[RFC 2011] Optimize non-consuming operators by c410-f3r · Pull Request #98337 · rust-lang/rust (original) (raw)

Tracking issue: #44838
Fifth step of #96496

The most non-invasive approach that will probably have very little to no performance impact.

Current behaviour

Captures are handled "on-the-fly", i.e., they are performed in the same place expressions are located.

// let a = 1; let b = 2; assert!(a > 1 && b < 100);

if !( { try capture a and then return a } > 1 && { try capture b and then return b } < 100 ) { panic!( ... ); }

As such, some overhead is likely to occur (Specially with very large chains of conditions).

When an operator is known to not take self, then it is possible to capture variables AFTER the condition.

// let a = 1; let b = 2; assert!(a > 1 && b < 100);

if !( a > 1 && b < 100 ) { { try capture a } { try capture b } panic!( ... ); }

So the possible impact on the runtime execution time will be diminished.