Fix "circular causes" error at raising exception

Author: andrykonchin

spec/ruby/core/kernel/raise_spec.rb

@@ -203,6 +203,65 @@
       e.cause.should == e1
     end
   end
+
+  it "re-raises a previously rescued exception that doesn't have a cause and isn't a cause of any other exception with setting a cause implicitly" do
+    begin
+      begin
+        raise "Error 1"
+      rescue => e1
+        begin
+          raise "Error 2"
+        rescue => e2
+          raise "Error 3"
+        end
+      end
+    rescue => e
+      e.message.should == "Error 3"
+      e.cause.should == e2
+    end
+  end
+
+  it "re-raises a previously rescued exception that doesn't have a cause and is a cause of other exception without setting a cause implicitly" do
+    begin
+      begin
+        raise "Error 1"
+      rescue => e1
+        begin
+          raise "Error 2"
+        rescue => e2
+          e1.cause.should == nil
+          e2.cause.should == e1
+          raise e1
+        end
+      end
+    rescue => e
+      e.should == e1
+      e.cause.should == nil
+    end
+  end
+
+  it "re-raises a previously rescued exception that has a cause but isn't a cause of any other exception without setting a cause implicitly" do
+    begin
+      begin
+        raise "Error 1"
+      rescue => e1
+        begin
+          raise "Error 2"
+        rescue => e2
+          begin
+            raise "Error 3", cause: RuntimeError.new("Error 4")
+          rescue => e3
+            e2.cause.should == e1
+            e3.cause.should_not == e2
+            raise e2
+          end
+        end
+      end
+    rescue => e
+      e.should == e2
+      e.cause.should == e1
+    end
+  end
 end
 
 describe "Kernel#raise" do

src/main/java/org/truffleruby/core/exception/ExceptionNodes.java

@@ -9,6 +9,7 @@
  */
 package org.truffleruby.core.exception;
 
+import com.oracle.truffle.api.dsl.Fallback;
 import com.oracle.truffle.api.interop.InteropLibrary;
 import com.oracle.truffle.api.library.CachedLibrary;
 import com.oracle.truffle.api.object.Shape;
@@ -368,4 +369,35 @@ Object getRaiseException(RubyException exception) {
 
     }
 
+    @Primitive(name = "exception_used_as_a_cause?")
+    public abstract static class IsUsedAsACauseNode extends PrimitiveArrayArgumentsNode {
+
+        @Specialization
+        boolean isUsedAsACause(RubyException exception) {
+            return exception.usedAsACause;
+        }
+
+        @Fallback
+        boolean isUsedAsACauseForeignException(Object exception) {
+            return false;
+        }
+
+    }
+
+    @Primitive(name = "exception_used_as_a_cause!")
+    public abstract static class UsedAsACauseNode extends PrimitiveArrayArgumentsNode {
+
+        @Specialization
+        Object usedAsACause(RubyException exception) {
+            exception.usedAsACause = true;
+            return nil;
+        }
+
+        @Fallback
+        Object usedAsACauseForeignException(Object exception) {
+            return nil;
+        }
+
+    }
+
 }

src/main/java/org/truffleruby/core/exception/RubyException.java

@@ -50,6 +50,7 @@ public class RubyException extends RubyDynamicObject implements ObjectGraphNode
     public Object backtraceLocations = null;
     /** null (not set), RubyArray of Strings, or nil (empty) */
     public Object customBacktrace = null;
+    public boolean usedAsACause = false;
 
     public RubyException(RubyClass rubyClass, Shape shape, Object message, Backtrace backtrace, Object cause) {
         super(rubyClass, shape);

src/main/ruby/truffleruby/core/kernel.rb

@@ -698,25 +698,29 @@ def raise(exc = undefined, msg = undefined, ctx = nil, cause: undefined, **kwarg
         msg = kwargs
       end
 
+      exc = Truffle::ExceptionOperations.build_exception_for_raise(exc, msg)
+      exc.set_backtrace(ctx) if ctx
+      Primitive.exception_capture_backtrace(exc, 1) unless Truffle::ExceptionOperations.backtrace?(exc)
+
       if cause_given
         unless Primitive.is_a?(cause, ::Exception) || Primitive.nil?(cause)
           Truffle::ExceptionOperations.exception_object_expected!
         end
       else
-        cause = $!
+        if Primitive.nil?(exc.cause) && !Primitive.exception_used_as_a_cause?(exc)
+          cause = $!
+        else
+          cause = nil
+        end
       end
 
-      exc = Truffle::ExceptionOperations.build_exception_for_raise(exc, msg)
-
-      exc.set_backtrace(ctx) if ctx
-      Primitive.exception_capture_backtrace(exc, 1) unless Truffle::ExceptionOperations.backtrace?(exc)
-
       if !Primitive.nil?(cause) && (cause_given || Primitive.nil?(exc.cause)) && !Primitive.equal?(cause, exc)
         if Truffle::ExceptionOperations.circular_cause?(cause, exc)
           raise ArgumentError, 'circular causes'
         end
 
         Primitive.exception_set_cause exc, cause
+        Primitive.exception_used_as_a_cause!(cause)
       end
     end
 

test/mri/excludes/TestException.rb

@@ -3,7 +3,6 @@
 exclude :test_cause_raised_in_rescue, "cause should not be overwritten by reraise."
 exclude :test_cause_thread_with_cause, "NoMethodError: undefined method `message' for nil:NilClass"
 exclude :test_circular_cause, "Expected #<RuntimeError: error 2> to be nil."
-exclude :test_circular_cause_handle, "Exception(ArgumentError) with message matches to /circular cause/."
 exclude :test_errinfo_encoding_in_debug, "Expected \"\" to include \"#<Module:0x608>::Cエラー\"."
 exclude :test_errinfo_in_debug, "needs investigation"
 exclude :test_exception_in_ensure_with_next, "NameError: uninitialized constant TestException::RubyVM"