The C++ frontend accepts the following (IMHO invalid) variable declaration
since gcc 3.0:
=========================
int ::i;
=========================
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Summary: [3.3/3.4/4.0 regression] int ::i; accepted
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Keywords: accepts-invalid, monitored
Severity: normal
Priority: P2
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: reichelt at gcc dot gnu dot org
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18466