Simplify setConstantInternal()

* The return value is anyway ignored for #autoload.
* Move checks in callers for redefined constants

Author: eregon

src/main/java/org/truffleruby/core/module/ModuleFields.java

@@ -340,13 +340,9 @@ private RubyConstant setConstantInternal(RubyContext context, Node currentNode,
             final SourceSection sourceSection = currentNode != null ?  currentNode.getSourceSection() : null;
             final RubyConstant newValue = new RubyConstant(rubyModuleObject, value, isPrivate, autoload, isDeprecated, sourceSection);
 
-            if ((previous == null) ? (constants.putIfAbsent(name, newValue) == null) : constants.replace(name, previous, newValue)) {
+            if (previous == null ? constants.putIfAbsent(name, newValue) == null : constants.replace(name, previous, newValue)) {
                 newConstantsVersion();
-                if (!autoload && previous != null && !previous.isAutoload()) {
-                    return previous;
-                } else {
-                    return null;
-                }
+                return previous;
             }
         }
     }

src/main/java/org/truffleruby/core/module/ModuleNodes.java

@@ -997,7 +997,7 @@ public Object setConstant(DynamicObject module, String name, Object value) {
         @TruffleBoundary
         public Object setConstantNoCheckName(DynamicObject module, String name, Object value) {
             final RubyConstant previous = Layouts.MODULE.getFields(module).setConstant(getContext(), this, name, value);
-            if (previous != null) {
+            if (previous != null && previous.hasValue()) {
                 warnAlreadyInitializedConstant(module, name, previous.getSourceSection());
             }
             return value;

src/main/java/org/truffleruby/language/constants/WriteConstantNode.java

@@ -16,6 +16,7 @@
 import com.oracle.truffle.api.source.SourceSection;
 import org.truffleruby.Layouts;
 import org.truffleruby.core.constant.WarnAlreadyInitializedNode;
+import org.truffleruby.core.module.ModuleOperations;
 import org.truffleruby.language.RubyConstant;
 import org.truffleruby.language.RubyGuards;
 import org.truffleruby.language.RubyNode;
@@ -47,7 +48,7 @@ public Object execute(VirtualFrame frame) {
         }
 
         final RubyConstant previous = Layouts.MODULE.getFields((DynamicObject) moduleObject).setConstant(getContext(), this, name, value);
-        if (previous != null) {
+        if (previous != null && previous.hasValue()) {
             warnAlreadyInitializedConstant((DynamicObject) moduleObject, name, previous.getSourceSection());
         }
         return value;