From c0a22a0209e82975614e51edc7927f4caedc886c Mon Sep 17 00:00:00 2001 From: Takayuki Maeda Date: Thu, 28 Jul 2022 09:55:12 +0900 Subject: [PATCH] suggest adding/removing `ref` for binding patterns --- compiler/rustc_typeck/src/check/pat.rs | 53 +++++++++++++++++-- src/test/ui/mismatched_types/E0409.stderr | 4 ++ ...-or-removing-ref-for-binding-pattern.fixed | 21 ++++++++ ...ing-or-removing-ref-for-binding-pattern.rs | 21 ++++++++ ...or-removing-ref-for-binding-pattern.stderr | 49 +++++++++++++++++ .../resolve-inconsistent-binding-mode.stderr | 8 +++ .../ui/resolve/resolve-inconsistent-names.rs | 1 + .../resolve/resolve-inconsistent-names.stderr | 9 +++- 8 files changed, 160 insertions(+), 6 deletions(-) create mode 100644 src/test/ui/mismatched_types/suggest-adding-or-removing-ref-for-binding-pattern.fixed create mode 100644 src/test/ui/mismatched_types/suggest-adding-or-removing-ref-for-binding-pattern.rs create mode 100644 src/test/ui/mismatched_types/suggest-adding-or-removing-ref-for-binding-pattern.stderr diff --git a/compiler/rustc_typeck/src/check/pat.rs b/compiler/rustc_typeck/src/check/pat.rs index c7318cd6e531f..373a824b0d53c 100644 --- a/compiler/rustc_typeck/src/check/pat.rs +++ b/compiler/rustc_typeck/src/check/pat.rs @@ -617,7 +617,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { // If there are multiple arms, make sure they all agree on // what the type of the binding `x` ought to be. if var_id != pat.hir_id { - self.check_binding_alt_eq_ty(pat.span, var_id, local_ty, ti); + self.check_binding_alt_eq_ty(ba, pat.span, var_id, local_ty, ti); } if let Some(p) = sub { @@ -627,7 +627,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { local_ty } - fn check_binding_alt_eq_ty(&self, span: Span, var_id: HirId, ty: Ty<'tcx>, ti: TopInfo<'tcx>) { + fn check_binding_alt_eq_ty( + &self, + ba: hir::BindingAnnotation, + span: Span, + var_id: HirId, + ty: Ty<'tcx>, + ti: TopInfo<'tcx>, + ) { let var_ty = self.local_ty(span, var_id).decl_ty; if let Some(mut err) = self.demand_eqtype_pat_diag(span, var_ty, ty, ti) { let hir = self.tcx.hir(); @@ -645,12 +652,50 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { }); let pre = if in_match { "in the same arm, " } else { "" }; err.note(&format!("{}a binding must have the same type in all alternatives", pre)); - // FIXME: check if `var_ty` and `ty` can be made the same type by adding or removing - // `ref` or `&` to the pattern. + self.suggest_adding_missing_ref_or_removing_ref( + &mut err, + span, + var_ty, + self.resolve_vars_with_obligations(ty), + ba, + ); err.emit(); } } + fn suggest_adding_missing_ref_or_removing_ref( + &self, + err: &mut Diagnostic, + span: Span, + expected: Ty<'tcx>, + actual: Ty<'tcx>, + ba: hir::BindingAnnotation, + ) { + match (expected.kind(), actual.kind(), ba) { + (ty::Ref(_, inner_ty, _), _, hir::BindingAnnotation::Unannotated) + if self.can_eq(self.param_env, *inner_ty, actual).is_ok() => + { + err.span_suggestion_verbose( + span.shrink_to_lo(), + "consider adding `ref`", + "ref ", + Applicability::MaybeIncorrect, + ); + } + (_, ty::Ref(_, inner_ty, _), hir::BindingAnnotation::Ref) + if self.can_eq(self.param_env, expected, *inner_ty).is_ok() => + { + err.span_suggestion_verbose( + span.with_hi(span.lo() + BytePos(4)), + "consider removing `ref`", + "", + Applicability::MaybeIncorrect, + ); + } + _ => (), + } + } + // Precondition: pat is a Ref(_) pattern fn borrow_pat_suggestion(&self, err: &mut Diagnostic, pat: &Pat<'_>) { let tcx = self.tcx; diff --git a/src/test/ui/mismatched_types/E0409.stderr b/src/test/ui/mismatched_types/E0409.stderr index ef03b67b1b0b1..7fec6ecd72573 100644 --- a/src/test/ui/mismatched_types/E0409.stderr +++ b/src/test/ui/mismatched_types/E0409.stderr @@ -17,6 +17,10 @@ LL | (0, ref y) | (y, 0) => {} | first introduced with type `&{integer}` here | = note: in the same arm, a binding must have the same type in all alternatives +help: consider adding `ref` + | +LL | (0, ref y) | (ref y, 0) => {} + | +++ error: aborting due to 2 previous errors diff --git a/src/test/ui/mismatched_types/suggest-adding-or-removing-ref-for-binding-pattern.fixed b/src/test/ui/mismatched_types/suggest-adding-or-removing-ref-for-binding-pattern.fixed new file mode 100644 index 0000000000000..56f93cfbfdcbe --- /dev/null +++ b/src/test/ui/mismatched_types/suggest-adding-or-removing-ref-for-binding-pattern.fixed @@ -0,0 +1,21 @@ +// run-rustfix +#![allow(dead_code, unused_variables)] + +fn main() { + enum Blah { + A(isize, isize, usize), + B(isize, usize), + } + + match Blah::A(1, 1, 2) { + Blah::A(_, x, ref y) | Blah::B(x, ref y) => {} + //~^ ERROR mismatched types + //~| ERROR variable `y` is bound inconsistently across alternatives separated by `|` + } + + match Blah::A(1, 1, 2) { + Blah::A(_, x, y) | Blah::B(x, y) => {} + //~^ ERROR mismatched types + //~| variable `y` is bound inconsistently across alternatives separated by `|` + } +} diff --git a/src/test/ui/mismatched_types/suggest-adding-or-removing-ref-for-binding-pattern.rs b/src/test/ui/mismatched_types/suggest-adding-or-removing-ref-for-binding-pattern.rs new file mode 100644 index 0000000000000..0c33f99a42e8b --- /dev/null +++ b/src/test/ui/mismatched_types/suggest-adding-or-removing-ref-for-binding-pattern.rs @@ -0,0 +1,21 @@ +// run-rustfix +#![allow(dead_code, unused_variables)] + +fn main() { + enum Blah { + A(isize, isize, usize), + B(isize, usize), + } + + match Blah::A(1, 1, 2) { + Blah::A(_, x, ref y) | Blah::B(x, y) => {} + //~^ ERROR mismatched types + //~| ERROR variable `y` is bound inconsistently across alternatives separated by `|` + } + + match Blah::A(1, 1, 2) { + Blah::A(_, x, y) | Blah::B(x, ref y) => {} + //~^ ERROR mismatched types + //~| variable `y` is bound inconsistently across alternatives separated by `|` + } +} diff --git a/src/test/ui/mismatched_types/suggest-adding-or-removing-ref-for-binding-pattern.stderr b/src/test/ui/mismatched_types/suggest-adding-or-removing-ref-for-binding-pattern.stderr new file mode 100644 index 0000000000000..e8357f9a37f8c --- /dev/null +++ b/src/test/ui/mismatched_types/suggest-adding-or-removing-ref-for-binding-pattern.stderr @@ -0,0 +1,49 @@ +error[E0409]: variable `y` is bound inconsistently across alternatives separated by `|` + --> $DIR/suggest-adding-or-removing-ref-for-binding-pattern.rs:11:43 + | +LL | Blah::A(_, x, ref y) | Blah::B(x, y) => {} + | - first binding ^ bound in different ways + +error[E0409]: variable `y` is bound inconsistently across alternatives separated by `|` + --> $DIR/suggest-adding-or-removing-ref-for-binding-pattern.rs:17:43 + | +LL | Blah::A(_, x, y) | Blah::B(x, ref y) => {} + | - first binding ^ bound in different ways + +error[E0308]: mismatched types + --> $DIR/suggest-adding-or-removing-ref-for-binding-pattern.rs:11:43 + | +LL | match Blah::A(1, 1, 2) { + | ---------------- this expression has type `Blah` +LL | Blah::A(_, x, ref y) | Blah::B(x, y) => {} + | ----- ^ expected `&usize`, found `usize` + | | + | first introduced with type `&usize` here + | + = note: in the same arm, a binding must have the same type in all alternatives +help: consider adding `ref` + | +LL | Blah::A(_, x, ref y) | Blah::B(x, ref y) => {} + | +++ + +error[E0308]: mismatched types + --> $DIR/suggest-adding-or-removing-ref-for-binding-pattern.rs:17:39 + | +LL | match Blah::A(1, 1, 2) { + | ---------------- this expression has type `Blah` +LL | Blah::A(_, x, y) | Blah::B(x, ref y) => {} + | - ^^^^^ expected `usize`, found `&usize` + | | + | first introduced with type `usize` here + | + = note: in the same arm, a binding must have the same type in all alternatives +help: consider removing `ref` + | +LL - Blah::A(_, x, y) | Blah::B(x, ref y) => {} +LL + Blah::A(_, x, y) | Blah::B(x, y) => {} + | + +error: aborting due to 4 previous errors + +Some errors have detailed explanations: E0308, E0409. +For more information about an error, try `rustc --explain E0308`. diff --git a/src/test/ui/resolve/resolve-inconsistent-binding-mode.stderr b/src/test/ui/resolve/resolve-inconsistent-binding-mode.stderr index 96c1869b4e726..c805c9eb125c8 100644 --- a/src/test/ui/resolve/resolve-inconsistent-binding-mode.stderr +++ b/src/test/ui/resolve/resolve-inconsistent-binding-mode.stderr @@ -31,6 +31,10 @@ LL | Opts::A(ref i) | Opts::B(i) => {} | first introduced with type `&isize` here | = note: in the same arm, a binding must have the same type in all alternatives +help: consider adding `ref` + | +LL | Opts::A(ref i) | Opts::B(ref i) => {} + | +++ error[E0308]: mismatched types --> $DIR/resolve-inconsistent-binding-mode.rs:18:34 @@ -43,6 +47,10 @@ LL | Opts::A(ref i) | Opts::B(i) => {} | first introduced with type `&isize` here | = note: in the same arm, a binding must have the same type in all alternatives +help: consider adding `ref` + | +LL | Opts::A(ref i) | Opts::B(ref i) => {} + | +++ error[E0308]: mismatched types --> $DIR/resolve-inconsistent-binding-mode.rs:27:38 diff --git a/src/test/ui/resolve/resolve-inconsistent-names.rs b/src/test/ui/resolve/resolve-inconsistent-names.rs index 989d2d4523099..9a40b20346c95 100644 --- a/src/test/ui/resolve/resolve-inconsistent-names.rs +++ b/src/test/ui/resolve/resolve-inconsistent-names.rs @@ -23,6 +23,7 @@ fn main() { //~| ERROR mismatched types //~| ERROR variable `c` is not bound in all patterns //~| HELP if you meant to match on unit variant `E::A`, use the full path in the pattern + //~| HELP consider removing `ref` } let z = (10, 20); diff --git a/src/test/ui/resolve/resolve-inconsistent-names.stderr b/src/test/ui/resolve/resolve-inconsistent-names.stderr index 9de191f7d327a..773c9f6cd1114 100644 --- a/src/test/ui/resolve/resolve-inconsistent-names.stderr +++ b/src/test/ui/resolve/resolve-inconsistent-names.stderr @@ -55,7 +55,7 @@ LL | (A, B) | (ref B, c) | (c, A) => () | first binding error[E0408]: variable `CONST1` is not bound in all patterns - --> $DIR/resolve-inconsistent-names.rs:30:23 + --> $DIR/resolve-inconsistent-names.rs:31:23 | LL | (CONST1, _) | (_, Const2) => () | ------ ^^^^^^^^^^^ pattern doesn't bind `CONST1` @@ -69,7 +69,7 @@ LL | const CONST1: usize = 10; | ^^^^^^^^^^^^^^^^^^^^^^^^^ not accessible error[E0408]: variable `Const2` is not bound in all patterns - --> $DIR/resolve-inconsistent-names.rs:30:9 + --> $DIR/resolve-inconsistent-names.rs:31:9 | LL | (CONST1, _) | (_, Const2) => () | ^^^^^^^^^^^ ------ variable not in all patterns @@ -92,6 +92,11 @@ LL | (A, B) | (ref B, c) | (c, A) => () | first introduced with type `E` here | = note: in the same arm, a binding must have the same type in all alternatives +help: consider removing `ref` + | +LL - (A, B) | (ref B, c) | (c, A) => () +LL + (A, B) | (B, c) | (c, A) => () + | error: aborting due to 9 previous errors