Given this code:

#[no_mangle]
pub extern "C" fn foo() {}

I get this output from rustc:

$ rustc +1.66.1 foo.rs --crate-type staticlib && ls -alh libfoo.a
-rw-r--r-- 1 acrichto acrichto 22M Jan 30 16:28 libfoo.a
$ rustc +1.67.0 foo.rs --crate-type staticlib && ls -alh libfoo.a
-rw------- 1 acrichto acrichto 22M Jan 30 16:28 libfoo.a

The most recent archive no longer has the "read" permission bit set for group/world owners. This ended up breaking Wasmtime's build because our files are built in a container with a different user and aren't then readable outside of the container. There's no particular reason we do this and we can work around this, but I also suspected that the change in permissions here probably wasn't intentional.

I think this is due to #97485 (cc @bjorn3), specifically this line. I haven't dug too deeply but my guess is that temp files specifically turn off other permission bits