[Bug c++/15287] New: G++ fails when encountering the combined `[]' and `.*' operators in the context of templatized method/function

[Bug c++/15287] New: G++ fails when encountering the combined `[]' and `.*' operators in the context of templatized method/function

[wirawan0 at softhome dot net]

DESCRIPTION

G++ 3.4 wrongly recognizes some valid C++ syntax as an error:
This in particular happens when a class/structure is operated upon with
both `[]' and `.*' operators, like this:

(Class[C].*BoolMethod)();                                     //<1>

where Class is any C++ object; C is a size_t variable, and BoolMethod is a
pointer to method. An attachment is given as a concrete example of the
problem.

Some generic conditions are required to trigger the bug:

* This problem was originally discovered when `Class' is of the type
  `std::vector<something>'. But it turns out that any C++ object would
  trigger the error.

* The statement //<1> must be in a templatized function or class method.
  Look at the example: Uncomment line //[4] and comment //[5], then
  the error will not happen in `void Proc(_type2)'.


WORKAROUND

A temporary workaround is possible, by FIRST caching the `[]' operator
result, then applying the `.*' operator. But this may or may not work,
depending on what actually happens with the `[]' operator.

Consider my given example:
* If you compile with -DWORK_AROUND_BUG, the error messages disappear.
* If you compile with -DWORK_AROUND_BUG=-1 instead, the same error message
  would re-appear. The addition of parantheses does not help.


VERSION KNOWN TO BE AFFECTED: 3.4

My gcc gives the following version/compilation info:

[wirawan@snowflake tmp]$ /usr/local/gcc-3.4.0/bin/g++ -v
Reading specs from /usr/local/gcc-3.4.0/lib/gcc/i686-pc-linux-gnu/3.4.0/specs
Configured with: ../gcc-3.4.0/configure --prefix=/usr/local/gcc-3.4.0
--disable-nls --enable-languages=c,c++,f77 --enable-shared --with-cpu=i686
--with-tune=i686 --with-arch=i686 --enable-threads=posix
--enable-__cxa_atexit
Thread model: posix
gcc version 3.4.0


OTHER VERSIONS

This error does NOT happen with GNU C++ version 3.3.x and earlier.

-- 
           Summary: G++ fails when encountering the combined `[]' and `.*'
                    operators in the context of templatized method/function
           Product: gcc
           Version: 3.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: wirawan0 at softhome dot net
                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=15287

[Bug c++/15287] G++ fails when encountering the combined `[]' and `.*' operators in the context of templatized method/function

[wirawan0 at softhome dot net]

------- Additional Comments From wirawan0 at softhome dot net  2004-05-04 22:56 -------
Created an attachment (id=6224)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=6224&action=view)
Sample code to trigger the error

The output of my g++ compiler is also given in the source code.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15287

[Bug c++/15287] [3.4/3.5 Regression] G++ fails when encountering the combined `[]' and `.*' operators in the context of templatized method/function

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-05-04 23:15 -------
Confirmed.
Reduced to:
-----------------------------
typedef __SIZE_TYPE__ size_t;
struct Structure {}; // empty, just a dummy placeholder
extern Structure& t;
struct Vector2
{
    typedef Structure& reference;
    reference operator[](int x) {return t;}
};
Vector2 Array;
template <int>//t
void Print(void (Structure::*BoolMethod)())
{
  size_t C = 0;
  (Array[C].*BoolMethod)();
}
-----------------------------

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |critical
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |rejects-valid
      Known to fail|                            |3.4.0 3.5.0
      Known to work|                            |3.3.3
   Last reconfirmed|0000-00-00 00:00:00         |2004-05-04 23:15:11
               date|                            |
            Summary|G++ fails when encountering |[3.4/3.5 Regression] G++
                   |the combined `[]' and `.*'  |fails when encountering the
                   |operators in the context of |combined `[]' and `.*'
                   |templatized method/function |operators in the context of
                   |                            |templatized method/function
   Target Milestone|---                         |3.4.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15287

[Bug c++/15287] [3.4/3.5 Regression] combination of operator[] and operator .* fails in templates

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2004-05-04 23:51 -------
Yes, and still a little smaller: 
---------------- 
struct S {}; 
 
struct Array { 
    S operator[](int); 
} array; 
 
void (S::*mem_fun_ptr)(); 
 
template <int> void foo() { 
  (array[0].*mem_fun_ptr)(); 
} 
-------------------- 
 
g/x> /home/bangerth/bin/gcc-3.3.4-pre/bin/c++ -c x.cc 
 
g/x> /home/bangerth/bin/gcc-3.4-pre/bin/c++ -c x.cc 
x.cc: In function `void foo()': 
x.cc:10: error: invalid operands of types `Array' and `int' to binary 
`operator+' 
 
Another workaround is to write 
  array.operator[](0) 
instead of 
  array[0] 
 
W. 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[3.4/3.5 Regression] G++    |[3.4/3.5 Regression]
                   |fails when encountering the |combination of operator[]
                   |combined `[]' and `.*'      |and operator .* fails in
                   |operators in the context of |templates
                   |templatized method/function |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15287

[Bug c++/15287] [3.4/3.5 Regression] combination of operator[] and operator .* fails in templates

[mmitchel at gcc dot gnu dot org]

------- Additional Comments From mmitchel at gcc dot gnu dot org  2004-05-22 18:26 -------
Working on a fix.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |mark at codesourcery dot com
                   |dot org                     |
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15287

[Bug c++/15287] [3.4/3.5 Regression] combination of operator[] and operator .* fails in templates

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-05-22 19:17 -------
Subject: Bug 15287

CVSROOT:	/cvs/gcc
Module name:	gcc
Branch: 	gcc-3_4-branch
Changes by:	mmitchel@gcc.gnu.org	2004-05-22 19:16:53

Modified files:
	gcc/cp         : ChangeLog class.c typeck.c 
	gcc/testsuite  : ChangeLog 
Added files:
	gcc/testsuite/g++.dg/inherit: union1.C 
	gcc/testsuite/g++.dg/template: addr1.C array5.C array6.C 

Log message:
	PR c++/15507
	* g++.dg/inherit/union1.C: New test.
	
	PR c++/15542
	* g++.dg/template/addr1.C: New test.
	
	PR c++/15427
	* g++.dg/template/array5.C: New test.
	
	PR c++/15287
	* g++.dg/template/array6.C: New test.
	
	PR c++/15507
	* g++.dg/inherit/union1.C: New test.
	
	PR c++/15542
	* g++.dg/template/addr1.C: New test.
	
	PR c++/15427
	* g++.dg/template/array5.C: New test.
	
	PR c++/15287
	* g++.dg/template/array6.C: New test.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.3892.2.100&r2=1.3892.2.101
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/class.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.595.4.7&r2=1.595.4.8
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/typeck.c.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.519.2.14&r2=1.519.2.15
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=1.3389.2.177&r2=1.3389.2.178
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/inherit/union1.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=NONE&r2=1.1.2.1
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/addr1.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=NONE&r2=1.1.2.1
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/array5.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=NONE&r2=1.1.2.1
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/array6.C.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&r1=NONE&r2=1.1.2.1



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15287

[Bug c++/15287] [3.4/3.5 Regression] combination of operator[] and operator .* fails in templates

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-05-22 19:28 -------
Subject: Bug 15287

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	mmitchel@gcc.gnu.org	2004-05-22 19:28:31

Modified files:
	gcc/cp         : ChangeLog class.c typeck.c 
	gcc/testsuite  : ChangeLog 
Added files:
	gcc/testsuite/g++.dg/inherit: union1.C 
	gcc/testsuite/g++.dg/template: addr1.C array5.C array6.C 

Log message:
	PR c++/15507
	* class.c (layout_nonempty_base_or_field): Do not try to avoid
	layout conflicts for unions.
	
	PR c++/15542
	* typeck.c (build_x_unary_op): Instantiate template class
	specializations before looking for "operator &".
	
	PR c++/15427
	* typeck.c (complete_type): Layout non-dependent array types, even
	in templates.
	
	PR c++/15287
	* typeck.c (build_unary_op): Do not optimize "&x[y]" when in a
	template.
	
	PR c++/15507
	* g++.dg/inherit/union1.C: New test.
	
	PR c++/15542
	* g++.dg/template/addr1.C: New test.
	
	PR c++/15427
	* g++.dg/template/array5.C: New test.
	
	PR c++/15287
	* g++.dg/template/array6.C: New test.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/ChangeLog.diff?cvsroot=gcc&r1=1.4050&r2=1.4051
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/class.c.diff?cvsroot=gcc&r1=1.612&r2=1.613
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/cp/typeck.c.diff?cvsroot=gcc&r1=1.542&r2=1.543
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.3769&r2=1.3770
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/inherit/union1.C.diff?cvsroot=gcc&r1=1.1&r2=1.2
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/addr1.C.diff?cvsroot=gcc&r1=1.1&r2=1.2
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/array5.C.diff?cvsroot=gcc&r1=1.1&r2=1.2
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/g++.dg/template/array6.C.diff?cvsroot=gcc&r1=1.1&r2=1.2



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15287

[Bug c++/15287] [3.4/3.5 Regression] combination of operator[] and operator .* fails in templates

[mmitchel at gcc dot gnu dot org]

------- Additional Comments From mmitchel at gcc dot gnu dot org  2004-05-22 19:31 -------
Fixed in GCC 3.4.1.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15287

[Bug c++/15287] [3.4/3.5 Regression] combination of operator[] and operator .* fails in templates

[mmitchel at gcc dot gnu dot org]

------- Additional Comments From mmitchel at gcc dot gnu dot org  2004-05-22 19:31 -------
Fixed in GCC 3.4.1.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15287