[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[bitti at iki dot fi]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

Matti Rintala <bitti at iki dot fi> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bitti at iki dot fi

--- Comment #12 from Matti Rintala <bitti at iki dot fi> 2010-12-17 11:21:06 UTC ---
Has there been any progress with this bug/problem? The latest C++0x draft still
explicitly allows "array a<T, N> = { initializer-list };" (23.3.1/2), but at
least gcc 4.5.1 still gives a warning with -Wall enabled.

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW
         AssignedTo|paolo.carlini at oracle dot |unassigned at gcc dot
                   |com                         |gnu.org

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

--- Comment #13 from Jonathan Wakely <redi at gcc dot gnu.org> 2010-12-17 11:33:48 UTC ---
GCC allows it too, otherwise it would be an error not a warning.

But no, there hasn't been any progress I know of, the warning is still given
for std::array in C++0x mode as well as tr1::array

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

--- Comment #14 from Paolo Carlini <paolo.carlini at oracle dot com> 2010-12-17 12:22:50 UTC ---
I'm sorry I don't mean to wrk on this over the next weeks, maybe sombody will
ne interested in picking my patch in this thread and completing it (both for C
and C++): http://gcc.gnu.org/ml/gcc/2009-11/msg00430.html
http://gcc.gnu.org/ml/gcc/2009-11/msg00468.html

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[baffo32 at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

baffo32 at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |baffo32 at gmail dot com

--- Comment #15 from baffo32 at gmail dot com 2011-08-27 08:53:59 UTC ---
(In reply to comment #13)
> GCC allows it too, otherwise it would be an error not a warning.

I believe GCC fails for multi-dimensional arrays?

array<array<int,2>,2> a{ {1,2},{3,4} }; // won't compile without another pair
of {}

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

Paolo Carlini <paolo.carlini at oracle dot com> changed:

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

--- Comment #16 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-08-30 09:41:23 UTC ---
Maybe Dodji is interested in working on this?!? Can be quite annoying with
tr1::array and std::array in C++11, of course.

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

Jason Merrill <jason at gcc dot gnu.org> changed:

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

--- Comment #17 from Jason Merrill <jason at gcc dot gnu.org> 2012-05-26 21:21:51 UTC ---
Hmm.  I see the argument, but it seems to me that the purpose of
-Wmissing-braces is precisely to warn about this sort of thing.  Perhaps it
just shouldn't be part of -Wall in C++ mode, particularly in C++11 since
initializer lists are a lot more flexible now.

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |paolo.carlini at oracle dot
                   |gnu.org                     |com
   Target Milestone|---                         |4.8.0

--- Comment #18 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-05-26 21:46:03 UTC ---
Let's take it out of C++ then.

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

Paolo Carlini <paolo.carlini at oracle dot com> changed:

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

--- Comment #19 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2012-05-28 17:42:34 UTC ---
Author: paolo
Date: Mon May 28 17:42:29 2012
New Revision: 187937

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=187937
Log:
/c-family
2012-05-28  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/25137
    * c-opts.c (c_common_handle_option): For C++ -Wall doesn't enable
    -Wmissing_braces.

2012-05-28  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/25137
    * doc/invoke.texi: Document -Wmissing-braces not enabled by -Wall
    for C++.

/testsuite
2012-05-28  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/25137
    * g++.dg/warn/Wbraces3.C: New.
    * g++.dg/warn/Wbraces4.C: Likewise.

Added:
    trunk/gcc/testsuite/g++.dg/warn/Wbraces3.C
    trunk/gcc/testsuite/g++.dg/warn/Wbraces4.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c-opts.c
    trunk/gcc/doc/invoke.texi
    trunk/gcc/testsuite/ChangeLog

--- Comment #20 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-05-28 17:44:52 UTC ---
Done.

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

--- Comment #19 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2012-05-28 17:42:34 UTC ---
Author: paolo
Date: Mon May 28 17:42:29 2012
New Revision: 187937

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=187937
Log:
/c-family
2012-05-28  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/25137
    * c-opts.c (c_common_handle_option): For C++ -Wall doesn't enable
    -Wmissing_braces.

2012-05-28  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/25137
    * doc/invoke.texi: Document -Wmissing-braces not enabled by -Wall
    for C++.

/testsuite
2012-05-28  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/25137
    * g++.dg/warn/Wbraces3.C: New.
    * g++.dg/warn/Wbraces4.C: Likewise.

Added:
    trunk/gcc/testsuite/g++.dg/warn/Wbraces3.C
    trunk/gcc/testsuite/g++.dg/warn/Wbraces4.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c-opts.c
    trunk/gcc/doc/invoke.texi
    trunk/gcc/testsuite/ChangeLog

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

Paolo Carlini <paolo.carlini at oracle dot com> changed:

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

--- Comment #20 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-05-28 17:44:52 UTC ---
Done.

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

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

--- Comment #21 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2012-05-29 08:03:07 UTC ---
Hi Paolo (cc. Jason),

for options that enable other options only in specific languages, it would be
good to use the new LangEnabledBy in the .opt files. (For example, this will
make -Wno-missing-braces -Wall work as expected).

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

--- Comment #22 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-05-29 09:05:51 UTC ---
Oops, sorry, I think at some point I wondered if something was in order but
then forgot. If you can tell me the right syntax, I can add it, must be quite
simple, right?

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

--- Comment #23 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2012-05-29 09:22:05 UTC ---
It is explained here
http://gcc.gnu.org/onlinedocs/gccint/Option-properties.html#Option-properties

A patch like the following should work (plus removing the special handling in
c-opts.c)

Index: c.opt
===================================================================
--- c.opt    (revision 187628)
+++ c.opt    (working copy)
@@ -463,7 +463,7 @@
 Warn about suspicious declarations of \"main\"

 Wmissing-braces
-C ObjC C++ ObjC++ Var(warn_missing_braces) Warning
+C ObjC C++ ObjC++ Var(warn_missing_braces) Warning LangEnabledBy(C ObjC, Wall)
 Warn about possibly missing braces around initializers


There is also EnabledBy, which is unconditional. The plan is to convert
sub-options to use this infrastructure. There is also some functionality
missing:

* An option enabled only if two options are combined. (-Wextra && -Wunused
enable -Wunused-parameter).

* An option enabled by some arbitrary condition.

And some options are problematic because they currently have bugs: warn_format
is 0 by default but the value of -Wformat in the gcc_opts structure is -1, thus
calling warning(OPT_Wformat) without checking warn_format means enabled by
default. Some tests expect such diagnostics to be enabled by default. :-(

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

--- Comment #24 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-05-29 09:41:01 UTC ---
Thanks. I'm going to test the patchlet momentarily, I think it qualifies as
obvious.

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[pcarlini at suse dot de]

------- Comment #11 from pcarlini at suse dot de  2007-09-21 16:50 -------
Looking into it: I mean to investigate whether a relaxed warning per Comment #9
is implementable in a decently clean way.


-- 

pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |pcarlini at suse dot de
                   |dot org                     |
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-09-21 16:50:22
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[pinskia at gcc dot gnu dot org]

------- Comment #10 from pinskia at gcc dot gnu dot org  2006-04-04 05:44 -------
*** Bug 27015 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |lidaobing at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[gcc-bugzilla at kayari dot org]

------- Comment #9 from gcc-bugzilla at kayari dot org  2005-12-06 13:07 -------
I've often found this warning to be a nuisance, because it's correct and
well-defined to omit some braces from the initializer.

There are many cases where the warning is useful, e.g. with aggregates that
have several members (which may be aggregates themselves), but when the type
contains a single member (possibly of array type) then the extra braces are
often just clutter.

Pff the top of my head, I would like a way to disable the warning iff the
aggregate has a single member and iff the initializer contains exactly the
right number of elements to initialize that single member.  e.g.

struct S { int s[3]; };
S s1 = { 1, 1, 1 };       // OK   - missing braces but correct number
S s2 = { 1, 1 };          // WARN - no initializer for s2.s[2]
S s3 = { { 1, 1 } };      // OK   - braces correct but missing init

I don't think this would be useful only for tr1::array, but for lots of similar
code.  Obvious and closely-related examples are the block and carray templates
in Austern and Josuttis's books.


-- 

gcc-bugzilla at kayari dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gcc-bugzilla at kayari dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[gdr at gcc dot gnu dot org]

------- Comment #8 from gdr at gcc dot gnu dot org  2005-12-04 05:04 -------
(In reply to comment #0)
> The following code:
> 
> struct S
> { int x[3]; };
> 
> void f()
> { S s = {1,2,3};}
> 
> With -Wmissing-braces (which is implied by -Wall, among others) gives:
> 
> warning: missing braces around initializer for 'int [3]'
> 
> In the specific case where a struct contains only a single array, adding the
> extra braces doesn't really seem that useful.
> 
> The reason it would be nice to fix this that in the definition of tr1::array in
> the TR1 specification (page 88, 6.2.2) says

After more thoughts on this issue, it appears to me that it is asking for
a special casing  justforo tr1::array<> to work.  I don't know whether
that is a workable approach.  I would reommend -Wno-missing-braces in this
specific case.  Thoughts?


-- 

gdr at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gdr at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[gdr at integrable-solutions dot net]

------- Comment #7 from gdr at integrable-solutions dot net  2005-11-28 18:46 -------
Subject: Re:  Warning "missing braces around initializer" causing problems with
tr1::array

"chris at bubblescope dot net" <gcc-bugzilla@gcc.gnu.org> writes:

| Actually, is a report really approriate? Writing array<int,3> = {1,2,3} is
| perfectly valid C++, just warned about with -Wmissing-braces

You're absolutely right!  I forgot 8.5.1/11!

Can't we have simple, general rules, without list of special cases? :-(

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[chris at bubblescope dot net]

------- Comment #6 from chris at bubblescope dot net  2005-11-28 16:33 -------
Actually, is a report really approriate? Writing array<int,3> = {1,2,3} is
perfectly valid C++, just warned about with -Wmissing-braces


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[chris at bubblescope dot net]

------- Comment #5 from chris at bubblescope dot net  2005-11-28 16:28 -------
I'll make a report. Don't worry, I'm clear on the difference between tr1::array
and a C array, I just wanted to check that we agree this should produce a
warning (in which case I will go through the tr1::array testcases, and add the
extra pair of {})


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[gdr at integrable-solutions dot net]

------- Comment #4 from gdr at integrable-solutions dot net  2005-11-28 16:18 -------
Subject: Re:   New: Warning "missing braces around initializer" causing
problems with tr1::array

"chris at bubblescope dot net" <gcc-bugzilla@gcc.gnu.org> writes:

| The following code:
| 
| struct S
| { int x[3]; };
| 
| void f()
| { S s = {1,2,3};}
| 
| With -Wmissing-braces (which is implied by -Wall, among others) gives:
| 
| warning: missing braces around initializer for 'int [3]'
| 
| In the specific case where a struct contains only a single array, adding the
| extra braces doesn't really seem that useful.
| 
| The reason it would be nice to fix this that in the definition of tr1::array
in
| the TR1 specification (page 88, 6.2.2) says
| 
| 2.An array is an aggregate ([dcl.init.aggr]) that can be initialized with the
| syntax 
| array a = { initializer-list }; 


I believe there is a slight confusion between a "C-array" and a TR1
class-type called "array".  You have found a bug in the TR1; would you
mind making a report?

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[gdr at integrable-solutions dot net]

------- Comment #3 from gdr at integrable-solutions dot net  2005-11-28 16:15 -------
Subject: Re:  Warning "missing braces around initializer" causing problems with
tr1::array

"pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> writes:

| I don't see why the warning is not useful at all, in fact I rather
| have the C++  standard fix their wording of TR1's array.

it is not the C++ standard; but definitely a bug in the specification.
he problem shoul dbe reported there.

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[chris at bubblescope dot net]

------- Comment #2 from chris at bubblescope dot net  2005-11-28 15:17 -------
Thats an option too, but I thought I'd see about gcc's opinion first, as I
expected a much faster reply than I would get from the C++ steering committee
:)

I find the warning helpful for constructs like:

struct S { int x[3]; int y[3]; }, or struct T {int x; S s;}; and such things, I
felt it was less useful for a single array inside a struct.

I'm guessing one of the major reasons that it would be nice to keep the style:

array<int,3> s = {1,2,3};

is to make it look as possible like:

int s[3] = {1,2,3};


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137

[Bug c++/25137] Warning "missing braces around initializer" causing problems with tr1::array

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2005-11-28 14:52 -------
I don't see why the warning is not useful at all, in fact I rather have the C++
standard fix their wording of TR1's array.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25137