", binding, __FILE__, __LINE__)
     }.should raise_error(NameError) { |e| e.name.should == :@@doesnt_exist }
   end
 
diff --git a/spec/ruby/core/exception/receiver_spec.rb b/spec/ruby/core/exception/receiver_spec.rb
index 7c57d63c3e..d1c23b67be 100644
--- a/spec/ruby/core/exception/receiver_spec.rb
+++ b/spec/ruby/core/exception/receiver_spec.rb
@@ -28,10 +28,8 @@ describe "NameError#receiver" do
 
   it "returns the Object class when an undefined class variable is called" do
     -> {
-      -> {
-        @@doesnt_exist
-      }.should complain(/class variable access from toplevel/)
-    }.should raise_error(NameError) {|e| e.receiver.should equal(Object) }
+      eval("class singleton_class::A; @@doesnt_exist end", binding, __FILE__, __LINE__)
+    }.should raise_error(NameError) {|e| e.receiver.should equal(singleton_class::A) }
   end
 
   it "returns a class when an undefined class variable is called in a subclass' namespace" do
diff --git a/spec/ruby/language/defined_spec.rb b/spec/ruby/language/defined_spec.rb
index ed61ed3b53..f2da8a9293 100644
--- a/spec/ruby/language/defined_spec.rb
+++ b/spec/ruby/language/defined_spec.rb
@@ -275,9 +275,7 @@ describe "The defined? keyword for an expression" do
     end
 
     it "returns nil for an expression with '!' and an unset class variable" do
-      -> {
-        @result = defined?(!@@defined_specs_undefined_class_variable)
-      }.should complain(/class variable access from toplevel/)
+      @result = eval("class singleton_class::A; defined?(!@@doesnt_exist) end", binding, __FILE__, __LINE__)
       @result.should be_nil
     end
 
@@ -286,9 +284,7 @@ describe "The defined? keyword for an expression" do
     end
 
     it "returns nil for an expression with 'not' and an unset class variable" do
-      -> {
-        @result = defined?(not @@defined_specs_undefined_class_variable)
-      }.should complain(/class variable access from toplevel/)
+      @result = eval("class singleton_class::A; defined?(not @@doesnt_exist) end", binding, __FILE__, __LINE__)
       @result.should be_nil
     end
 
@@ -897,17 +893,21 @@ describe "The defined? keyword for a variable scoped constant" do
   end
 
   it "returns nil if the class scoped constant is not defined" do
-    -> {
-      @@defined_specs_obj = DefinedSpecs::Basic
-      defined?(@@defined_specs_obj::Undefined).should be_nil
-    }.should complain(/class variable access from toplevel/)
+    eval(<<-END, binding, __FILE__, __LINE__)
+      class singleton_class::A
+        @@defined_specs_obj = DefinedSpecs::Basic
+        defined?(@@defined_specs_obj::Undefined).should be_nil
+      end
+    END
   end
 
   it "returns 'constant' if the constant is defined in the scope of the class variable" do
-    -> {
-      @@defined_specs_obj = DefinedSpecs::Basic
-      defined?(@@defined_specs_obj::A).should == "constant"
-    }.should complain(/class variable access from toplevel/)
+    eval(<<-END, binding, __FILE__, __LINE__)
+      class singleton_class::A
+        @@defined_specs_obj = DefinedSpecs::Basic
+        defined?(@@defined_specs_obj::A).should == "constant"
+      end
+    END
   end
 
   it "returns nil if the local scoped constant is not defined" do