[Bug c++/49395] New: Non-class prvalues seem to have cv-qualification with GCC

[Bug c++/49395] New: Non-class prvalues seem to have cv-qualification with GCC

[hstong at ca dot ibm.com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49395

           Summary: Non-class prvalues seem to have cv-qualification with
                    GCC
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: hstong@ca.ibm.com
                CC: michaelw@ca.ibm.com
              Host: powerpc64-unknown-linux-gnu
            Target: powerpc64-unknown-linux-gnu


C++03 subclause 3.10 [basic.lval] paragraph 9 says that "non-class rvalues
always have cv-unqualified types". When compiling with GCC, some forms of
expressions producing non-class rvalues still act as if they have cv-qualified
type. The test case below is meant to compile clean.

### Self-contained source (a.cpp):
volatile int foo();
struct A { volatile int i; };
typedef volatile int vi;

volatile int i;

const int& ir1 = foo();
const int& ir2 = A().i;  // line 8
const int& ir3 = static_cast<volatile int>(i);
const int& ir4 = vi();  // line 10


### Compiler Invocation:
g++-4.6.0 -c a.cpp -o a.o


### Compiler output:
a.cpp:8:22: error: invalid initialization of reference of type 'const int&'
from expression of type 'volatile int'
a.cpp:10:21: error: invalid initialization of reference of type 'const int&'
from expression of type 'vi'


### g++ -v output:
Using built-in specs.
Target: powerpc64-unknown-linux-gnu
Configured with: ./configure --prefix=/data/gcc --program-suffix=-4.6.0
--disable-libssp --disable-libgcj --enable-version-specific-runtime-libs
--with-cpu=default32 --enable-secureplt --with-long-double-128 --enable-shared
--enable-__cxa_atexit --enable-threads=posix --enable-languages=c,c++,fortran
--with-gmp=/usr/local
Thread model: posix
gcc version 4.6.0 (GCC)

[Bug c++/49395] Non-class prvalues seem to have cv-qualification with GCC

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49395

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2011.06.22 20:36:09
                 CC|                            |jason at gcc dot gnu.org
         AssignedTo|unassigned at gcc dot       |jason at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #1 from Jason Merrill <jason at gcc dot gnu.org> 2011-06-22 20:36:09 UTC ---
I think line 10 is definitely a bug, line 8 may be a standards issue; I notice
that EDG also complains about that line.  Since A().i is a subobject of a class
prvalue, we might want to treat it differently from a normal int prvalue.

[Bug c++/49395] Non-class prvalues seem to have cv-qualification with GCC

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49395

--- Comment #2 from Jason Merrill <jason at gcc dot gnu.org> 2011-06-23 16:52:44 UTC ---
Author: jason
Date: Thu Jun 23 16:52:41 2011
New Revision: 175339

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=175339
Log:
    PR c++/49395
    * init.c (build_zero_init_1): Strip cv-quals from scalar types.

Added:
    trunk/gcc/testsuite/g++.dg/init/ref18.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/init.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/49395] Non-class prvalues seem to have cv-qualification with GCC

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49395

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> 2011-06-23 17:09:18 UTC ---
Fixed line 10.

[Bug c++/49395] Non-class prvalues seem to have cv-qualification with GCC

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49395

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |SUSPENDED
         AssignedTo|jason at gcc dot gnu.org    |unassigned at gcc dot
                   |                            |gnu.org

[Bug c++/49395] Non-class prvalues seem to have cv-qualification with GCC

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49395

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
line 8 is rejected by clang and MSVC also.

[Bug c++/49395] Non-class prvalues seem to have cv-qualification with GCC

[hstong at ca dot ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49395

Hubert Tong <hstong at ca dot ibm.com> changed:

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

--- Comment #6 from Hubert Tong <hstong at ca dot ibm.com> ---
A().i on line 8 is specified to be an xvalue of type "volatile int" nowadays.