For example, a codegen test:

//@ needs-llvm-components: riscv64 //@ compile-flags: --target riscv64gc-unknown-linux-gnu #![crate_type = "lib"] #![no_std] #![no_core] #![feature(no_core, lang_items)] extern crate minicore; // CHECK: fail!

riscv64 isn't a real LLVM component (only riscv). However, the test never errors; instead it always gets ignored. It seems pretty likely that there are at least a few in-tree tests that never get run because of a typo here.

It should be reasonably easy to keep a list of valid LLVM components and validate against that in compiletest.