[Bug bootstrap/98323] New: current trunk won't build with clang

[Bug bootstrap/98323] New: current trunk won't build with clang

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98323

            Bug ID: 98323
           Summary: current trunk won't build with clang
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

Current trunk has hash 5098d35fb1997aa6.

I tried building it with clang version 11.0.0
and got this:

../../trunk.git/gcc/cp/module.cc:4156:43: error: expected ')'
      size_t alloc = (offsetof (impl, impl::stack)
                                          ^
../../trunk.git/gcc/cp/module.cc:4156:23: note: to match this '('
      size_t alloc = (offsetof (impl, impl::stack)
                      ^
/usr/lib64/clang/11.0.0/include/stddef.h:104:42: note: expanded from macro
'offsetof'
#define offsetof(t, d) __builtin_offsetof(t, d)
                                         ^

For the record, it builds happily with recent gcc.

[Bug bootstrap/98323] current trunk won't build with clang

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98323

David Binderman <dcb314 at hotmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nathan at gcc dot gnu.org

--- Comment #1 from David Binderman <dcb314 at hotmail dot com> ---
git blame says

4efde6781bba (Nathan Sidwell 2020-12-14 11:40:44 -0800  4153)       /* Create
or extend the dump implementor.  */
4efde6781bba (Nathan Sidwell 2020-12-14 11:40:44 -0800  4154)       unsigned
current = dumps ? dumps->stack.length () : 0;
4efde6781bba (Nathan Sidwell 2020-12-14 11:40:44 -0800  4155)       unsigned
count = current ? current * 2 : EXPERIMENT (1, 20);
4efde6781bba (Nathan Sidwell 2020-12-14 11:40:44 -0800  4156)       size_t
alloc = (offsetof (impl, impl::stack)
4efde6781bba (Nathan Sidwell 2020-12-14 11:40:44 -0800  4157)                 +
impl::stack_t::embedded_size (count));
4efde6781bba (Nathan Sidwell 2020-12-14 11:40:44 -0800  4158)       dumps =
XRESIZEVAR (impl, dumps, alloc);
4efde6781bba (Nathan Sidwell 2020-12-14 11:40:44 -0800  4159)      
dumps->stack.embedded_init (count, current);

Adding Nathan.

[Bug bootstrap/98323] current trunk won't build with clang

[nathan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98323

Nathan Sidwell <nathan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |nathan at gcc dot gnu.org

--- Comment #2 from Nathan Sidwell <nathan at gcc dot gnu.org> ---
stupid underspecified offsetof

[Bug bootstrap/98323] current trunk won't build with clang

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98323

--- Comment #3 from David Binderman <dcb314 at hotmail dot com> ---
(In reply to Nathan Sidwell from comment #2)
> stupid underspecified offsetof

I did try commenting out the offending block of code and a re-build
and got further errors ;-<

I don't know if you have access to clang, but if you don't,
may I be so bold as to suggest you install a copy and, if
you have the time, attempt a full build with clang ?

That should flush out all the gcc specific code in your recent changes.

Excellent compiler, BTW.

[Bug bootstrap/98323] current trunk won't build with clang

[nathan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98323

Nathan Sidwell <nathan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #4 from Nathan Sidwell <nathan at gcc dot gnu.org> ---
Fixed 8379916b167

[Bug bootstrap/98323] current trunk won't build with clang

[nathan at acm dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98323

--- Comment #5 from Nathan Sidwell <nathan at acm dot org> ---
On 12/16/20 12:45 PM, dcb314 at hotmail dot com wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98323
> 
> --- Comment #3 from David Binderman <dcb314 at hotmail dot com> ---
> (In reply to Nathan Sidwell from comment #2)
>> stupid underspecified offsetof
> 
> I did try commenting out the offending block of code and a re-build
> and got further errors ;-<
> 
> I don't know if you have access to clang, but if you don't,
> may I be so bold as to suggest you install a copy and, if
> you have the time, attempt a full build with clang ?

but, but, that'd require me to do actual work !

> 
> That should flush out all the gcc specific code in your recent changes.
> 
> Excellent compiler, BTW.

which, clang or GCC?  (why not both ¯\_(ツ)_/¯)

nathan

[Bug bootstrap/98323] current trunk won't build with clang

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98323

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |egallager at gcc dot gnu.org

--- Comment #6 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Nathan Sidwell from comment #2)
> stupid underspecified offsetof

Is this related to bug 65254?

[Bug bootstrap/98323] current trunk won't build with clang

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98323

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #6)
> (In reply to Nathan Sidwell from comment #2)
> > stupid underspecified offsetof
> 
> Is this related to bug 65254?

Is that a bug?
Looking at both C and C++, offsetof seems underspecified, it doesn't say what
exactly the member-designator is or can be.
C talks about
static type t;
and
&(t.member-designator)
but one can put there say foo.bar.baz or qux[2].corge in that expression.
C++ defers mostly to the C standard, and if type is say
struct S { int s; };
then in C++ with
static S t;
the following
&(t.S::s)
is valid expression and S::s designates the member.
So it is unclear on what makes clang think that anything but an identifier as
member-designator is non-standard.

[Bug bootstrap/98323] current trunk won't build with clang

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98323

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
See also http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2396.htm#dr_496

[Bug bootstrap/98323] current trunk won't build with clang

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98323

--- Comment #9 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
The original intent in the C standard was definitely to allow at least 
some cases of subobjects; the May 20, 1988 list of changes in the third 
public review draft of C89 has as item 10 "The offsetof macro has been 
generalized to allow more than just a simple identifier as its second 
argument.".