This header is intentionally valid in C++14 mode, because no conforming
C++14 program will try to include <charconv> and so it's OK to add new
(non-reserved in C++14) names to namespace std. However, other headers
must not include <charconv> transitively prior to C++17, so that we
don't add those non-reserved names without the user requesting it.
This adds a comment to the header explaining that.
* include/std/charconv: Add comment.
Tested powerpc64le-linux, committed to master.
commit cfbc8fbb37e7b406ab2567ac35629793d4b499e7
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Mon Feb 17 15:44:03 2020 +0000
libstdc++: Add comment to <charconv> explaining C++14 status
This header is intentionally valid in C++14 mode, because no conforming
C++14 program will try to include <charconv> and so it's OK to add new
(non-reserved in C++14) names to namespace std. However, other headers
must not include <charconv> transitively prior to C++17, so that we
don't add those non-reserved names without the user requesting it.
This adds a comment to the header explaining that.
* include/std/charconv: Add comment.
diff --git a/libstdc++-v3/include/std/charconv
b/libstdc++-v3/include/std/charconv
index 9b5a1f7cab8..ff7dfa12268 100644
--- a/libstdc++-v3/include/std/charconv
+++ b/libstdc++-v3/include/std/charconv
@@ -31,6 +31,10 @@
#pragma GCC system_header
+// As an extension we support <charconv> in C++14, but this header should not
+// be included by any other library headers in C++14 mode. This ensures that
+// the names defined in this header are not added to namespace std unless a
+// user explicitly includes <charconv> in C++14 code.
#if __cplusplus >= 201402L
#include <type_traits>
