[Bug pch/55399] New: pch tests fail on mips-mti-linux-gnu target

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55399

             Bug #: 55399
           Summary: pch tests fail on mips-mti-linux-gnu target
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: pch
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: sje@gcc.gnu.org
                CC: joseph@codesourcery.com


Starting with r192715 a large number (almost all) of the pch tests started
failing on the mips-mti-linux-gnu target.  I have verified that they pass using
r192714.

I think the problem has something to do with when/where/if pch_cpp_save_state()
is called but I am not sure.  I noticed that done_preinclude is an
uninitialized
global variable, but explicitly initializing it to false did not fix the
problem.

I have no idea why this would not be affecting other targets as I don't see any
MIPS specific changes in this patch but I have not seen it on other targets.

The patch that caused the regression is mostly in libcpp:

2012-10-23  Joseph Myers  <joseph@codesourcery.com>

    * files.c (struct _cpp_file): Add implicit_preinclude.
    (pch_open_file): Allow a previously opened implicitly included
    file.
    (_cpp_find_file): Add implicit_preinclude argument.  Free file and
    do not call open_file_failed if implicit_preinclude.  Store
    implicit_preinclude value.
    (_cpp_stack_include, _cpp_fake_include, _cpp_compare_file_date):
    Update calls to _cpp_find_file.
    (_cpp_stack_include): Handle IT_DEFAULT.
    (cpp_push_default_include): New.
    * include/cpplib.h (cpp_push_default_include): Declare.
    * init.c (cpp_read_main_file): Update call to _cpp_find_file.
    * internal.h (enum include_type): Add IT_DEFAULT.
    (_cpp_find_file): Update prototype.