Add --sanitizer=none

[mateon1]

Currently it is impossible to make cargo-fuzz NOT use a sanitizer. This is usually worked around by using threadsan, as it doesn't do much for most programs, but I'm pretty sure that incurs some runtime cost.

I want to compile in release mode with no sanitizers to achieve maximum performance while looking for panics, as Rust eliminates most errors the sanitizers are made to detect.

[Manishearth]

This isn't possible, you must use a sanitizer to get the fuzzing instrumentation to work. This could perhaps be fixed by a PR to upstream rust.

[alex]

In C it's possible to get -fsanitize-coverage=<trace-pc-guard, etc.> without -fsanitize=<address|memory|...>

Is that not possible here?

[PaulGrandperrin]

It's true that right now, building without a sanitizer (by building your own version of cargo-fuzz) produces non-working targets but that shouldn't be the case.
While debugging an issue in rustc/llvm rust-lang/rust#47953 , I came to build a toolchain with llvm6.0 and libfuzzer6.0.
And with this toolchain and a modified cargo-fuzz (without any sanitizers but more coverage trace points), the fuzzing works really well and is very fast!

[PaulGrandperrin]

for the record: https://github.com/rust-fuzz/libfuzzer-sys/issues/29

[kevincox]

Another use case for this is building with musl for a static library. This makes it really easy to ship a fuzzer to multiple machines. Right now none of the sanitizers are supported for musl. If I could build without sanitizers I believe I could build with musl.

[fitzgen]

This is supported now.