Name mangling fails for intrinsic wrappers

[elliottslaughter]

I noticed that core::stackwalk::walk_stack runs out of stack space because of a name collision between the core::stackwalk::frame_address wrapper function and the core::stackwalk::rusti::frame_address intrinsic that it calls. It appears that the name mangler is missing the "rusti" path element from the native module, and thus is causing a name collision between the two functions.

You can see the failure by running the tests for stackwalk with optimizations turned off:

make check-stage1-core TESTNAME=stackwalk

As a temporary workaround, you can change the name of stackwalk::frame_address to e.g. wrap_frame_address.

[brson]

This may also only manifest with @elliottslaughter's newer llvm build, since I haven't seen it.

Note that there are currently two significantly different codepaths for emitting intrinsics: one for those with type parameters and one without. The frame_address intrinsic is the only intrinsic without type parameters, so it's worth investigating whether this affects all intrinsics or just some.

I have previously suspected that this problem also exists for all natives, that we name the wrapper for bar in native mod foo { fn bar(); } without including the native module portion of the path. If that's true I would also expect the following to be wonky:

native mod rustrt {
    fn rust_dbg_test();
}

fn rust_dbg_test() { }

[brson]

This may be fixed by 277f06d

[elliottslaughter]

Confirmed fixed by 277f06d.