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Re: GCC 3.4 issue
- From: Gary Thomas <gary at mlbassoc dot com>
- To: Andrew Lunn <andrew at lunn dot ch>
- Cc: eCos development <ecos-devel at ecos dot sourceware dot org>
- Date: Fri, 27 Feb 2004 09:11:02 -0700
- Subject: Re: GCC 3.4 issue
- Organization: MLB Associates
- References: <1077896266.4222.568.camel@hermes> <20040227155343.GI28206@lunn.ch>
On Fri, 2004-02-27 at 08:53, Andrew Lunn wrote:
> On Fri, Feb 27, 2004 at 08:37:46AM -0700, Gary Thomas wrote:
> > Just for grins, I thought I'd give 3.4 (pre-release) a spin. Lo and behold,
> > there are problems (PPC at least):
> >
> > powerpc-eabi-gcc -c -I/work/moab/t/install/include -I/work2/ecos/packages/io/fileio/current -I/work2/ecos/packages/io/fileio/current/src -I/work2/ecos/packages/io/fileio/current/tests -I. -I/work2/ecos/packages/io/fileio/current/src/ -msoft-float -mcpu=405 -Wall -Wpointer-arith -Wstrict-prototypes -Winline -Wundef -Woverloaded-virtual -g -O2 -ffunction-sections -fdata-sections -fno-rtti -fno-exceptions -Wp,-MD,src/file.tmp -o src/io_fileio_file.o /work2/ecos/packages/io/fileio/current/src/file.cxx
> > cc1plus: warning: command line option "-Wstrict-prototypes" is valid for C/ObjC but not for C++
> > /tmp/cchuPi8h.s: Assembler messages:
> > /tmp/cchuPi8h.s:105: Error: symbol `__cygvar_discard_me__' is already defined
> >
> > This comes from use of this macro:
> >
> > // -------------------------------------------------------------------------
> > // Reference a symbol without explicitly making use of it. Ensures that
> > // the object containing the symbol will be included when linking.
> >
> > #define CYG_REFERENCE_OBJECT(__object__) \
> > CYG_MACRO_START \
> > static void *__cygvar_discard_me__ __attribute__ ((unused)) = \
> > &(__object__); \
> > CYG_MACRO_END
>
> Have you looked at the assembly code to work out what is going on?
>
> Im guessing there are multiple invocations of CYG_REFERENCE_OBJECT()
> and its not respecting the static keyword. If thats true its a bug in
> GCC which should be fixed.
I think __attribute__((unused)) isn't having any effect. What happens
is if the same file has more than one call to CYG_REFERENCE_OBJECT, then
you end up with multiple declarations of __cygvar_discard_me__.
I'll investigate how it used to work and probably ask the GCC folks
about it.
--
Gary Thomas <gary@mlbassoc.com>
MLB Associates