Fix incorrect NEEDED entry due to unneeded shared lib reference

[parth-07]

This commit fixes the incorrect NEEDED entry when --as-needed is used and a shared library symbol is referenced by an another unneeded shared library.

The root cause of the issue was the logic that was used to determine whether a shared library symbol ResolveInfo should have an outSymbol or not.

Resolves #668

[quic-seaswara]

Should the condition be changed here ?

[parth-07]

No, this does not need to be changed.

[quic-seaswara]

Fails with this test

cat > 1.c << \!
int main() {
return 0;
}
!

cat > 2.c << \!
extern int foo();
int bar() { return foo(); }
!

cat > 3.c << \!
int foo() { return 0; }
!

clang -c 1.c -fPIC
clang -c 2.c -fPIC
clang -c 3.c -fPIC
$LD -shared 2.o -o lib2.so
$LD -shared 3.o -o lib3.so
$LD 1.o lib2.so lib3.so -o one
llvm-readelf -d one | grep NEEDED
$LD 1.o  lib2.so --as-needed lib3.so --no-as-needed -o two
llvm-readelf -d two | grep NEEDED

Try with ld.bfd and ld.eld. I think lld also has an issue here.

[parth-07]

Hi @quic-seaswara,

$LD 1.o  lib2.so --as-needed lib3.so --no-as-needed -o two
llvm-readelf -d two | grep NEEDED

Here lib2.so should always be marked as NEEDED because it is not enclosed within --as-needed.

In issue #668, eld marks as NEEDED an used shared library that is enclosed within --as-needed. lld and bfd do not have the bug described in #668.

[parth-07]

Hi @quic-seaswara

Thank you for finding the issue and sharing the test case. I have improved the fix to correctly handle the case shared by you.