Linking C & extern(C) on OS X: duplicate symbols not flagged

[Jacob Carlborg]

On 2013-08-30 00:04, "Luís Marques" <luis at luismarques.eu>" wrote:
> On Linux, the following gives out a "multiple definition" error, as
> expected:
>
>      c/test.c:
>      void dotest(void) { printf("C\n"); }
>
>      d/test.d:
>      extern(C) void dotest() { writeln("D"); }
>
> On OS X no error is flagged, and the C function is always called,
> irrespective of which order I specify the .o files to link. Yet,
> compiling and linking two .c files with a duplication symbol does give
> an error on the linking phase, as expected. So why the discrepancy? I'm
> guessing the cause is the section where the symbols appear:
>
> On Ubuntu:
>
>      $ nm d/test.o | grep dotest; echo "--"; nm c/test.o | grep dotest
>      0000000000000000 T dotest
>      --
>      0000000000000000 T dotest
>
> On OS X:
>
>      $ nm d/test.o | grep dotest; echo "--"; nm c/test.o | grep dotest
>      0000000000001490 S _dotest   <-- not in text section, as in Linux
>      --
>      0000000000000000 T _dotest
>      0000000000000060 S _dotest.eh
>
> As you might imagine, this situation can be highly disruptive (I'm
> progressively converting a C application to D). Do you know why the
> functions appear in the S section on OS X? Do you know of any
> workaround, to assure that duplicate symbols are correctly flagged?

How does it behave on Mac OS X if you just use C?

-- 
/Jacob Carlborg