Fix gsl/util for c++20 compilers without <span>

For instance, clang 10 sets __cplusplus >= 202002L yet does not have span, which causes build errors: https://gcc.godbolt.org/z/Yq345zGea
microsoft · Sep 7, 2021 · 199c375 · 199c375
1 parent 8a4b9ed
commit 199c375
Showing 1 changed file with 5 additions and 2 deletions.
diff --git a/include/gsl/util b/include/gsl/util
@@ -25,9 +25,12 @@
 #include <type_traits> // for is_signed, integral_constant
 #include <utility> // for exchange, forward
 
-#if defined(__cplusplus) && __cplusplus >= 202002L
+#if defined(__has_include) && __has_include(<version>)
+#include <version>
+#if defined(__cpp_lib_span) && __cpp_lib_span >= 202002L
 #include <span>
-#endif // __cplusplus >= 202002L
+#endif // __cpp_lib_span >= 202002L
+#endif //__has_include(<version>)
 
 #if defined(_MSC_VER) && !defined(__clang__)