[Bug c/84685] Designated initializers warning

[Bug c/84685] Designated initializers warning

[chrubis at suse dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84685

Cyril Hrubis <chrubis at suse dot cz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |chrubis at suse dot cz

--- Comment #4 from Cyril Hrubis <chrubis at suse dot cz> ---
Created attachment 48519
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48519&action=edit
Simplified reproducer.

I got a plenty of these useless warnings as well for LTP
https://github.com/linux-test-project/ltp.

It also looks like the warning is not printed in the compound literal is last
in the structure. In my case swapping struct bar *b and int a silences the
warning.

[Bug c/84685] Designated initializers warning

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84685

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
                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I have a patch.

[Bug c/84685] Designated initializers warning

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84685

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:4b7d9f8f51bd96d290aac230c71e501fcb6b21a6

commit r12-7772-g4b7d9f8f51bd96d290aac230c71e501fcb6b21a6
Author: Marek Polacek <polacek@redhat.com>
Date:   Tue Mar 22 14:37:02 2022 -0400

    c: -Wmissing-field-initializers and designated inits [PR82283, PR84685]

    This patch fixes two kinds of wrong -Wmissing-field-initializers
    warnings.  Our docs say that this warning "does not warn about designated
    initializers", but we give a warning for

    1) the array case:

      struct S {
        struct N {
          int a;
          int b;
        } c[1];
      } d = {
        .c[0].a = 1,
        .c[0].b = 1, // missing initializer for field 'b' of 'struct N'
      };

    we warn because push_init_level, when constructing an array, clears
    constructor_designated (which the warning relies on), and we forget
    that we were in a designated initializer context.  Fixed by the
    push_init_level hunk; and

    2) the compound literal case:

      struct T {
        int a;
        int *b;
        int c;
      };

      struct T t = { .b = (int[]){1} }; // missing initializer for field 'c' of
'struct T'

    where set_designator properly sets constructor_designated to 1, but the
    compound literal causes us to create a whole new initializer_stack in
    start_init, which clears constructor_designated.  Then, after we've parsed
    the compound literal, finish_init flushes the initializer_stack entry,
    but doesn't restore constructor_designated, so we forget we were in
    a designated initializer context, which causes the bogus warning.  (The
    designated flag is also tracked in constructor_stack, but in this case,
    we didn't perform push_init_level between set_designator and start_init
    so it wasn't saved anywhere.)

            PR c/82283
            PR c/84685

    gcc/c/ChangeLog:

            * c-typeck.cc (struct initializer_stack): Add 'designated' member.
            (start_init): Set it.
            (finish_init): Restore constructor_designated.
            (push_init_level): Set constructor_designated to the value of
            constructor_designated in the upper constructor_stack.

    gcc/testsuite/ChangeLog:

            * gcc.dg/Wmissing-field-initializers-1.c: New test.
            * gcc.dg/Wmissing-field-initializers-2.c: New test.
            * gcc.dg/Wmissing-field-initializers-3.c: New test.
            * gcc.dg/Wmissing-field-initializers-4.c: New test.
            * gcc.dg/Wmissing-field-initializers-5.c: New test.

[Bug c/84685] Designated initializers warning

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84685

--- Comment #7 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Patch seems safe to backport to 11.

[Bug c/84685] Designated initializers warning

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84685

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Marek Polacek
<mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:0fa9022aa30b9c4dde965a0406943c8c0af5eb54

commit r11-9715-g0fa9022aa30b9c4dde965a0406943c8c0af5eb54
Author: Marek Polacek <polacek@redhat.com>
Date:   Tue Mar 22 14:37:02 2022 -0400

    c: -Wmissing-field-initializers and designated inits [PR82283, PR84685]

    This patch fixes two kinds of wrong -Wmissing-field-initializers
    warnings.  Our docs say that this warning "does not warn about designated
    initializers", but we give a warning for

    1) the array case:

      struct S {
        struct N {
          int a;
          int b;
        } c[1];
      } d = {
        .c[0].a = 1,
        .c[0].b = 1, // missing initializer for field 'b' of 'struct N'
      };

    we warn because push_init_level, when constructing an array, clears
    constructor_designated (which the warning relies on), and we forget
    that we were in a designated initializer context.  Fixed by the
    push_init_level hunk; and

    2) the compound literal case:

      struct T {
        int a;
        int *b;
        int c;
      };

      struct T t = { .b = (int[]){1} }; // missing initializer for field 'c' of
'struct T'

    where set_designator properly sets constructor_designated to 1, but the
    compound literal causes us to create a whole new initializer_stack in
    start_init, which clears constructor_designated.  Then, after we've parsed
    the compound literal, finish_init flushes the initializer_stack entry,
    but doesn't restore constructor_designated, so we forget we were in
    a designated initializer context, which causes the bogus warning.  (The
    designated flag is also tracked in constructor_stack, but in this case,
    we didn't perform push_init_level between set_designator and start_init
    so it wasn't saved anywhere.)

            PR c/82283
            PR c/84685

    gcc/c/ChangeLog:

            * c-typeck.c (struct initializer_stack): Add 'designated' member.
            (start_init): Set it.
            (finish_init): Restore constructor_designated.
            (push_init_level): Set constructor_designated to the value of
            constructor_designated in the upper constructor_stack.

    gcc/testsuite/ChangeLog:

            * gcc.dg/Wmissing-field-initializers-1.c: New test.
            * gcc.dg/Wmissing-field-initializers-2.c: New test.
            * gcc.dg/Wmissing-field-initializers-3.c: New test.
            * gcc.dg/Wmissing-field-initializers-4.c: New test.
            * gcc.dg/Wmissing-field-initializers-5.c: New test.

    (cherry picked from commit 4b7d9f8f51bd96d290aac230c71e501fcb6b21a6)

[Bug c/84685] Designated initializers warning

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84685

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

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

--- Comment #9 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed for GCC 11+.