1 files changed, 36 insertions, 0 deletions
diff --git a/compiler/rustc_const_eval/src/util/find_self_call.rs b/compiler/rustc_const_eval/src/util/find_self_call.rs
new file mode 100644
index 000000000..33ad128ee
--- /dev/null
+++ b/compiler/rustc_const_eval/src/util/find_self_call.rs
@@ -0,0 +1,36 @@
+use rustc_middle::mir::*;
+use rustc_middle::ty::subst::SubstsRef;
+use rustc_middle::ty::{self, TyCtxt};
+use rustc_span::def_id::DefId;
+
+/// Checks if the specified `local` is used as the `self` parameter of a method call
+/// in the provided `BasicBlock`. If it is, then the `DefId` of the called method is
+/// returned.
+pub fn find_self_call<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    body: &Body<'tcx>,
+    local: Local,
+    block: BasicBlock,
+) -> Option<(DefId, SubstsRef<'tcx>)> {
+    debug!("find_self_call(local={:?}): terminator={:?}", local, &body[block].terminator);
+    if let Some(Terminator { kind: TerminatorKind::Call { func, args, .. }, .. }) =
+        &body[block].terminator
+    {
+        debug!("find_self_call: func={:?}", func);
+        if let Operand::Constant(box Constant { literal, .. }) = func {
+            if let ty::FnDef(def_id, substs) = *literal.ty().kind() {
+                if let Some(ty::AssocItem { fn_has_self_parameter: true, .. }) =
+                    tcx.opt_associated_item(def_id)
+                {
+                    debug!("find_self_call: args={:?}", args);
+                    if let [Operand::Move(self_place) | Operand::Copy(self_place), ..] = **args {
+                        if self_place.as_local() == Some(local) {
+                            return Some((def_id, substs));
+                        }
+                    }
+                }
+            }
+        }
+    }
+    None
+}