[Bug c++/100608] New: [10/11/12 Regression] -Wshadow=compatible-local false positive: function local type declaration shadows variable of different type

[Bug c++/100608] New: [10/11/12 Regression] -Wshadow=compatible-local false positive: function local type declaration shadows variable of different type

[nok.raven at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100608

            Bug ID: 100608
           Summary: [10/11/12 Regression] -Wshadow=compatible-local false
                    positive: function local type declaration shadows
                    variable of different type
           Product: gcc
           Version: 10.3.1
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nok.raven at gmail dot com
  Target Milestone: ---

template <typename> class X {};

void foo()
{
    auto a = X<class a>{};
}

<source>: In function 'void foo()':
<source>:5:22: warning: declaration of 'struct foo()::a' shadows a previous
local [-Wshadow=compatible-local]
    5 |     auto a = X<class a>{};
      |                      ^
<source>:5:10: note: shadowed declaration is here
    5 |     auto a = X<class a>{};
      |          ^

https://godbolt.org/z/hzoro9v3Y

[Bug c++/100608] [10/11/12 Regression] -Wshadow=compatible-local false positive: function local type declaration shadows variable of different type

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100608

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
   Target Milestone|---                         |10.4

[Bug c++/100608] [10/11/12 Regression] -Wshadow=compatible-local false positive: function local type declaration shadows variable of different type

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100608

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Depends on|                            |92024
   Last reconfirmed|                            |2022-04-05
     Ever confirmed|0                           |1
           Assignee|unassigned at gcc dot gnu.org      |jason at gcc dot gnu.org
             Status|UNCONFIRMED                 |ASSIGNED
                 CC|                            |edlinger at gcc dot gnu.org,
                   |                            |jason at gcc dot gnu.org

--- Comment #1 from Jason Merrill <jason at gcc dot gnu.org> ---
This was changed by the patch for PR92024.  In the comment for that patch,
Bernd wrote "I think shadowing one type with another type of the same name is
always a no no" but then warns if either old or new decl is a type.  I think a
type and a non-type can't really be considered compatible.  Testing a patch.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92024
[Bug 92024] crash in check_local_shadow

[Bug c++/100608] [10/11/12 Regression] -Wshadow=compatible-local false positive: function local type declaration shadows variable of different type

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100608

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:fd0024e48e94008915a6b18112efbbd8abc81ed8

commit r12-8021-gfd0024e48e94008915a6b18112efbbd8abc81ed8
Author: Jason Merrill <jason@redhat.com>
Date:   Tue Apr 5 16:02:04 2022 -0400

    c++: -Wshadow=compatible-local type vs var [PR100608]

    The patch for PR92024 changed -Wshadow=compatible-local to warn if either
    new or old decl was a type, but the rationale only talked about the case
    where both are types.  If only one is, they aren't compatible.

            PR c++/100608

    gcc/cp/ChangeLog:

            * name-lookup.cc (check_local_shadow): Use -Wshadow=local
            if exactly one of 'old' and 'decl' is a type.

    gcc/testsuite/ChangeLog:

            * g++.dg/warn/Wshadow-compatible-local-3.C: New test.

[Bug c++/100608] [10/11 Regression] -Wshadow=compatible-local false positive: function local type declaration shadows variable of different type

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100608

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jason Merrill
<jason@gcc.gnu.org>:

https://gcc.gnu.org/g:c52cd0b35d356565f67f7956f4defc022dfa2172

commit r11-9829-gc52cd0b35d356565f67f7956f4defc022dfa2172
Author: Jason Merrill <jason@redhat.com>
Date:   Tue Apr 5 16:02:04 2022 -0400

    c++: -Wshadow=compatible-local type vs var [PR100608]

    The patch for PR92024 changed -Wshadow=compatible-local to warn if either
    new or old decl was a type, but the rationale only talked about the case
    where both are types.  If only one is, they aren't compatible.

            PR c++/100608

    gcc/cp/ChangeLog:

            * name-lookup.c (check_local_shadow): Use -Wshadow=local
            if exactly one of 'old' and 'decl' is a type.

    gcc/testsuite/ChangeLog:

            * g++.dg/warn/Wshadow-compatible-local-3.C: New test.

[Bug c++/100608] [10 Regression] -Wshadow=compatible-local false positive: function local type declaration shadows variable of different type

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100608

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jason Merrill
<jason@gcc.gnu.org>:

https://gcc.gnu.org/g:b01044ec7fbed24e9394bcf49e524acdd52849e7

commit r10-10720-gb01044ec7fbed24e9394bcf49e524acdd52849e7
Author: Jason Merrill <jason@redhat.com>
Date:   Tue Apr 5 16:02:04 2022 -0400

    c++: -Wshadow=compatible-local type vs var [PR100608]

    The patch for PR92024 changed -Wshadow=compatible-local to warn if either
    new or old decl was a type, but the rationale only talked about the case
    where both are types.  If only one is, they aren't compatible.

            PR c++/100608

    gcc/cp/ChangeLog:

            * name-lookup.c (check_local_shadow): Use -Wshadow=local
            if exactly one of 'old' and 'decl' is a type.

    gcc/testsuite/ChangeLog:

            * g++.dg/warn/Wshadow-compatible-local-3.C: New test.

[Bug c++/100608] [10 Regression] -Wshadow=compatible-local false positive: function local type declaration shadows variable of different type

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100608

Jason Merrill <jason at gcc dot gnu.org> changed:

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

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed.