diff options
| -rw-r--r-- | compiler/rustc_codegen_ssa/src/mir/mod.rs | 7 | ||||
| -rw-r--r-- | compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs | 20 | ||||
| -rw-r--r-- | compiler/rustc_middle/src/traits/mod.rs | 4 | ||||
| -rw-r--r-- | compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs | 6 | ||||
| -rw-r--r-- | tests/ui/unsized-locals/unsized-exprs-rpass.rs | 5 | ||||
| -rw-r--r-- | tests/ui/unsized-locals/unsized-exprs.stderr | 12 | ||||
| -rw-r--r-- | tests/ui/unsized-locals/unsized-non-place-exprs.rs | 27 | ||||
| -rw-r--r-- | tests/ui/unsized-locals/unsized-non-place-exprs.stderr | 81 |
8 files changed, 153 insertions, 9 deletions
diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs index 4e35b143173..fa69820d5d2 100644 --- a/compiler/rustc_codegen_ssa/src/mir/mod.rs +++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs @@ -141,7 +141,12 @@ enum LocalRef<'tcx, V> { /// `UnsizedPlace(p)`: `p` itself is a thin pointer (indirect place). /// `*p` is the wide pointer that references the actual unsized place. /// - /// Rust has no alloca and thus no ability to move the unsized place. + /// MIR only supports unsized args, not dynamically-sized locals, so + /// new unsized temps don't exist and we must reuse the referred-to place. + /// + /// FIXME: Since the removal of unsized locals in <https://github.com/rust-lang/rust/pull/142911>, + /// can we maybe use `Place` here? Or refactor it in another way? There are quite a few + /// `UnsizedPlace => bug` branches now. UnsizedPlace(PlaceRef<'tcx, V>), /// The backend [`OperandValue`] has already been generated. Operand(OperandRef<'tcx, V>), diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs index eeb8d33ef65..eb8d671c939 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs @@ -241,6 +241,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { arg_expr.span, ObligationCauseCode::WellFormed(None), ); + + self.check_place_expr_if_unsized(fn_input_ty, arg_expr); } // First, let's unify the formal method signature with the expectation eagerly. @@ -543,6 +545,21 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } } + /// If `unsized_fn_params` is active, check that unsized values are place expressions. Since + /// the removal of `unsized_locals` in <https://github.com/rust-lang/rust/pull/142911> we can't + /// store them in MIR locals as temporaries. + /// + /// If `unsized_fn_params` is inactive, this will be checked in borrowck instead. + fn check_place_expr_if_unsized(&self, ty: Ty<'tcx>, expr: &'tcx hir::Expr<'tcx>) { + if self.tcx.features().unsized_fn_params() && !expr.is_syntactic_place_expr() { + self.require_type_is_sized( + ty, + expr.span, + ObligationCauseCode::UnsizedNonPlaceExpr(expr.span), + ); + } + } + fn report_arg_errors( &self, compatibility_diagonal: IndexVec<ProvidedIdx, Compatibility<'tcx>>, @@ -1873,7 +1890,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { }); } hir::StmtKind::Semi(expr) => { - self.check_expr(expr); + let ty = self.check_expr(expr); + self.check_place_expr_if_unsized(ty, expr); } } diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs index 1a5a9765ce7..5bdde3a514e 100644 --- a/compiler/rustc_middle/src/traits/mod.rs +++ b/compiler/rustc_middle/src/traits/mod.rs @@ -412,6 +412,10 @@ pub enum ObligationCauseCode<'tcx> { /// Obligations emitted during the normalization of a free type alias. TypeAlias(ObligationCauseCodeHandle<'tcx>, Span, DefId), + + /// Only reachable if the `unsized_fn_params` feature is used. Unsized function arguments must + /// be place expressions because we can't store them in MIR locals as temporaries. + UnsizedNonPlaceExpr(Span), } /// Whether a value can be extracted into a const. diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs index 362052e9fdb..c5b85c95ba2 100644 --- a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs +++ b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs @@ -3624,6 +3624,12 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> { ); suggest_remove_deref(err, &expr); } + ObligationCauseCode::UnsizedNonPlaceExpr(span) => { + err.span_note( + span, + "unsized values must be place expressions and cannot be put in temporaries", + ); + } } } diff --git a/tests/ui/unsized-locals/unsized-exprs-rpass.rs b/tests/ui/unsized-locals/unsized-exprs-rpass.rs index 54ecd000343..ce31bd63f7c 100644 --- a/tests/ui/unsized-locals/unsized-exprs-rpass.rs +++ b/tests/ui/unsized-locals/unsized-exprs-rpass.rs @@ -18,11 +18,6 @@ impl std::ops::Add<i32> for A<[u8]> { } fn main() { - udrop::<[u8]>(loop { - break *foo(); - }); - udrop::<[u8]>(if true { *foo() } else { *foo() }); - udrop::<[u8]>({ *foo() }); udrop::<[u8]>((*foo())); *afoo() + 42; udrop as fn([u8]); diff --git a/tests/ui/unsized-locals/unsized-exprs.stderr b/tests/ui/unsized-locals/unsized-exprs.stderr index 1b61254870f..0455edbe8e7 100644 --- a/tests/ui/unsized-locals/unsized-exprs.stderr +++ b/tests/ui/unsized-locals/unsized-exprs.stderr @@ -10,7 +10,11 @@ note: required because it appears within the type `A<[u8]>` | LL | struct A<X: ?Sized>(X); | ^ - = note: structs must have a statically known size to be initialized +note: unsized values must be place expressions and cannot be put in temporaries + --> $DIR/unsized-exprs.rs:19:22 + | +LL | udrop::<A<[u8]>>(A { 0: *foo() }); + | ^^^^^^^^^^^^^^^ error[E0277]: the size for values of type `[u8]` cannot be known at compilation time --> $DIR/unsized-exprs.rs:21:22 @@ -24,7 +28,11 @@ note: required because it appears within the type `A<[u8]>` | LL | struct A<X: ?Sized>(X); | ^ - = note: the return type of a function must have a statically known size +note: unsized values must be place expressions and cannot be put in temporaries + --> $DIR/unsized-exprs.rs:21:22 + | +LL | udrop::<A<[u8]>>(A(*foo())); + | ^^^^^^^^^ error: aborting due to 2 previous errors diff --git a/tests/ui/unsized-locals/unsized-non-place-exprs.rs b/tests/ui/unsized-locals/unsized-non-place-exprs.rs new file mode 100644 index 00000000000..d724fcf81a4 --- /dev/null +++ b/tests/ui/unsized-locals/unsized-non-place-exprs.rs @@ -0,0 +1,27 @@ +//! `#![feature(unsized_fn_params)]` lets you use unsized function parameters. In particular this +//! is load bearing for `Box<dyn FnOnce()>: FnOnce()`. To do that, borrowck relaxes the requirement +//! that certain places must be `Sized`. But in #142911 we removed alloca support, so these +//! arguments cannot be put in temporaries (or ICE at codegen) That means when `unsized_fn_params` +//! is enabled, we must explicitly check that unsized function arguments are place expressions. +//! +//! Also see tests/ui/unsized_locals/unsized-exprs-rpass.rs + +#![feature(unsized_fn_params)] + +fn foo() -> Box<[u8]> { + Box::new(*b"foo") +} + +fn udrop<T: ?Sized>(_x: T) {} + +fn main(){ + // NB The ordering of the following operations matters, otherwise errors get swallowed somehow. + + udrop::<[u8]>(if true { *foo() } else { *foo() }); //~ERROR the size for values of type `[u8]` cannot be known at compilation time + udrop::<[u8]>({ *foo() }); //~ERROR the size for values of type `[u8]` cannot be known at compilation time + udrop(match foo() { x => *x }); //~ERROR the size for values of type `[u8]` cannot be known at compilation time + udrop::<[u8]>({ loop { break *foo(); } }); //~ERROR the size for values of type `[u8]` cannot be known at compilation time + + { *foo() }; //~ERROR the size for values of type `[u8]` cannot be known at compilation time + { loop { break *foo(); } }; //~ERROR the size for values of type `[u8]` cannot be known at compilation time +} diff --git a/tests/ui/unsized-locals/unsized-non-place-exprs.stderr b/tests/ui/unsized-locals/unsized-non-place-exprs.stderr new file mode 100644 index 00000000000..f9507e9a888 --- /dev/null +++ b/tests/ui/unsized-locals/unsized-non-place-exprs.stderr @@ -0,0 +1,81 @@ +error[E0277]: the size for values of type `[u8]` cannot be known at compilation time + --> $DIR/unsized-non-place-exprs.rs:20:19 + | +LL | udrop::<[u8]>(if true { *foo() } else { *foo() }); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time + | + = help: the trait `Sized` is not implemented for `[u8]` +note: unsized values must be place expressions and cannot be put in temporaries + --> $DIR/unsized-non-place-exprs.rs:20:19 + | +LL | udrop::<[u8]>(if true { *foo() } else { *foo() }); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error[E0277]: the size for values of type `[u8]` cannot be known at compilation time + --> $DIR/unsized-non-place-exprs.rs:21:19 + | +LL | udrop::<[u8]>({ *foo() }); + | ^^^^^^^^^^ doesn't have a size known at compile-time + | + = help: the trait `Sized` is not implemented for `[u8]` +note: unsized values must be place expressions and cannot be put in temporaries + --> $DIR/unsized-non-place-exprs.rs:21:19 + | +LL | udrop::<[u8]>({ *foo() }); + | ^^^^^^^^^^ + +error[E0277]: the size for values of type `[u8]` cannot be known at compilation time + --> $DIR/unsized-non-place-exprs.rs:22:11 + | +LL | udrop(match foo() { x => *x }); + | ^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time + | + = help: the trait `Sized` is not implemented for `[u8]` +note: unsized values must be place expressions and cannot be put in temporaries + --> $DIR/unsized-non-place-exprs.rs:22:11 + | +LL | udrop(match foo() { x => *x }); + | ^^^^^^^^^^^^^^^^^^^^^^^ + +error[E0277]: the size for values of type `[u8]` cannot be known at compilation time + --> $DIR/unsized-non-place-exprs.rs:23:19 + | +LL | udrop::<[u8]>({ loop { break *foo(); } }); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time + | + = help: the trait `Sized` is not implemented for `[u8]` +note: unsized values must be place expressions and cannot be put in temporaries + --> $DIR/unsized-non-place-exprs.rs:23:19 + | +LL | udrop::<[u8]>({ loop { break *foo(); } }); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error[E0277]: the size for values of type `[u8]` cannot be known at compilation time + --> $DIR/unsized-non-place-exprs.rs:25:5 + | +LL | { *foo() }; + | ^^^^^^^^^^ doesn't have a size known at compile-time + | + = help: the trait `Sized` is not implemented for `[u8]` +note: unsized values must be place expressions and cannot be put in temporaries + --> $DIR/unsized-non-place-exprs.rs:25:5 + | +LL | { *foo() }; + | ^^^^^^^^^^ + +error[E0277]: the size for values of type `[u8]` cannot be known at compilation time + --> $DIR/unsized-non-place-exprs.rs:26:5 + | +LL | { loop { break *foo(); } }; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time + | + = help: the trait `Sized` is not implemented for `[u8]` +note: unsized values must be place expressions and cannot be put in temporaries + --> $DIR/unsized-non-place-exprs.rs:26:5 + | +LL | { loop { break *foo(); } }; + | ^^^^^^^^^^^^^^^^^^^^^^^^^^ + +error: aborting due to 6 previous errors + +For more information about this error, try `rustc --explain E0277`. |