From b75cb8392bdf5f8c12072eac3adbdaad53d1e8d2 Mon Sep 17 00:00:00 2001
From: Damien George
Date: Thu, 8 Feb 2018 14:02:50 +1100
Subject: py/parsenum: Fix parsing of floats that are close to subnormal.

Prior to this patch, a float literal that was close to subnormal would
have a loss of precision when parsed.  The worst case was something like
float('10000000000000000000e-326') which returned 0.0.
---
 tests/float/float_parse.py            | 5 +++++
 tests/float/float_parse_doubleprec.py | 5 +++++
 2 files changed, 10 insertions(+)

(limited to 'tests/float')

diff --git a/tests/float/float_parse.py b/tests/float/float_parse.py
index 448eff3bc..de4ea455f 100644
--- a/tests/float/float_parse.py
+++ b/tests/float/float_parse.py
@@ -20,3 +20,8 @@ print(float('.' + '9' * 70 + 'e-50') == float('1e-50'))
 print(float('.' + '0' * 60 + '1e10') == float('1e-51'))
 print(float('.' + '0' * 60 + '9e25'))
 print(float('.' + '0' * 60 + '9e40'))
+
+# ensure that accuracy is retained when value is close to a subnormal
+print(float('1.00000000000000000000e-37'))
+print(float('10.0000000000000000000e-38'))
+print(float('100.000000000000000000e-39'))
diff --git a/tests/float/float_parse_doubleprec.py b/tests/float/float_parse_doubleprec.py
index 356601130..2ea7842f3 100644
--- a/tests/float/float_parse_doubleprec.py
+++ b/tests/float/float_parse_doubleprec.py
@@ -14,3 +14,8 @@ print(float('.' + '9' * 400 + 'e-100'))
 print(float('.' + '0' * 400 + '9e100'))
 print(float('.' + '0' * 400 + '9e200'))
 print(float('.' + '0' * 400 + '9e400'))
+
+# ensure that accuracy is retained when value is close to a subnormal
+print(float('1.00000000000000000000e-307'))
+print(float('10.0000000000000000000e-308'))
+print(float('100.000000000000000000e-309'))
-- 
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