From b648e98ad01d7f5c4aa102c4848507b5c31c859e Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Wed, 26 Aug 2015 15:45:06 +0100
Subject: [PATCH] py/objstr: Fix error reporting for unexpected end of modulo
 format str.

---
 py/objstr.c                          | 3 ++-
 tests/basics/string_format_modulo.py | 5 +++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/py/objstr.c b/py/objstr.c
index 98360d9e11..f91e1731c5 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -1299,7 +1299,7 @@ STATIC mp_obj_t str_modulo_format(mp_obj_t pattern, mp_uint_t n_args, const mp_o
             continue;
         }
         if (++str >= top) {
-            break;
+            goto incomplete_format;
         }
         if (*str == '%') {
             vstr_add_byte(&vstr, '%');
@@ -1369,6 +1369,7 @@ STATIC mp_obj_t str_modulo_format(mp_obj_t pattern, mp_uint_t n_args, const mp_o
         }
 
         if (str >= top) {
+incomplete_format:
             if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
                 terse_str_format_value_error();
             } else {
diff --git a/tests/basics/string_format_modulo.py b/tests/basics/string_format_modulo.py
index 05b00ef14f..2e4909220a 100644
--- a/tests/basics/string_format_modulo.py
+++ b/tests/basics/string_format_modulo.py
@@ -111,3 +111,8 @@ try:
     '%l' % 1
 except ValueError:
     print('ValueError')
+
+try:
+    'a%' % 1
+except ValueError:
+    print('ValueError')