Forward port MvL's fix in 43227:

Fix crash when a Unicode string containing an encoding declaration is
compile()d. Fixes #1115379.

Lib/test/test_compile.py

@@ -284,6 +284,10 @@ def f():
         f1, f2 = f()
         self.assertNotEqual(id(f1.func_code), id(f2.func_code))
 
+    def test_unicode_encoding(self):
+        code = u"# -*- coding: utf-8 -*-\npass\n"
+        self.assertRaises(SyntaxError, compile, code, "tmp", "exec")
+
     def test_subscripts(self):
         # SF bug 1448804
         # Class to make testing subscript results easy

Misc/NEWS

@@ -12,6 +12,9 @@ What's New in Python 2.5 alpha 1?
 Core and builtins
 -----------------
 
+- Bug #1115379: Compiling a Unicode string with an encoding declaration
+  now gives a SyntaxError.
+
 - Previously, Python code had no easy way to access the contents of a
   cell object. Now, a ``cell_contents`` attribute has been added
   (closes patch #1170323).

Python/ast.c

@@ -191,6 +191,10 @@ PyAST_FromNode(const node *n, PyCompilerFlags *flags, const char *filename,
 
     if (flags && flags->cf_flags & PyCF_SOURCE_IS_UTF8) {
         c.c_encoding = "utf-8";
+        if (TYPE(n) == encoding_decl) {
+                ast_error(n, "encoding declaration in Unicode string");
+                goto error;
+        }
     } else if (TYPE(n) == encoding_decl) {
         c.c_encoding = STR(n);
         n = CHILD(n, 0);