Inline asm doesn't complain about invalid clobbers

[Vlad-Shcherbina]

To reproduce

Try compiling the following program:

#![feature(asm)]
fn main() {
    unsafe {
        asm!("" : : : "whatever");
    }
}

Expected result

It should fail with an error

unknown register name ‘whatever’ in ‘asm’

Like how gcc and clang do in inline asm in C.

Actual result

It compiles without an error.

---

Version info:

> rustc --version --verbose
rustc 1.44.0-nightly (52fa23add 2020-04-18)
binary: rustc
commit-hash: 52fa23add6fb0776b32cc591ac928618391bdf41
commit-date: 2020-04-18
host: x86_64-pc-windows-msvc
release: 1.44.0-nightly
LLVM version: 9.0

[Amanieu]

This issue does not apply to the new asm! (RFC 2850) which properly validates all register names.

The legacy llvm_asm! is deprecated and is no longer maintained.