[Bug sanitizer/64717] New: -fsanitize=vptr leads to warning: ‘<anonymous>’ may be used uninitialized in this function [-Wmaybe-uninitialized]

[Bug sanitizer/64717] New: -fsanitize=vptr leads to warning: ‘<anonymous>’ may be used uninitialized in this function [-Wmaybe-uninitialized]

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64717

            Bug ID: 64717
           Summary: -fsanitize=vptr leads to warning: ‘<anonymous>’ may be
                    used uninitialized in this function
                    [-Wmaybe-uninitialized]
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
                CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
                    jakub at gcc dot gnu.org, kcc at gcc dot gnu.org

Created attachment 34522
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34522&action=edit
Testcase (test.ii), compile with: -Wmaybe-uninitialized -fsanitize=vptr

Using -fsanitize=vptr on a mid-size C++ code leads to a few hundreds of the
following warnings:

warning: ‘<anonymous>’ may be used uninitialized in this function
[-Wmaybe-uninitialized]


The test case shows with
  g++ -S -Wmaybe-uninitialized -fsanitize=vptr test.ii
also that message.
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Subject: [Bug ipa/64710] [5 Regression] lto1: internal compiler error: Segmentation fault
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idd710

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1

[Bug sanitizer/64717] -fsanitize=vptr leads to warning: ‘<anonymous>’ may be used uninitialized in this function [-Wmaybe-uninitialized]

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64717

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2015-01-29
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 34619
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34619&action=edit
gcc5-pr64717.patch

Untested fix.  The SAVE_EXPR in there was needed in earlier versions of =vptr
support, where it emitted the __ubsan_* calls early, but right now it is used
just once, and the SAVE_EXPR causes problems when the same dtor call is used
shared in multiple locations (finally and cleanup).  There is still a possible
SAVE_EXPR if the address of the object has side-effects, but I hope dtors are
never called that way if they'd could appear in cleanups.

[Bug sanitizer/64717] -fsanitize=vptr leads to warning: ‘<anonymous>’ may be used uninitialized in this function [-Wmaybe-uninitialized]

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64717

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |5.0

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed.

[Bug sanitizer/64717] -fsanitize=vptr leads to warning: ‘<anonymous>’ may be used uninitialized in this function [-Wmaybe-uninitialized]

[gerrit.los at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64717

--- Comment #6 from Gert-jan Los <gerrit.los at gmail dot com> ---
I want to confirm that all false warnings in my code are fixed by your patch.

Thanks.