The <span> header is empty unless Concepts are supported, but <version>
defines the __cpp_lib_span feature test macro unconditionally. It should
be guarded by the same conditions as in <span>.
libstdc++-v3/ChangeLog:
PR libstdc++/97869
* include/precompiled/stdc++.h: Include <coroutine>.
* include/std/version (__cpp_lib_span): Check __cpp_lib_concepts
before defining.
Tested powerpc64le-linux. Committed to trunk.
This also needs to be backported to gcc-10.
commit ecf65330c11544ebf35e198087b4a42be089c620
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Tue Nov 17 15:26:29 2020
libstdc++: Fix unconditional definition of __cpp_lib_span in <version> [PR
97869}
The <span> header is empty unless Concepts are supported, but <version>
defines the __cpp_lib_span feature test macro unconditionally. It should
be guarded by the same conditions as in <span>.
libstdc++-v3/ChangeLog:
PR libstdc++/97869
* include/precompiled/stdc++.h: Include <coroutine>.
* include/std/version (__cpp_lib_span): Check __cpp_lib_concepts
before defining.
diff --git a/libstdc++-v3/include/precompiled/stdc++.h
b/libstdc++-v3/include/precompiled/stdc++.h
index 8899c323a281..a418c46288de 100644
--- a/libstdc++-v3/include/precompiled/stdc++.h
+++ b/libstdc++-v3/include/precompiled/stdc++.h
@@ -137,6 +137,9 @@
#include <bit>
#include <compare>
#include <concepts>
+#if __cpp_impl_coroutine
+# include <coroutine>
+#endif
#include <numbers>
#include <ranges>
#include <span>
diff --git a/libstdc++-v3/include/std/version b/libstdc++-v3/include/std/version
index 7f51ef3a6c4f..12455ad93146 100644
--- a/libstdc++-v3/include/std/version
+++ b/libstdc++-v3/include/std/version
@@ -226,7 +226,9 @@
# define __cpp_lib_ranges 201911L
#endif
#define __cpp_lib_shift 201806L
-#define __cpp_lib_span 202002L
+#if __cpp_lib_concepts
+# define __cpp_lib_span 202002L
+#endif
#define __cpp_lib_ssize 201902L
#define __cpp_lib_starts_ends_with 201711L
# if _GLIBCXX_USE_CXX11_ABI
