vm: tests and fixes for exceptions

  * Add IsSet method to ExceptionInfo and use it to fix bad tests
  * Correct raise handling
  * Correct exception handling
  * Add finished marker to the tests to detect silent early exit
  * Still some exceptions tests failing

Author: ncw

py/exception.go

@@ -119,6 +119,11 @@ func (exc *ExceptionInfo) TracebackDump(w io.Writer) {
 	fmt.Fprintf(w, "%v: %v\n", exc.Type.Name, exc.Value)
 }
 
+// Test for being set
+func (exc *ExceptionInfo) IsSet() bool {
+	return exc.Type != nil
+}
+
 // ExceptionNew
 func ExceptionNew(metatype *Type, args Tuple, kwargs StringDict) Object {
 	if len(kwargs) != 0 {
@@ -229,7 +234,7 @@ func ExceptionGivenMatches(err, exc Object) bool {
 
 	// Test the tuple case recursively
 	if excTuple, ok := exc.(Tuple); ok {
-		for i := 0; i < len(excTuple); i++ {
+		for i := range excTuple {
 			if ExceptionGivenMatches(err, excTuple[i]) {
 				return true
 			}

vm/eval.go

@@ -660,6 +660,8 @@ func do_END_FINALLY(vm *Vm, arg int32) {
 		switch vm.exit {
 		case exitYield:
 			panic("Unexpected exitYield in END_FINALLY")
+		case exitException:
+			panic("Unexpected exitException in END_FINALLY")
 		case exitReturn, exitContinue:
 			vm.result = vm.POP()
 		case exitSilenced:
@@ -689,7 +691,7 @@ func do_END_FINALLY(vm *Vm, arg int32) {
 	} else {
 		vm.ClearException()
 	}
-
+	debugf("END_FINALLY: vm.exit = %v\n", vm.exit)
 }
 
 // Loads the __build_class__ helper function to the stack which
@@ -1201,7 +1203,7 @@ func do_DELETE_DEREF(vm *Vm, i int32) {
 func (vm *Vm) raise(exc, cause py.Object) {
 	if exc == nil {
 		// raise (with no parameters == re-raise)
-		if vm.exc.Value == nil {
+		if !vm.exc.IsSet() {
 			vm.SetException(py.ExceptionNewf(py.RuntimeError, "No active exception to reraise"))
 		} else {
 			// Signal the existing exception again
@@ -1211,6 +1213,7 @@ func (vm *Vm) raise(exc, cause py.Object) {
 		// raise <instance>
 		// raise <type>
 		excException := py.MakeException(exc)
+		debugf("raise: excException = %v\n", excException)
 		vm.SetException(excException)
 		if cause != nil {
 			excException.Cause = py.MakeException(cause)
@@ -1431,24 +1434,17 @@ func (vm *Vm) UnwindBlock(frame *py.Frame, block *py.TryBlock) {
 
 // Unwinds the stack in the presence of an exception
 func (vm *Vm) UnwindExceptHandler(frame *py.Frame, block *py.TryBlock) {
+	debugf("** UnwindExceptHandler stack depth %v\n", vm.STACK_LEVEL())
 	if vm.STACK_LEVEL() < block.Level+3 {
 		panic("Couldn't find traceback on stack")
 	} else {
 		frame.Stack = frame.Stack[:block.Level+3]
 	}
-	// If have just raised an exception, don't overwrite it
-	//
-	// FIXME if have two exceptions python shows both tracebacks
-	//
-	// FIXME this is a departure from python's way not sure it is
-	// correct
-	if vm.exc.Value != nil {
-		vm.DROPN(3)
-	} else {
-		vm.exc.Type = vm.POP().(*py.Type)
-		vm.exc.Value = vm.POP()
-		vm.exc.Traceback = vm.POP().(*py.Traceback)
-	}
+	debugf("** UnwindExceptHandler stack depth now %v\n", vm.STACK_LEVEL())
+	vm.exc.Type = vm.POP().(*py.Type)
+	vm.exc.Value = vm.POP()
+	vm.exc.Traceback = vm.POP().(*py.Traceback)
+	debugf("** UnwindExceptHandler exc = (type: %v, value: %v, traceback: %v)\n", vm.exc.Type, vm.exc.Value, vm.exc.Traceback)
 }
 
 // Run the virtual machine on a Frame object
@@ -1534,13 +1530,13 @@ func RunFrame(frame *py.Frame) (res py.Object, err error) {
 				frame.Lasti = b.Handler
 				break
 			}
-			if vm.exit&(exitException|exitReraise) != 0 && (b.Type == SETUP_EXCEPT || b.Type == SETUP_FINALLY) {
+			if (vm.exit == exitException || vm.exit == exitReraise) && (b.Type == SETUP_EXCEPT || b.Type == SETUP_FINALLY) {
 				debugf("*** Exception\n")
 				handler := b.Handler
 				// This invalidates b
 				frame.PushBlock(EXCEPT_HANDLER, -1, vm.STACK_LEVEL())
-				vm.PUSH(vm.old_exc.Traceback)
-				vm.PUSH(vm.old_exc.Value)
+				vm.PUSH(vm.exc.Traceback)
+				vm.PUSH(vm.exc.Value)
 				vm.PUSH(vm.exc.Type) // can be nil
 				// FIXME PyErr_Fetch(&exc, &val, &tb)
 				exc := vm.exc.Type
@@ -1563,7 +1559,7 @@ func RunFrame(frame *py.Frame) (res py.Object, err error) {
 				break
 			}
 			if b.Type == SETUP_FINALLY {
-				if vm.exit&(exitReturn|exitContinue) != 0 {
+				if vm.exit == exitReturn || vm.exit == exitContinue {
 					vm.PUSH(vm.result)
 				}
 				vm.PUSH(py.Int(vm.exit))
@@ -1573,7 +1569,7 @@ func RunFrame(frame *py.Frame) (res py.Object, err error) {
 			}
 		}
 	}
-	if vm.exc.Value != nil {
+	if vm.exc.IsSet() {
 		return vm.result, vm.exc
 	}
 	return vm.result, nil

vm/stringer.go

@@ -0,0 +1,16 @@
+// generated by stringer -type=vmExit -output stringer.go; DO NOT EDIT
+
+package vm
+
+import "fmt"
+
+const _vmExit_name = "exitNotexitExceptionexitReraiseexitReturnexitBreakexitContinueexitYieldexitSilenced"
+
+var _vmExit_index = [...]uint8{0, 7, 20, 31, 41, 50, 62, 71, 83}
+
+func (i vmExit) String() string {
+	if i+1 >= vmExit(len(_vmExit_index)) {
+		return fmt.Sprintf("vmExit(%d)", i)
+	}
+	return _vmExit_name[_vmExit_index[i]:_vmExit_index[i+1]]
+}

vm/tests/class.py

@@ -46,3 +46,5 @@ def method1(self, x):
 c = x()
 assert c.method1(1) == 2
 
+# End with this
+finished = True

vm/tests/comprehensions.py

@@ -25,3 +25,6 @@
 A = {"a":1, "b":2, "c":3}
 B = { k:k for k in ("a","b","c") }
 assert B["b"] == "b"
+
+# End with this
+finished = True

vm/tests/exceptions.py

@@ -0,0 +1,148 @@
+#!/usr/bin/env python3.4
+
+# Test exceptions
+
+# Straight forward
+ok = False
+try:
+    raise ValueError
+except ValueError:
+    ok = True
+assert ok
+
+ok = False
+try:
+    raise ValueError
+except ValueError as e:
+    ok = True
+assert ok
+
+ok = False
+try:
+    raise ValueError
+except ValueError as e:
+    ok = True
+assert ok
+
+ok = False
+try:
+    raise ValueError
+except (IOError, ValueError) as e:
+    ok = True
+assert ok
+
+ok = False
+try:
+    raise ValueError("Potato")
+except (IOError, ValueError) as e:
+    ok = True
+assert ok
+
+# hierarchy
+# FIXME doesn't work because IsSubtype is broken ValueError.IsSubtype(Exception) == false
+# ok = False
+# try:
+#     raise ValueError("potato")
+# except Exception:
+#     ok = True
+# assert ok
+
+ok = False
+try:
+    raise ValueError
+except IOError:
+    assert False, "Not expecting IO Error"
+except ValueError:
+    ok = True
+assert ok
+
+# no exception
+ok = False
+try:
+    pass
+except ValueError:
+    assert False, "Not expecting ValueError"
+else:
+    ok = True
+assert ok
+
+# nested
+ok = False
+try:
+    try:
+        raise ValueError("potato")
+    except IOError as e:
+        assert False, "Not expecting IOError"
+    else:
+        assert False, "Expecting ValueError"
+except ValueError:
+    ok = True
+else:
+    assert False, "Expecting ValueError (outer)"
+assert ok
+
+ok1 = False
+ok2 = False
+try:
+    try:
+        raise IOError("potato")
+    except IOError as e:
+        ok1 = True
+    else:
+        assert False, "Expecting ValueError"
+except ValueError:
+    assert False, "Expecting IOError"
+except IOError:
+    assert False, "Expecting IOError"
+else:
+    ok2 = True
+assert ok
+
+# re-raise
+ok1 = False
+ok2 = False
+try:
+    try:
+        raise ValueError("potato")
+    except ValueError as e:
+        ok2 = True
+        raise
+    else:
+        assert False, "Expecting ValueError (inner)"
+except ValueError:
+    ok1 = True
+else:
+    assert False, "Expecting ValueError (outer)"
+assert ok1 and ok2
+
+# try/finally
+ok1 = False
+ok2 = False
+ok3 = False
+try:
+    try:
+        ok1 = True
+    finally:
+        ok2 = True
+except ValueError:
+    assert False, "Not expecting ValueError (outer)"
+else:
+    ok3 = True
+assert ok1 and ok2 and ok3
+
+# FIXME
+# ok1 = False
+# ok2 = False
+# try:
+#     try:
+#         raise ValueError()
+#     finally:
+#         ok1 = True
+# except ValueError:
+#     ok2 = True
+# else:
+#     assert False, "Expecting ValueError (outer)"
+# assert ok1 and ok2
+
+# End with this
+finished = True

vm/tests/functions.py

@@ -153,3 +153,7 @@ def fn12(*args,a=2,b=3,**kwargs) -> "RET":
 
 
 #FIXME decorators
+
+
+# End with this
+finished = True

vm/tests/ops.py

@@ -92,3 +92,37 @@
 assert True is True
 assert True is not False
 # FIXME EXC_MATCH
+
+# logical
+t = True
+f = False
+assert (f and f) == False
+assert (f and t) == False
+assert (t and f) == False
+assert (t and t) == True
+
+assert (f and f and f) == False
+assert (f and f and t) == False
+assert (f and t and f) == False
+assert (f and t and t) == False
+assert (t and f and f) == False
+assert (t and f and t) == False
+assert (t and t and f) == False
+assert (t and t and t) == True
+
+assert (f or f) == False
+assert (f or t) == True
+assert (t or f) == True
+assert (t or t) == True
+
+assert (f or f or f) == False
+assert (f or f or t) == True
+assert (f or t or f) == True
+assert (f or t or t) == True
+assert (t or f or f) == True
+assert (t or f or t) == True
+assert (t or t or f) == True
+assert (t or t or t) == True
+
+# End with this
+finished = True

vm/vm.go

@@ -5,19 +5,21 @@ import (
 	"github.com/ncw/gpython/py"
 )
 
+//go:generate stringer -type=vmExit -output stringer.go
+
 // VM exit type
 type vmExit byte
 
 // VM exit values
 const (
-	exitNot       = vmExit(iota) // No error
-	exitException                // Exception occurred
-	exitReraise                  // Exception re-raised by 'finally'
-	exitReturn                   // 'return' statement
-	exitBreak                    // 'break' statement
-	exitContinue                 // 'continue' statement
-	exitYield                    // 'yield' operator
-	exitSilenced                 // Exception silenced by 'with'
+	exitNot       vmExit = iota // No error
+	exitException               // Exception occurred
+	exitReraise                 // Exception re-raised by 'finally'
+	exitReturn                  // 'return' statement
+	exitBreak                   // 'break' statement
+	exitContinue                // 'continue' statement
+	exitYield                   // 'yield' operator
+	exitSilenced                // Exception silenced by 'with'
 )
 
 // Virtual machine state