[Bug c++/103177] New: incorrect error message for ambiguous lookup

[Bug c++/103177] New: incorrect error message for ambiguous lookup

[jens.maurer at gmx dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103177

            Bug ID: 103177
           Summary: incorrect error message for ambiguous lookup
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jens.maurer at gmx dot net
  Target Milestone: ---

This is clearly a case of ambiguous lookup:

struct B {
   static int foo(int);
};

struct B2 {
   int foo();
};

struct D : private B, public B2 {
};

void f()
{
   D d;
   d.foo();
}

Yet, gcc complains about an inaccessible member. (Note that access is checked
at the end of overload resolution, but we should never get to that point.)

g++ -Wfatal-errors x.cc

x.cc: In function ‘void f()’:
x.cc:18:5: error: ‘static int B::foo(int)’ is inaccessible within this 
context
    18 |   d.foo();
       |     ^~~
compilation terminated due to -Wfatal-errors.

[Bug c++/103177] incorrect error message for ambiguous lookup

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103177

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
           Keywords|                            |diagnostic
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-11-10

[Bug c++/103177] incorrect error message for ambiguous lookup with a static member function from a private base

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103177

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|incorrect error message for |incorrect error message for
                   |ambiguous lookup            |ambiguous lookup with a
                   |                            |static member function from
                   |                            |a private base

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So if I remove static from B::foo, the inaccessible error message is gone.

[Bug c++/103177] incorrect error message for ambiguous lookup with a static member function from a private base

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103177

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

https://gcc.gnu.org/g:ffe9c0a0d3564a6083ea6194eb3374a89c29c085

commit r12-7656-gffe9c0a0d3564a6083ea6194eb3374a89c29c085
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue Mar 15 08:50:24 2022 -0400

    c++: extraneous access error with ambiguous lookup [PR103177]

    When a lookup is ambiguous, lookup_member still attempts to check
    access of the first member found before diagnosing the ambiguity and
    propagating the error, and this may cause us to issue an extraneous
    access error as in the testcase below (for B1::foo).

    This patch fixes this by swapping the order of the ambiguity and access
    checks within lookup_member.  In passing, since the only thing that could
    go wrong during lookup_field_r is ambiguity, we might as well hardcode
    that in lookup_member and get rid of lookup_field_info::errstr.

            PR c++/103177

    gcc/cp/ChangeLog:

            * search.cc (lookup_field_info::errstr): Remove this data
            member.
            (lookup_field_r): Don't set errstr.
            (lookup_member): Check ambiguity before checking access.
            Simplify accordingly after errstr removal.  Exit early upon
            error or empty result.

    gcc/testsuite/ChangeLog:

            * g++.dg/lookup/ambig6.C: New test.

[Bug c++/103177] incorrect error message for ambiguous lookup with a static member function from a private base

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103177

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
   Target Milestone|---                         |12.0
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot gnu.org
                 CC|                            |ppalka at gcc dot gnu.org
             Status|NEW                         |RESOLVED

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 12.