[Bug c++/50817] New: G++ emits errors containing lowered vtable references

[Bug c++/50817] New: G++ emits errors containing lowered vtable references

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50817

             Bug #: 50817
           Summary: G++ emits errors containing lowered vtable references
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: manu@gcc.gnu.org


struct a {
    virtual int bar();
  };

  struct foo : public virtual a {
  };

  void test(foo *P) {
    return P->bar() + *P;
  }

g++ revision 180166: 

 void test(foo*)
vtable.cc:9:22: error: no match for ‘operator+’ in ‘(((a*)P) +
((sizetype)(*(long int*)(P->foo::<anonymous>.a::_vptr.a +
0xffffffffffffffffffffffffffffffe0u))))->a::bar() + * P’
vtable.cc:9:22: error: return-statement with a value, in function returning
'void' [-fpermissive]

clang:

 t.cc:9:18: error: invalid operands to binary expression ('int' and 'foo')
    return P->bar() + *P;
           ~~~~~~~~ ^ ~~

[Bug c++/50817] G++ emits errors containing lowered vtable references

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50817

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |paolo.carlini at oracle dot
                   |                            |com
            Version|unknown                     |4.7.0

--- Comment #1 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2011-10-21 08:18:43 UTC ---
Which has a simple fix: Do not print expressions but types like clang does.
This fix will also fix a couple of other PRs.

[Bug c++/50817] G++ emits errors containing lowered vtable references

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50817

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-10-21
     Ever Confirmed|0                           |1

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-10-21 08:33:28 UTC ---
wow! I've seen some bad ones, but this is the worst example of trying to
reconstruct expressions!

[Bug c++/50817] G++ emits errors containing lowered vtable references

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50817

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-10-21 08:34:47 UTC ---
I'm not sure this qualifies as an enhancement, I'd call it a plain ol' bug

[Bug c++/50817] G++ emits errors containing lowered vtable references

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50817

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
           Severity|enhancement                 |normal

--- Comment #4 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2011-10-21 10:16:44 UTC ---
(In reply to comment #2)
> wow! I've seen some bad ones, but this is the worst example of trying to
> reconstruct expressions!

It is a very old and well-known example: http://clang.llvm.org/diagnostics.html

(In reply to comment #3)
> I'm not sure this qualifies as an enhancement, I'd call it a plain ol' bug

As you wish.

[Bug c++/50817] G++ emits errors containing lowered vtable references

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50817

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-10-21 11:32:16 UTC ---
Of course agreed about the substance, but I'm still finding a bit puzzling the
"simple fix" assessment, I don't see tons of lazy people around not willing to
spend 5 minutes on this, do you? ;)

[Bug c++/50817] G++ emits errors containing lowered vtable references

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50817

--- Comment #6 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2011-10-21 11:38:43 UTC ---
(In reply to comment #5)
> Of course agreed about the substance, but I'm still finding a bit puzzling the
> "simple fix" assessment, I don't see tons of lazy people around not willing to
> spend 5 minutes on this, do you? ;)

Of course, my "simple" was meant to be "conceptually simple". I know by
experience how much effort takes to fix any bug at all in GCC, and in
particular, trying to get a patch approved to fix this will end up in an
endless discussion whether the expression could be better pretty-printed. Not a
five minutes fix for sure.

[Bug c++/50817] G++ emits errors containing lowered vtable references

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50817

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |DUPLICATE

--- Comment #7 from Manuel López-Ibáñez <manu at gcc dot gnu.org> 2011-12-01 17:50:25 UTC ---
Duplicate.

*** This bug has been marked as a duplicate of bug 22238 ***