bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Auto merge of #117134 - lcnr:dropck_outlives-coroutine, r=compiler-errors

Browse source 
dropck_outlives check whether generator witness needs_drop

see https://rust-lang.zulipchat.com/#narrow/stream/326866-t-types.2Fnominated/topic/.23116242.3A.20Code.20no.20longer.20compiles.20after.20-Zdrop-tracking-mir.20.E2.80.A6/near/398311627 for an explanation.

Fixes #116242 (or well, the repro by `@jamuraa` in https://github.com/rust-lang/rust/issues/116242#issuecomment-1739802047). I did not add a regression test as it depends on other crates. We do have 1 test going from fail to pass, showing the intended behavior.

r? types
This commit is contained in:
bors 2023-11-02 22:03:38 +00:00
commit a2f5f9691b
11 changed files with 110 additions and 59 deletions
Download patch file Download diff file Expand all files Collapse all files

35
compiler/rustc_trait_selection/src/traits/query/dropck_outlives.rs
View file

@ -133,7 +133,7 @@ pub fn compute_dropck_outlives_inner<'tcx>(
result.overflows.len(),
ty_stack.len()
);
dtorck_constraint_for_ty_inner(tcx, DUMMY_SP, for_ty, depth, ty, &mut constraints)?;
dtorck_constraint_for_ty_inner(tcx, param_env, DUMMY_SP, depth, ty, &mut constraints)?;
// "outlives" represent types/regions that may be touched
// by a destructor.
@ -185,16 +185,15 @@ pub fn compute_dropck_outlives_inner<'tcx>(
/// Returns a set of constraints that needs to be satisfied in
/// order for `ty` to be valid for destruction.
#[instrument(level = "debug", skip(tcx, param_env, span, constraints))]
pub fn dtorck_constraint_for_ty_inner<'tcx>(
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
span: Span,
for_ty: Ty<'tcx>,
depth: usize,
ty: Ty<'tcx>,
constraints: &mut DropckConstraint<'tcx>,
) -> Result<(), NoSolution> {
debug!("dtorck_constraint_for_ty_inner({:?}, {:?}, {:?}, {:?})", span, for_ty, depth, ty);
if !tcx.recursion_limit().value_within_limit(depth) {
constraints.overflows.push(ty);
return Ok(());
@ -224,13 +223,13 @@ pub fn dtorck_constraint_for_ty_inner<'tcx>(
ty::Array(ety, _) | ty::Slice(ety) => {
// single-element containers, behave like their element
rustc_data_structures::stack::ensure_sufficient_stack(|| {
dtorck_constraint_for_ty_inner(tcx, span, for_ty, depth + 1, *ety, constraints)
dtorck_constraint_for_ty_inner(tcx, param_env, span, depth + 1, *ety, constraints)
})?;
}
ty::Tuple(tys) => rustc_data_structures::stack::ensure_sufficient_stack(|| {
for ty in tys.iter() {
dtorck_constraint_for_ty_inner(tcx, span, for_ty, depth + 1, ty, constraints)?;
dtorck_constraint_for_ty_inner(tcx, param_env, span, depth + 1, ty, constraints)?;
}
Ok::<_, NoSolution>(())
})?,
@ -249,7 +248,14 @@ pub fn dtorck_constraint_for_ty_inner<'tcx>(
rustc_data_structures::stack::ensure_sufficient_stack(|| {
for ty in args.as_closure().upvar_tys() {
dtorck_constraint_for_ty_inner(tcx, span, for_ty, depth + 1, ty, constraints)?;
dtorck_constraint_for_ty_inner(
tcx,
param_env,
span,
depth + 1,
ty,
constraints,
)?;
}
Ok::<_, NoSolution>(())
})?
@ -278,8 +284,8 @@ pub fn dtorck_constraint_for_ty_inner<'tcx>(
// only take place through references with lifetimes
// derived from lifetimes attached to the upvars and resume
// argument, and we *do* incorporate those here.
if !args.as_coroutine().is_valid() {
let args = args.as_coroutine();
if !args.is_valid() {
// By the time this code runs, all type variables ought to
// be fully resolved.
tcx.sess.delay_span_bug(
@ -289,10 +295,13 @@ pub fn dtorck_constraint_for_ty_inner<'tcx>(
return Err(NoSolution);
}
constraints
.outlives
.extend(args.as_coroutine().upvar_tys().iter().map(ty::GenericArg::from));
constraints.outlives.push(args.as_coroutine().resume_ty().into());
// While we conservatively assume that all coroutines require drop
// to avoid query cycles during MIR building, we can check the actual
// witness during borrowck to avoid unnecessary liveness constraints.
if args.witness().needs_drop(tcx, tcx.erase_regions(param_env)) {
constraints.outlives.extend(args.upvar_tys().iter().map(ty::GenericArg::from));
constraints.outlives.push(args.resume_ty().into());
}
}
ty::Adt(def, args) => {