ICE: LLVM Assertion S->getType()->isPtrOrPtrVectorTy() fails with raw/fat pointer cast

[mbrubeck]

This code causes the compiler to crash:

fn main() { &0u8 as *const u8 as *const PartialEq<u8>; }

with this LLVM assertion failure:

rustc: /buildslave/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/llvm/lib/IR/Constants.cpp:1649: static llvm::Constant* llvm::ConstantExpr::getPointerCast(llvm::Constant*, llvm::Type*): Assertion `S->getType()->isPtrOrPtrVectorTy() && "Invalid cast"' failed.
Aborted (core dumped)