[Bug c/60784] New: Spurious -Wmissing-field-initializers warning for anonymous structure

[Bug c/60784] New: Spurious -Wmissing-field-initializers warning for anonymous structure

[peter at lekensteyn dot nl]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60784

            Bug ID: 60784
           Summary: Spurious -Wmissing-field-initializers warning for
                    anonymous structure
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: peter at lekensteyn dot nl

When an anonymous structure gets initialized, gcc always starts complaining
about the last field:
//////////////////////////////////////////
gcc -Wextra warn.c -o /dev/null
//////////////////////////////////////////
struct foo {
    struct {
        char a;
        char b;
    };
};

int main(void) {
    struct foo test = {
        .a = 1,
        .b = 2,
    };

    return test.a == 1;
}
///////////////////////////////////////////

Output:
warn.c: In function ‘main’:
warn.c:12:9: warning: missing initializer for field ‘b’ of ‘struct <anonymous>’
[-Wmissing-field-initializers]
         .b = 2,
         ^
warn.c:5:14: note: ‘b’ declared here
         char b;
              ^

It gets even worse when adding more fields. For fun, add "char c;" between
"char a;" and "char b;". The first warning mentions "c", but the line
thereafter points to "b":
warn.c: In function ‘main’:
warn.c:13:9: warning: missing initializer for field ‘c’ of ‘struct <anonymous>’
[-Wmissing-field-initializers]
         .b = 2,
         ^
warn.c:5:14: note: ‘c’ declared here
         char c;
              ^

Expected result: no warnings for the first case.

This is gcc-multilib 4.8.2-8 on Arch Linux x86_64.

COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-unknown-linux-gnu/4.8.2/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: /build/gcc-multilib/src/gcc-4.8-20140206/configure
--prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man
--infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/
--enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-shared
--enable-threads=posix --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-clocale=gnu --disable-libstdcxx-pch
--disable-libssp --enable-gnu-unique-object --enable-linker-build-id
--enable-cloog-backend=isl --disable-cloog-version-check --enable-lto
--enable-plugin --enable-install-libiberty --with-linker-hash-style=gnu
--enable-multilib --disable-werror --enable-checking=release
Thread model: posix
gcc version 4.8.2 20140206 (prerelease) (GCC)
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From: "law at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/60657] [4.9 Regression] ICE: error: insn does not satisfy its constraints
Date: Mon, 07 Apr 2014 22:47:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id`657

--- Comment #13 from Jeffrey A. Law <law at redhat dot com> ---
The new predicates make the predicate test match the constraint test.   It
looks like your patch exposes a relationship between the operands, and, yes,
the only way to handle that would be in the insn's condition.

I'm not ARM savvy enough to know if that's the right condition or not though.

jeff

[Bug c/60784] Spurious -Wmissing-field-initializers warning for anonymous structure

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60784

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-04-08
                 CC|                            |mpolacek at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Confirmed.

.b = X is designated initializer and -Wmissing-field-initializers shouldn't
warn for them.

[Bug c/60784] Spurious -Wmissing-field-initializers warning for anonymous structure

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60784

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
This regtested/bootstrapped patch fixes it, but I'm not fully confident it's
the Right Place.  The problem is that constructor_designated wasn't set
properly when entering pop_init_level from c_parser_braced_init, since
push_init_level called earlier set it to 0.

diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 65aad45..9813698 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -7750,6 +7750,7 @@ set_init_label (tree fieldname, struct obstack *
braced_init_obstack)
     do
       {
        constructor_fields = TREE_VALUE (field);
+       constructor_designated = 1;
        designator_depth++;
        designator_erroneous = 0;
        if (constructor_range_stack)

[Bug c/60784] Spurious -Wmissing-field-initializers warning for anonymous structure

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60784

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org
   Target Milestone|---                         |4.10.0

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Potential fix: http://gcc.gnu.org/ml/gcc-patches/2014-04/msg00623.html

[Bug c/60784] Spurious -Wmissing-field-initializers warning for anonymous structure

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60784

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Fri May  2 05:40:38 2014
New Revision: 209998

URL: http://gcc.gnu.org/viewcvs?rev=209998&root=gcc&view=rev
Log:
    PR c/60784
    * c-typeck.c (push_init_level): Set constructor_designated to
    p->designated for structures.

    * gcc.dg/pr60784.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr60784.c
Modified:
    trunk/gcc/c/ChangeLog
    trunk/gcc/c/c-typeck.c
    trunk/gcc/testsuite/ChangeLog

[Bug c/60784] Spurious -Wmissing-field-initializers warning for anonymous structure

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60784

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

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

--- Comment #6 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Should be fixed now.

[Bug c/60784] Spurious -Wmissing-field-initializers warning for anonymous structure

[peter at lekensteyn dot nl]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60784

--- Comment #7 from Peter Wu <peter at lekensteyn dot nl> ---
This bug is still present in GCC 4.9.2 and 4.9.3 (prerelease 20141210). Now
building gcc-5-20141207 to verify. (Not sure whether this gets backported to
4.9.x, just checking.)

//////////////////////////////////////////
gcc -Wextra bug.c -o /dev/null
//////////////////////////////////////////
typedef struct HidppMessage {
    struct {
        int feature_index;
        int func;
    };
} HidppMessage;

int main(void) {
    HidppMessage req = {
        .feature_index  = 0xFF,
        .func           = 1
    };
    return req.func;
}
//////////////////////////////////////////

Strange enough, replacing 0xFF by 0x00 hides the warning.

[Bug c/60784] Spurious -Wmissing-field-initializers warning for anonymous structure

[peter at lekensteyn dot nl]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60784

--- Comment #8 from Peter Wu <peter at lekensteyn dot nl> ---
GCC 5 is OK, the question is whether 4.9 will or will not receive a fix?