[Bug c++/36628] New: incorrect declspec() handling of conditional operator

[Bug c++/36628] New: incorrect declspec() handling of conditional operator

[abarbati at iaanus dot com]

I compiled the following code with gcc 4.3.0 mingw (more details at the end of
the report) with:

  g++ -std=c++0x test.cpp

----
#include <iostream>
#include <typeinfo>

int  rvalue();
int& lvalueref();
int&& rvalueref();

decltype(true ? rvalue() : rvalue()) f()
{}

decltype(true ? lvalueref() : lvalueref()) g()
{}

decltype(true ? rvalueref() : rvalueref()) h()
{}

int main()
{
        std::cout << typeid(f).name() << "\n";
        std::cout << typeid(g).name() << "\n";
        std::cout << typeid(h).name() << "\n";
}
-----

The output is:

FivE
FRivE
FOivE

this suggests that declspec() was interpreted respectively as int, int& and
int&&. However a careful reading of clause 5, paragraph 5 and 6, makes it clear
that the result should have been int in all three cases, so correct output
should have been:

FivE
FivE
FivE

The fact is that, when evaluating the type of the arguments of the conditional
operator, int& and int&& should be adjusted to int "prior to any further
analysis". Once both the second and third parameters are adjusted to int, the
conditional operator can't help returning an int (5.16/6). To be precise, the
results are an lvalue of type int and rvalue of type int, respectively, but
that is very different from saying that they are int& and int&& and declspec
should be aware of that.

Additional compiler info:

$ g++ -v
Using built-in specs.
Target: mingw32
Configured with: ../gcc-4.3.0/configure
--enable-languages=c,ada,c++,fortran,java,objc,obj-c++
--disable-sjlj-exceptions --enable-shared --enable-libgcj --enable-libgomp
--with-dwarf2 --disable-win32-registry --enable-libstdcxx-debug
--enable-concept-checks --enable-version-specific-runtime-libs --build=mingw32
--with-bugurl=http://www.mingw.org/bugs.shtml --prefix=/mingw
--with-gmp=/mingw/src/gcc/gmp-mpfr-root
--with-mpfr=/mingw/src/gcc/gmp-mpfr-root
--with-libiconv-prefix=/mingw/src/gcc/libiconv-root
Thread model: win32
gcc version 4.3.0 20080305 (alpha-testing) mingw-20080502 (GCC)


-- 
           Summary: incorrect declspec() handling of conditional operator
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: abarbati at iaanus dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36628

[Bug c++/36628] [c++0x] incorrect decltype() handling of conditional operator

[paolo dot carlini at oracle dot com]

------- Comment #1 from paolo dot carlini at oracle dot com  2008-06-25 09:15 -------
You mean decltype, right? And I would guess you stumbled on the issue while
implementing common_type... Let's CC Doug, the main author of the code.


-- 

paolo dot carlini at oracle dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |doug dot gregor at gmail dot
                   |                            |com
            Summary|incorrect declspec()        |[c++0x] incorrect decltype()
                   |handling of conditional     |handling of conditional
                   |operator                    |operator


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36628

[Bug c++/36628] [c++0x] incorrect decltype() handling of conditional operator

[abarbati at iaanus dot com]

------- Comment #2 from abarbati at iaanus dot com  2008-06-26 11:39 -------
After a more careful reading of 5/5, 5.16/4 and 7.1.6.2/4, I believe that gcc
is correctly handling the int& case, that is the expected output should be:

FivE
FRivE
FivE

Only the int&& case is thus incorrect, according to my interpretation.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36628

[Bug c++/36628] [c++0x] incorrect decltype() handling of conditional operator

[dgregor at gcc dot gnu dot org]

------- Comment #3 from dgregor at gcc dot gnu dot org  2008-07-07 23:28 -------
The problem here is that fold() is simplifying the expression before we look at
its type. The simplification here turns something that's not a function call (a
conditional expression) into a function call, thereby triggering a different
branch in the decltype code (which returns the return type of a function being
called).


-- 

dgregor at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |dgregor at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2008-07-07 23:28:02
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36628

[Bug c++/36628] [c++0x] incorrect decltype() handling of conditional operator

[jason at gcc dot gnu dot org]

-- 

jason at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|dgregor at gcc dot gnu dot  |unassigned at gcc dot gnu
                   |org                         |dot org
             Status|ASSIGNED                    |NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36628

[Bug c++/36628] [c++0x] incorrect decltype() handling of conditional operator

[jason at gcc dot gnu dot org]

------- Comment #4 from jason at gcc dot gnu dot org  2009-07-12 21:10 -------
Subject: Bug 36628

Author: jason
Date: Sun Jul 12 21:10:09 2009
New Revision: 149536

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=149536
Log:
        PR c++/36628
        * tree.c (rvalue): Use lvalue_or_rvalue_with_address_p.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/decltype17.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/tree.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36628

[Bug c++/36628] [c++0x] incorrect decltype() handling of conditional operator

[jason at gcc dot gnu dot org]

------- Comment #5 from jason at gcc dot gnu dot org  2009-07-13 06:06 -------
Subject: Bug 36628

Author: jason
Date: Mon Jul 13 06:06:27 2009
New Revision: 149543

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=149543
Log:
        PR c++/36628
        * tree.c (rvalue): Use lvalue_or_rvalue_with_address_p.

        PR c++/37206
        * cp-tree.h (enum cp_lvalue_kind_flags): Add clk_rvalueref.
        * tree.c (lvalue_p_1): Return it.  Remove
        treat_class_rvalues_as_lvalues parm.
        (real_lvalue_p): Disallow pseudo-lvalues here.
        (lvalue_or_rvalue_with_address_p): New fn.
        * call.c (initialize_reference): Use it instead of real_lvalue_p.

        PR c++/40689
        * init.c (build_new_1): Handle initializer list as array initializer.
        (build_vec_init): Likewise.
        * typeck.c (cp_build_modify_expr): Likewise.
        * typeck2.c (process_init_constructor_array): Error rather than abort
        if too many initializers.


Added:
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/cpp0x/decltype17.C
      - copied unchanged from r149536,
trunk/gcc/testsuite/g++.dg/cpp0x/decltype17.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/cpp0x/initlist20.C
      - copied unchanged from r149534,
trunk/gcc/testsuite/g++.dg/cpp0x/initlist20.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/cpp0x/initlist21.C
      - copied unchanged from r149534,
trunk/gcc/testsuite/g++.dg/cpp0x/initlist21.C
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/cpp0x/rv10.C
      - copied unchanged from r149534, trunk/gcc/testsuite/g++.dg/cpp0x/rv10.C
Modified:
    branches/gcc-4_4-branch/gcc/cp/ChangeLog
    branches/gcc-4_4-branch/gcc/cp/ChangeLog-2007   (props changed)
    branches/gcc-4_4-branch/gcc/cp/ChangeLog-2008   (props changed)
    branches/gcc-4_4-branch/gcc/cp/call.c
    branches/gcc-4_4-branch/gcc/cp/cp-tree.h
    branches/gcc-4_4-branch/gcc/cp/init.c
    branches/gcc-4_4-branch/gcc/cp/tree.c
    branches/gcc-4_4-branch/gcc/cp/typeck.c
    branches/gcc-4_4-branch/gcc/cp/typeck2.c
    branches/gcc-4_4-branch/gcc/testsuite/ChangeLog
    branches/gcc-4_4-branch/gcc/testsuite/ChangeLog-2008   (props changed)
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/   (props changed)
    branches/gcc-4_4-branch/gcc/testsuite/g++.dg/cpp0x/decltype-38655.C  
(props changed)
    branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/torture/pr36227.c   (props
changed)
    branches/gcc-4_4-branch/gcc/testsuite/gcc.target/x86_64/abi/callabi/  
(props changed)

Propchange: branches/gcc-4_4-branch/gcc/cp/ChangeLog-2007
            ('svn:mergeinfo' modified)

Propchange: branches/gcc-4_4-branch/gcc/cp/ChangeLog-2008
            ('svn:mergeinfo' modified)

Propchange: branches/gcc-4_4-branch/gcc/testsuite/ChangeLog-2008
            ('svn:mergeinfo' modified)

Propchange: branches/gcc-4_4-branch/gcc/testsuite/g++.dg/
            ('svn:mergeinfo' modified)

Propchange: branches/gcc-4_4-branch/gcc/testsuite/g++.dg/cpp0x/decltype-38655.C
            ('svn:mergeinfo' modified)

Propchange: branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/torture/pr36227.c
            ('svn:mergeinfo' modified)

Propchange:
branches/gcc-4_4-branch/gcc/testsuite/gcc.target/x86_64/abi/callabi/
            ('svn:mergeinfo' modified)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36628

[Bug c++/36628] [c++0x] incorrect decltype() handling of conditional operator

[jason at gcc dot gnu dot org]

------- Comment #6 from jason at gcc dot gnu dot org  2009-07-14 05:17 -------
Fixed for 4.4.1.


-- 

jason at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.4.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36628