[Bug c++/60304] Including <atomic> disables -Wconversion-null

["redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60304

--- Comment #21 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Manuel López-Ibáñez from comment #19) 
> This is exactly what G++'s stdbool.h is doing with -std=gnu++98 and
> -std=c++98.

<stdbool.h> is a "header" which is C++ standardese for a standard library
header. The rule only applies to user code, not std::lib headers. In your
testcase sys.h is OK but nonsys.h is not.

Although you can argue that since <stdbool.h> is not defined by the C++98
standard it is not a "header" and must not define the macro in __STRICT_ANSI__
mode.

> (Also, why is this not an error with -std=c++11 -pedantic-errors?)

Because noone has ever implemented the diagnostic. Note that it only applies to
user-code that includes a "header" so it's OK to define macros using the names
of keywords as long as you never include a standard header. That makes it a bit
more complicated to implement the diagnostic.
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From: "y.gribov at samsung dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug sanitizer/63638] [4.9 Regression] internal compiler error: in asan_expand_check_ifn (with -fsanitize­dress)
Date: Fri, 24 Oct 2014 14:58:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idc638

Yury Gribov <y.gribov at samsung dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |y.gribov at samsung dot com

--- Comment #1 from Yury Gribov <y.gribov at samsung dot com> ---
Created attachment 33803
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id3803&actioníit
Proposed patch

Thanks, I was aware of this problem. For GCC 5.0 Maxim is going to fix this
with his dont-sanitize-builtins patch (currently reviewed in gcc-patches). Here
is a trivial patch for 4.9 but I only had time to perform short regtesting
(make check RUNTESTFLAGS=asan.exp).