[Bug c/52880] New: -Woverride-init emitts unexpected error

[Bug c/52880] New: -Woverride-init emitts unexpected error

[eparis at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52880

             Bug #: 52880
           Summary: -Woverride-init emitts unexpected error
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: eparis@redhat.com


struct s1 {
    int s1i;
    int s1j;
};

struct s2 {
    struct s1 s1;
    int s2x;
    int s2y;
};

int main(void)
{
    struct s2 s2 = {
        .s1.s1i    = 0,
        .s2y    = 1,
        .s2x    = 2,
        .s1.s1j    = 3,
    };

    return 0;
}

$ gcc -o /tmp/tmp /tmp/tmp.c -Woverride-init
/tmp/tmp.c: In function ‘main’:
/tmp/tmp.c:18:3: warning: initialized field overwritten [-Woverride-init]
/tmp/tmp.c:18:3: warning: (near initialization for ‘s2’) [-Woverride-init]

If you twiddle any of the testcase, it doesn't complain.  switching the order
you initialize s2x and s2y causes it to not complain.  If you want to get 2
warnings you can declare s1 between s2x and s2y.

I see this on both:
gcc-4.7.0-1.fc17.x86_64
gcc-4.4.6-4.el6.x86_64

[Bug c/52880] -Woverride-init emitts unexpected error

[eparis at redhat dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52880

eparis at redhat dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |trivial

[Bug c/52880] -Woverride-init emitts unexpected error

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52880

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2012-04-06
                 CC|                            |manu at gcc dot gnu.org
     Ever Confirmed|0                           |1

--- Comment #1 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2012-04-06 20:16:05 UTC ---
A patch would be welcome. We don't have many people looking at C diagnostic
issues, so any help is greatly appreciated.

[Bug c/52880] -Woverride-init emitts unexpected error

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52880

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-19 17:42:01 UTC ---
Created attachment 27193
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27193
gcc48-pr52880.patch

This patch works for me on this testcase, not sure if it is the right fix
though.

The problem is I think in that we are moving initializers back and forth
between
constructor_elements (a vector) and constructor_pending_elts (AVL tree).  The
move from constructor_elements to AVL tree happens in set_nonincremental_init
and all constructor_elements are moved there into the AVL (and -Woverride-init
warnings emitted).  The other direction is in output_pending_init_elements,
when constructor_elements is repopulated, but nothing is removed from the AVL
tree (without -Woverride-init that is just fine, saving the need to free and
realloc AVL nodes all the time).
So, if an initializer is first added to AVL tree, then copied to
constructor_elements when all fields until .e are specified, then again moved
into AVL tree, we get a warning.

I believe that during set_nonincremental_init we should never warn about
-Woverride-init, if in incremental mode the AVL tree should be either empty, or
contain initializers already copied to constructor_elements during
output_pending_init_elements.  An attempt to override already specified
initializer should always happen in non-incremental mode IMHO, so if in
incremental mode set_nonincremental_init will happen first.

[Bug c/52880] -Woverride-init emitts unexpected error

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52880

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-25 09:14:14 UTC ---
Author: jakub
Date: Wed Apr 25 09:14:02 2012
New Revision: 186808

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186808
Log:
    PR c/52880
    * c-typeck.c (set_nonincremental_init,
    set_nonincremental_init_from_string): Pass true instead of false
    as IMPLICIT to add_pending_init.

    * gcc.dg/pr52880.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr52880.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/c-typeck.c
    trunk/gcc/testsuite/ChangeLog

[Bug c/52880] -Woverride-init emitts unexpected error

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52880

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-25 09:19:00 UTC ---
Author: jakub
Date: Wed Apr 25 09:18:49 2012
New Revision: 186809

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=186809
Log:
    PR c/52880
    * c-typeck.c (set_nonincremental_init,
    set_nonincremental_init_from_string): Pass true instead of false
    as IMPLICIT to add_pending_init.

    * gcc.dg/pr52880.c: New test.

Added:
    branches/gcc-4_7-branch/gcc/testsuite/gcc.dg/pr52880.c
Modified:
    branches/gcc-4_7-branch/gcc/ChangeLog
    branches/gcc-4_7-branch/gcc/c-typeck.c
    branches/gcc-4_7-branch/gcc/testsuite/ChangeLog

[Bug c/52880] -Woverride-init emitts unexpected error

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52880

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |jakub at gcc dot gnu.org
         Resolution|                            |FIXED

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-04-25 11:38:45 UTC ---
Fixed for 4.7+.