Issue #6850: Fix bug in Decimal._parse_format_specifier for formats

with no type specifier.

Lib/decimal.py

@@ -5512,7 +5512,7 @@ def _parse_format_specifier(format_spec, _localeconv=None):
     # if format type is 'g' or 'G' then a precision of 0 makes little
     # sense; convert it to 1.  Same if format type is unspecified.
     if format_dict['precision'] == 0:
-        if format_dict['type'] in 'gG' or format_dict['type'] is None:
+        if format_dict['type'] is None or format_dict['type'] in 'gG':
             format_dict['precision'] = 1
 
     # determine thousands separator, grouping, and decimal separator, and

Lib/test/test_decimal.py

@@ -760,6 +760,9 @@ class DecimalFormatTest(unittest.TestCase):
             (',%', '123.456789', '12,345.6789%'),
             (',e', '123456', '1.23456e+5'),
             (',E', '123456', '1.23456E+5'),
+
+            # issue 6850
+            ('a=-7.0', '0.12345', 'aaaa0.1'),
             ]
         for fmt, d, result in test_values:
             self.assertEqual(format(Decimal(d), fmt), result)

Misc/NEWS

@@ -366,6 +366,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #6850: Fix bug in Decimal._parse_format_specifier for formats
+  with no type specifier.
+
 - Issue #4937: plat-mac/bundlebuilder revers to non-existing version.plist
 
 - Issue #6838: Use a list to accumulate the value instead of