Sep 17, 2024 · Sep 17, 2024 · Sep 17, 2024 · Sep 17, 2024 · Sep 17, 2024 · Sep 17, 2024
diff --git a/Misc/NEWS.d/next/Library/2024-09-17-18-06-42.gh-issue-124171.PHCvRJ.rst b/Misc/NEWS.d/next/Library/2024-09-17-18-06-42.gh-issue-124171.PHCvRJ.rst
 Add workaround for broken :c:func:`!fmod()` implementations on Windows, that
 loose zero sign (e.g. ``fmod(-10, 1)`` returns ``0.0``).  Patch by Sergey B
 Kirpichev.
diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
        return PyFloat_FromDouble(x);
    errno = 0;
    r = fmod(x, y);
 #ifdef _MSC_VER
    /* Windows (e.g. Windows 10 with MSC v.1916) loose sign
       for zero result.  But C99+ says: "if y is nonzero, the result
       has the same sign as x".
     */
    if (r == 0.0 && y != 0.0) {
        r = copysign(r, x);
    }
 #endif
    if (isnan(r)) {
        if (!isnan(x) && !isnan(y))
            errno = EDOM;
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,3 @@
		Add workaround for broken :c:func:`!fmod()` implementations on Windows, that
		loose zero sign (e.g. ``fmod(-10, 1)`` returns ``0.0``). Patch by Sergey B
		Kirpichev.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -2348,6 +2348,15 @@ math_fmod_impl(PyObject *module, double x, double y)
		return PyFloat_FromDouble(x);
		errno = 0;
		r = fmod(x, y);
		#ifdef _MSC_VER
		/* Windows (e.g. Windows 10 with MSC v.1916) loose sign
		for zero result. But C99+ says: "if y is nonzero, the result
		has the same sign as x".
		*/
		if (r == 0.0 && y != 0.0) {
		r = copysign(r, x);
		}
		#endif
		if (isnan(r)) {
		if (!isnan(x) && !isnan(y))
		errno = EDOM;
Expand Down