[Bug c++/64117] New: warning control #pragmas in precompiled headers are not obeyed for template code

["gcc-oren@ben-kiki.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64117

            Bug ID: 64117
           Summary: warning control #pragmas in precompiled headers are
                    not obeyed for template code
           Product: gcc
           Version: 4.8.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc-oren@ben-kiki.org

Created attachment 34140
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34140&action=edit
A header file, a source file, and a RUNME script using them to demonstrate the
problem.

Temporarily disabling warnings surrounding template code works fine, except
when included in a precompiled header. Then, the warnings remain in effect, and
are triggered in any C++ code that uses the template.

In my project, this means I just can't use precompiled headers. We are missing
out on cutting down our build time as a result.

BTW, speaking of precompiled headers, it sucks that `#pragma once` is not
allowed when precompiling a header file ("#pragma once in main file"), but
that's a minor annoyance - one can switch back to the bad old days of guard
macros.