Make third param of HPyMethSSizeObjArgProcRoot optional

Author: fangerer

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/cext/hpy/GraalHPyHandle.java

@@ -177,6 +177,11 @@ Object readMember(String key) throws UnknownIdentifierException {
         }
         throw UnknownIdentifierException.create(key);
     }
+    
+    @ExportMessage
+    boolean isNull() {
+        return id == 0;
+    }
 
     public GraalHPyHandle copy() {
         return new GraalHPyHandle(delegate);

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/cext/hpy/GraalHPyNodes.java

@@ -1795,8 +1795,8 @@ HPyCloseArgHandlesNode createCloseHandleNode() {
     }
 
     /**
-     * Always closes handle parameter at position {@code destOffset} and {@code destOffset + 2}
-     * (assuming that these are handles).
+     * Always closes handle parameter at position {@code destOffset} and also closes parameter at
+     * position {@code destOffset + 2} if it is not a {@code NULL} handle.
      */
     public abstract static class HPySSizeObjArgProcCloseNode extends HPyCloseArgHandlesNode {
 
@@ -1805,7 +1805,10 @@ static void doConvert(GraalHPyContext hpyContext, Object[] dest, int destOffset,
                         @Cached ConditionProfile isAllocatedProfile,
                         @Cached HPyEnsureHandleNode ensureHandleNode) {
             ensureHandleNode.execute(hpyContext, dest[destOffset]).close(hpyContext, isAllocatedProfile);
-            ensureHandleNode.execute(hpyContext, dest[destOffset + 2]).close(hpyContext, isAllocatedProfile);
+            GraalHPyHandle arg2Handle = ensureHandleNode.execute(hpyContext, dest[destOffset + 2]);
+            if (!arg2Handle.isNull()) {
+                arg2Handle.close(hpyContext, isAllocatedProfile);
+            }
         }
     }
 

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/cext/hpy/HPyExternalFunctionNodes.java

@@ -162,6 +162,8 @@ static PBuiltinFunction createWrapperFunction(PythonLanguage language, HPyFuncSi
                 break;
             case SSIZEOBJARGPROC:
                 rootNode = new HPyMethSSizeObjArgProcRoot(language, name);
+                // the third argument is optional
+                numDefaults = 1;
                 break;
             case INQUIRY:
                 rootNode = new HPyMethInquiryRoot(language, name);