lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Mon, 22 Oct 2018 19:49:21 +0200
From:   Bernd Petrovitsch <>
To:     Miguel Ojeda <>,
        Dan <>
Cc:     "Ted Ts'o" <>, Greg KH <>,
        linux-kernel <>,
        Andreas Dilger <>,
        Masahiro Yamada <>,
        Michal Marek <>,
        Steven Rostedt <>,
        Mauro Carvalho Chehab <>,
        Olof Johansson <>,
        Konstantin Ryabitsev <>,
        David Miller <>,
        Andrey Ryabinin <>,
        Kees Cook <>,
        Thomas Gleixner <>,
        Ingo Molnar <>,
        Paul Lawrence <>,
        Sandipan Das <>,
        Andrey Konovalov <>,
        David Woodhouse <>,
        Will Deacon <>,
        Philippe Ombredanne <>,
        Paul Burton <>,
        David Rientjes <>, Willy Tarreau <>,
        Martin Sebor <>,
        Christopher Li <>,
        Jonathan Corbet <>,
        Geert Uytterhoeven <>,
        Rasmus Villemoes <>,
        Joe Perches <>, Arnd Bergmann <>,
        Dominique Martinet <>,
        Stefan Agner <>,
        Luc Van Oostenryck <>,
        Nick Desaulniers <>,
        Andrew Morton <>,
        Linus Torvalds <>,
        Linux Doc Mailing List <>,
        Ext4 Developers List <>,,,
Subject: Re: [PATCH 1/2] Compiler Attributes: add support for __fallthrough
 (gcc >= 7.1)

Hi all!

On 22/10/18 13:07, Miguel Ojeda wrote:
> On Mon, Oct 22, 2018 at 12:54 PM Dan Carpenter <> wrote:
>> Doing both is super ugly.  Let's just do comments until Eclipse gets
>> updated.

Yes, "Eclipse" as the IDE.

And yes but IMHO better super ugly than loosing the warning - YMMV.

For the archives: I have Eclipse Photon/June 2016 here. And "no break"
is the (default) string in a comment used by Eclipse (it can be
customized and is actually a regexp but it must be in a comment).

>> I had wanted to move to the attribute because that would simplify things
>> in Smatch but it's not a huge deal to delay for another year.
> I can re-send them later on, no problem. On the other hand, doing the
> changes will push tools to get updated sooner ;-)
> If tools were doing something as fancy as comment parsing for
> diagnostics, they should have been updated with the attribute support
> (either gcc's or C++17's) -- it has been more than a year now since
> gcc 7.1 and the C++17 final draft. (Note that this does not apply for
> things like clang, since they weren't doing comment parsing to begin
> with.)

That would be nice. And if they agree on the same texts (or accept per
default all somewhat widely used and/or old ones).

After stumbling over,
looking into Eclipses Window -> Preferences -> C/C++ -> Code Analysis ->
"No break at the end of case" screen (that's the screenshot there) and I
tried various things:

I have
----  snip  ----
#define __fallthrough __attribute__((fallthrough))
----  snip  ----
for gcc >= 7 (because clang doesn't know it and I had also older
gcc's in use before).

- Adding a comment to the #define doesn't change anything for Eclipse.
- Eclipse looks *only* in comments for the string/regexp given
  the warnings configuration (and that comment must be on the line
  directly before the "case").
- Eclipse understands [[fallthrough]] out-of-the-box though (which
  is C++11 AFAIK) as does g++-7 (I use -std=gnu++17 - most of the
  sources are C++, but not all) and clang++-6 (all the current standard
  Ubuntu-18.06/Bionic packages).
  Eclipse "accepts" [[fallthrough]] only in C++ sources (and not in C
- Neither gcc nor clang understand [[fallthrough]] (so it's probably a
  no-go for the Kernel with C89 anyways).


PS: clang++ errors with "fallthrough annotation in unreachable code" if
    [[fallthrough]] is after an assert(). clang-devs there, please, the
    fallthrough doesn't really generated code (I hope;-).
    I have lots of switch()es which catch undefined values (for enums
    et. al.) with "default"+assert() and fall through to the most safe
    case (for the deployed version).
"I dislike type abstraction if it has no real reason. And saving
on typing is not a good reason - if your typing speed is the main
issue when you're coding, you're doing something seriously wrong."
    - Linus Torvalds

Download attachment "pEpkey.asc" of type "application/pgp-keys" (2473 bytes)

Powered by blists - more mailing lists