Re: Compile problem on Mac OS X 10.4/gcc 4.0

[Per P. <per...@ma...>]

On May 8, 2005, at 18:47, Hans-Bernhard Broeker wrote:

> Per Persson wrote:
>> I've had a report that gnuplot won't compile on OS X 10.4 and gcc 4.0 
>> because of a conflict with a static char array "Class" in gplt_x11.c 
>> and the Objective-C type "Class". It has not been a problem before so 
>> it seems gcc 4 is pickier about this than gcc 3.x.
>
> Or maybe it's plain wrong about it.  Stranger bugs have crept into 
> little-used corners of GCC before.

Agreed.

>
>> When detecting Mac OS X and libaquaterm "-ObjC" is added to CFLAGS 
>> (apple.m4), and every file is compiled as ObjC although only 
>> aquaterm.trm needs the "-ObjC" flag.
>> As I see it, there are two ways to fix this:
>> 1) Change the name "Class" in gplt_x11.c
>> 2) Increase granularity in buildsystem to only compile aquaterm.trm 
>> (or term.c) with "-ObjC"
>
> I'm not convinced that (2) can work.  -ObjC effectively switches to a 
> different language, with possibly different calling conventions and 
> name mangling rules.

ObjC is a strict superset of C, in the sense that any C (well make that 
C89 or whatever) code *should* compile using the ObjC compiler. There 
is no C++ style name mangling going on in ObjC. It is common practice 
to mix C and ObjC using each where it is best suited.

> I wouldn't be surprised in any way if this broke the
> link completely.

Not a linker issue, it is the compiler complaining...
The following is from a bugreport to DarwinPorts (package manager) list:

> if gcc -DHAVE_CONFIG_H -I. -I. -I..  -I../term -I../term 
> -DBINDIR=\"/opt/local/bin\" -
> DX11_DRIVER_DIR=\"/opt/local/libexec/gnuplot/4.0\" -DCONTACT=\"gnuplot-
> bugs at lists.sourceforge.net\" 
> -DHELPFILE=\"/opt/local/share/gnuplot/4.0/gnuplot.gih\" -I/opt/local/
> include -no-cpp-precomp  -I/usr/X11R6/include -I/opt/local/include 
> -I/opt/local/include  -g -O2 -
> ObjC -MT gplt_x11.o -MD -MP -MF ".deps/gplt_x11.Tpo" \
>   -c -o gplt_x11.o `test -f 'gplt_x11.c' || echo './'`gplt_x11.c; \
> then mv ".deps/gplt_x11.Tpo" ".deps/gplt_x11.Po"; \
> else rm -f ".deps/gplt_x11.Tpo"; exit 1; \
> fi
> gplt_x11.c:519: error: 'Class' redeclared as different kind of symbol
> <built-in>:0: error: previous declaration of 'Class' was here
> make[3]: *** [gplt_x11.o] Error 1
> make[2]: *** [all-recursive] Error 1
> make[1]: *** [all-recursive] Error 1
> make: *** [all] Error 2

As I said, until I get 10.4 installed I really can't explore this 
further. Still, I think that (2) would be nice to implement some time 
from a pure cleanlyness perpspective...

/Per