Index: Python/Python-ast.c
===================================================================
--- Python/Python-ast.c	(revision 86416)
+++ Python/Python-ast.c	(working copy)
@@ -610,7 +610,7 @@
         PyObject *s = PyObject_Repr(obj);
         if (s == NULL) return 1;
         PyErr_Format(PyExc_ValueError, "invalid integer value: %.400s",
-                     PyBytes_AS_STRING(s));
+                     _PyUnicode_AsString(s));
         Py_DECREF(s);
         return 1;
     }
@@ -3516,7 +3516,7 @@
 
         tmp = PyObject_Repr(obj);
         if (tmp == NULL) goto failed;
-        PyErr_Format(PyExc_TypeError, "expected some sort of mod, but got %.400s", PyBytes_AS_STRING(tmp));
+        PyErr_Format(PyExc_TypeError, "expected some sort of mod, but got %.400s", _PyUnicode_AsString(tmp));
 failed:
         Py_XDECREF(tmp);
         return 1;
@@ -4714,7 +4714,7 @@
 
         tmp = PyObject_Repr(obj);
         if (tmp == NULL) goto failed;
-        PyErr_Format(PyExc_TypeError, "expected some sort of stmt, but got %.400s", PyBytes_AS_STRING(tmp));
+        PyErr_Format(PyExc_TypeError, "expected some sort of stmt, but got %.400s", _PyUnicode_AsString(tmp));
 failed:
         Py_XDECREF(tmp);
         return 1;
@@ -5832,7 +5832,7 @@
 
         tmp = PyObject_Repr(obj);
         if (tmp == NULL) goto failed;
-        PyErr_Format(PyExc_TypeError, "expected some sort of expr, but got %.400s", PyBytes_AS_STRING(tmp));
+        PyErr_Format(PyExc_TypeError, "expected some sort of expr, but got %.400s", _PyUnicode_AsString(tmp));
 failed:
         Py_XDECREF(tmp);
         return 1;
@@ -5895,7 +5895,7 @@
 
         tmp = PyObject_Repr(obj);
         if (tmp == NULL) goto failed;
-        PyErr_Format(PyExc_TypeError, "expected some sort of expr_context, but got %.400s", PyBytes_AS_STRING(tmp));
+        PyErr_Format(PyExc_TypeError, "expected some sort of expr_context, but got %.400s", _PyUnicode_AsString(tmp));
 failed:
         Py_XDECREF(tmp);
         return 1;
@@ -6020,7 +6020,7 @@
 
         tmp = PyObject_Repr(obj);
         if (tmp == NULL) goto failed;
-        PyErr_Format(PyExc_TypeError, "expected some sort of slice, but got %.400s", PyBytes_AS_STRING(tmp));
+        PyErr_Format(PyExc_TypeError, "expected some sort of slice, but got %.400s", _PyUnicode_AsString(tmp));
 failed:
         Py_XDECREF(tmp);
         return 1;
@@ -6051,7 +6051,7 @@
 
         tmp = PyObject_Repr(obj);
         if (tmp == NULL) goto failed;
-        PyErr_Format(PyExc_TypeError, "expected some sort of boolop, but got %.400s", PyBytes_AS_STRING(tmp));
+        PyErr_Format(PyExc_TypeError, "expected some sort of boolop, but got %.400s", _PyUnicode_AsString(tmp));
 failed:
         Py_XDECREF(tmp);
         return 1;
@@ -6162,7 +6162,7 @@
 
         tmp = PyObject_Repr(obj);
         if (tmp == NULL) goto failed;
-        PyErr_Format(PyExc_TypeError, "expected some sort of operator, but got %.400s", PyBytes_AS_STRING(tmp));
+        PyErr_Format(PyExc_TypeError, "expected some sort of operator, but got %.400s", _PyUnicode_AsString(tmp));
 failed:
         Py_XDECREF(tmp);
         return 1;
@@ -6209,7 +6209,7 @@
 
         tmp = PyObject_Repr(obj);
         if (tmp == NULL) goto failed;
-        PyErr_Format(PyExc_TypeError, "expected some sort of unaryop, but got %.400s", PyBytes_AS_STRING(tmp));
+        PyErr_Format(PyExc_TypeError, "expected some sort of unaryop, but got %.400s", _PyUnicode_AsString(tmp));
 failed:
         Py_XDECREF(tmp);
         return 1;
@@ -6304,7 +6304,7 @@
 
         tmp = PyObject_Repr(obj);
         if (tmp == NULL) goto failed;
-        PyErr_Format(PyExc_TypeError, "expected some sort of cmpop, but got %.400s", PyBytes_AS_STRING(tmp));
+        PyErr_Format(PyExc_TypeError, "expected some sort of cmpop, but got %.400s", _PyUnicode_AsString(tmp));
 failed:
         Py_XDECREF(tmp);
         return 1;
@@ -6475,7 +6475,7 @@
 
         tmp = PyObject_Repr(obj);
         if (tmp == NULL) goto failed;
-        PyErr_Format(PyExc_TypeError, "expected some sort of excepthandler, but got %.400s", PyBytes_AS_STRING(tmp));
+        PyErr_Format(PyExc_TypeError, "expected some sort of excepthandler, but got %.400s", _PyUnicode_AsString(tmp));
 failed:
         Py_XDECREF(tmp);
         return 1;
Index: Misc/NEWS
===================================================================
--- Misc/NEWS	(revision 86416)
+++ Misc/NEWS	(working copy)
@@ -10,6 +10,9 @@
 Core and Builtins
 -----------------
 
+- Issue #10391: Fix a crash in error-handling when invoking ``compile`` on
+  malformed ``ast`` trees.
+
 - Issue #10372: Import the warnings module only after the IO library is
   initialized, so as to avoid bootstrap issues with the '-W' option.
 
Index: Parser/asdl_c.py
===================================================================
--- Parser/asdl_c.py	(revision 86416)
+++ Parser/asdl_c.py	(working copy)
@@ -375,7 +375,7 @@
         # there's really nothing more we can do if this fails ...
         self.emit("if (tmp == NULL) goto failed;", 1)
         error = "expected some sort of %s, but got %%.400s" % name
-        format = "PyErr_Format(PyExc_TypeError, \"%s\", PyBytes_AS_STRING(tmp));"
+        format = "PyErr_Format(PyExc_TypeError, \"%s\", _PyUnicode_AsString(tmp));"
         self.emit(format % error, 1, reflow=False)
         self.emit("failed:", 0)
         self.emit("Py_XDECREF(tmp);", 1)
@@ -805,7 +805,7 @@
         PyObject *s = PyObject_Repr(obj);
         if (s == NULL) return 1;
         PyErr_Format(PyExc_ValueError, "invalid integer value: %.400s",
-                     PyBytes_AS_STRING(s));
+                     _PyUnicode_AsString(s));
         Py_DECREF(s);
         return 1;
     }
Index: Lib/test/test_compile.py
===================================================================
--- Lib/test/test_compile.py	(revision 86416)
+++ Lib/test/test_compile.py	(working copy)
@@ -433,6 +433,13 @@
         ast.body = [_ast.BoolOp()]
         self.assertRaises(TypeError, compile, ast, '<ast>', 'exec')
 
+        # raise exception when expr is not an expression:
+        self.assertRaises(TypeError, compile,
+                          _ast.Module(body=[_ast.Expr(_ast.Assign(lineno=0,
+                                                                  col_offset=0),
+                                                      lineno=0, col_offset=0)],
+                                      lineno=0),
+                          'test', 'exec')
 
 def test_main():
     support.run_unittest(TestSpecifics)