From c5205e9d56d3c632e83e1e5f0853d3bd82f16c0e Mon Sep 17 00:00:00 2001 From: Michael Goulet Date: Sun, 11 Aug 2024 12:28:15 -0400 Subject: [PATCH 1/3] Normalize struct tail properly in borrowck and hir typeck --- .../src/type_check/canonical.rs | 47 +++++++++++++++++++ compiler/rustc_borrowck/src/type_check/mod.rs | 13 +---- compiler/rustc_hir_typeck/src/cast.rs | 2 + ...different-regions-id-trait.current.stderr} | 2 +- ...obj-different-regions-id-trait.next.stderr | 15 ++++++ ...to-trait-obj-different-regions-id-trait.rs | 3 ++ 6 files changed, 70 insertions(+), 12 deletions(-) rename tests/ui/cast/{ptr-to-trait-obj-different-regions-id-trait.stderr => ptr-to-trait-obj-different-regions-id-trait.current.stderr} (91%) create mode 100644 tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.next.stderr diff --git a/compiler/rustc_borrowck/src/type_check/canonical.rs b/compiler/rustc_borrowck/src/type_check/canonical.rs index 86cd8b918fc..2558cf6347d 100644 --- a/compiler/rustc_borrowck/src/type_check/canonical.rs +++ b/compiler/rustc_borrowck/src/type_check/canonical.rs @@ -7,6 +7,7 @@ use rustc_middle::mir::ConstraintCategory; use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, Upcast}; use rustc_span::def_id::DefId; use rustc_span::Span; +use rustc_trait_selection::traits::query::type_op::custom::CustomTypeOp; use rustc_trait_selection::traits::query::type_op::{self, TypeOpOutput}; use rustc_trait_selection::traits::ObligationCause; @@ -165,6 +166,52 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { result.unwrap_or(value) } + #[instrument(skip(self), level = "debug")] + pub(super) fn struct_tail( + &mut self, + ty: Ty<'tcx>, + location: impl NormalizeLocation, + ) -> Ty<'tcx> { + let tcx = self.tcx(); + if self.infcx.next_trait_solver() { + let body = self.body; + let param_env = self.param_env; + self.fully_perform_op( + location.to_locations(), + ConstraintCategory::Boring, + CustomTypeOp::new( + |ocx| { + let structurally_normalize = |ty| { + ocx.structurally_normalize( + &ObligationCause::misc( + location.to_locations().span(body), + body.source.def_id().expect_local(), + ), + param_env, + ty, + ) + .unwrap_or_else(|_| bug!("struct tail should have been computable, since we computed it in HIR")) + }; + + let tail = tcx.struct_tail_with_normalize( + ty, + structurally_normalize, + || {}, + ); + + Ok(tail) + }, + "normalizing struct tail", + ), + ) + .unwrap_or_else(|guar| Ty::new_error(tcx, guar)) + } else { + let mut normalize = |ty| self.normalize(ty, location); + let tail = tcx.struct_tail_with_normalize(ty, &mut normalize, || {}); + normalize(tail) + } + } + #[instrument(skip(self), level = "debug")] pub(super) fn ascribe_user_type( &mut self, diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs index b13773ffe14..6bab0f33c19 100644 --- a/compiler/rustc_borrowck/src/type_check/mod.rs +++ b/compiler/rustc_borrowck/src/type_check/mod.rs @@ -2329,17 +2329,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { let cast_ty_to = CastTy::from_ty(*ty); match (cast_ty_from, cast_ty_to) { (Some(CastTy::Ptr(src)), Some(CastTy::Ptr(dst))) => { - let mut normalize = |t| self.normalize(t, location); - - // N.B. `struct_tail_with_normalize` only "structurally resolves" - // the type. It is not fully normalized, so we have to normalize it - // afterwards. - let src_tail = - tcx.struct_tail_with_normalize(src.ty, &mut normalize, || ()); - let src_tail = normalize(src_tail); - let dst_tail = - tcx.struct_tail_with_normalize(dst.ty, &mut normalize, || ()); - let dst_tail = normalize(dst_tail); + let src_tail = self.struct_tail(src.ty, location); + let dst_tail = self.struct_tail(dst.ty, location); // This checks (lifetime part of) vtable validity for pointer casts, // which is irrelevant when there are aren't principal traits on both sides (aka only auto traits). diff --git a/compiler/rustc_hir_typeck/src/cast.rs b/compiler/rustc_hir_typeck/src/cast.rs index de702733904..7cd97166ed1 100644 --- a/compiler/rustc_hir_typeck/src/cast.rs +++ b/compiler/rustc_hir_typeck/src/cast.rs @@ -97,6 +97,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { return Ok(Some(PointerKind::Thin)); } + let t = self.try_structurally_resolve_type(span, t); + Ok(match *t.kind() { ty::Slice(_) | ty::Str => Some(PointerKind::Length), ty::Dynamic(tty, _, ty::Dyn) => Some(PointerKind::VTable(tty)), diff --git a/tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.stderr b/tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.current.stderr similarity index 91% rename from tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.stderr rename to tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.current.stderr index d1d598e603f..5a5b4bfcacf 100644 --- a/tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.stderr +++ b/tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.current.stderr @@ -1,5 +1,5 @@ error: lifetime may not live long enough - --> $DIR/ptr-to-trait-obj-different-regions-id-trait.rs:21:17 + --> $DIR/ptr-to-trait-obj-different-regions-id-trait.rs:24:17 | LL | fn m<'a>() { | -- lifetime `'a` defined here diff --git a/tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.next.stderr b/tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.next.stderr new file mode 100644 index 00000000000..5a5b4bfcacf --- /dev/null +++ b/tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.next.stderr @@ -0,0 +1,15 @@ +error: lifetime may not live long enough + --> $DIR/ptr-to-trait-obj-different-regions-id-trait.rs:24:17 + | +LL | fn m<'a>() { + | -- lifetime `'a` defined here +LL | let unsend: *const dyn Cat<'a> = &(); +LL | let _send = unsend as *const S>; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type annotation requires that `'a` must outlive `'static` + | + = note: requirement occurs because of the type `S>`, which makes the generic argument `dyn Cat<'_>` invariant + = note: the struct `S` is invariant over the parameter `T` + = help: see for more information about variance + +error: aborting due to 1 previous error + diff --git a/tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.rs b/tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.rs index cdd55e24392..f968dca4fd3 100644 --- a/tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.rs +++ b/tests/ui/cast/ptr-to-trait-obj-different-regions-id-trait.rs @@ -1,3 +1,6 @@ +//@ revisions: current next +//@ ignore-compare-mode-next-solver (explicit revisions) +//@[next] compile-flags: -Znext-solver //@ check-fail // // Make sure we can't trick the compiler by using a projection. From b5d2079fb9c9ac9f0fe594f65452b4097e71c2de Mon Sep 17 00:00:00 2001 From: Michael Goulet Date: Sun, 11 Aug 2024 12:30:38 -0400 Subject: [PATCH 2/3] Rename normalization functions to raw --- .../rustc_borrowck/src/type_check/canonical.rs | 4 ++-- .../rustc_const_eval/src/const_eval/valtrees.rs | 2 +- compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs | 2 +- compiler/rustc_middle/src/ty/layout.rs | 2 +- compiler/rustc_middle/src/ty/sty.rs | 6 +++--- compiler/rustc_middle/src/ty/util.rs | 16 +++++++++------- .../rustc_trait_selection/src/traits/project.rs | 2 +- 7 files changed, 18 insertions(+), 16 deletions(-) diff --git a/compiler/rustc_borrowck/src/type_check/canonical.rs b/compiler/rustc_borrowck/src/type_check/canonical.rs index 2558cf6347d..b58691fbeae 100644 --- a/compiler/rustc_borrowck/src/type_check/canonical.rs +++ b/compiler/rustc_borrowck/src/type_check/canonical.rs @@ -193,7 +193,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { .unwrap_or_else(|_| bug!("struct tail should have been computable, since we computed it in HIR")) }; - let tail = tcx.struct_tail_with_normalize( + let tail = tcx.struct_tail_raw( ty, structurally_normalize, || {}, @@ -207,7 +207,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> { .unwrap_or_else(|guar| Ty::new_error(tcx, guar)) } else { let mut normalize = |ty| self.normalize(ty, location); - let tail = tcx.struct_tail_with_normalize(ty, &mut normalize, || {}); + let tail = tcx.struct_tail_raw(ty, &mut normalize, || {}); normalize(tail) } } diff --git a/compiler/rustc_const_eval/src/const_eval/valtrees.rs b/compiler/rustc_const_eval/src/const_eval/valtrees.rs index 8227c045948..460c9797f36 100644 --- a/compiler/rustc_const_eval/src/const_eval/valtrees.rs +++ b/compiler/rustc_const_eval/src/const_eval/valtrees.rs @@ -195,7 +195,7 @@ fn reconstruct_place_meta<'tcx>( let mut last_valtree = valtree; // Traverse the type, and update `last_valtree` as we go. - let tail = tcx.struct_tail_with_normalize( + let tail = tcx.struct_tail_raw( layout.ty, |ty| ty, || { diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs index 841d25b54cc..b169f75796b 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs @@ -404,7 +404,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { code: traits::ObligationCauseCode<'tcx>, ) { if !ty.references_error() { - let tail = self.tcx.struct_tail_with_normalize( + let tail = self.tcx.struct_tail_raw( ty, |ty| { if self.next_trait_solver() { diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs index 9204405d58f..684574825e3 100644 --- a/compiler/rustc_middle/src/ty/layout.rs +++ b/compiler/rustc_middle/src/ty/layout.rs @@ -362,7 +362,7 @@ impl<'tcx> SizeSkeleton<'tcx> { ty::Ref(_, pointee, _) | ty::RawPtr(pointee, _) => { let non_zero = !ty.is_unsafe_ptr(); - let tail = tcx.struct_tail_with_normalize( + let tail = tcx.struct_tail_raw( pointee, |ty| match tcx.try_normalize_erasing_regions(param_env, ty) { Ok(ty) => ty, diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs index 8c97de1c59b..8781a670acb 100644 --- a/compiler/rustc_middle/src/ty/sty.rs +++ b/compiler/rustc_middle/src/ty/sty.rs @@ -1590,7 +1590,7 @@ impl<'tcx> Ty<'tcx> { tcx: TyCtxt<'tcx>, normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>, ) -> Result, Ty<'tcx>> { - let tail = tcx.struct_tail_with_normalize(self, normalize, || {}); + let tail = tcx.struct_tail_raw(self, normalize, || {}); match tail.kind() { // Sized types ty::Infer(ty::IntVar(_) | ty::FloatVar(_)) @@ -1614,10 +1614,10 @@ impl<'tcx> Ty<'tcx> { | ty::Foreign(..) // `dyn*` has metadata = (). | ty::Dynamic(_, _, ty::DynStar) - // If returned by `struct_tail_with_normalize` this is a unit struct + // If returned by `struct_tail_raw` this is a unit struct // without any fields, or not a struct, and therefore is Sized. | ty::Adt(..) - // If returned by `struct_tail_with_normalize` this is the empty tuple, + // If returned by `struct_tail_raw` this is the empty tuple, // a.k.a. unit type, which is Sized | ty::Tuple(..) => Ok(tcx.types.unit), diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs index 365f434a264..fc5e0c44d96 100644 --- a/compiler/rustc_middle/src/ty/util.rs +++ b/compiler/rustc_middle/src/ty/util.rs @@ -176,7 +176,7 @@ impl<'tcx> TyCtxt<'tcx> { /// if input `ty` is not a structure at all. pub fn struct_tail_without_normalization(self, ty: Ty<'tcx>) -> Ty<'tcx> { let tcx = self; - tcx.struct_tail_with_normalize(ty, |ty| ty, || {}) + tcx.struct_tail_raw(ty, |ty| ty, || {}) } /// Returns the deeply last field of nested structures, or the same type if @@ -188,7 +188,7 @@ impl<'tcx> TyCtxt<'tcx> { /// normalization attempt may cause compiler bugs. pub fn struct_tail_for_codegen(self, ty: Ty<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Ty<'tcx> { let tcx = self; - tcx.struct_tail_with_normalize(ty, |ty| tcx.normalize_erasing_regions(param_env, ty), || {}) + tcx.struct_tail_raw(ty, |ty| tcx.normalize_erasing_regions(param_env, ty), || {}) } /// Returns the deeply last field of nested structures, or the same type if @@ -196,12 +196,14 @@ impl<'tcx> TyCtxt<'tcx> { /// and its type can be used to determine unsizing strategy. /// /// This is parameterized over the normalization strategy (i.e. how to - /// handle `::Assoc` and `impl Trait`); pass the identity - /// function to indicate no normalization should take place. + /// handle `::Assoc` and `impl Trait`). You almost certainly do + /// **NOT** want to pass the identity function here, unless you know what + /// you're doing, or you're within normalization code itself and will handle + /// an unnormalized tail recursively. /// /// See also `struct_tail_for_codegen`, which is suitable for use /// during codegen. - pub fn struct_tail_with_normalize( + pub fn struct_tail_raw( self, mut ty: Ty<'tcx>, mut normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>, @@ -281,7 +283,7 @@ impl<'tcx> TyCtxt<'tcx> { param_env: ty::ParamEnv<'tcx>, ) -> (Ty<'tcx>, Ty<'tcx>) { let tcx = self; - tcx.struct_lockstep_tails_with_normalize(source, target, |ty| { + tcx.struct_lockstep_tails_raw(source, target, |ty| { tcx.normalize_erasing_regions(param_env, ty) }) } @@ -294,7 +296,7 @@ impl<'tcx> TyCtxt<'tcx> { /// /// See also `struct_lockstep_tails_for_codegen`, which is suitable for use /// during codegen. - pub fn struct_lockstep_tails_with_normalize( + pub fn struct_lockstep_tails_raw( self, source: Ty<'tcx>, target: Ty<'tcx>, diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs index 4b62a5c59b2..0e4233ba7bc 100644 --- a/compiler/rustc_trait_selection/src/traits/project.rs +++ b/compiler/rustc_trait_selection/src/traits/project.rs @@ -1110,7 +1110,7 @@ fn assemble_candidates_from_impls<'cx, 'tcx>( | ty::Error(_) => false, } } else if tcx.is_lang_item(trait_ref.def_id, LangItem::PointeeTrait) { - let tail = selcx.tcx().struct_tail_with_normalize( + let tail = selcx.tcx().struct_tail_raw( self_ty, |ty| { // We throw away any obligations we get from this, since we normalize From f15997ffeca4c7da66e7de9e348ccb8d3cccc946 Mon Sep 17 00:00:00 2001 From: Michael Goulet Date: Sun, 11 Aug 2024 19:21:33 -0400 Subject: [PATCH 3/3] Remove struct_tail_no_normalization --- compiler/rustc_const_eval/src/const_eval/eval_queries.rs | 2 +- compiler/rustc_hir_typeck/src/expectation.rs | 3 ++- compiler/rustc_middle/src/ty/util.rs | 8 -------- compiler/rustc_trait_selection/src/traits/project.rs | 4 ++-- compiler/rustc_ty_utils/src/layout.rs | 6 +++++- 5 files changed, 10 insertions(+), 13 deletions(-) diff --git a/compiler/rustc_const_eval/src/const_eval/eval_queries.rs b/compiler/rustc_const_eval/src/const_eval/eval_queries.rs index ff27e400016..96b3ec6f187 100644 --- a/compiler/rustc_const_eval/src/const_eval/eval_queries.rs +++ b/compiler/rustc_const_eval/src/const_eval/eval_queries.rs @@ -226,7 +226,7 @@ pub(super) fn op_to_const<'tcx>( let pointee_ty = imm.layout.ty.builtin_deref(false).unwrap(); // `false` = no raw ptrs debug_assert!( matches!( - ecx.tcx.struct_tail_without_normalization(pointee_ty).kind(), + ecx.tcx.struct_tail_for_codegen(pointee_ty, ecx.param_env).kind(), ty::Str | ty::Slice(..), ), "`ConstValue::Slice` is for slice-tailed types only, but got {}", diff --git a/compiler/rustc_hir_typeck/src/expectation.rs b/compiler/rustc_hir_typeck/src/expectation.rs index 91deae4174b..76ae41db5c5 100644 --- a/compiler/rustc_hir_typeck/src/expectation.rs +++ b/compiler/rustc_hir_typeck/src/expectation.rs @@ -70,7 +70,8 @@ impl<'a, 'tcx> Expectation<'tcx> { /// See the test case `test/ui/coerce-expect-unsized.rs` and #20169 /// for examples of where this comes up,. pub(super) fn rvalue_hint(fcx: &FnCtxt<'a, 'tcx>, ty: Ty<'tcx>) -> Expectation<'tcx> { - match fcx.tcx.struct_tail_without_normalization(ty).kind() { + // FIXME: This is not right, even in the old solver... + match fcx.tcx.struct_tail_raw(ty, |ty| ty, || {}).kind() { ty::Slice(_) | ty::Str | ty::Dynamic(..) => ExpectRvalueLikeUnsized(ty), _ => ExpectHasType(ty), } diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs index fc5e0c44d96..6be3dc423de 100644 --- a/compiler/rustc_middle/src/ty/util.rs +++ b/compiler/rustc_middle/src/ty/util.rs @@ -171,14 +171,6 @@ impl<'tcx> TyCtxt<'tcx> { } } - /// Attempts to returns the deeply last field of nested structures, but - /// does not apply any normalization in its search. Returns the same type - /// if input `ty` is not a structure at all. - pub fn struct_tail_without_normalization(self, ty: Ty<'tcx>) -> Ty<'tcx> { - let tcx = self; - tcx.struct_tail_raw(ty, |ty| ty, || {}) - } - /// Returns the deeply last field of nested structures, or the same type if /// not a structure at all. Corresponds to the only possible unsized field, /// and its type can be used to determine unsizing strategy. diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs index 0e4233ba7bc..8a17d7ed641 100644 --- a/compiler/rustc_trait_selection/src/traits/project.rs +++ b/compiler/rustc_trait_selection/src/traits/project.rs @@ -1149,10 +1149,10 @@ fn assemble_candidates_from_impls<'cx, 'tcx>( | ty::Never // Extern types have unit metadata, according to RFC 2850 | ty::Foreign(_) - // If returned by `struct_tail_without_normalization` this is a unit struct + // If returned by `struct_tail` this is a unit struct // without any fields, or not a struct, and therefore is Sized. | ty::Adt(..) - // If returned by `struct_tail_without_normalization` this is the empty tuple. + // If returned by `struct_tail` this is the empty tuple. | ty::Tuple(..) // Integers and floats are always Sized, and so have unit type metadata. | ty::Infer(ty::InferTy::IntVar(_) | ty::InferTy::FloatVar(..)) => true, diff --git a/compiler/rustc_ty_utils/src/layout.rs b/compiler/rustc_ty_utils/src/layout.rs index 1eb03fc3bd6..244a6afcf97 100644 --- a/compiler/rustc_ty_utils/src/layout.rs +++ b/compiler/rustc_ty_utils/src/layout.rs @@ -219,9 +219,13 @@ fn layout_of_uncached<'tcx>( // its struct tail cannot be normalized either, so try to get a // more descriptive layout error here, which will lead to less confusing // diagnostics. + // + // We use the raw struct tail function here to get the first tail + // that is an alias, which is likely the cause of the normalization + // error. match tcx.try_normalize_erasing_regions( param_env, - tcx.struct_tail_without_normalization(pointee), + tcx.struct_tail_raw(pointee, |ty| ty, || {}), ) { Ok(_) => {} Err(better_err) => {