[Bug c++/20420] New: Unrecognized double declarations

[Bug c++/20420] New: Unrecognized double declarations

[wolfgang dot roehrl at de dot gi-de dot com]

Dear all,

I would like to post a bug report for the GNU C/C++ compiler 3.3-e500.

We use the compiler to generate code for a PowerPC processor.

Used invokation line for the GNU C++ compiler:

ccppc -c -x c++ -ansi -Wall -Werror -mcpu=8540 -fverbose-asm -mbig
      -fmerge-templates -mmultiple -mno-string -mstrict-align -O3
      -fno-exceptions -fno-rtti -fno-builtin-printf
      -I<different include paths>
      -D<differen #define's>
      K.CPP -oK.O


// file K.CPP

class B
{
protected:
    enum E { E1, E2, E3 };
    struct S { int i; E e; };
};

class D : private B
{
public:
    using B::E;
    using B::S;

private:
    enum E {};
    struct S {};
};


The compiler does not complain about the double declarations of enum E and
struct S. (By the way, the Comeau online compiler recognizes the doubly
declared items.)

Kind regards
W. Roehrl

-- 
           Summary: Unrecognized double declarations
           Product: gcc
           Version: 3.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: wolfgang dot roehrl at de dot gi-de dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: sparc-sun-solaris2.5.1
  GCC host triplet: i386-pc-mingw32
GCC target triplet: powerpc-wrs-vxworks


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20420

[Bug c++/20420] Unrecognized double declarations

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2005-03-11 14:50 -------
Confirmed, with all gcc versions I have on my system. Here's what icc says: 
 
g/x> icc -Xc -ansi -c x.cc 
x.cc(15): error: "E" has already been declared in the current scope 
      enum E {}; 
           ^ 
 
x.cc(16): error: "S" has already been declared in the current scope 
      struct S {}; 
             ^ 
 
compilation aborted for x.cc (code 2) 
 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |accepts-invalid
      Known to fail|                            |2.95.3 3.2.3 3.3.1 3.3.4
                   |                            |3.4.3 4.0.0
   Last reconfirmed|0000-00-00 00:00:00         |2005-03-11 14:50:52
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20420

[Bug c++/20420] Incorrectly Accepts double declarations

[lerdsuwa at gcc dot gnu dot org]

------- Additional Comments From lerdsuwa at gcc dot gnu dot org  2005-03-12 06:18 -------
It's xref_tag/push_tag bug.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |lerdsuwa at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2005-03-11 14:50:52         |2005-03-12 06:18:58
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20420

[Bug c++/20420] Incorrectly Accepts double declarations

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20420

Paolo Carlini <paolo.carlini at oracle dot com> changed:

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

--- Comment #10 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-08-23 09:53:40 UTC ---
Fixed for 4.8.0.

[Bug c++/20420] Incorrectly Accepts double declarations

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20420

--- Comment #9 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2012-08-23 09:44:12 UTC ---
Author: paolo
Date: Thu Aug 23 09:44:08 2012
New Revision: 190618

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=190618
Log:
/cp
2012-08-23  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/20420
    * name-lookup.c (supplement_binding_1): Handle specially enums
    only in class templates.
    (validate_nonmember_using_decl): Enforce 7.3.3/10 about duplicate
    using declarations at function scope.

/testsuite
2012-08-23  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/20420
    * g++.dg/lookup/using53.C: New.

Added:
    trunk/gcc/testsuite/g++.dg/lookup/using53.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/name-lookup.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/20420] Incorrectly Accepts double declarations

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20420

--- Comment #8 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-08-22 00:01:27 UTC ---
For Comment #4: the validate_nonmember_using_decl call at the beginning of
do_local_using_decl returns NULL_TREE for the second using declaration, but we 
ignore that and return without error. That doesn't seem right for VAR_DECLs.

This combo patchlet passes testing:

Index: name-lookup.c
===================================================================
--- name-lookup.c    (revision 190569)
+++ name-lookup.c    (working copy)
@@ -441,7 +441,8 @@ supplement_binding_1 (cxx_binding *binding, tree d
          template in order to handle late matching of underlying
          type on an opaque-enum-declaration followed by an
          enum-specifier.  */
-      || (TREE_CODE (TREE_TYPE (target_decl)) == ENUMERAL_TYPE
+      || (processing_template_decl
+          && TREE_CODE (TREE_TYPE (target_decl)) == ENUMERAL_TYPE
           && TREE_CODE (TREE_TYPE (target_bval)) == ENUMERAL_TYPE
           && (dependent_type_p (ENUM_UNDERLYING_TYPE
                     (TREE_TYPE (target_decl)))
@@ -2581,7 +2582,11 @@ do_local_using_decl (tree decl, tree scope, tree n

   decl = validate_nonmember_using_decl (decl, scope, name);
   if (decl == NULL_TREE)
-    return;
+    {
+      if (TREE_CODE (orig_decl) == VAR_DECL)
+    error ("%qD is already declared in this scope", name);
+      return;
+    }

   if (building_stmt_list_p ()
       && at_function_scope_p ())

[Bug c++/20420] Incorrectly Accepts double declarations

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20420

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|gcc-bugs at gcc dot gnu.org |
         AssignedTo|unassigned at gcc dot       |paolo.carlini at oracle dot
                   |gnu.org                     |com
      Known to fail|                            |

--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-08-21 19:25:05 UTC ---
Currently, the original testcase is *almost* handled correctly - we need
something like the below to avoid an ICE with enums - but we still accept the
snippet in Comment #4: I just checked and apparently per C++11 too we should
reject it. Looking a bit into this, maybe for now I will end up submitting only
the patchlet.

Index: name-lookup.c
===================================================================
--- name-lookup.c    (revision 190569)
+++ name-lookup.c    (working copy)
@@ -441,7 +441,8 @@ supplement_binding_1 (cxx_binding *binding, tree d
          template in order to handle late matching of underlying
          type on an opaque-enum-declaration followed by an
          enum-specifier.  */
-      || (TREE_CODE (TREE_TYPE (target_decl)) == ENUMERAL_TYPE
+      || (processing_template_decl
+          && TREE_CODE (TREE_TYPE (target_decl)) == ENUMERAL_TYPE
           && TREE_CODE (TREE_TYPE (target_bval)) == ENUMERAL_TYPE
           && (dependent_type_p (ENUM_UNDERLYING_TYPE
                     (TREE_TYPE (target_decl)))

[Bug c++/20420] Incorrectly Accepts double declarations

[andrew dot stubbs at st dot com]

------- Comment #6 from andrew dot stubbs at st dot com  2006-09-12 07:44 -------
Subject: Re:  Incorrectly Accepts double declarations

bangerth at dealii dot org wrote:
> No, that code is definitely legal and unobjectionable. Just as having two
> extern declarations of the same variable in the same scope (or two forward
> declarations of a function) is not a problem.

Not according to the C++ standard. Section 7.3.3 clause 8 explicitly 
outlaws this example.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20420

[Bug c++/20420] Incorrectly Accepts double declarations

[bangerth at dealii dot org]

------- Comment #5 from bangerth at dealii dot org  2006-09-12 04:00 -------
(In reply to comment #4)
> I suppose this is the same basic problem?

No, that code is definitely legal and unobjectionable. Just as having two
extern declarations of the same variable in the same scope (or two forward
declarations of a function) is not a problem.

W.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20420

[Bug c++/20420] Incorrectly Accepts double declarations

[amylaar at gcc dot gnu dot org]

------- Comment #4 from amylaar at gcc dot gnu dot org  2006-09-11 21:45 -------
I suppose this is the same basic problem?

namespace N
{
  int i;
}

void
f ()
{
  using N::i;
  using N::i;
}


-- 

amylaar at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|2.95.3 3.2.3 3.3.1 3.3.4    |2.95.3 3.2.3 3.3.1 3.3.4
                   |3.4.3 4.0.0                 |3.4.3 4.0.0 4.2.0
   Last reconfirmed|2006-01-20 00:58:45         |2006-09-11 21:45:13
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20420

[Bug c++/20420] Incorrectly Accepts double declarations

[lerdsuwa at gcc dot gnu dot org]

------- Comment #3 from lerdsuwa at gcc dot gnu dot org  2005-10-22 13:58 -------
Won't work on it for a long while.


-- 

lerdsuwa at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|lerdsuwa 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=20420