[Bug c/94188] New: [10 Regression] error: request for member ‘node’ in something not a structure or union since r10-7127-gcb99630f254aaec6

[Bug c/94188] New: [10 Regression] error: request for member ‘node’ in something not a structure or union since r10-7127-gcb99630f254aaec6

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94188

            Bug ID: 94188
           Summary: [10 Regression] error: request for member ‘node’ in
                    something not a structure or union since
                    r10-7127-gcb99630f254aaec6
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
  Target Milestone: ---

Reduced from lvm2:

$ cat libdm.i
struct dm_tree_link {
  int list;
  int node;
} fn1() {
  0 ? ((struct dm_tree_link *)((char *)fn1 -
                               (char *)&((struct dm_tree_link *)0)->list))
          ->node
    : 0;
}

$ gcc-9 libdm.i -c
$ gcc libdm.i -c
libdm.i: In function ‘fn1’:
libdm.i:7:11: error: request for member ‘node’ in something not a structure or
union
    7 |           ->node
      |           ^~

[Bug c/94188] [10 Regression] error: request for member ‘node’ in something not a structure or union since r10-7127-gcb99630f254aaec6

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94188

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2020-03-16
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |rguenth at gcc dot gnu.org
      Known to work|                            |9.3.0
             Status|UNCONFIRMED                 |NEW
      Known to fail|                            |10.0
     Ever confirmed|0                           |1
   Target Milestone|---                         |10.0
           Priority|P3                          |P1

[Bug c/94188] [10 Regression] error: request for member ‘node’ in something not a structure or union since r10-7127-gcb99630f254aaec6

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94188

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
I have a patch.

[Bug c/94188] [10 Regression] error: request for member ‘node’ in something not a structure or union since r10-7127-gcb99630f254aaec6

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94188

--- Comment #2 from Martin Liška <marxin at gcc dot gnu.org> ---
Just for the record, I also see it in acpica package:

$ cat cfg.i
enum act_name { ACT_HTTP_REQ_AUTH };
struct act_rule {
  int list;
  enum act_name action
} fn1() {
  fn2(((struct act_rule *)((void *)fn2 - (void *)&((struct act_rule
*)0)->list))
          ->action);
}

[Bug c/94188] [10 Regression] error: request for member ‘node’ in something not a structure or union since r10-7127-gcb99630f254aaec6

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94188

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 48043
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48043&action=edit
patch in testing

This is what I have now, bootstrapped OK after the extra two hunks but I still
see ICEs during testing.  Still fixing build_fold_addr_expr_with_type looks
inevitable ... (other option would be to remove the optimization when the type
doesn't match, but I guess that will regress as well).

[Bug c/94188] [10 Regression] error: request for member ‘node’ in something not a structure or union since r10-7127-gcb99630f254aaec6

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94188

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #3)
> Created attachment 48043 [details]
> patch in testing
> 
> This is what I have now, bootstrapped OK after the extra two hunks but I
> still
> see ICEs during testing.  Still fixing build_fold_addr_expr_with_type looks
> inevitable ... (other option would be to remove the optimization when the
> type
> doesn't match, but I guess that will regress as well).

We can always do the match.pd change as optimization only, when the type
matches or it isn't too hard to handle it, and tweak the PTA to handle the
(pointer) (pointer - pointer_constant) case as lame pointer offsetting that
preserves points-to of the first operand.

[Bug c/94188] [10 Regression] error: request for member ‘node’ in something not a structure or union since r10-7127-gcb99630f254aaec6

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94188

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:4e3d3e40726e1b68bf52fa205c68495124ea60b8

commit r10-7237-g4e3d3e40726e1b68bf52fa205c68495124ea60b8
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Mar 18 09:13:17 2020 +0100

    middle-end/94188 fix fold of addr expression generation

    This adds a missing type conversion to build_fold_addr_expr and adjusts
    fallout - build_fold_addr_expr was used as a convenience to build an
    ADDR_EXPR but some callers do not expect the result to be simplified
    to something else.

    2020-03-18  Richard Biener  <rguenther@suse.de>

            PR middle-end/94188
            * fold-const.c (build_fold_addr_expr): Convert address to
            correct type.
            * asan.c (maybe_create_ssa_name): Strip useless type conversions.
            * gimple-fold.c (gimple_fold_stmt_to_constant_1): Use build1
            to build the ADDR_EXPR which we don't really want to simplify.
            * tree-ssa-dom.c (record_equivalences_from_stmt): Likewise.
            * tree-ssa-loop-im.c (gather_mem_refs_stmt): Likewise.
            * tree-ssa-forwprop.c (forward_propagate_addr_expr_1): Likewise.
            (simplify_builtin_call): Strip useless type conversions.
            * tree-ssa-strlen.c (new_strinfo): Likewise.

            * gcc.dg/pr94188.c: New testcase.

[Bug c/94188] [10 Regression] error: request for member ‘node’ in something not a structure or union since r10-7127-gcb99630f254aaec6

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94188

Richard Biener <rguenth at gcc dot gnu.org> changed:

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

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.