compiler/rustc_const_eval/src/util/collect_writes.rs

   1 use rustc_middle::mir::visit::PlaceContext;
   2 use rustc_middle::mir::visit::Visitor;
   3 use rustc_middle::mir::{Body, Local, Location};
   4
   5 pub trait FindAssignments {
   6     // Finds all statements that assign directly to local (i.e., X = ...)
   7     // and returns their locations.
   8     fn find_assignments(&self, local: Local) -> Vec<Location>;
   9 }
  10
  11 impl<'tcx> FindAssignments for Body<'tcx> {
  12     fn find_assignments(&self, local: Local) -> Vec<Location> {
  13         let mut visitor = FindLocalAssignmentVisitor { needle: local, locations: vec![] };
  14         visitor.visit_body(self);
  15         visitor.locations
  16     }
  17 }
  18
  19 // The Visitor walks the MIR to return the assignment statements corresponding
  20 // to a Local.
  21 struct FindLocalAssignmentVisitor {
  22     needle: Local,
  23     locations: Vec<Location>,
  24 }
  25
  26 impl<'tcx> Visitor<'tcx> for FindLocalAssignmentVisitor {
  27     fn visit_local(&mut self, local: Local, place_context: PlaceContext, location: Location) {
  28         if self.needle != local {
  29             return;
  30         }
  31
  32         if place_context.is_place_assignment() {
  33             self.locations.push(location);
  34         }
  35     }
  36 }