[Bug c++/18354] New: expression "+1" not considered constant (as template parameter).

[Bug c++/18354] New: expression "+1" not considered constant (as template parameter).

[fsm at robots dot ox dot ac dot uk]

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Have class templated over "int". Compiler does not accept "+1" as template
parameter on the grounds that it is not a constant expression. Compiler accepts
both "-1" and "1".

This bug appears in:  gcc version 4.0.0 20041107 (experimental)
                      gcc version 4.0.0 20041106 (experimental)

It did not appear in: gcc version 4.0.0 20040927 (experimental)

The following code reproduces the problem.
---------------------8<-------------------
template <int N>
struct X { };

void f()
{
  X< 1> a;
  X<-1> b;
  X<+1> c;  // <-- error here.
}
---------------------8<-------------------


$ g++ -c f.cxx
f.cxx: In function ‘void f()’:
f.cxx:8: error: ‘1’ is not a valid template argument for type ‘int’ because it
is a non-constant expression
f.cxx:8: error: invalid type in declaration before ‘;’ token



$ uname -a
Linux theseus 2.4.20-8smp #1 SMP Thu Mar 13 17:45:54 EST 2003 i686 i686 i386
GNU/Linux




$ g++ -v
Reading specs from /lvm/fred/gcc/cvs/install/lib/gcc/i686-pc-linux-gnu/4.0.0/specs
Configured with: ../gcc/configure --prefix=/lvm/fred/gcc/cvs/install
--enable-static --enable-shared --enable-languages=c,c++,f95
--with-mpfr=/lvm/fred/pkg/gmp/install
Thread model: posix
gcc version 4.0.0 20041107 (experimental)

-- 
           Summary: expression "+1" not considered constant (as template
                    parameter).
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: fsm at robots dot ox dot ac dot uk
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18354

[Bug c++/18354] [4.0 Regression] expression "+1" not considered constant (as template parameter).

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-07 15:46 -------
Confirmed a regression.

: Search converges between 2004-11-04-014001-trunk (#614) and 2004-11-04-161001-trunk 
(#615).

Caused by:
2004-11-04  Giovanni Bajo  <giovannibajo@gcc.gnu.org>

        DR 49, 100
        * cp-tree.h (TYPE_REF_OBJ_P): New macro.
        (TYPE_PTR_P, TYPE_PTROB_P, TYPE_PTROBV_P, TYPE_PTRFN_P,
        TYPE_REFFN_P): Document.
        (fold_decl_constant_value): New prototype.
        * pt.c (convert_nontype_argument_function): Rewrite and extract
        parts into...
        (fold_decl_constant_value, convert_nontype_argument_function): New.
        (lookup_template_class): Add comment about useless double call.
        * mangle.c (write_expression): Strip conversions before lowering
        pointer to members.
        * cvt.c (ocp_convert): Check LOOKUP_COMPLAIN for a pedwarn. Disallow
        enum to enum conversion.

The Comeau online C++ tester accepts the code also.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |giovannibajo at gcc dot gnu
                   |                            |dot org, pinskia at gcc dot
                   |                            |gnu dot org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |rejects-valid
      Known to fail|                            |4.0.0
      Known to work|                            |3.4.0
   Last reconfirmed|0000-00-00 00:00:00         |2004-11-07 15:46:06
               date|                            |
            Summary|expression "+1" not         |[4.0 Regression] expression
                   |considered constant (as     |"+1" not considered constant
                   |template parameter).        |(as template parameter).
   Target Milestone|---                         |4.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18354

[Bug c++/18354] [4.0 Regression] expression "+1" not considered constant (as template parameter).

[giovannibajo at libero dot it]

------- Additional Comments From giovannibajo at libero dot it  2004-11-07 20:54 -------
I was waiting for this, in a way

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |giovannibajo at libero dot
                   |dot org                     |it
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18354

[Bug c++/18354] [4.0 Regression] expression "+1" not considered constant (as template parameter).

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-11-14 01:56 -------
Patch here: <http://gcc.gnu.org/ml/gcc-patches/2004-11/msg01133.html>.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18354

[Bug c++/18354] [4.0 Regression] expression "+1" not considered constant (as template parameter).

[giovannibajo at libero dot it]

------- Additional Comments From giovannibajo at libero dot it  2004-11-15 02:01 -------
Updated patch:
http://gcc.gnu.org/ml/gcc-patches/2004-11/msg01191.html

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18354

[Bug c++/18354] [4.0 Regression] expression "+1" not considered constant (as template parameter).

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-11-22 12:16 -------
Subject: Bug 18354

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	giovannibajo@gcc.gnu.org	2004-11-22 12:15:54

Modified files:
	gcc/cp         : ChangeLog typeck.c 
	gcc/testsuite  : ChangeLog 
Added files:
	gcc/testsuite/g++.dg/template: nontype11.C 

Log message:
	PR c++/18354
	* typeck.c (build_unary_op) <CONVERT_EXPR, NEGATE_EXPR>: Unify code.
	Make sure the result is always a rvalue.
	
	PR c++/18354
	* g++.dg/template/nontype11.C: New test.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/ChangeLog.diff?cvsroot=gcc&r1=1.4486&r2=1.4487
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/typeck.c.diff?cvsroot=gcc&r1=1.596&r2=1.597
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.4626&r2=1.4627
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/nontype11.C.diff?cvsroot=gcc&r1=NONE&r2=1.1



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18354

[Bug c++/18354] [4.0 Regression] expression "+1" not considered constant (as template parameter).

[giovannibajo at libero dot it]

------- Additional Comments From giovannibajo at libero dot it  2004-11-22 12:17 -------
Committed after Nathan's approval. This bug is now fixed for GCC 4.0, thank you 
for your report!

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18354