Fix excepthook (RustPython#5830)

Author: youknowone

Lib/test/test_exceptions.py

@@ -701,8 +701,6 @@ def test_str(self):
         self.assertTrue(str(Exception('a')))
         self.assertTrue(str(Exception('a', 'b')))
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_exception_cleanup_names(self):
         # Make sure the local variable bound to the exception instance by
         # an "except" statement is only visible inside the except block.
@@ -725,8 +723,6 @@ def test_exception_cleanup_names2(self):
         with self.assertRaises(UnboundLocalError):
             e
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def testExceptionCleanupState(self):
         # Make sure exception state is cleaned up as soon as the except
         # block is left. See #2507
@@ -1573,8 +1569,6 @@ def inner():
         gc_collect()  # For PyPy or other GCs.
         self.assertEqual(wr(), None)
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     @no_tracing
     @unittest.skipIf(sys.platform == 'win32', 'TODO: RUSTPYTHON Windows')
     def test_recursion_error_cleanup(self):

Lib/test/test_sys.py

@@ -167,8 +167,6 @@ def test_excepthook_bytes_filename(self):
         self.assertIn("""    text\n""", err)
         self.assertTrue(err.endswith("SyntaxError: msg\n"))
 
-    # TODO: RUSTPYTHON, print argument error to stderr in sys.excepthook instead of throwing
-    @unittest.expectedFailure
     def test_excepthook(self):
         with test.support.captured_output("stderr") as stderr:
             sys.excepthook(1, '1', 1)

compiler/codegen/src/compile.rs

@@ -1317,6 +1317,14 @@ impl Compiler<'_> {
             self.compile_statements(body)?;
             emit!(self, Instruction::PopException);
 
+            // Delete the exception variable if it was bound
+            if let Some(alias) = name {
+                // Set the variable to None before deleting (as CPython does)
+                self.emit_load_const(ConstantData::None);
+                self.store_name(alias.as_str())?;
+                self.compile_name(alias.as_str(), NameUsage::Delete)?;
+            }
+
             if !finalbody.is_empty() {
                 emit!(self, Instruction::PopBlock); // pop excepthandler block
                 // We enter the finally block, without exception.

compiler/codegen/src/snapshots/rustpython_codegen__compile__tests__nested_double_async_with.snap

@@ -363,9 +363,24 @@ mod sys {
         exc_tb: PyObjectRef,
         vm: &VirtualMachine,
     ) -> PyResult<()> {
-        let exc = vm.normalize_exception(exc_type, exc_val, exc_tb)?;
         let stderr = super::get_stderr(vm)?;
-        vm.write_exception(&mut crate::py_io::PyWriter(stderr, vm), &exc)
+
+        // Try to normalize the exception. If it fails, print error to stderr like CPython
+        match vm.normalize_exception(exc_type.clone(), exc_val.clone(), exc_tb) {
+            Ok(exc) => vm.write_exception(&mut crate::py_io::PyWriter(stderr, vm), &exc),
+            Err(_) => {
+                // CPython prints error message to stderr instead of raising exception
+                let type_name = exc_val.class().name();
+                // TODO: fix error message
+                let msg = format!(
+                    "TypeError: print_exception(): Exception expected for value, {} found\n",
+                    type_name
+                );
+                use crate::py_io::Write;
+                write!(&mut crate::py_io::PyWriter(stderr, vm), "{}", msg)?;
+                Ok(())
+            }
+        }
     }
 
     #[pyfunction(name = "__breakpointhook__")]