Improve error detection further.

include/boost/math/ccmath/abs.hpp

@@ -8,15 +8,16 @@
 #ifndef BOOST_MATH_CCMATH_ABS
 #define BOOST_MATH_CCMATH_ABS
 
-#include <boost/math/tools/assert.hpp>
 #include <boost/math/ccmath/detail/config.hpp>
-#include <boost/math/ccmath/isnan.hpp>
-#include <boost/math/ccmath/isinf.hpp>
 
 #ifdef BOOST_MATH_NO_CCMATH
 #error "The header <boost/math/abs.hpp> can only be used in C++17 and later."
 #endif
 
+#include <boost/math/tools/assert.hpp>
+#include <boost/math/ccmath/isnan.hpp>
+#include <boost/math/ccmath/isinf.hpp>
+
 namespace boost::math::ccmath {
 
 namespace detail {

include/boost/math/ccmath/ceil.hpp

@@ -6,9 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_CEIL_HPP
 #define BOOST_MATH_CCMATH_CEIL_HPP
 
-#include <cmath>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/ceil.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/floor.hpp>
 #include <boost/math/ccmath/abs.hpp>
 #include <boost/math/ccmath/isinf.hpp>

include/boost/math/ccmath/fabs.hpp

@@ -8,6 +8,12 @@
 #ifndef BOOST_MATH_CCMATH_FABS
 #define BOOST_MATH_CCMATH_FABS
 
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/fabs.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/abs.hpp>
 
 namespace boost::math::ccmath {

include/boost/math/ccmath/fdim.hpp

@@ -6,10 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_FDIM_HPP
 #define BOOST_MATH_CCMATH_FDIM_HPP
 
-#include <cmath>
-#include <limits>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/fdim.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/tools/promotion.hpp>
 #include <boost/math/ccmath/isnan.hpp>
 

include/boost/math/ccmath/floor.hpp

@@ -6,10 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_FLOOR_HPP
 #define BOOST_MATH_CCMATH_FLOOR_HPP
 
-#include <cmath>
-#include <limits>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/floor.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/abs.hpp>
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>

include/boost/math/ccmath/fma.hpp

@@ -7,13 +7,14 @@
 #define BOOST_MATH_CCMATH_FMA_HPP
 
 #include <boost/math/ccmath/detail/config.hpp>
-#include <boost/math/ccmath/isinf.hpp>
-#include <boost/math/ccmath/isnan.hpp>
 
 #ifdef BOOST_MATH_NO_CCMATH
 #error "The header <boost/math/fma.hpp> can only be used in C++17 and later."
 #endif
 
+#include <boost/math/ccmath/isinf.hpp>
+#include <boost/math/ccmath/isnan.hpp>
+
 namespace boost::math::ccmath {
 
 namespace detail {

include/boost/math/ccmath/fmax.hpp

@@ -6,10 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_FMAX_HPP
 #define BOOST_MATH_CCMATH_FMAX_HPP
 
-#include <cmath>
-#include <limits>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/fmax.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/tools/promotion.hpp>
 #include <boost/math/ccmath/isnan.hpp>
 

include/boost/math/ccmath/fmin.hpp

@@ -6,10 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_FMIN_HPP
 #define BOOST_MATH_CCMATH_FMIN_HPP
 
-#include <cmath>
-#include <limits>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/fmin.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/tools/promotion.hpp>
 #include <boost/math/ccmath/isnan.hpp>
 

include/boost/math/ccmath/fmod.hpp

@@ -6,12 +6,14 @@
 #ifndef BOOST_MATH_CCMATH_FMOD_HPP
 #define BOOST_MATH_CCMATH_FMOD_HPP
 
-#include <cmath>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/fmod.hpp> can only be used in C++17 and later."
+#endif
+
 #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>
 #include <boost/math/ccmath/isnan.hpp>

include/boost/math/ccmath/fpclassify.hpp

@@ -6,10 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_FPCLASSIFY
 #define BOOST_MATH_CCMATH_FPCLASSIFY
 
-#include <cmath>
-#include <limits>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/fpclassify.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/special_functions/fpclassify.hpp>
 #include <boost/math/ccmath/abs.hpp>
 #include <boost/math/ccmath/isinf.hpp>

include/boost/math/ccmath/frexp.hpp

@@ -7,9 +7,12 @@
 #ifndef BOOST_MATH_CCMATH_FREXP_HPP
 #define BOOST_MATH_CCMATH_FREXP_HPP
 
-#include <cmath>
-#include <limits>
-#include <type_traits>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/frexp.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>
 #include <boost/math/ccmath/isfinite.hpp>

include/boost/math/ccmath/hypot.hpp

@@ -7,12 +7,14 @@
 #ifndef BOOST_MATH_CCMATH_HYPOT_HPP
 #define BOOST_MATH_CCMATH_HYPOT_HPP
 
-#include <cmath>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/hypot.hpp> can only be used in C++17 and later."
+#endif
+
 #include <array>
-#include <limits>
-#include <type_traits>
 #include <boost/math/tools/config.hpp>
-#include <boost/math/tools/is_constant_evaluated.hpp>
 #include <boost/math/tools/promotion.hpp>
 #include <boost/math/ccmath/sqrt.hpp>
 #include <boost/math/ccmath/abs.hpp>

include/boost/math/ccmath/ilogb.hpp

@@ -6,9 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_ILOGB_HPP
 #define BOOST_MATH_CCMATH_ILOGB_HPP
 
-#include <cmath>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/ilogb.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/logb.hpp>
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>

include/boost/math/ccmath/isfinite.hpp

@@ -6,20 +6,15 @@
 #ifndef BOOST_MATH_CCMATH_ISFINITE
 #define BOOST_MATH_CCMATH_ISFINITE
 
-#include <cmath>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/isfinite.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>
 
-#include <boost/math/tools/is_standalone.hpp>
-#ifndef BOOST_MATH_STANDALONE
-#include <boost/config.hpp>
-#ifdef BOOST_NO_CXX17_IF_CONSTEXPR
-#error "The header <boost/math/norms.hpp> can only be used in C++17 and later."
-#endif
-#endif
-
 namespace boost::math::ccmath {
 
 template <typename T>

include/boost/math/ccmath/isgreater.hpp

@@ -6,9 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_ISGREATER_HPP
 #define BOOST_MATH_CCMATH_ISGREATER_HPP
 
-#include <cmath>
-#include <limits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/isgreater.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/isnan.hpp>
 
 namespace boost::math::ccmath {

include/boost/math/ccmath/isgreaterequal.hpp

@@ -6,9 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_ISGREATEREQUAL_HPP
 #define BOOST_MATH_CCMATH_ISGREATEREQUAL_HPP
 
-#include <cmath>
-#include <limits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/islessequal.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/isnan.hpp>
 
 namespace boost::math::ccmath {

include/boost/math/ccmath/isless.hpp

@@ -6,9 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_ISLESS_HPP
 #define BOOST_MATH_CCMATH_ISLESS_HPP
 
-#include <cmath>
-#include <limits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/isless.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/isnan.hpp>
 
 namespace boost::math::ccmath {

include/boost/math/ccmath/islessequal.hpp

@@ -6,9 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_ISLESSEQUAL_HPP
 #define BOOST_MATH_CCMATH_ISLESSEQUAL_HPP
 
-#include <cmath>
-#include <limits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/islessequal.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/isnan.hpp>
 
 namespace boost::math::ccmath {

include/boost/math/ccmath/isnormal.hpp

@@ -7,14 +7,15 @@
 #define BOOST_MATH_ISNORMAL_HPP
 
 #include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/isnormal.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/abs.hpp>
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>
 
-#ifdef BOOST_MATH_NO_CCMATH
-#error "The header <boost/math/abs.hpp> can only be used in C++17 and later."
-#endif
-
 namespace boost::math::ccmath {
 
 template <typename T>

include/boost/math/ccmath/isunordered.hpp

@@ -6,8 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_ISUNORDERED_HPP
 #define BOOST_MATH_CCMATH_ISUNORDERED_HPP
 
-#include <cmath>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/isunordered.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/isnan.hpp>
 
 namespace boost::math::ccmath {

include/boost/math/ccmath/ldexp.hpp

@@ -7,8 +7,13 @@
 #ifndef BOOST_MATH_CCMATH_LDEXP_HPP
 #define BOOST_MATH_CCMATH_LDEXP_HPP
 
-#include <stdexcept>
 #include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/ldexp.hpp> can only be used in C++17 and later."
+#endif
+
+#include <stdexcept>
 #include <boost/math/ccmath/abs.hpp>
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>

include/boost/math/ccmath/logb.hpp

@@ -6,10 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_LOGB_HPP
 #define BOOST_MATH_CCMATH_LOGB_HPP
 
-#include <cmath>
-#include <limits>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/logb.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/frexp.hpp>
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>

include/boost/math/ccmath/modf.hpp

@@ -6,10 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_MODF_HPP
 #define BOOST_MATH_CCMATH_MODF_HPP
 
-#include <cmath>
-#include <limits>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/modf.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/abs.hpp>
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>

include/boost/math/ccmath/next.hpp

@@ -7,17 +7,19 @@
 #ifndef BOOST_MATH_CCMATH_NEXT_HPP
 #define BOOST_MATH_CCMATH_NEXT_HPP
 
-#include <cmath>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/next.hpp> can only be used in C++17 and later."
+#endif
+
+#include <stdexcept>
 #include <cfloat>
 #include <cstdint>
-#include <limits>
-#include <type_traits>
-#include <stdexcept>
 #include <boost/math/policies/policy.hpp>
 #include <boost/math/policies/error_handling.hpp>
 #include <boost/math/tools/assert.hpp>
 #include <boost/math/tools/config.hpp>
-#include <boost/math/tools/is_constant_evaluated.hpp>
 #include <boost/math/tools/precision.hpp>
 #include <boost/math/tools/traits.hpp>
 #include <boost/math/tools/promotion.hpp>

include/boost/math/ccmath/remainder.hpp

@@ -6,12 +6,14 @@
 #ifndef BOOST_MATH_CCMATH_REMAINDER_HPP
 #define BOOST_MATH_CCMATH_REMAINDER_HPP
 
-#include <cmath>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/remainder.hpp> can only be used in C++17 and later."
+#endif
+
 #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>
 #include <boost/math/ccmath/isnan.hpp>

include/boost/math/ccmath/round.hpp

@@ -8,15 +8,16 @@
 
 #include <stdexcept>
 #include <boost/math/ccmath/detail/config.hpp>
-#include <boost/math/ccmath/abs.hpp>
-#include <boost/math/ccmath/isinf.hpp>
-#include <boost/math/ccmath/isnan.hpp>
-#include <boost/math/ccmath/modf.hpp>
 
 #ifdef BOOST_MATH_NO_CCMATH
 #error "The header <boost/math/round.hpp> can only be used in C++17 and later."
 #endif
 
+#include <boost/math/ccmath/abs.hpp>
+#include <boost/math/ccmath/isinf.hpp>
+#include <boost/math/ccmath/isnan.hpp>
+#include <boost/math/ccmath/modf.hpp>
+
 namespace boost::math::ccmath {
 
 namespace detail {

include/boost/math/ccmath/scalbln.hpp

@@ -6,10 +6,13 @@
 #ifndef BOOST_MATH_CCMATH_SCALBLN_HPP
 #define BOOST_MATH_CCMATH_SCALBLN_HPP
 
-#include <cmath>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/scalbln.hpp> can only be used in C++17 and later."
+#endif
+
 #include <cfloat>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
 #include <boost/math/ccmath/scalbn.hpp>
 #include <boost/math/ccmath/abs.hpp>
 #include <boost/math/ccmath/isinf.hpp>

include/boost/math/ccmath/scalbn.hpp

@@ -7,11 +7,13 @@
 #ifndef BOOST_MATH_CCMATH_SCALBN_HPP
 #define BOOST_MATH_CCMATH_SCALBN_HPP
 
-#include <cmath>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/scalbn.hpp> can only be used in C++17 and later."
+#endif
+
 #include <cfloat>
-#include <limits>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
 #include <boost/math/ccmath/abs.hpp>
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>

include/boost/math/ccmath/signbit.hpp

@@ -6,17 +6,18 @@
 #ifndef BOOST_MATH_CCMATH_SIGNBIT_HPP
 #define BOOST_MATH_CCMATH_SIGNBIT_HPP
 
-#include <cstdint>
-#include <boost/math/tools/assert.hpp>
 #include <boost/math/ccmath/detail/config.hpp>
-#include <boost/math/special_functions/detail/fp_traits.hpp>
-#include <boost/math/ccmath/isnan.hpp>
-#include <boost/math/ccmath/abs.hpp>
 
 #ifdef BOOST_MATH_NO_CCMATH
 #error "The header <boost/math/signbit.hpp> can only be used in C++17 and later."
 #endif
 
+#include <cstdint>
+#include <boost/math/tools/assert.hpp>
+#include <boost/math/special_functions/detail/fp_traits.hpp>
+#include <boost/math/ccmath/isnan.hpp>
+#include <boost/math/ccmath/abs.hpp>
+
 #ifdef __has_include
 #  if __has_include(<bit>)
 #    include <bit>

include/boost/math/ccmath/sqrt.hpp

@@ -8,9 +8,12 @@
 #ifndef BOOST_MATH_CCMATH_SQRT
 #define BOOST_MATH_CCMATH_SQRT
 
-#include <cmath>
-#include <limits>
-#include <type_traits>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/sqrt.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/abs.hpp>
 #include <boost/math/ccmath/isnan.hpp>
 #include <boost/math/ccmath/isinf.hpp>

include/boost/math/ccmath/trunc.hpp

@@ -6,9 +6,12 @@
 #ifndef BOOST_MATH_CCMATH_TRUNC_HPP
 #define BOOST_MATH_CCMATH_TRUNC_HPP
 
-#include <cmath>
-#include <type_traits>
-#include <boost/math/tools/is_constant_evaluated.hpp>
+#include <boost/math/ccmath/detail/config.hpp>
+
+#ifdef BOOST_MATH_NO_CCMATH
+#error "The header <boost/math/trunc.hpp> can only be used in C++17 and later."
+#endif
+
 #include <boost/math/ccmath/abs.hpp>
 #include <boost/math/ccmath/isinf.hpp>
 #include <boost/math/ccmath/isnan.hpp>