| Summary: | Implicit shared library dependencies are not handled correctly | ||
|---|---|---|---|
| Product: | binutils | Reporter: | Kris Van Hees <kris.van.hees> |
| Component: | gold | Assignee: | Ian Lance Taylor <ian> |
| Status: | RESOLVED WONTFIX | ||
| Severity: | normal | CC: | bug-binutils |
| Priority: | P2 | ||
| Version: | 2.19 | ||
| Target Milestone: | --- | ||
| Host: | Target: | ||
| Build: | Last reconfirmed: | ||
This is intentional.
In order to implement this correctly, it's necessary for the linker to exactly
emulate the dynamic linker. This is rather complicated on GNU/Linux; look at
code like gld${EMULATION_NAME}_try_needed in src/ld/emultempl/elf32.em.
Historically there have been many bugs in this code, and the effect has been
both inappropriate errors and inappropriate non-errors.
Also, searching for dependent shared libraries is very rarely useful, and it
slows down the linker. I don't know of any reason why it is required, except
for better error reporting in some cases (which is the reason that it was
originally implemented in the GNU linker).
While clearly this is a change in behaviour, I don't think it will affect very
many programs. And the fix is simple: either link against the shared library
which defines the symbol you need, or use the appropriate --unresolved-symbols
option (here I have to admit that gold does not yet implement that option).
|
Gold does not seem to handle implicit shared library dependencies. The following test case fails: bar.c: ------ int bar() { return 0; } foo.c: ------ extern int bar(); int foo() { return bar(); } app.c: ------ extern int foo(); extern int bar(); int main(int argc, char *argv[]) { foo(); bar(); } Sequence of commands to reproduce: ---------------------------------- gcc -c -o app.o app.c gcc -fpic -c -o foo.o foo.c gcc -fpic -c -o bar.o bar.c ld -shared -olibbar.so bar.o ld -shared -olibfoo.so -L. -lbar foo.o gcc -o app -Wl,-rpath,. -L. -lfoo app.o Output: ------- /usr/bin/ld: app.o: in function main:app.c(.text+0x1f): undefined reference to 'bar' collect2: ld returned 1 exit status Reference: ---------- This example works perfectly with the old linker.