From e2e627fa106cdb42a89f8519f55890b11f5937eb Mon Sep 17 00:00:00 2001
From: Matt Borland <matt@mattborland.com>
Date: Fri, 1 Jul 2022 16:56:45 -0700
Subject: [PATCH] Fix unsafe bool warning in fmod and refactor

---
 include/boost/math/ccmath/fmod.hpp | 75 ++++++++++++++++--------------
 1 file changed, 39 insertions(+), 36 deletions(-)

diff --git a/include/boost/math/ccmath/fmod.hpp b/include/boost/math/ccmath/fmod.hpp
index 12e67d8c0..5f1e08cea 100644
--- a/include/boost/math/ccmath/fmod.hpp
+++ b/include/boost/math/ccmath/fmod.hpp
@@ -1,4 +1,4 @@
-//  (C) Copyright Matt Borland 2021.
+//  (C) Copyright Matt Borland 2021 - 2022.
 //  Use, modification and distribution are subject to the
 //  Boost Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
@@ -10,6 +10,7 @@
 #include <cstdint>
 #include <limits>
 #include <type_traits>
+#include <boost/math/tools/promotion.hpp>
 #include <boost/math/tools/is_constant_evaluated.hpp>
 #include <boost/math/ccmath/abs.hpp>
 #include <boost/math/ccmath/isinf.hpp>
@@ -20,38 +21,57 @@ namespace boost::math::ccmath {
 
 namespace detail {
 
-template <typename ReturnType, typename T1, typename T2>
-inline constexpr ReturnType fmod_impl(T1 x, T2 y) noexcept
+template <typename T>
+constexpr T fmod_impl(T x, T y)
 {
-    if(x == y)
+    if (x == y)
     {
-        return ReturnType(0);
+        return static_cast<T>(0);
     }
     else
     {
-        while(x >= y)
+        while (x >= y)
         {
             x -= y;
         }
 
-        return static_cast<ReturnType>(x);
+        return static_cast<T>(x);
     }
 }
 
 } // Namespace detail
 
 template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
-inline constexpr Real fmod(Real x, Real y) noexcept
+constexpr Real fmod(Real x, Real y)
 {
     if(BOOST_MATH_IS_CONSTANT_EVALUATED(x))
     {
-        return boost::math::ccmath::abs(x) == Real(0) && y != Real(0) ? x :
-               boost::math::ccmath::isinf(x) && !boost::math::ccmath::isnan(y) ? std::numeric_limits<Real>::quiet_NaN() :
-               boost::math::ccmath::abs(y) == Real(0) && !boost::math::ccmath::isnan(x) ? std::numeric_limits<Real>::quiet_NaN() :
-               boost::math::ccmath::isinf(y) && boost::math::ccmath::isfinite(x) ? x :
-               boost::math::ccmath::isnan(x) ? std::numeric_limits<Real>::quiet_NaN() :
-               boost::math::ccmath::isnan(y) ? std::numeric_limits<Real>::quiet_NaN() :
-               boost::math::ccmath::detail::fmod_impl<Real>(x, y);
+        if (boost::math::ccmath::abs(x) == static_cast<Real>(0) && y != static_cast<Real>(0))
+        {
+            return x;
+        }
+        else if (boost::math::ccmath::isinf(x) && !boost::math::ccmath::isnan(y))
+        {
+            return std::numeric_limits<Real>::quiet_NaN();
+        }
+        else if (boost::math::ccmath::abs(y) == static_cast<Real>(0) && !boost::math::ccmath::isnan(x))
+        {
+            return std::numeric_limits<Real>::quiet_NaN();
+        }
+        else if (boost::math::ccmath::isinf(y) && boost::math::ccmath::isfinite(x))
+        {
+            return x;
+        }
+        else if (boost::math::ccmath::isnan(x))
+        {
+            return x;
+        }
+        else if (boost::math::ccmath::isnan(y))
+        {
+            return y;
+        }
+
+        return boost::math::ccmath::detail::fmod_impl<Real>(x, y);
     }
     else
     {
@@ -61,28 +81,11 @@ inline constexpr Real fmod(Real x, Real y) noexcept
 }
 
 template <typename T1, typename T2>
-inline constexpr auto fmod(T1 x, T2 y) noexcept
+constexpr auto fmod(T1 x, T2 y)
 {
     if(BOOST_MATH_IS_CONSTANT_EVALUATED(x))
     {
-        // If the type is an integer (e.g. epsilon == 0) then set the epsilon value to 1 so that type is at a minimum 
-        // cast to double
-        constexpr auto T1p = std::numeric_limits<T1>::epsilon() > 0 ? std::numeric_limits<T1>::epsilon() : 1;
-        constexpr auto T2p = std::numeric_limits<T2>::epsilon() > 0 ? std::numeric_limits<T2>::epsilon() : 1;
-        
-        using promoted_type = 
-                              #ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
-                              std::conditional_t<T1p <= LDBL_EPSILON && T1p <= T2p, T1,
-                              std::conditional_t<T2p <= LDBL_EPSILON && T2p <= T1p, T2,
-                              #endif
-                              std::conditional_t<T1p <= DBL_EPSILON && T1p <= T2p, T1,
-                              std::conditional_t<T2p <= DBL_EPSILON && T2p <= T1p, T2, double
-                              #ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
-                              >>>>;
-                              #else
-                              >>;
-                              #endif
-
+        using promoted_type = boost::math::tools::promote_args_t<T1, T2>;
         return boost::math::ccmath::fmod(promoted_type(x), promoted_type(y));
     }
     else
@@ -92,13 +95,13 @@ inline constexpr auto fmod(T1 x, T2 y) noexcept
     }
 }
 
-inline constexpr float fmodf(float x, float y) noexcept
+constexpr float fmodf(float x, float y)
 {
     return boost::math::ccmath::fmod(x, y);
 }
 
 #ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
-inline constexpr long double fmodl(long double x, long double y) noexcept
+constexpr long double fmodl(long double x, long double y)
 {
     return boost::math::ccmath::fmod(x, y);
 }