[Bug c++/61600] New: #pragma GCC diagnostic pop leaves warnings enabled

["redi at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61600

            Bug ID: 61600
           Summary: #pragma GCC diagnostic pop  leaves warnings enabled
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
            Blocks: 58876

#pragma GCC diagnostic push
#pragma GCC diagnostic warning "-Wunused-parameter"
void foo(int i) { }
#pragma GCC diagnostic pop

void bar(int i) { }

int main()
{
  bar(1);
}

I expect a warning for foo() but not bar(), however compiling with no options I
get:

sys.cc:3:6: warning: unused parameter âiâ [-Wunused-parameter]
 void foo(int i) { }
      ^
sys.cc:7:6: warning: unused parameter âiâ [-Wunused-parameter]
 void bar(int i) { }
      ^

It appears that once I turn a warning on I can't disable it.

Have I misunderstood the feature?