Open Radar

 
ld64 crashes when invoking clang with -flto and a mix of FullLTO and ThinLTO objects.

Create the following 3 files with the contents as described below:
$ cat a.c
int b();
int a() { return b(); }
$ cat b.c
int b() { return 0; }
$ cat main.c
int a();
int main() { return a(); }

Compile a.c in FullLTO mode, and b.c in ThinLTO mode:
$ clang -c -flto a.c
$ clang -c -flto=thin b.c

Compile main.c in FullLTO mode, and invoke the linker:
$ clang -flto main.c a.o b.o

Expected behavior:
The created executable is linked successfully, or an error message is shown if such a configuration isn’t expected to work.

What actually happens:
ld64 crashes in the LLVM backend because `-object_path_lto` points to a file, while the backend wants to save ThinLTO temp files into the *directory* specified with `-object_path_lto`.

This message is displayed:
$ clang -flto main.c a.o b.o
LLVM ERROR: Unexistent dir: '/var/folders/36/94h1n3rx1js05ry_50tclgs40000gn/T/cc-3024cb.o'
clang: error: unable to execute command: Abort trap: 6
clang: error: linker command failed due to signal (use -v to see invocation)