diff mbox series

Define __THROW to noexcept for C++11 and later

Message ID 20200922132047.GW6061@redhat.com
State Committed
Commit d445d9ca8d961148ffde8ec597ecc0e050542024
Headers
Series Define __THROW to noexcept for C++11 and later |

Commit Message

Jonathan Wakely Sept. 22, 2020, 1:20 p.m. UTC 
  The __THROW macro and friends expand to "throw ()" for C++ code, but
that syntax is deprecated in C++11 and no longer supported at all since
C++20. In order for glibc headers to be compatible with C++20,
"noexcept" should be used instead.

This patch uses "noexcept (true)" rather than just "noexcept", which is
semantically equivalent, but avoids any possibility of parsing
ambiguities if the next preprocessor token happens to be an opening
parenthesis. This is probably unnecessary, but it seems safer to be
cautious.

Built and tested successfully with "make check" on
x86_64-pc-linux-gnu.
From d445d9ca8d961148ffde8ec597ecc0e050542024 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Tue, 22 Sep 2020 11:54:38 +0100
Subject: [PATCH] Define __THROW to noexcept for C++11 and later

The __THROW macro and friends expand to "throw ()" for C++ code, but
that syntax is deprecated in C++11 and no longer supported at all since
C++20. In order for glibc headers to be compatible with C++20,
"noexcept" should be used instead.

This patch uses "noexcept (true)" rather than just "noexcept", which is
semantically equivalent, but avoids any possibility of parsing
ambiguities if the next preprocessor token happens to be an opening
parenthesis. This is probably unnecessary, but it seems safer to be
cautious.
---
 misc/sys/cdefs.h | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

Comments

Andreas Schwab Sept. 22, 2020, 1:34 p.m. UTC | #1 
On Sep 22 2020, Jonathan Wakely via Libc-alpha wrote:

> The __THROW macro and friends expand to "throw ()" for C++ code, but
> that syntax is deprecated in C++11 and no longer supported at all since
> C++20. In order for glibc headers to be compatible with C++20,
> "noexcept" should be used instead.
>
> This patch uses "noexcept (true)" rather than just "noexcept", which is
> semantically equivalent, but avoids any possibility of parsing
> ambiguities if the next preprocessor token happens to be an opening
> parenthesis. This is probably unnecessary, but it seems safer to be
> cautious.
>
> Built and tested successfully with "make check" on
> x86_64-pc-linux-gnu.

Ok.

Andreas.
diff mbox series

Patch

diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index 19d9cc5cfe..6b9763a92a 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -58,10 +58,14 @@ 
 #  define __NTHNL(fct)  __attribute__ ((__nothrow__)) fct
 # else
 #  if defined __cplusplus && __GNUC_PREREQ (2,8)
-#   define __THROW	throw ()
-#   define __THROWNL	throw ()
-#   define __NTH(fct)	__LEAF_ATTR fct throw ()
-#   define __NTHNL(fct) fct throw ()
+#   if __cplusplus >= 201103L
+#    define __THROW	noexcept (true)
+#   else
+#    define __THROW	throw ()
+#   endif
+#   define __THROWNL	__THROW
+#   define __NTH(fct)	__LEAF_ATTR fct __THROW
+#   define __NTHNL(fct) fct __THROW
 #  else
 #   define __THROW
 #   define __THROWNL