diff options
11 files changed, 422 insertions, 88 deletions
diff --git a/compiler/rustc_hir_typeck/src/pat.rs b/compiler/rustc_hir_typeck/src/pat.rs index 7520782930a..f9502153afd 100644 --- a/compiler/rustc_hir_typeck/src/pat.rs +++ b/compiler/rustc_hir_typeck/src/pat.rs @@ -177,16 +177,20 @@ enum PeelKind { /// Only peel reference types. This is used for explicit `deref!(_)` patterns, which dereference /// any number of `&`/`&mut` references, plus a single smart pointer. ExplicitDerefPat, - /// Implicitly peel any number of references, and if `deref_patterns` is enabled, smart pointer - /// ADTs. In order to peel only as much as necessary for the pattern to match, the `until_adt` - /// field contains the ADT def that the pattern is a constructor for, if applicable, so that we - /// don't peel it. See [`ResolvedPat`] for more information. - Implicit { until_adt: Option<DefId> }, + /// Implicitly peel references, and if `deref_patterns` is enabled, smart pointer ADTs. + Implicit { + /// The ADT the pattern is a constructor for, if applicable, so that we don't peel it. See + /// [`ResolvedPat`] for more information. + until_adt: Option<DefId>, + /// The number of references at the head of the pattern's type, so we can leave that many + /// untouched. This is `1` for string literals, and `0` for most patterns. + pat_ref_layers: usize, + }, } impl AdjustMode { const fn peel_until_adt(opt_adt_def: Option<DefId>) -> AdjustMode { - AdjustMode::Peel { kind: PeelKind::Implicit { until_adt: opt_adt_def } } + AdjustMode::Peel { kind: PeelKind::Implicit { until_adt: opt_adt_def, pat_ref_layers: 0 } } } const fn peel_all() -> AdjustMode { AdjustMode::peel_until_adt(None) @@ -488,9 +492,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { match pat.kind { // Peel off a `&` or `&mut` from the scrutinee type. See the examples in // `tests/ui/rfcs/rfc-2005-default-binding-mode`. - _ if let AdjustMode::Peel { .. } = adjust_mode + _ if let AdjustMode::Peel { kind: peel_kind } = adjust_mode && pat.default_binding_modes - && let ty::Ref(_, inner_ty, inner_mutability) = *expected.kind() => + && let ty::Ref(_, inner_ty, inner_mutability) = *expected.kind() + && self.should_peel_ref(peel_kind, expected) => { debug!("inspecting {:?}", expected); @@ -531,24 +536,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { // If `deref_patterns` is enabled, peel a smart pointer from the scrutinee type. See the // examples in `tests/ui/pattern/deref_patterns/`. _ if self.tcx.features().deref_patterns() - && let AdjustMode::Peel { kind: PeelKind::Implicit { until_adt } } = adjust_mode + && let AdjustMode::Peel { kind: peel_kind } = adjust_mode && pat.default_binding_modes - // For simplicity, only apply overloaded derefs if `expected` is a known ADT. - // FIXME(deref_patterns): we'll get better diagnostics for users trying to - // implicitly deref generics if we allow them here, but primitives, tuples, and - // inference vars definitely should be stopped. Figure out what makes most sense. - && let ty::Adt(scrutinee_adt, _) = *expected.kind() - // Don't peel if the pattern type already matches the scrutinee. E.g., stop here if - // matching on a `Cow<'a, T>` scrutinee with a `Cow::Owned(_)` pattern. - && until_adt != Some(scrutinee_adt.did()) - // At this point, the pattern isn't able to match `expected` without peeling. Check - // that it implements `Deref` before assuming it's a smart pointer, to get a normal - // type error instead of a missing impl error if not. This only checks for `Deref`, - // not `DerefPure`: we require that too, but we want a trait error if it's missing. - && let Some(deref_trait) = self.tcx.lang_items().deref_trait() - && self - .type_implements_trait(deref_trait, [expected], self.param_env) - .may_apply() => + && self.should_peel_smart_pointer(peel_kind, expected) => { debug!("scrutinee ty {expected:?} is a smart pointer, inserting overloaded deref"); // The scrutinee is a smart pointer; implicitly dereference it. This adds a @@ -680,21 +670,32 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { // String and byte-string literals result in types `&str` and `&[u8]` respectively. // All other literals result in non-reference types. - // As a result, we allow `if let 0 = &&0 {}` but not `if let "foo" = &&"foo" {}`. - // - // Call `resolve_vars_if_possible` here for inline const blocks. - PatKind::Expr(lt) => match self.resolve_vars_if_possible(self.check_pat_expr_unadjusted(lt)).kind() { - ty::Ref(..) => AdjustMode::Pass, - _ => { - // Path patterns have already been handled, and inline const blocks currently - // aren't possible to write, so any handling for them would be untested. - if cfg!(debug_assertions) - && self.tcx.features().deref_patterns() - && !matches!(lt.kind, PatExprKind::Lit { .. }) - { - span_bug!(lt.span, "FIXME(deref_patterns): adjust mode unimplemented for {:?}", lt.kind); + // As a result, we allow `if let 0 = &&0 {}` but not `if let "foo" = &&"foo" {}` unless + // `deref_patterns` is enabled. + PatKind::Expr(lt) => { + // Path patterns have already been handled, and inline const blocks currently + // aren't possible to write, so any handling for them would be untested. + if cfg!(debug_assertions) + && self.tcx.features().deref_patterns() + && !matches!(lt.kind, PatExprKind::Lit { .. }) + { + span_bug!(lt.span, "FIXME(deref_patterns): adjust mode unimplemented for {:?}", lt.kind); + } + // Call `resolve_vars_if_possible` here for inline const blocks. + let lit_ty = self.resolve_vars_if_possible(self.check_pat_expr_unadjusted(lt)); + // If `deref_patterns` is enabled, allow `if let "foo" = &&"foo" {}`. + if self.tcx.features().deref_patterns() { + let mut peeled_ty = lit_ty; + let mut pat_ref_layers = 0; + while let ty::Ref(_, inner_ty, mutbl) = *peeled_ty.kind() { + // We rely on references at the head of constants being immutable. + debug_assert!(mutbl.is_not()); + pat_ref_layers += 1; + peeled_ty = inner_ty; } - AdjustMode::peel_all() + AdjustMode::Peel { kind: PeelKind::Implicit { until_adt: None, pat_ref_layers } } + } else { + if lit_ty.is_ref() { AdjustMode::Pass } else { AdjustMode::peel_all() } } }, @@ -720,6 +721,67 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } } + /// Assuming `expected` is a reference type, determine whether to peel it before matching. + fn should_peel_ref(&self, peel_kind: PeelKind, mut expected: Ty<'tcx>) -> bool { + debug_assert!(expected.is_ref()); + let pat_ref_layers = match peel_kind { + PeelKind::ExplicitDerefPat => 0, + PeelKind::Implicit { pat_ref_layers, .. } => pat_ref_layers, + }; + + // Most patterns don't have reference types, so we'll want to peel all references from the + // scrutinee before matching. To optimize for the common case, return early. + if pat_ref_layers == 0 { + return true; + } + debug_assert!( + self.tcx.features().deref_patterns(), + "Peeling for patterns with reference types is gated by `deref_patterns`." + ); + + // If the pattern has as many or more layers of reference as the expected type, we can match + // without peeling more, unless we find a smart pointer or `&mut` that we also need to peel. + // We don't treat `&` and `&mut` as interchangeable, but by peeling `&mut`s before matching, + // we can still, e.g., match on a `&mut str` with a string literal pattern. This is because + // string literal patterns may be used where `str` is expected. + let mut expected_ref_layers = 0; + while let ty::Ref(_, inner_ty, mutbl) = *expected.kind() { + if mutbl.is_mut() { + // Mutable references can't be in the final value of constants, thus they can't be + // at the head of their types, thus we should always peel `&mut`. + return true; + } + expected_ref_layers += 1; + expected = inner_ty; + } + pat_ref_layers < expected_ref_layers || self.should_peel_smart_pointer(peel_kind, expected) + } + + /// Determine whether `expected` is a smart pointer type that should be peeled before matching. + fn should_peel_smart_pointer(&self, peel_kind: PeelKind, expected: Ty<'tcx>) -> bool { + // Explicit `deref!(_)` patterns match against smart pointers; don't peel in that case. + if let PeelKind::Implicit { until_adt, .. } = peel_kind + // For simplicity, only apply overloaded derefs if `expected` is a known ADT. + // FIXME(deref_patterns): we'll get better diagnostics for users trying to + // implicitly deref generics if we allow them here, but primitives, tuples, and + // inference vars definitely should be stopped. Figure out what makes most sense. + && let ty::Adt(scrutinee_adt, _) = *expected.kind() + // Don't peel if the pattern type already matches the scrutinee. E.g., stop here if + // matching on a `Cow<'a, T>` scrutinee with a `Cow::Owned(_)` pattern. + && until_adt != Some(scrutinee_adt.did()) + // At this point, the pattern isn't able to match `expected` without peeling. Check + // that it implements `Deref` before assuming it's a smart pointer, to get a normal + // type error instead of a missing impl error if not. This only checks for `Deref`, + // not `DerefPure`: we require that too, but we want a trait error if it's missing. + && let Some(deref_trait) = self.tcx.lang_items().deref_trait() + && self.type_implements_trait(deref_trait, [expected], self.param_env).may_apply() + { + true + } else { + false + } + } + fn check_pat_expr_unadjusted(&self, lt: &'tcx hir::PatExpr<'tcx>) -> Ty<'tcx> { let ty = match <.kind { rustc_hir::PatExprKind::Lit { lit, negated } => { diff --git a/src/doc/unstable-book/src/language-features/deref-patterns.md b/src/doc/unstable-book/src/language-features/deref-patterns.md index 0cc7106da48..fb6df290cc1 100644 --- a/src/doc/unstable-book/src/language-features/deref-patterns.md +++ b/src/doc/unstable-book/src/language-features/deref-patterns.md @@ -65,15 +65,26 @@ let deref!(x) = Box::new(NoCopy) else { unreachable!() }; drop::<NoCopy>(x); ``` -Additionally, when `deref_patterns` is enabled, string literal patterns may be written where `str` -is expected. Likewise, byte string literal patterns may be written where `[u8]` or `[u8; _]` is -expected. This lets them be used in `deref!(_)` patterns: +Additionally, `deref_patterns` implements changes to string and byte string literal patterns, +allowing then to be used in deref patterns: ```rust # #![feature(deref_patterns)] # #![allow(incomplete_features)] -match ("test".to_string(), b"test".to_vec()) { - (deref!("test"), deref!(b"test")) => {} +match ("test".to_string(), Box::from("test"), b"test".to_vec()) { + ("test", "test", b"test") => {} + _ => panic!(), +} + +// This works through multiple layers of reference and smart pointer: +match (&Box::new(&"test".to_string()), &&&"test") { + ("test", "test") => {} + _ => panic!(), +} + +// `deref!("...")` syntax may also be used: +match "test".to_string() { + deref!("test") => {} _ => panic!(), } @@ -82,10 +93,16 @@ match *"test" { "test" => {} _ => panic!(), } +match *b"test" { + b"test" => {} + _ => panic!(), +} +match *(b"test" as &[u8]) { + b"test" => {} + _ => panic!(), +} ``` -Implicit deref pattern syntax is not yet supported for string or byte string literals. - [`box_patterns`]: ./box-patterns.md [`string_deref_patterns`]: ./string-deref-patterns.md [smart pointers in the standard library]: https://doc.rust-lang.org/std/ops/trait.DerefPure.html#implementors diff --git a/tests/ui/pattern/deref-patterns/byte-string-type-errors.rs b/tests/ui/pattern/deref-patterns/byte-string-type-errors.rs index 64acc4748af..fdcc6cb4611 100644 --- a/tests/ui/pattern/deref-patterns/byte-string-type-errors.rs +++ b/tests/ui/pattern/deref-patterns/byte-string-type-errors.rs @@ -33,4 +33,23 @@ fn main() { if let b"test" = *b"this array is too long" {} //~^ ERROR mismatched types //~| NOTE expected an array with a size of 22, found one with a size of 4 + + // Test matching on `&mut T`: we peel the `&mut` before applying the usual special cases. + // No special cases apply to `()`, so the "found" type is the type of the literal. + if let b"test" = &mut () {} + //~^ ERROR mismatched types + //~| NOTE expected `()`, found `&[u8; 4]` + + // If the pointee is an array or slice, the usual special cases will apply to the "found" type: + if let b"test" = &mut [] as &mut [i8] {} + //~^ ERROR mismatched type + //~| NOTE expected `[i8]`, found `[u8]` + + if let b"test" = &mut [()] {} + //~^ ERROR mismatched types + //~| NOTE expected `[(); 1]`, found `[u8; 4]` + + if let b"test" = &mut *b"this array is too long" {} + //~^ ERROR mismatched type + //~| NOTE expected an array with a size of 22, found one with a size of 4 } diff --git a/tests/ui/pattern/deref-patterns/byte-string-type-errors.stderr b/tests/ui/pattern/deref-patterns/byte-string-type-errors.stderr index 0317b7209e1..046682004be 100644 --- a/tests/ui/pattern/deref-patterns/byte-string-type-errors.stderr +++ b/tests/ui/pattern/deref-patterns/byte-string-type-errors.stderr @@ -47,6 +47,44 @@ LL | if let b"test" = *b"this array is too long" {} | | | expected an array with a size of 22, found one with a size of 4 -error: aborting due to 5 previous errors +error[E0308]: mismatched types + --> $DIR/byte-string-type-errors.rs:39:12 + | +LL | if let b"test" = &mut () {} + | ^^^^^^^ ------- this expression has type `&mut ()` + | | + | expected `()`, found `&[u8; 4]` + +error[E0308]: mismatched types + --> $DIR/byte-string-type-errors.rs:44:12 + | +LL | if let b"test" = &mut [] as &mut [i8] {} + | ^^^^^^^ -------------------- this expression has type `&mut [i8]` + | | + | expected `[i8]`, found `[u8]` + | + = note: expected slice `[i8]` + found slice `[u8]` + +error[E0308]: mismatched types + --> $DIR/byte-string-type-errors.rs:48:12 + | +LL | if let b"test" = &mut [()] {} + | ^^^^^^^ --------- this expression has type `&mut [(); 1]` + | | + | expected `[(); 1]`, found `[u8; 4]` + | + = note: expected array `[(); 1]` + found array `[u8; 4]` + +error[E0308]: mismatched types + --> $DIR/byte-string-type-errors.rs:52:12 + | +LL | if let b"test" = &mut *b"this array is too long" {} + | ^^^^^^^ ------------------------------- this expression has type `&mut [u8; 22]` + | | + | expected an array with a size of 22, found one with a size of 4 + +error: aborting due to 9 previous errors For more information about this error, try `rustc --explain E0308`. diff --git a/tests/ui/pattern/deref-patterns/const-pats-do-not-mislead-inference.rs b/tests/ui/pattern/deref-patterns/const-pats-do-not-mislead-inference.rs new file mode 100644 index 00000000000..3a2531f4b95 --- /dev/null +++ b/tests/ui/pattern/deref-patterns/const-pats-do-not-mislead-inference.rs @@ -0,0 +1,54 @@ +//@ revisions: stable deref_patterns +//@[deref_patterns] check-pass +//! `deref_patterns` allows string and byte string literal patterns to implicitly peel references +//! and smart pointers from the scrutinee before matching. Since strings and byte strings themselves +//! have reference types, we need to make sure we don't peel too much. By leaving the type of the +//! match scrutinee partially uninferred, these tests make sure we only peel as much as needed in +//! order to match. In particular, when peeling isn't needed, the results should be the same was +//! we'd get without `deref_patterns` enabled. + +#![cfg_attr(deref_patterns, feature(deref_patterns))] +#![cfg_attr(deref_patterns, expect(incomplete_features))] + +fn uninferred<T>() -> T { unimplemented!() } + +// Assert type equality without allowing coercions. +trait Is<T> {} +impl<T> Is<T> for T {} +fn has_type<T>(_: impl Is<T>) {} + +fn main() { + // We don't need to peel anything to unify the type of `x` with `&str`, so `x: &str`. + let x = uninferred(); + if let "..." = x {} + has_type::<&str>(x); + + // We don't need to peel anything to unify the type of `&x` with `&[u8; 3]`, so `x: [u8; 3]`. + let x = uninferred(); + if let b"..." = &x {} + has_type::<[u8; 3]>(x); + + // Peeling a single `&` lets us unify the type of `&x` with `&[u8; 3]`, giving `x: [u8; 3]`. + let x = uninferred(); + if let b"..." = &&x {} + //[stable]~^ ERROR: mismatched types + has_type::<[u8; 3]>(x); + + // We have to peel both the `&` and the box before unifying the type of `x` with `&str`. + let x = uninferred(); + if let "..." = &Box::new(x) {} + //[stable]~^ ERROR mismatched types + has_type::<&str>(x); + + // After peeling the box, we can unify the type of `&x` with `&[u8; 3]`, giving `x: [u8; 3]`. + let x = uninferred(); + if let b"..." = Box::new(&x) {} + //[stable]~^ ERROR mismatched types + has_type::<[u8; 3]>(x); + + // `&` and `&mut` aren't interchangeable: `&mut`s need to be peeled before unifying, like boxes: + let mut x = uninferred(); + if let "..." = &mut x {} + //[stable]~^ ERROR mismatched types + has_type::<&str>(x); +} diff --git a/tests/ui/pattern/deref-patterns/const-pats-do-not-mislead-inference.stable.stderr b/tests/ui/pattern/deref-patterns/const-pats-do-not-mislead-inference.stable.stderr new file mode 100644 index 00000000000..61079718c5d --- /dev/null +++ b/tests/ui/pattern/deref-patterns/const-pats-do-not-mislead-inference.stable.stderr @@ -0,0 +1,55 @@ +error[E0308]: mismatched types + --> $DIR/const-pats-do-not-mislead-inference.rs:33:12 + | +LL | if let b"..." = &&x {} + | ^^^^^^ --- this expression has type `&&_` + | | + | expected `&&_`, found `&[u8; 3]` + | + = note: expected reference `&&_` + found reference `&'static [u8; 3]` + +error[E0308]: mismatched types + --> $DIR/const-pats-do-not-mislead-inference.rs:39:12 + | +LL | if let "..." = &Box::new(x) {} + | ^^^^^ ------------ this expression has type `&Box<_>` + | | + | expected `&Box<_>`, found `&str` + | + = note: expected reference `&Box<_>` + found reference `&'static str` +help: consider dereferencing to access the inner value using the Deref trait + | +LL | if let "..." = &*Box::new(x) {} + | + + +error[E0308]: mismatched types + --> $DIR/const-pats-do-not-mislead-inference.rs:45:12 + | +LL | if let b"..." = Box::new(&x) {} + | ^^^^^^ ------------ this expression has type `Box<&_>` + | | + | expected `Box<&_>`, found `&[u8; 3]` + | + = note: expected struct `Box<&_>` + found reference `&'static [u8; 3]` +help: consider dereferencing to access the inner value using the Deref trait + | +LL | if let b"..." = *Box::new(&x) {} + | + + +error[E0308]: mismatched types + --> $DIR/const-pats-do-not-mislead-inference.rs:51:12 + | +LL | if let "..." = &mut x {} + | ^^^^^ ------ this expression has type `&mut _` + | | + | types differ in mutability + | + = note: expected mutable reference `&mut _` + found reference `&'static str` + +error: aborting due to 4 previous errors + +For more information about this error, try `rustc --explain E0308`. diff --git a/tests/ui/pattern/deref-patterns/needs-gate.rs b/tests/ui/pattern/deref-patterns/needs-gate.rs index 7944744ee83..953051f7b04 100644 --- a/tests/ui/pattern/deref-patterns/needs-gate.rs +++ b/tests/ui/pattern/deref-patterns/needs-gate.rs @@ -29,4 +29,30 @@ fn main() { //~^ ERROR: mismatched types _ => {} } + + // `deref_patterns` allows string and byte string patterns to implicitly peel references. + match &"str" { + "str" => {} + //~^ ERROR: mismatched types + _ => {} + } + match &b"str" { + b"str" => {} + //~^ ERROR: mismatched types + _ => {} + } + match "str".to_owned() { + "str" => {} + //~^ ERROR: mismatched types + _ => {} + } + + // `deref_patterns` allows string and byte string patterns to match on mutable references. + // See also `tests/ui/pattern/byte-string-mutability-mismatch.rs`. + if let "str" = &mut *"str".to_string() {} + //~^ ERROR mismatched types + if let b"str" = &mut b"str".clone() {} + //~^ ERROR mismatched types + if let b"str" = &mut b"str".clone()[..] {} + //~^ ERROR mismatched types } diff --git a/tests/ui/pattern/deref-patterns/needs-gate.stderr b/tests/ui/pattern/deref-patterns/needs-gate.stderr index e886ca98055..3d938a7e23f 100644 --- a/tests/ui/pattern/deref-patterns/needs-gate.stderr +++ b/tests/ui/pattern/deref-patterns/needs-gate.stderr @@ -47,7 +47,70 @@ LL | match *(b"test" as &[u8]) { LL | b"test" => {} | ^^^^^^^ expected `[u8]`, found `&[u8; 4]` -error: aborting due to 5 previous errors +error[E0308]: mismatched types + --> $DIR/needs-gate.rs:35:9 + | +LL | match &"str" { + | ------ this expression has type `&&str` +LL | "str" => {} + | ^^^^^ expected `&&str`, found `&str` + | + = note: expected reference `&&_` + found reference `&'static _` + +error[E0308]: mismatched types + --> $DIR/needs-gate.rs:40:9 + | +LL | match &b"str" { + | ------- this expression has type `&&[u8; 3]` +LL | b"str" => {} + | ^^^^^^ expected `&&[u8; 3]`, found `&[u8; 3]` + | + = note: expected reference `&&_` + found reference `&'static _` + +error[E0308]: mismatched types + --> $DIR/needs-gate.rs:45:9 + | +LL | match "str".to_owned() { + | ---------------- this expression has type `String` +LL | "str" => {} + | ^^^^^ expected `String`, found `&str` + +error[E0308]: mismatched types + --> $DIR/needs-gate.rs:52:12 + | +LL | if let "str" = &mut *"str".to_string() {} + | ^^^^^ ----------------------- this expression has type `&mut str` + | | + | types differ in mutability + | + = note: expected mutable reference `&mut _` + found reference `&'static _` + +error[E0308]: mismatched types + --> $DIR/needs-gate.rs:54:12 + | +LL | if let b"str" = &mut b"str".clone() {} + | ^^^^^^ ------------------- this expression has type `&mut [u8; 3]` + | | + | types differ in mutability + | + = note: expected mutable reference `&mut _` + found reference `&'static _` + +error[E0308]: mismatched types + --> $DIR/needs-gate.rs:56:12 + | +LL | if let b"str" = &mut b"str".clone()[..] {} + | ^^^^^^ ----------------------- this expression has type `&mut [u8]` + | | + | types differ in mutability + | + = note: expected mutable reference `&mut _` + found reference `&'static _` + +error: aborting due to 11 previous errors Some errors have detailed explanations: E0308, E0658. For more information about an error, try `rustc --explain E0308`. diff --git a/tests/ui/pattern/deref-patterns/strings.rs b/tests/ui/pattern/deref-patterns/strings.rs index 536e943b3f6..fac15a9aee3 100644 --- a/tests/ui/pattern/deref-patterns/strings.rs +++ b/tests/ui/pattern/deref-patterns/strings.rs @@ -14,10 +14,26 @@ fn main() { }; assert_eq!(test_actual, test_expect); - // Test string literals in explicit `deref!(_)` patterns. + // Test matching on `&mut str`. + let test_actual = match &mut *test_in.to_string() { + "zero" => 0, + "one" => 1, + _ => 2, + }; + assert_eq!(test_actual, test_expect); + + // Test string literals in deref patterns. let test_actual = match test_in.to_string() { deref!("zero") => 0, - deref!("one") => 1, + "one" => 1, + _ => 2, + }; + assert_eq!(test_actual, test_expect); + + // Test peeling references in addition to smart pointers. + let test_actual = match &test_in.to_string() { + deref!("zero") => 0, + "one" => 1, _ => 2, }; assert_eq!(test_actual, test_expect); @@ -47,18 +63,34 @@ fn main() { }; assert_eq!(test_actual, test_expect); - // Test byte string literals used as arrays in explicit `deref!(_)` patterns. + // Test matching on `&mut [u8; N]`. + let test_actual = match &mut test_in.clone() { + b"0" => 0, + b"1" => 1, + _ => 2, + }; + assert_eq!(test_actual, test_expect); + + // Test matching on `&mut [u8]`. + let test_actual = match &mut test_in.clone()[..] { + b"0" => 0, + b"1" => 1, + _ => 2, + }; + assert_eq!(test_actual, test_expect); + + // Test byte string literals used as arrays in deref patterns. let test_actual = match Box::new(*test_in) { deref!(b"0") => 0, - deref!(b"1") => 1, + b"1" => 1, _ => 2, }; assert_eq!(test_actual, test_expect); - // Test byte string literals used as slices in explicit `deref!(_)` patterns. + // Test byte string literals used as slices in deref patterns. let test_actual = match test_in.to_vec() { deref!(b"0") => 0, - deref!(b"1") => 1, + b"1" => 1, _ => 2, }; assert_eq!(test_actual, test_expect); diff --git a/tests/ui/pattern/deref-patterns/typeck_fail.rs b/tests/ui/pattern/deref-patterns/typeck_fail.rs index 52d84f7a34d..6ae87bb7bc3 100644 --- a/tests/ui/pattern/deref-patterns/typeck_fail.rs +++ b/tests/ui/pattern/deref-patterns/typeck_fail.rs @@ -2,19 +2,6 @@ #![allow(incomplete_features)] fn main() { - // FIXME(deref_patterns): fails to typecheck because string literal patterns don't peel - // references from the scrutinee. - match "foo".to_string() { - "foo" => {} - //~^ ERROR: mismatched types - _ => {} - } - match &"foo".to_string() { - "foo" => {} - //~^ ERROR: mismatched types - _ => {} - } - // Make sure we don't try implicitly dereferncing any ADT. match Some(0) { Ok(0) => {} diff --git a/tests/ui/pattern/deref-patterns/typeck_fail.stderr b/tests/ui/pattern/deref-patterns/typeck_fail.stderr index e87528c1c51..fc29caac563 100644 --- a/tests/ui/pattern/deref-patterns/typeck_fail.stderr +++ b/tests/ui/pattern/deref-patterns/typeck_fail.stderr @@ -1,24 +1,5 @@ error[E0308]: mismatched types - --> $DIR/typeck_fail.rs:8:9 - | -LL | match "foo".to_string() { - | ----------------- this expression has type `String` -LL | "foo" => {} - | ^^^^^ expected `String`, found `&str` - -error[E0308]: mismatched types - --> $DIR/typeck_fail.rs:13:9 - | -LL | match &"foo".to_string() { - | ------------------ this expression has type `&String` -LL | "foo" => {} - | ^^^^^ expected `&String`, found `&str` - | - = note: expected reference `&String` - found reference `&'static str` - -error[E0308]: mismatched types - --> $DIR/typeck_fail.rs:20:9 + --> $DIR/typeck_fail.rs:7:9 | LL | match Some(0) { | ------- this expression has type `Option<{integer}>` @@ -28,6 +9,6 @@ LL | Ok(0) => {} = note: expected enum `Option<{integer}>` found enum `Result<_, _>` -error: aborting due to 3 previous errors +error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0308`. |