Fix amalgamate.ph and add header for constexpr macros

include/fast_float/constexpr_feature_detect.h

@@ -0,0 +1,40 @@
+#ifndef FASTFLOAT_CONSTEXPR_FEATURE_DETECT_H
+#define FASTFLOAT_CONSTEXPR_FEATURE_DETECT_H
+
+#ifdef __has_include
+#if __has_include(<version>)
+#include <version>
+#endif
+#endif
+
+// Testing for https://wg21.link/N3652, adopted in C++14
+#if __cpp_constexpr >= 201304
+#define FASTFLOAT_CONSTEXPR14 constexpr
+#else
+#define FASTFLOAT_CONSTEXPR14
+#endif
+
+#if __cpp_lib_bit_cast >= 201806L
+#define FASTFLOAT_HAS_BIT_CAST 1
+#else
+#define FASTFLOAT_HAS_BIT_CAST 0
+#endif
+
+#if __cpp_lib_is_constant_evaluated >= 201811L
+#define FASTFLOAT_HAS_IS_CONSTANT_EVALUATED 1
+#else
+#define FASTFLOAT_HAS_IS_CONSTANT_EVALUATED 0
+#endif
+
+// Testing for relevant C++20 constexpr library features
+#if FASTFLOAT_HAS_IS_CONSTANT_EVALUATED \
+    && FASTFLOAT_HAS_BIT_CAST \
+    && __cpp_lib_constexpr_algorithms >= 201806L /*For std::copy and std::fill*/
+#define FASTFLOAT_CONSTEXPR20 constexpr
+#define FASTFLOAT_IS_CONSTEXPR 1
+#else
+#define FASTFLOAT_CONSTEXPR20
+#define FASTFLOAT_IS_CONSTEXPR 0
+#endif
+
+#endif // FASTFLOAT_CONSTEXPR_FEATURE_DETECT_H

include/fast_float/fast_float.h

@@ -3,7 +3,7 @@
 
 #include <system_error>
 
-#include "float_common.h"
+#include "constexpr_feature_detect.h"
 
 namespace fast_float {
 enum chars_format {

include/fast_float/float_common.h

@@ -7,23 +7,8 @@
 #include <cstring>
 #include <type_traits>
 
-#ifdef __has_include
+#if FASTFLOAT_HAS_BIT_CAST
-#if __has_include(<version>)
-#include <version>
-#endif
-#endif
-
-#if __cpp_lib_bit_cast >= 201806L
 #include <bit>
-#define FASTFLOAT_HAS_BIT_CAST 1
-#else
-#define FASTFLOAT_HAS_BIT_CAST 0
-#endif
-
-#if __cpp_lib_is_constant_evaluated >= 201811L
-#define FASTFLOAT_HAS_IS_CONSTANT_EVALUATED 1
-#else
-#define FASTFLOAT_HAS_IS_CONSTANT_EVALUATED 0
 #endif
 
 #if (defined(__x86_64) || defined(__x86_64__) || defined(_M_X64)   \
@@ -110,24 +95,6 @@
 // rust style `try!()` macro, or `?` operator
 #define FASTFLOAT_TRY(x) { if (!(x)) return false; }
 
-// Testing for https://wg21.link/N3652, adopted in C++14
-#if __cpp_constexpr >= 201304
-#define FASTFLOAT_CONSTEXPR14 constexpr
-#else
-#define FASTFLOAT_CONSTEXPR14
-#endif
-
-// Testing for relevant C++20 constexpr library features
-#if FASTFLOAT_HAS_IS_CONSTANT_EVALUATED \
-    && FASTFLOAT_HAS_BIT_CAST \
-    && __cpp_lib_constexpr_algorithms >= 201806L /*For std::copy and std::fill*/
-#define FASTFLOAT_CONSTEXPR20 constexpr
-#define FASTFLOAT_IS_CONSTEXPR 1
-#else
-#define FASTFLOAT_CONSTEXPR20
-#define FASTFLOAT_IS_CONSTEXPR 0
-#endif
-
 namespace fast_float {
 
 fastfloat_really_inline constexpr bool cpp20_and_in_constexpr() {

script/amalgamate.py

@@ -31,7 +31,7 @@ for filename in ['LICENSE-MIT', 'LICENSE-APACHE']:
   processed_files[filename] = text
 
 # code
-for filename in [ 'float_common.h', 'fast_float.h', 'ascii_number.h', 
+for filename in [ 'constexpr_feature_detect.h', 'fast_float.h', 'float_common.h', 'ascii_number.h', 
                   'fast_table.h', 'decimal_to_binary.h', 'bigint.h',
                   'ascii_number.h', 'digit_comparison.h', 'parse_number.h']:
   with open('include/fast_float/' + filename, encoding='utf8') as f:
@@ -75,7 +75,8 @@ def license_content(license_arg):
 text = ''.join([
   processed_files['AUTHORS'], processed_files['CONTRIBUTORS'], 
   *license_content(args.license),
-  processed_files['float_common.h'], processed_files['fast_float.h'],
+  processed_files['constexpr_feature_detect.h'],
+  processed_files['fast_float.h'], processed_files['float_common.h'], 
   processed_files['ascii_number.h'], processed_files['fast_table.h'],
   processed_files['decimal_to_binary.h'], processed_files['bigint.h'],
   processed_files['ascii_number.h'], processed_files['digit_comparison.h'],