Module resugar 

Passes that undo some lowering done by rustc to recover an operation closer to what the user wrote.

Modules

move_asserts_to_statements

Micro-pass: if we want to reconstruct fallible operations, the first step

reconstruct_asserts

In the MIR AST, it seems assert are introduced to check preconditions (for the binops for example). The assert! introduced by the user introduce if ... then { panic!(...) } else { ...}. This pass introduces assert instead in order to make the code shorter.

reconstruct_box_derefs

Resugar the box derefs that got desugared in elaborated MIR.

reconstruct_fallible_operations

Micro-pass: remove the dynamic checks for array/slice bounds, overflow, and division by zero.

reconstruct_intrinsics

reconstruct_matches

The way to match on enums in MIR is in two steps: first read the discriminant, then switch on the resulting integer. This pass records the enum place as the switch scrutinee and replaces the integer cases with symbolic enum discriminants.

reconstruct_panic_calls

Transform calls to builtin panicking functions into TerminatorKind::Panic.

reconstruct_static_accesses

MIR places can’t name statics, so rustc accesses a static through a temporary holding its address, e.g. _1 = const {alloc}; _0 = copy (*_1) where the constant points to the static. We turn *_1 back into the static itself and remove the temporary. This is needed to reliably tell what static accesses are unsafe (see HasSafety), as rustc will lower safe static access to otherwise unsafe raw pointer accesses.

reconstruct_vec_boxes

Reconstruct rustc’s vec![..] lowering based on Box<MaybeUninit<[T; N]>>.

resugar_drops

Reconstruct conditional drops using the drop flags identified by detect_drop_flags.