From af2ce8b7022c92de0702bea09f2fb50b80343d2d Mon Sep 17 00:00:00 2001 From: Waffle Lapkin Date: Fri, 24 Jan 2025 06:11:23 +0100 Subject: [PATCH 1/3] don't drop types with no drop glue when tailcalling this is required as otherwise drops of `&mut` refs count as a usage of a 'two-phase temporary' causing an ICE. --- compiler/rustc_mir_build/src/builder/scope.rs | 9 +++++++++ .../tail_call_drops.f.ElaborateDrops.panic-abort.diff | 1 - .../tail_call_drops.f.ElaborateDrops.panic-unwind.diff | 1 - .../tail_call_drops.f.built.after.panic-abort.mir | 1 - .../tail_call_drops.f.built.after.panic-unwind.mir | 1 - ...call_drops.f_with_arg.ElaborateDrops.panic-abort.diff | 1 - ...all_drops.f_with_arg.ElaborateDrops.panic-unwind.diff | 1 - ...ail_call_drops.f_with_arg.built.after.panic-abort.mir | 1 - ...il_call_drops.f_with_arg.built.after.panic-unwind.mir | 1 - tests/ui/explicit-tail-calls/ctfe-arg-bad-borrow.stderr | 7 +++---- 10 files changed, 12 insertions(+), 12 deletions(-) diff --git a/compiler/rustc_mir_build/src/builder/scope.rs b/compiler/rustc_mir_build/src/builder/scope.rs index 20441530a4790..945f02821d999 100644 --- a/compiler/rustc_mir_build/src/builder/scope.rs +++ b/compiler/rustc_mir_build/src/builder/scope.rs @@ -785,6 +785,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { let local = place.as_local().unwrap_or_else(|| bug!("projection in tail call args")); + if !self.local_decls[local].ty.needs_drop(self.tcx, self.typing_env()) { + return None; + } + Some(DropData { source_info, local, kind: DropKind::Value }) } Operand::Constant(_) => None, @@ -795,6 +799,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { self.scopes.scopes.iter().rev().nth(1).unwrap().region_scope, DUMMY_SP, ); + let typing_env = self.typing_env(); let unwind_drops = &mut self.scopes.unwind_drops; // the innermost scope contains only the destructors for the tail call arguments @@ -805,6 +810,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> { let source_info = drop_data.source_info; let local = drop_data.local; + if !self.local_decls[local].ty.needs_drop(self.tcx, typing_env) { + continue; + } + match drop_data.kind { DropKind::Value => { // `unwind_to` should drop the value that we're about to diff --git a/tests/mir-opt/tail_call_drops.f.ElaborateDrops.panic-abort.diff b/tests/mir-opt/tail_call_drops.f.ElaborateDrops.panic-abort.diff index 17c64d4baf0ef..9a4f27a497d18 100644 --- a/tests/mir-opt/tail_call_drops.f.ElaborateDrops.panic-abort.diff +++ b/tests/mir-opt/tail_call_drops.f.ElaborateDrops.panic-abort.diff @@ -66,7 +66,6 @@ bb6: { + _8 = const false; StorageDead(_4); - StorageDead(_3); drop(_2) -> [return: bb7, unwind: bb12]; } diff --git a/tests/mir-opt/tail_call_drops.f.ElaborateDrops.panic-unwind.diff b/tests/mir-opt/tail_call_drops.f.ElaborateDrops.panic-unwind.diff index 58d8a87986d6b..f13ee78aa368c 100644 --- a/tests/mir-opt/tail_call_drops.f.ElaborateDrops.panic-unwind.diff +++ b/tests/mir-opt/tail_call_drops.f.ElaborateDrops.panic-unwind.diff @@ -66,7 +66,6 @@ bb6: { + _8 = const false; StorageDead(_4); - StorageDead(_3); - drop(_2) -> [return: bb7, unwind continue]; + drop(_2) -> [return: bb7, unwind: bb12]; } diff --git a/tests/mir-opt/tail_call_drops.f.built.after.panic-abort.mir b/tests/mir-opt/tail_call_drops.f.built.after.panic-abort.mir index 2c3d62491d715..e017424a4ccdd 100644 --- a/tests/mir-opt/tail_call_drops.f.built.after.panic-abort.mir +++ b/tests/mir-opt/tail_call_drops.f.built.after.panic-abort.mir @@ -63,7 +63,6 @@ fn f() -> () { bb6: { StorageDead(_4); - StorageDead(_3); drop(_2) -> [return: bb7, unwind: bb17]; } diff --git a/tests/mir-opt/tail_call_drops.f.built.after.panic-unwind.mir b/tests/mir-opt/tail_call_drops.f.built.after.panic-unwind.mir index 2c3d62491d715..e017424a4ccdd 100644 --- a/tests/mir-opt/tail_call_drops.f.built.after.panic-unwind.mir +++ b/tests/mir-opt/tail_call_drops.f.built.after.panic-unwind.mir @@ -63,7 +63,6 @@ fn f() -> () { bb6: { StorageDead(_4); - StorageDead(_3); drop(_2) -> [return: bb7, unwind: bb17]; } diff --git a/tests/mir-opt/tail_call_drops.f_with_arg.ElaborateDrops.panic-abort.diff b/tests/mir-opt/tail_call_drops.f_with_arg.ElaborateDrops.panic-abort.diff index 1a51601bc56f5..a8c57d2cfe009 100644 --- a/tests/mir-opt/tail_call_drops.f_with_arg.ElaborateDrops.panic-abort.diff +++ b/tests/mir-opt/tail_call_drops.f_with_arg.ElaborateDrops.panic-abort.diff @@ -80,7 +80,6 @@ bb8: { + _12 = const false; StorageDead(_6); - StorageDead(_5); drop(_4) -> [return: bb9, unwind: bb16]; } diff --git a/tests/mir-opt/tail_call_drops.f_with_arg.ElaborateDrops.panic-unwind.diff b/tests/mir-opt/tail_call_drops.f_with_arg.ElaborateDrops.panic-unwind.diff index 1a51601bc56f5..a8c57d2cfe009 100644 --- a/tests/mir-opt/tail_call_drops.f_with_arg.ElaborateDrops.panic-unwind.diff +++ b/tests/mir-opt/tail_call_drops.f_with_arg.ElaborateDrops.panic-unwind.diff @@ -80,7 +80,6 @@ bb8: { + _12 = const false; StorageDead(_6); - StorageDead(_5); drop(_4) -> [return: bb9, unwind: bb16]; } diff --git a/tests/mir-opt/tail_call_drops.f_with_arg.built.after.panic-abort.mir b/tests/mir-opt/tail_call_drops.f_with_arg.built.after.panic-abort.mir index 744f1989acc92..f89b98a320536 100644 --- a/tests/mir-opt/tail_call_drops.f_with_arg.built.after.panic-abort.mir +++ b/tests/mir-opt/tail_call_drops.f_with_arg.built.after.panic-abort.mir @@ -77,7 +77,6 @@ fn f_with_arg(_1: String, _2: String) -> () { bb8: { StorageDead(_6); - StorageDead(_5); drop(_4) -> [return: bb9, unwind: bb23]; } diff --git a/tests/mir-opt/tail_call_drops.f_with_arg.built.after.panic-unwind.mir b/tests/mir-opt/tail_call_drops.f_with_arg.built.after.panic-unwind.mir index 744f1989acc92..f89b98a320536 100644 --- a/tests/mir-opt/tail_call_drops.f_with_arg.built.after.panic-unwind.mir +++ b/tests/mir-opt/tail_call_drops.f_with_arg.built.after.panic-unwind.mir @@ -77,7 +77,6 @@ fn f_with_arg(_1: String, _2: String) -> () { bb8: { StorageDead(_6); - StorageDead(_5); drop(_4) -> [return: bb9, unwind: bb23]; } diff --git a/tests/ui/explicit-tail-calls/ctfe-arg-bad-borrow.stderr b/tests/ui/explicit-tail-calls/ctfe-arg-bad-borrow.stderr index 75fb13c378c24..ece581dc62638 100644 --- a/tests/ui/explicit-tail-calls/ctfe-arg-bad-borrow.stderr +++ b/tests/ui/explicit-tail-calls/ctfe-arg-bad-borrow.stderr @@ -4,10 +4,9 @@ error[E0597]: `local` does not live long enough LL | let local = Type; | ----- binding `local` declared here LL | become takes_borrow(&local); - | ^^^^^^ borrowed value does not live long enough -LL | -LL | } - | - `local` dropped here while still borrowed + | ^^^^^^- `local` dropped here while still borrowed + | | + | borrowed value does not live long enough error: aborting due to 1 previous error From 83339bf37291758a243a894db9418e989f0e0818 Mon Sep 17 00:00:00 2001 From: Waffle Lapkin Date: Fri, 24 Jan 2025 06:18:28 +0100 Subject: [PATCH 2/3] add a regression test --- tests/crashes/128097.rs | 6 ------ tests/ui/explicit-tail-calls/two-phase.rs | 14 ++++++++++++++ 2 files changed, 14 insertions(+), 6 deletions(-) delete mode 100644 tests/crashes/128097.rs create mode 100644 tests/ui/explicit-tail-calls/two-phase.rs diff --git a/tests/crashes/128097.rs b/tests/crashes/128097.rs deleted file mode 100644 index 6ffca640cbd6b..0000000000000 --- a/tests/crashes/128097.rs +++ /dev/null @@ -1,6 +0,0 @@ -//@ known-bug: #128097 -#![feature(explicit_tail_calls)] -fn f(x: &mut ()) { - let _y: String; - become f(x); -} diff --git a/tests/ui/explicit-tail-calls/two-phase.rs b/tests/ui/explicit-tail-calls/two-phase.rs new file mode 100644 index 0000000000000..91365b5e739c6 --- /dev/null +++ b/tests/ui/explicit-tail-calls/two-phase.rs @@ -0,0 +1,14 @@ +// regression test for . +// this test used to ICE because we tried to run drop glue of `x` +// if dropping `_y` (happening at the `become` site) panicked and caused an unwind. +// +//@ check-pass +#![expect(incomplete_features)] +#![feature(explicit_tail_calls)] + +fn f(x: &mut ()) { + let _y = String::new(); + become f(x); +} + +fn main() {} From 9b82f2026133642f884ff9f019edcf9eb270894b Mon Sep 17 00:00:00 2001 From: Waffle Lapkin Date: Fri, 24 Jan 2025 19:33:15 +0100 Subject: [PATCH 3/3] bless miri test I'm not sure why the span improved but that's nice! --- .../miri/tests/fail/tail_calls/dangling-local-var.stderr | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/tools/miri/tests/fail/tail_calls/dangling-local-var.stderr b/src/tools/miri/tests/fail/tail_calls/dangling-local-var.stderr index 6acd69ab3f8cf..33e1e53ea0605 100644 --- a/src/tools/miri/tests/fail/tail_calls/dangling-local-var.stderr +++ b/src/tools/miri/tests/fail/tail_calls/dangling-local-var.stderr @@ -14,8 +14,8 @@ LL | let local = 0; help: ALLOC was deallocated here: --> tests/fail/tail_calls/dangling-local-var.rs:LL:CC | -LL | } - | ^ +LL | become g(ptr) + | ^^^^^^^^^^^^^ = note: BACKTRACE (of the first span): = note: inside `g` at tests/fail/tail_calls/dangling-local-var.rs:LL:CC note: inside `main`