Misc/NEWS entries for issue 7117.
diff --git a/Misc/NEWS b/Misc/NEWS
index fcda7fd..9e659ac 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -15,11 +15,40 @@
- Issue #7085: Fix crash when importing some extensions in a thread
on MacOSX 10.6.
+- Issue #7117: repr(x) for a float x returns a result based on the
+ shortest decimal string that's guaranteed to round back to x under
+ correct rounding (with round-half-to-even rounding mode).
+ Previously it gave a string based on rounding x to 17 decimal digits.
+ repr(x) for a complex number behaves similarly. On platforms where
+ the correctly-rounded strtod and dtoa code is not supported (see below),
+ repr is unchanged.
+
+- Issue #7117: On almost all platforms: float-to-string and
+ string-to-float conversions within Python are now correctly rounded.
+ Places these conversions occur include: str for floats and complex
+ numbers; the float and complex constructors; old-style and new-style
+ numeric formatting; serialization and deserialization of floats and
+ complex numbers using marshal, pickle and json; parsing of float and
+ imaginary literals in Python code; Decimal-to-float conversion.
+
+ The conversions use a Python-adapted version of David Gay's
+ well-known dtoa.c, providing correctly-rounded strtod and dtoa C
+ functions. This code is supported on Windows, and on Unix-like
+ platforms using gcc, icc or suncc as the C compiler. There may be a
+ small number of platforms on which correct operation of this code
+ cannot be guaranteed, so the code is not used: notably, this applies
+ to platforms where the C double format is not IEEE 754 binary64, and
+ to platforms on x86 hardware where the x87 FPU is set to 64-bit
+ precision and Python's configure script is unable to determine how
+ to change the FPU precision. On these platforms conversions use the
+ platform strtod and dtoa, as before.
+
- Issue #7117: Backport round implementation from Python 3.x. round
- now uses David Gay's correctly-rounded string <-> double conversions
- (when available), and so produces correctly rounded results. There
- are two related small changes: (1) round now accepts any class with
- an __index__ method for its second argument (but no longer accepts
+ now uses the correctly-rounded string <-> float conversions
+ described above (when available), and so produces correctly rounded
+ results that will display nicely under the float repr. There are
+ two related small changes: (1) round now accepts any class with an
+ __index__ method for its second argument (but no longer accepts
floats for the second argument), and (2) an excessively large second
integer argument (e.g., round(1.234, 10**100)) no longer raises an
exception.