From a662df817fdbd0604f61fd5a3b2b345c571b2041 Mon Sep 17 00:00:00 2001
From: Daniel Lemire <daniel@lemire.me>
Date: Sun, 26 Mar 2023 20:43:33 -0400
Subject: [PATCH] If we detect that the compiler supports
 FASTFLOAT_IS_CONSTEXPR, then let us run the tests automatically.

---
 tests/CMakeLists.txt |  2 +-
 tests/basictest.cpp  | 10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 2dc784e..37f6c7f 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -60,7 +60,7 @@ fast_float_add_cpp_test(rcppfastfloat_test)
 fast_float_add_cpp_test(example_test)
 fast_float_add_cpp_test(example_comma_test)
 fast_float_add_cpp_test(basictest)
-option(FASTFLOAT_CONSTEXPR_TESTS "Constexpr tests" OFF)
+option(FASTFLOAT_CONSTEXPR_TESTS "Require constexpr tests (build will fail if the compiler won't support it)" OFF)
 if (FASTFLOAT_CONSTEXPR_TESTS)
   target_compile_features(basictest PRIVATE cxx_std_20)
   target_compile_definitions(basictest PRIVATE FASTFLOAT_CONSTEXPR_TESTS)
diff --git a/tests/basictest.cpp b/tests/basictest.cpp
index 5615b5d..3ed10f0 100644
--- a/tests/basictest.cpp
+++ b/tests/basictest.cpp
@@ -13,6 +13,12 @@
 #include <type_traits>
 #include <cfenv>
 
+#if FASTFLOAT_IS_CONSTEXPR
+#ifndef FASTFLOAT_CONSTEXPR_TESTS
+#define FASTFLOAT_CONSTEXPR_TESTS 1
+#endif // #ifndef FASTFLOAT_CONSTEXPR_TESTS
+#endif // FASTFLOAT_IS_CONSTEXPR
+
 #if FASTFLOAT_HAS_BIT_CAST
 #include <bit>
 #endif
@@ -74,6 +80,10 @@ const char * round_name(int d) {
 
 TEST_CASE("system_info") {
     std::cout << "system info:" << std::endl;
+#ifdef FASTFLOAT_CONSTEXPR_TESTS
+    SHOW_DEFINE(FASTFLOAT_CONSTEXPR_TESTS);
+
+#endif
 #ifdef _MSC_VER
     SHOW_DEFINE(_MSC_VER);
 #endif