[newlib-cygwin/main] sys/features.h: Define _ISOC2X_SOURCE and __ISO_C_VISIBLE

[newlib-cygwin/main] sys/features.h: Define _ISOC2X_SOURCE and __ISO_C_VISIBLE

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=290b56a87947620f171f65190616116fc1e0082c

commit 290b56a87947620f171f65190616116fc1e0082c
Author:     Corinna Vinschen <corinna@vinschen.de>
AuthorDate: Wed Aug 2 16:52:27 2023 +0200
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Wed Aug 2 16:56:24 2023 +0200

    sys/features.h: Define _ISOC2X_SOURCE and __ISO_C_VISIBLE
    
    Add feature test for C2X code. Add matching definitions
    _ISOC2X_SOURCE for requesting sources and __ISO_C_VISIBLE
    to be used in headers.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 newlib/libc/include/sys/features.h | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/newlib/libc/include/sys/features.h b/newlib/libc/include/sys/features.h
index 45476ce4ad50..a7d4bc52d18f 100644
--- a/newlib/libc/include/sys/features.h
+++ b/newlib/libc/include/sys/features.h
@@ -87,6 +87,9 @@ extern "C" {
  * _ISOC11_SOURCE or gcc -std=c11 or g++ -std=c++11
  * 	ISO C11
  *
+ * _ISOC2x_SOURCE or gcc -std=c2x or g++ -std=c++20
+ * 	ISO C11
+ *
  * _ATFILE_SOURCE (implied by _POSIX_C_SOURCE >= 200809L)
  *	"at" functions
  *
@@ -114,6 +117,8 @@ extern "C" {
 #define	_ISOC99_SOURCE		1
 #undef _ISOC11_SOURCE
 #define	_ISOC11_SOURCE		1
+#undef _ISOC2X_SOURCE
+#define	_ISOC2X_SOURCE		1
 #undef _POSIX_SOURCE
 #define	_POSIX_SOURCE		1
 #undef _POSIX_C_SOURCE
@@ -215,6 +220,11 @@ extern "C" {
  * 	g++ -std=c++11 or newer (on by default since GCC 6), or with
  * 	_ISOC11_SOURCE.
  *
+ * __ISO_C_VISIBLE >= 2020
+ * 	ISO C2x; enabled with gcc -std=c2x or newer,
+ * 	g++ -std=c++20 or newer, or with
+ * 	_ISOC2X_SOURCE.
+ *
  * __ATFILE_VISIBLE
  *	"at" functions; enabled by default, with _ATFILE_SOURCE,
  * 	_POSIX_C_SOURCE >= 200809L, or _XOPEN_SOURCE >= 700.
@@ -261,7 +271,10 @@ extern "C" {
 #define	__GNU_VISIBLE		0
 #endif
 
-#if defined(_ISOC11_SOURCE) || \
+#if defined(_ISOC2X_SOURCE) || \
+  (__STDC_VERSION__ - 0) > 201710L || (__cplusplus - 0) >= 202002L
+#define __ISO_C_VISIBLE		2020
+#elif defined(_ISOC11_SOURCE) || \
   (__STDC_VERSION__ - 0) >= 201112L || (__cplusplus - 0) >= 201103L
 #define	__ISO_C_VISIBLE		2011
 #elif defined(_ISOC99_SOURCE) || (_POSIX_C_SOURCE - 0) >= 200112L || \