bpo-35560: Remove assertion from format(float, "n") (GH-11288)

tirkarthi · vstinner · commit 3f7983a25a3d · 2019-01-07T16:09:14.000+01:00
Fix an assertion error in format() in debug build for floating point
formatting with "n" format, zero padding and small width. Release build is
not impacted. Patch by Karthikeyan Singaravelan.
diff --git a/Lib/test/test_float.py b/Lib/test/test_float.py
@@ -701,6 +701,25 @@ def test_issue5864(self):
         self.assertEqual(format(1234.56, '.4'), '1.235e+03')
         self.assertEqual(format(12345.6, '.4'), '1.235e+04')
 
+    def test_issue35560(self):
+        self.assertEqual(format(123.0, '00'), '123.0')
+        self.assertEqual(format(123.34, '00f'), '123.340000')
+        self.assertEqual(format(123.34, '00e'), '1.233400e+02')
+        self.assertEqual(format(123.34, '00g'), '123.34')
+        self.assertEqual(format(123.34, '00.10f'), '123.3400000000')
+        self.assertEqual(format(123.34, '00.10e'), '1.2334000000e+02')
+        self.assertEqual(format(123.34, '00.10g'), '123.34')
+        self.assertEqual(format(123.34, '01f'), '123.340000')
+
+        self.assertEqual(format(-123.0, '00'), '-123.0')
+        self.assertEqual(format(-123.34, '00f'), '-123.340000')
+        self.assertEqual(format(-123.34, '00e'), '-1.233400e+02')
+        self.assertEqual(format(-123.34, '00g'), '-123.34')
+        self.assertEqual(format(-123.34, '00.10f'), '-123.3400000000')
+        self.assertEqual(format(-123.34, '00.10f'), '-123.3400000000')
+        self.assertEqual(format(-123.34, '00.10e'), '-1.2334000000e+02')
+        self.assertEqual(format(-123.34, '00.10g'), '-123.34')
+
 class ReprTestCase(unittest.TestCase):
     def test_repr(self):
         floats_file = open(os.path.join(os.path.split(__file__)[0],
diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-12-22-22-19-51.bpo-35560.9vMWSP.rst b/Misc/NEWS.d/next/Core and Builtins/2018-12-22-22-19-51.bpo-35560.9vMWSP.rst
@@ -0,0 +1,3 @@
+Fix an assertion error in :func:`format` in debug build for floating point
+formatting with "n" format, zero padding and small width. Release build is
+not impacted. Patch by Karthikeyan Singaravelan.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
@@ -9381,6 +9381,7 @@ _PyUnicode_InsertThousandsGrouping(
     PyObject *thousands_sep,
     Py_UCS4 *maxchar)
 {
+    min_width = Py_MAX(0, min_width);
     if (writer) {
         assert(digits != NULL);
         assert(maxchar == NULL);
@@ -9391,7 +9392,6 @@ _PyUnicode_InsertThousandsGrouping(
     }
     assert(0 <= d_pos);
     assert(0 <= n_digits);
-    assert(0 <= min_width);
     assert(grouping != NULL);
 
     if (digits != NULL) {

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	+Fix an assertion error in :func:`format` in debug build for floating point
	`2`	`+formatting with "n" format, zero padding and small width. Release build is`
	`3`	`+not impacted. Patch by Karthikeyan Singaravelan.`
Original file line number	Diff line number	Diff line change
`@@ -9381,6 +9381,7 @@ _PyUnicode_InsertThousandsGrouping(`
`9381`	`9381`	`PyObject *thousands_sep,`
`9382`	`9382`	`Py_UCS4 *maxchar)`
`9383`	`9383`	`{`
	`9384`	`+ min_width = Py_MAX(0, min_width);`
`9384`	`9385`	`if (writer) {`
`9385`	`9386`	`assert(digits != NULL);`
`9386`	`9387`	`assert(maxchar == NULL);`
`@@ -9391,7 +9392,6 @@ _PyUnicode_InsertThousandsGrouping(`
`9391`	`9392`	`}`
`9392`	`9393`	`assert(0 <= d_pos);`
`9393`	`9394`	`assert(0 <= n_digits);`
`9394`		`- assert(0 <= min_width);`
`9395`	`9395`	`assert(grouping != NULL);`
`9396`	`9396`
`9397`	`9397`	`if (digits != NULL) {`