[lmi] Warnings in gcc system headers [Was: wx-2.9.0-RC2 testing]

[Greg Chicares]

On 2009-05-07 17:49Z, Vadim Zeitlin wrote:
> On Wed, 06 May 2009 21:07:54 +0000 Greg Chicares <address@hidden> wrote:
> 
> GC> > excluding of
> GC> > GC> course a couple hundred lines like this:
> GC> > GC>   stl_uninitialized.h:82: warning: '__cur' might be used 
> uninitialized in this function
> GC> > GC> that I don't believe we can do anything about.
> GC> > 
> GC> >  Wouldn't using -isystem for this directory help?
> GC> 
> GC> I have read the '-isystem' documentation. Let me ask which directory
> GC> you would suggest using it for: the wx source directory? If you mean
> GC> gcc's 'include/c++/3.4.5/bits/' directory, then...well, shouldn't
> GC> gcc already consider that a "system" directory?
> 
>  I think it should but I believe it doesn't, for whatever reason (mix up
> between DOS and Unix style paths is one thing coming to mind). Otherwise I
> don't see why should it give warnings in files inside it. Of course, this
> is, once again, untested so I could be totally wrong but I thought that
> using it for the directory containing stl_uninitialized.h might help.

Here's a small testcase that builds a lot faster:

make build_type=safestdlib \
  CXXFLAGS='-isystem 
C:/MinGW-20090203/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/ 
-Wno-system-headers'
  unit_tests unit_test_targets=expression_template_0_test.exe

With or without 'CXXFLAGS' defined as above, I get:

C:/MinGW-20090203/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/debug/debug.h:
 \
  In instantiation of `_InputIterator __gnu_debug::__check_valid_range(const 
_InputIterator&, const _InputIterator&) [with _InputIterator = double*]':
C:/MinGW-20090203/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/debug/vector:86:
 \
  instantiated from `__gnu_debug_def::vector<_Tp, 
_Allocator>::vector(_InputIterator, _InputIterator, const _Allocator&) \
  [with _InputIterator = double*, _Tp = double, _Allocator = 
std::allocator<double>]' \
  /lmi/src/lmi/expression_template_0_test.cpp:355:   instantiated from here
C:/MinGW-20090203/bin/../lib/gcc/mingw32/3.4.5/../../../../include/c++/3.4.5/debug/debug.h:395:
 \
  warning: unused parameter '__last'
make[1]: *** [expression_template_0_test.o] Error 1

Even adding '-Wno-system-headers' as above doesn't prevent this problem.

A similar problem for gcc-4 was reported here:
  http://lists.apple.com/archives/Xcode-users//2006/Nov/msg00251.html
but received no reply. Here's a recent report for MinGW-gcc-3.4.5:
  http://www.prog.org.ru/topic_7119_0.html
Also see:
  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30680
and
  http://cygwin.com/ml/cygwin-apps/2005-06/msg00168.html
  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22207
which suggests (in comment number five) modifying the system headers.
I'd rather not do that, so I'm very selectively suppressing the
warnings, e.g. as follows:

ifeq (safestdlib,$(findstring safestdlib,$(build_type)))
  ifeq (3.4.5,$(gcc_version))
    expression_template_0_test.o: gcc_common_extra_warnings += 
-Wno-unused-parameter

for lmi code, and using 'sed' to filter them out when building wx.