[Bug c++/101747] New: Two-argument version of attribute malloc does not perform overload resolution

[Bug c++/101747] New: Two-argument version of attribute malloc does not perform overload resolution

[fweimer at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101747

            Bug ID: 101747
           Summary: Two-argument version of attribute malloc does not
                    perform overload resolution
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fweimer at redhat dot com
  Target Milestone: ---

This:

struct T1;
struct T2;

void close(T1*);
void close(T2*);

T1* open(const char *) __attribute__ ((__malloc__ (close, 1)));

results in:

t.cc:7:62: error: ‘malloc’ attribute argument 1 is ambiguous
    7 | T1* open(const char *) __attribute__ ((__malloc__ (close, 1)));
      |                                                              ^
t.cc:7:62: note: use a cast to the expected type to disambiguate

This can be observed when building RawTherapee with glibc 2.34:
https://github.com/Beep6581/RawTherapee/issues/6324

Performing overload resolution in this context seems useful, given that the
exact type of the argument should be known at this point (the return type of
the function).

I'm not sure if should add the cast to the glibc sources to work around this.

[Bug c++/101747] Two-argument version of attribute malloc does not perform overload resolution

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101747

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-08-03
                 CC|                            |msebor at gcc dot gnu.org
           Keywords|                            |rejects-valid
     Ever confirmed|0                           |1

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
I suppose the return type of the allocator could be used for the
disambiguation.  The difficulty here is that the attribute handler is in code
shared by the C and C++ front ends with no good way to call a language-specific
routine to do overload resolution.  Maybe the attribute should accept a string
with the mangled name of the function in addition to a function name.

IIRC, attribute copy has the same limitation.

[Bug c++/101747] Two-argument version of attribute malloc does not perform overload resolution

[ro at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101747

Rainer Orth <ro at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ro at gcc dot gnu.org

--- Comment #2 from Rainer Orth <ro at gcc dot gnu.org> ---
I've recently run into what seems to be the same issue, cf. GDB PR build/29791
for details: all of gdbsupport fails to compile with gcc 12.2.0 on Solaris like
this:

In file included from /usr/include/sys/time.h:448,
                 from ../gnulib/import/sys/time.h:39,
                 from /usr/include/sys/select.h:27,
                 from ../gnulib/import/sys/select.h:36,
                 from /usr/include/sys/types.h:665,
                 from ../gnulib/import/sys/types.h:39,
                 from ../gnulib/import/stdio.h:58,
                 from
/vol/src/gnu/gdb/hg/master/dist/gdbsupport/common-defs.h:86,
                 from /vol/src/gnu/gdb/hg/master/dist/gdbsupport/ptid.cc:20:
../gnulib/config.h:1693:72: error: ‘malloc’ attribute argument 1 is ambiguous
 1693 | # define _GL_ATTRIBUTE_DEALLOC(f, i) __attribute__ ((__malloc__ (f,
i)))
      |                                                                       
^
../gnulib/config.h:1693:72: note: use a cast to the expected type to
disambiguate
../gnulib/config.h:1693:72: error: ‘malloc’ attribute argument 1 is ambiguous

The preprocessed testcase (not reduced) is attached to that PR:

  https://sourceware.org/bugzilla/show_bug.cgi?id=29791

Unfortunately, nobody has been able to determine yet where exactly the
ambiguity
lies, and unlike other cases, g++ doesn't show that.  Any suggestions on how to
proceed?

[Bug c++/101747] Two-argument version of attribute malloc does not perform overload resolution

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101747

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=89299

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I suspect this is the same issue as PR 89299 really, just for cleanup attribute
rather than malloc attribute.

[Bug c++/101747] Two-argument version of attribute malloc does not perform overload resolution

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101747

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|https://gcc.gnu.org/bugzill |https://gcc.gnu.org/bugzill
                   |a/show_bug.cgi?id=89299     |a/show_bug.cgi?id=69020

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Sorry I mean PR 69020.