Consider a cargo project (dead) with this src/lib.rs file:

pub fn fun0() {} pub fn fun1<T>() {} pub trait Trait { fn fun2(&self); fn fun3(&self) {} } impl Trait for () { fn fun2(&self) {} }

Running

cargo clean && RUSTFLAGS='-C link-dead-code' cargo test && cargo sym -C target/debug/dead* | grep dead:: 

outputs

0000000000015e60 dead::fun0::he72896c4e971b738 0000000000015e70 <() as dead::Trait>::fun2::h21fa8b5ef4270ce1 0000000000015e90 dead::__test::main::h824aaf01f68ecd0a 

We can observe that that only fun0 and <() as Trait>::fun2 is included (also checked with nm and running kcov). Not including fun1 and Trait::fun2 makes code coverage inflates (using kcov).

I can see that fun1 and Trait::fun2 is not included because they need to be monomorphised. One partial solution would be to monomorphise the default methods implementations for every type that implements the trait, but I think this could blow the binary size and compilation time.

Would it be possible to add this symbols without monomorphisation? Or maybe creating a monomorphised version that just panics? (Could all generic paramaters be set to !?)