From: Akim Demaille <akim.demaille@gmail.com>
To: Bruno Haible <bruno@clisp.org>
Cc: bug-gnulib@gnu.org
Subject: Re: undefined behaviour findings in bitset
Date: Fri, 22 Mar 2019 17:00:43 +0100 [thread overview]
Message-ID: <EE6CA906-21A3-47A8-94DF-96D5DC20DA6A@gmail.com> (raw)
In-Reply-To: <334DD9B5-B8E4-4A48-BBAA-9677F912FFF2@lrde.epita.fr>
Hi Bruno,
> Le 19 mars 2019 à 07:07, Akim Demaille <akim@lrde.epita.fr> a écrit :
>
> Hi Bruno,
>
>> Le 18 mars 2019 à 22:03, Bruno Haible <bruno@clisp.org> a écrit :
>>
>> Hi Akim,
>>
>>> Also, the relationship with noreturn.h is not completely clear for
>>> me either.
>>
>> There are a couple of comment in noreturn.h lines 33..41. But I agree,
>> some text in the documentation would be better.
>>
>>> Clang 7 pretends to be GCC 4.2 (__GNUC__ __GNUC_MINOR__).
>>
>>> For instance I see it already has the above fix for
>>> GCC 4.7, but in a different way.
>>>
>>> /* Use ISO C++11 syntax when the compiler supports it. */
>>> # if (__cplusplus >= 201103 && !(__GNUC__ == 4 && __GNUC_MINOR__ == 7)) \
>>> || (_MSC_VER >= 1900)
>>> # define _GL_NORETURN_FUNC [[noreturn]]
>>
>> Right, this snippet gets clang++ and MSVC++ support right. How about this
>> patch?
>
> Yes, I agree this is the best option so far, thanks!
Well, it does not work with G++ in C++98 mode: _Noreturn is not supported there.
This works with Bison's CI:
commit b2a7dec46c0b702b5f7618994641e7381c8ff86f
Author: Akim Demaille <akim.demaille@gmail.com>
Date: Fri Mar 22 08:25:53 2019 +0100
_Noreturn: beware of C's _Noreturn in C++ pre C++11
* lib/_Noreturn.h, m4/gnulib-common.m4: Using C's _Noreturn in
C++98 appears to be supported by Clang, but not by GCC nor ICC.
diff --git a/ChangeLog b/ChangeLog
index 62c522e65..b694c3512 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2019-03-22 Akim Demaille <akim@lrde.epita.fr>
+
+ _Noreturn: beware of C's _Noreturn in C++ pre C++11.
+ * lib/_Noreturn.h, m4/gnulib-common.m4: Using C's _Noreturn in
+ C++98 appears to be supported by Clang, but not by GCC nor ICC.
+
2019-03-19 Akim Demaille <akim@lrde.epita.fr>
bitset: fix memory leaks
diff --git a/lib/_Noreturn.h b/lib/_Noreturn.h
index 1629cef39..7594e4b0c 100644
--- a/lib/_Noreturn.h
+++ b/lib/_Noreturn.h
@@ -3,8 +3,9 @@
&& ((201103 <= __cplusplus && !(__GNUC__ == 4 && __GNUC_MINOR__ == 7)) \
|| (defined _MSC_VER && 1900 <= _MSC_VER)))
# define _Noreturn [[noreturn]]
-# elif (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) \
- || 4 < __GNUC__ + (7 <= __GNUC_MINOR__))
+# elif ((!defined __cplusplus || defined __clang__) \
+ && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) \
+ || 4 < __GNUC__ + (7 <= __GNUC_MINOR__)))
/* _Noreturn works as-is. */
# elif 2 < __GNUC__ + (8 <= __GNUC_MINOR__) || 0x5110 <= __SUNPRO_C
# define _Noreturn __attribute__ ((__noreturn__))
diff --git a/m4/gnulib-common.m4 b/m4/gnulib-common.m4
index 8ad963e35..57b94ed53 100644
--- a/m4/gnulib-common.m4
+++ b/m4/gnulib-common.m4
@@ -21,8 +21,9 @@ AC_DEFUN([gl_COMMON_BODY], [
&& ((201103 <= __cplusplus && !(__GNUC__ == 4 && __GNUC_MINOR__ == 7)) \
|| (defined _MSC_VER && 1900 <= _MSC_VER)))
# define _Noreturn [[noreturn]]
-# elif (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) \
- || 4 < __GNUC__ + (7 <= __GNUC_MINOR__))
+# elif ((!defined __cplusplus || defined __clang__) \
+ && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) \
+ || 4 < __GNUC__ + (7 <= __GNUC_MINOR__)))
/* _Noreturn works as-is. */
# elif 2 < __GNUC__ + (8 <= __GNUC_MINOR__) || 0x5110 <= __SUNPRO_C
# define _Noreturn __attribute__ ((__noreturn__))
next prev parent reply other threads:[~2019-03-22 16:05 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-09 19:33 undefined behaviour findings Bruno Haible
2019-03-09 19:37 ` undefined behaviour findings in bitset Bruno Haible
2019-03-16 16:38 ` Akim Demaille
2019-03-16 16:42 ` Akim Demaille
2019-03-16 19:53 ` Bruno Haible
2019-03-17 7:39 ` Akim Demaille
2019-03-17 18:36 ` Akim Demaille
2019-03-17 18:56 ` Paul Eggert
2019-03-17 19:27 ` Bruno Haible
2019-03-18 8:16 ` Akim Demaille
2019-03-18 21:03 ` Bruno Haible
2019-03-19 6:07 ` Akim Demaille
2019-03-22 16:00 ` Akim Demaille [this message]
2019-03-23 18:54 ` Bruno Haible
2019-03-20 3:39 ` Bruno Haible
2019-03-20 17:04 ` Akim Demaille
2019-03-09 21:22 ` undefined behaviour findings Bruno Haible
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