On 6/7/19 10:04 AM, Michael Haubenwallner wrote:
Hi,
so I'm encountering a strange problem related to object file order passed to
the linker, with any binutils and gcc version available to setup-x86_64.exe:
$ cat weak-func.c
extern void weakfunc() __attribute__((weak));
void weakfunc() {}
$ cat weak-main.c
extern void weakfunc() __attribute__((weak));
int main() { weakfunc(); }
$ gcc -o weak.exe weak-func.c weak-main.c
SUCCESS
But then, changing the order of input files on the command line does break
(does work on Linux of course):
$ gcc -o weak.exe weak-main.c weak-func.c
/usr/lib/gcc/x86_64-pc-cygwin/8.3.0/../../../../x86_64-pc-cygwin/bin/ld: /tmp/ccIthYHe.o:weak-main.c:(.text+0xe): relocation truncated to fit: R_X86_64_PC32 against undefined symbol `weakfunc'
collect2: error: ld returned 1 exit status
So the difference is that the object providing weakfunc is passed to
the linker after the object requiring weakfunc.
Attached is the weak-func.sh script that does perform these commands.
Thanks!
/haubi/
Unfortunately, PE doesn't really have a concept of weak symbols like
ELF, and is known to be broken in binutils.