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From: "yaghmour.shafik at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/62116] New: Allowing redeclaration of global variable x using ::x
Date: Wed, 13 Aug 2014 03:17:00 -0000
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X-Bugzilla-Version: 4.9.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62116

            Bug ID: 62116
           Summary: Allowing redeclaration of global variable x using ::x
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yaghmour.shafik at gmail dot com

Given the following code:

int x;

int main() {
    int(::x); //does not compile
    int(::x + 2); //compiles
}

gcc 4.9 will compile it without an error while gcc 4.8.x and clang 3.4 will
generate an error. For gcc 4.8.x the error is:

error: invalid use of qualified-name '::x'
     int(::x); //does not compile
            ^

and clang gives the following error:

error: definition or redeclaration of 'x' cannot name the global scope
    int(::x); //does not compile
        ~~^

as far as I can tell both gcc 4.8.x and clang are correct here based on my
reading of section 8.3 paragraph 6:

int(::x) ;

is equivalent to:

int ::x ;

which is not valid.

The problem originally cam up in the following Stackoverflow question:

http://stackoverflow.com/questions/24623071/is-typex-valid