Index: Python/ast.c
===================================================================
--- Python/ast.c	(revision 53526)
+++ Python/ast.c	(working copy)
@@ -1991,7 +1991,8 @@
                           "assignment");
                 return NULL;
         }
-        set_context(expr1, Store, ch);
+        if (!set_context(expr1, Store, ch))
+            return NULL;
 
         ch = CHILD(n, 2);
         if (TYPE(ch) == testlist)
@@ -2584,6 +2585,8 @@
     }
     else if (s[2] == 'i') {
         int i, n_elif, has_else = 0;
+        expr_ty expression;
+        asdl_seq *suite_seq;
         asdl_seq *orelse = NULL;
         n_elif = NCH(n) - 4;
         /* must reference the child n_elif+1 since 'else' token is third,
@@ -2596,8 +2599,7 @@
         n_elif /= 4;
 
         if (has_else) {
-            expr_ty expression;
-            asdl_seq *seq1, *seq2;
+            asdl_seq *suite_seq2;
 
             orelse = asdl_seq_new(1, c->c_arena);
             if (!orelse)
@@ -2605,14 +2607,14 @@
             expression = ast_for_expr(c, CHILD(n, NCH(n) - 6));
             if (!expression)
                 return NULL;
-            seq1 = ast_for_suite(c, CHILD(n, NCH(n) - 4));
-            if (!seq1)
+            suite_seq = ast_for_suite(c, CHILD(n, NCH(n) - 4));
+            if (!suite_seq)
                 return NULL;
-            seq2 = ast_for_suite(c, CHILD(n, NCH(n) - 1));
-            if (!seq2)
+            suite_seq2 = ast_for_suite(c, CHILD(n, NCH(n) - 1));
+            if (!suite_seq2)
                 return NULL;
 
-            asdl_seq_SET(orelse, 0, If(expression, seq1, seq2, 
+            asdl_seq_SET(orelse, 0, If(expression, suite_seq, suite_seq2, 
                                        LINENO(CHILD(n, NCH(n) - 6)), CHILD(n, NCH(n) - 6)->n_col_offset,
                                        c->c_arena));
             /* the just-created orelse handled the last elif */
@@ -2621,8 +2623,6 @@
 
         for (i = 0; i < n_elif; i++) {
             int off = 5 + (n_elif - i - 1) * 4;
-            expr_ty expression;
-            asdl_seq *suite_seq;
             asdl_seq *newobj = asdl_seq_new(1, c->c_arena);
             if (!newobj)
                 return NULL;
@@ -2638,9 +2638,14 @@
                             LINENO(CHILD(n, off)), CHILD(n, off)->n_col_offset, c->c_arena));
             orelse = newobj;
         }
-        return If(ast_for_expr(c, CHILD(n, 1)),
-                  ast_for_suite(c, CHILD(n, 3)),
-                  orelse, LINENO(n), n->n_col_offset, c->c_arena);
+        expression = ast_for_expr(c, CHILD(n, 1));
+        if (!expression)
+            return NULL;
+        suite_seq = ast_for_suite(c, CHILD(n, 3));
+        if (!suite_seq)
+            return NULL;
+        return If(expression, suite_seq, orelse,
+                  LINENO(n), n->n_col_offset, c->c_arena);
     }
 
     PyErr_Format(PyExc_SystemError,
Index: Lib/test/test_syntax.py
===================================================================
--- Lib/test/test_syntax.py	(revision 53526)
+++ Lib/test/test_syntax.py	(working copy)
@@ -367,6 +367,56 @@
      ...
    SystemError: too many statically nested blocks
 
+This tests assignment-context; there was a bug in Python 2.5 where compiling
+a complex 'if' (one with 'elif') would fail to notice an invalid suite,
+leading to spurious errors.
+
+   >>> if 1:
+   ...   x() = 1
+   ... elif 1:
+   ...   pass
+   Traceback (most recent call last):
+     ... 
+   SyntaxError: can't assign to function call (<doctest test.test_syntax[44]>, line 2)
+
+   >>> if 1:
+   ...   pass
+   ... elif 1:
+   ...   x() = 1
+   Traceback (most recent call last):
+     ... 
+   SyntaxError: can't assign to function call (<doctest test.test_syntax[45]>, line 4)
+
+   >>> if 1:
+   ...   x() = 1
+   ... elif 1:
+   ...   pass
+   ... else:
+   ...   pass
+   Traceback (most recent call last):
+     ... 
+   SyntaxError: can't assign to function call (<doctest test.test_syntax[46]>, line 2)
+
+   >>> if 1:
+   ...   pass
+   ... elif 1:
+   ...   x() = 1
+   ... else:
+   ...   pass
+   Traceback (most recent call last):
+     ... 
+   SyntaxError: can't assign to function call (<doctest test.test_syntax[47]>, line 4)
+
+   >>> if 1:
+   ...   pass
+   ... elif 1:
+   ...   pass
+   ... else:
+   ...   x() = 1
+   Traceback (most recent call last):
+     ... 
+   SyntaxError: can't assign to function call (<doctest test.test_syntax[48]>, line 6)
+
 """
 
 import re