1 files changed, 52 insertions, 0 deletions
diff --git a/src/tools/clippy/clippy_utils/src/mir/maybe_storage_live.rs b/src/tools/clippy/clippy_utils/src/mir/maybe_storage_live.rs
new file mode 100644
index 000000000..d262b335d
--- /dev/null
+++ b/src/tools/clippy/clippy_utils/src/mir/maybe_storage_live.rs
@@ -0,0 +1,52 @@
+use rustc_index::bit_set::BitSet;
+use rustc_middle::mir;
+use rustc_mir_dataflow::{AnalysisDomain, CallReturnPlaces, GenKill, GenKillAnalysis};
+
+/// Determines liveness of each local purely based on `StorageLive`/`Dead`.
+#[derive(Copy, Clone)]
+pub(super) struct MaybeStorageLive;
+
+impl<'tcx> AnalysisDomain<'tcx> for MaybeStorageLive {
+    type Domain = BitSet<mir::Local>;
+    const NAME: &'static str = "maybe_storage_live";
+
+    fn bottom_value(&self, body: &mir::Body<'tcx>) -> Self::Domain {
+        // bottom = dead
+        BitSet::new_empty(body.local_decls.len())
+    }
+
+    fn initialize_start_block(&self, body: &mir::Body<'tcx>, state: &mut Self::Domain) {
+        for arg in body.args_iter() {
+            state.insert(arg);
+        }
+    }
+}
+
+impl<'tcx> GenKillAnalysis<'tcx> for MaybeStorageLive {
+    type Idx = mir::Local;
+
+    fn statement_effect(&self, trans: &mut impl GenKill<Self::Idx>, stmt: &mir::Statement<'tcx>, _: mir::Location) {
+        match stmt.kind {
+            mir::StatementKind::StorageLive(l) => trans.gen(l),
+            mir::StatementKind::StorageDead(l) => trans.kill(l),
+            _ => (),
+        }
+    }
+
+    fn terminator_effect(
+        &self,
+        _trans: &mut impl GenKill<Self::Idx>,
+        _terminator: &mir::Terminator<'tcx>,
+        _loc: mir::Location,
+    ) {
+    }
+
+    fn call_return_effect(
+        &self,
+        _trans: &mut impl GenKill<Self::Idx>,
+        _block: mir::BasicBlock,
+        _return_places: CallReturnPlaces<'_, 'tcx>,
+    ) {
+        // Nothing to do when a call returns successfully
+    }
+}