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Fix variable deallocation order in panic unwinding paths #149435

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Fix variable deallocation order in panic unwinding paths #149435

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61f0416
Fix StorageDead and ForLint drops in tail calls and unwind paths
sladyn98 Jan 30, 2026
10dc4ca
Fix StorageDead on unwind paths and add MIR transform to remove them
sladyn98 Jan 31, 2026
7434abf
Fix assertion failure: only adjust unwind_to when drop matches
sladyn98 Feb 1, 2026
d8b66ab
Update mir-opt test expectations
sladyn98 Feb 1, 2026
cdeb9af
Fix rust-analyzer lifetime issues blocking CI
sladyn98 Feb 1, 2026
0be6738
Fix assertion failure in break_for_tail_call for StorageDead and ForLint
sladyn98 Feb 1, 2026
6896e85
Simplify StorageDead logic: always add when needed, clean up later
sladyn98 Feb 9, 2026
a69fa17
Fix clippy::needless_bool in scope.rs and update test expectations
sladyn98 Feb 9, 2026
3fd5fc6
Update mir-opt test expectations for StorageDead on unwind
sladyn98 Mar 1, 2026
8d797b7
Address StorageDead review feedback
May 17, 2026
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263 changes: 187 additions & 76 deletions compiler/rustc_mir_build/src/builder/scope.rs
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15 changes: 15 additions & 0 deletions compiler/rustc_mir_transform/src/cleanup_post_borrowck.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,10 @@
//! - [`FakeRead`]
//! - [`Assign`] statements with a [`Fake`] borrow
//! - [`Coverage`] statements of kind [`BlockMarker`] or [`SpanMarker`]
//! - [`StorageDead`] statements in cleanup blocks (unwind paths) - these are only needed
//! for borrow-checking and are removed from cleanup blocks after borrowck completes.
//! StorageDead on normal paths may be needed by later passes (e.g., coroutine transforms)
//! and will be conditionally removed by RemoveStorageMarkers during optimization if enabled.
//!
//! [`AscribeUserType`]: rustc_middle::mir::StatementKind::AscribeUserType
//! [`Assign`]: rustc_middle::mir::StatementKind::Assign
Expand All @@ -15,6 +19,7 @@
//! [`Coverage`]: rustc_middle::mir::StatementKind::Coverage
//! [`BlockMarker`]: rustc_middle::mir::coverage::CoverageKind::BlockMarker
//! [`SpanMarker`]: rustc_middle::mir::coverage::CoverageKind::SpanMarker
//! [`StorageDead`]: rustc_middle::mir::StatementKind::StorageDead

use rustc_middle::mir::coverage::CoverageKind;
use rustc_middle::mir::*;
Expand All @@ -28,6 +33,11 @@ impl<'tcx> crate::MirPass<'tcx> for CleanupPostBorrowck {
// Manually invalidate CFG caches if we actually change a terminator's edges.
let mut invalidate_cfg = false;
for basic_block in body.basic_blocks.as_mut_preserves_cfg().iter_mut() {
// Only remove StorageDead from cleanup blocks (unwind paths).
// StorageDead on normal paths may be needed by later passes (e.g., coroutine
// transforms) and may be used by codegen backends. RemoveStorageMarkers will
// conditionally remove them during optimization if enabled (when mir_opt_level > 0
// and lifetime markers are not being emitted).
for statement in basic_block.statements.iter_mut() {
match statement.kind {
StatementKind::AscribeUserType(..)
Expand All @@ -41,6 +51,11 @@ impl<'tcx> crate::MirPass<'tcx> for CleanupPostBorrowck {
| StatementKind::BackwardIncompatibleDropHint { .. } => {
statement.make_nop(true)
}
StatementKind::StorageDead(..)
if basic_block.is_cleanup && body.coroutine.is_none() =>
{
statement.make_nop(true)
}
StatementKind::Assign(box (
_,
Rvalue::Cast(
Expand Down
5 changes: 3 additions & 2 deletions src/tools/rust-analyzer/crates/hir-def/src/import_map.rs
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@ShoyuVanilla ShoyuVanilla Feb 2, 2026

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From your commit message:

This fixes compilation errors that are blocking CI, though these are
pre-existing issues unrelated to the StorageDead changes.

I guess this breakage comes from this PR rather than pre-existing, as this isn't failing in other PRs?

Original file line number Diff line number Diff line change
Expand Up @@ -426,11 +426,10 @@ pub fn search_dependencies(
let import_maps: Vec<_> =
krate.data(db).dependencies.iter().map(|dep| db.import_map(dep.crate_id)).collect();

let mut op = fst::map::OpBuilder::new();

match query.search_mode {
SearchMode::Exact => {
let automaton = fst::automaton::Str::new(&query.lowercased);
let mut op = fst::map::OpBuilder::new();

for map in &import_maps {
op = op.add(map.fst.search(&automaton));
Expand All @@ -439,6 +438,7 @@ pub fn search_dependencies(
}
SearchMode::Fuzzy => {
let automaton = fst::automaton::Subsequence::new(&query.lowercased);
let mut op = fst::map::OpBuilder::new();

for map in &import_maps {
op = op.add(map.fst.search(&automaton));
Expand All @@ -447,6 +447,7 @@ pub fn search_dependencies(
}
SearchMode::Prefix => {
let automaton = fst::automaton::Str::new(&query.lowercased).starts_with();
let mut op = fst::map::OpBuilder::new();

for map in &import_maps {
op = op.add(map.fst.search(&automaton));
Expand Down
5 changes: 3 additions & 2 deletions src/tools/rust-analyzer/crates/ide-db/src/symbol_index.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -569,11 +569,10 @@ impl Query {
cb: impl FnMut(&'db FileSymbol<'db>) -> ControlFlow<T>,
) -> Option<T> {
let _p = tracing::info_span!("symbol_index::Query::search").entered();

let mut op = fst::map::OpBuilder::new();
match self.mode {
SearchMode::Exact => {
let automaton = fst::automaton::Str::new(&self.lowercased);
let mut op = fst::map::OpBuilder::new();

for index in indices.iter() {
op = op.add(index.map.search(&automaton));
Expand All @@ -582,6 +581,7 @@ impl Query {
}
SearchMode::Fuzzy => {
let automaton = fst::automaton::Subsequence::new(&self.lowercased);
let mut op = fst::map::OpBuilder::new();

for index in indices.iter() {
op = op.add(index.map.search(&automaton));
Expand All @@ -590,6 +590,7 @@ impl Query {
}
SearchMode::Prefix => {
let automaton = fst::automaton::Str::new(&self.lowercased).starts_with();
let mut op = fst::map::OpBuilder::new();

for index in indices.iter() {
op = op.add(index.map.search(&automaton));
Expand Down
5 changes: 5 additions & 0 deletions tests/mir-opt/basic_assignment.main.SimplifyCfg-initial.after.mir
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Original file line number Diff line number Diff line change
Expand Up @@ -73,14 +73,19 @@ fn main() -> () {
}

bb6 (cleanup): {
StorageDead(_6);
drop(_5) -> [return: bb7, unwind terminate(cleanup)];
}

bb7 (cleanup): {
StorageDead(_5);
drop(_4) -> [return: bb8, unwind terminate(cleanup)];
}

bb8 (cleanup): {
StorageDead(_4);
StorageDead(_2);
StorageDead(_1);
resume;
}
}
33 changes: 26 additions & 7 deletions tests/mir-opt/building/logical_or_in_conditional.test_complex.built.after.mir
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ fn test_complex() -> () {
bb0: {
StorageLive(_1);
StorageLive(_2);
_2 = E::f() -> [return: bb1, unwind: bb35];
_2 = E::f() -> [return: bb1, unwind: bb38];
}

bb1: {
Expand All @@ -42,7 +42,7 @@ fn test_complex() -> () {

bb5: {
StorageLive(_4);
_4 = always_true() -> [return: bb6, unwind: bb35];
_4 = always_true() -> [return: bb6, unwind: bb38];
}

bb6: {
Expand All @@ -64,7 +64,7 @@ fn test_complex() -> () {
}

bb9: {
drop(_7) -> [return: bb11, unwind: bb35];
drop(_7) -> [return: bb11, unwind: bb37];
}

bb10: {
Expand All @@ -78,7 +78,7 @@ fn test_complex() -> () {
}

bb12: {
drop(_7) -> [return: bb13, unwind: bb35];
drop(_7) -> [return: bb13, unwind: bb37];
}

bb13: {
Expand All @@ -98,7 +98,7 @@ fn test_complex() -> () {
}

bb15: {
drop(_10) -> [return: bb17, unwind: bb35];
drop(_10) -> [return: bb17, unwind: bb36];
}

bb16: {
Expand Down Expand Up @@ -139,7 +139,7 @@ fn test_complex() -> () {
StorageDead(_4);
StorageDead(_1);
StorageLive(_11);
_11 = always_true() -> [return: bb23, unwind: bb35];
_11 = always_true() -> [return: bb23, unwind: bb38];
}

bb23: {
Expand All @@ -156,7 +156,7 @@ fn test_complex() -> () {

bb26: {
StorageLive(_12);
_12 = E::f() -> [return: bb27, unwind: bb35];
_12 = E::f() -> [return: bb27, unwind: bb38];
}

bb27: {
Expand Down Expand Up @@ -199,6 +199,25 @@ fn test_complex() -> () {
}

bb35 (cleanup): {
StorageDead(_10);
StorageDead(_9);
StorageDead(_2);
goto -> bb38;
}

bb36 (cleanup): {
StorageDead(_10);
StorageDead(_9);
goto -> bb38;
}

bb37 (cleanup): {
StorageDead(_7);
StorageDead(_6);
goto -> bb38;
}

bb38 (cleanup): {
resume;
}
}
17 changes: 15 additions & 2 deletions tests/mir-opt/building/logical_or_in_conditional.test_or.built.after.mir
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ fn test_or() -> () {
}

bb1: {
drop(_3) -> [return: bb3, unwind: bb13];
drop(_3) -> [return: bb3, unwind: bb14];
}

bb2: {
Expand All @@ -34,7 +34,7 @@ fn test_or() -> () {
}

bb4: {
drop(_3) -> [return: bb5, unwind: bb13];
drop(_3) -> [return: bb5, unwind: bb14];
}

bb5: {
Expand Down Expand Up @@ -86,6 +86,19 @@ fn test_or() -> () {
}

bb13 (cleanup): {
StorageDead(_6);
StorageDead(_5);
goto -> bb15;
}

bb14 (cleanup): {
StorageDead(_3);
StorageDead(_2);
goto -> bb15;
}

bb15 (cleanup): {
StorageDead(_1);
resume;
}
}
62 changes: 45 additions & 17 deletions tests/mir-opt/building/match/array_len.const_array_len.built.after.panic-unwind.mir
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ fn const_array_len(_1: [T; 5]) -> () {
StorageLive(_6);
StorageLive(_7);
_7 = move _2;
_6 = opaque::<T>(move _7) -> [return: bb3, unwind: bb17];
_6 = opaque::<T>(move _7) -> [return: bb3, unwind: bb20];
}

bb3: {
Expand All @@ -52,7 +52,7 @@ fn const_array_len(_1: [T; 5]) -> () {
StorageLive(_8);
StorageLive(_9);
_9 = move _3;
_8 = opaque::<T>(move _9) -> [return: bb4, unwind: bb16];
_8 = opaque::<T>(move _9) -> [return: bb4, unwind: bb18];
}

bb4: {
Expand All @@ -61,7 +61,7 @@ fn const_array_len(_1: [T; 5]) -> () {
StorageLive(_10);
StorageLive(_11);
_11 = move _4;
_10 = opaque::<[T; 2]>(move _11) -> [return: bb5, unwind: bb15];
_10 = opaque::<[T; 2]>(move _11) -> [return: bb5, unwind: bb16];
}

bb5: {
Expand All @@ -77,7 +77,7 @@ fn const_array_len(_1: [T; 5]) -> () {
StorageDead(_13);
StorageDead(_12);
_0 = const ();
drop(_5) -> [return: bb8, unwind: bb19];
drop(_5) -> [return: bb8, unwind: bb23];
}

bb7: {
Expand All @@ -87,17 +87,17 @@ fn const_array_len(_1: [T; 5]) -> () {

bb8: {
StorageDead(_5);
drop(_4) -> [return: bb9, unwind: bb20];
drop(_4) -> [return: bb9, unwind: bb24];
}

bb9: {
StorageDead(_4);
drop(_3) -> [return: bb10, unwind: bb21];
drop(_3) -> [return: bb10, unwind: bb25];
}

bb10: {
StorageDead(_3);
drop(_2) -> [return: bb11, unwind: bb22];
drop(_2) -> [return: bb11, unwind: bb26];
}

bb11: {
Expand All @@ -106,50 +106,78 @@ fn const_array_len(_1: [T; 5]) -> () {
}

bb12: {
drop(_1) -> [return: bb13, unwind: bb23];
drop(_1) -> [return: bb13, unwind: bb27];
}

bb13: {
return;
}

bb14 (cleanup): {
drop(_13) -> [return: bb18, unwind terminate(cleanup)];
drop(_13) -> [return: bb15, unwind terminate(cleanup)];
}

bb15 (cleanup): {
drop(_11) -> [return: bb18, unwind terminate(cleanup)];
StorageDead(_13);
StorageDead(_12);
goto -> bb22;
}

bb16 (cleanup): {
drop(_9) -> [return: bb18, unwind terminate(cleanup)];
drop(_11) -> [return: bb17, unwind terminate(cleanup)];
}

bb17 (cleanup): {
drop(_7) -> [return: bb18, unwind terminate(cleanup)];
StorageDead(_11);
StorageDead(_10);
goto -> bb22;
}

bb18 (cleanup): {
drop(_5) -> [return: bb19, unwind terminate(cleanup)];
drop(_9) -> [return: bb19, unwind terminate(cleanup)];
}

bb19 (cleanup): {
drop(_4) -> [return: bb20, unwind terminate(cleanup)];
StorageDead(_9);
StorageDead(_8);
goto -> bb22;
}

bb20 (cleanup): {
drop(_3) -> [return: bb21, unwind terminate(cleanup)];
drop(_7) -> [return: bb21, unwind terminate(cleanup)];
}

bb21 (cleanup): {
drop(_2) -> [return: bb22, unwind terminate(cleanup)];
StorageDead(_7);
StorageDead(_6);
goto -> bb22;
}

bb22 (cleanup): {
drop(_1) -> [return: bb23, unwind terminate(cleanup)];
drop(_5) -> [return: bb23, unwind terminate(cleanup)];
}

bb23 (cleanup): {
StorageDead(_5);
drop(_4) -> [return: bb24, unwind terminate(cleanup)];
}

bb24 (cleanup): {
StorageDead(_4);
drop(_3) -> [return: bb25, unwind terminate(cleanup)];
}

bb25 (cleanup): {
StorageDead(_3);
drop(_2) -> [return: bb26, unwind terminate(cleanup)];
}

bb26 (cleanup): {
StorageDead(_2);
drop(_1) -> [return: bb27, unwind terminate(cleanup)];
}

bb27 (cleanup): {
resume;
}
}
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