raise when __doc__ is not representable as utf-8

Author: timfel

graalpython/com.oracle.graal.python.test/src/tests/unittest_tags/test_builtin.txt

@@ -50,4 +50,5 @@
 *graalpython.lib-python.3.test.test_builtin.TestBreakpoint.test_envar_unimportable
 *graalpython.lib-python.3.test.test_builtin.TestSorted.test_basic
 *graalpython.lib-python.3.test.test_builtin.TestSorted.test_inputtypes
+*graalpython.lib-python.3.test.test_builtin.TestType.test_type_doc
 *graalpython.lib-python.3.test.test_builtin.TestType.test_type_nokwargs

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/BuiltinConstructors.java

@@ -84,6 +84,9 @@
 import static com.oracle.graal.python.runtime.exception.PythonErrorType.ValueError;
 
 import java.math.BigInteger;
+import java.nio.charset.Charset;
+import java.nio.charset.CodingErrorAction;
+import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
@@ -160,6 +163,7 @@
 import com.oracle.graal.python.nodes.BuiltinNames;
 import com.oracle.graal.python.nodes.ErrorMessages;
 import com.oracle.graal.python.nodes.PGuards;
+import com.oracle.graal.python.nodes.SpecialAttributeNames;
 import com.oracle.graal.python.nodes.SpecialMethodNames;
 import com.oracle.graal.python.nodes.attributes.GetAttributeNode;
 import com.oracle.graal.python.nodes.attributes.GetAttributeNode.GetAnyAttributeNode;
@@ -2309,6 +2313,22 @@ private PythonClass typeMetaclass(VirtualFrame frame, String name, PTuple bases,
                     } else {
                         pythonClass.setAttribute(key, value);
                     }
+                } else if (SpecialAttributeNames.__DOC__.equals(key)) {
+                    // CPython sets tp_doc to a copy of dict['__doc__'], if that is a string. It
+                    // forcibly encodes the string as UTF-8, and raises an error if that is not
+                    // possible.
+                    String doc = null;
+                    if (value instanceof String) {
+                        doc = (String) value;
+                    } else if (value instanceof PString) {
+                        doc = ((PString) value).getValue();
+                    }
+                    if (doc != null) {
+                        if (!canEncode(doc)) {
+                            throw raise(PythonBuiltinClassType.UnicodeEncodeError, ErrorMessages.CANNOT_ENCODE_DOCSTR, doc);
+                        }
+                    }
+                    pythonClass.setAttribute(key, value);
                 } else {
                     pythonClass.setAttribute(key, value);
                 }
@@ -2379,6 +2399,11 @@ private PythonClass typeMetaclass(VirtualFrame frame, String name, PTuple bases,
             return pythonClass;
         }
 
+        @TruffleBoundary
+        private static boolean canEncode(String doc) {
+            return StandardCharsets.UTF_8.newEncoder().canEncode(doc);
+        }
+
         @TruffleBoundary
         private PTuple copySlots(String className, SequenceStorage slotList, int slotlen, boolean add_dict, boolean add_weak, PDict namespace, HashingStorageLibrary nslib) {
             SequenceStorage newSlots = new ObjectSequenceStorage(slotlen - PInt.intValue(add_dict) - PInt.intValue(add_weak));

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/ErrorMessages.java

@@ -517,4 +517,5 @@ public abstract class ErrorMessages {
     public static final String S_ALIGNMENT_FLAG_NOT_ALLOWED_FOR_COMPLEX_FMT = "'%c' alignment flag is not allowed in complex format specifier";
     public static final String ZERO_PADDING_NOT_ALLOWED_FOR_COMPLEX_FMT = "Zero padding is not allowed in complex format specifier";
     public static final String POW_THIRD_ARG_CANNOT_BE_ZERO = "pow() 3rd argument cannot be 0";
+    public static final String CANNOT_ENCODE_DOCSTR = "'utf-8' codec can't encode docstring '%s'";
 }