diff --git a/src/librustc_typeck/check/pat.rs b/src/librustc_typeck/check/pat.rs index b7aac707a9838..dd4b407ac52cb 100644 --- a/src/librustc_typeck/check/pat.rs +++ b/src/librustc_typeck/check/pat.rs @@ -63,6 +63,22 @@ struct TopInfo<'tcx> { /// found type `std::result::Result<_, _>` /// ``` span: Option, + /// This refers to the parent pattern. Used to provide extra diagnostic information on errors. + /// ```text + /// error[E0308]: mismatched types + /// --> $DIR/const-in-struct-pat.rs:8:17 + /// | + /// L | struct f; + /// | --------- unit struct defined here + /// ... + /// L | let Thing { f } = t; + /// | ^ + /// | | + /// | expected struct `std::string::String`, found struct `f` + /// | `f` is interpreted as a unit struct, not a new binding + /// | help: bind the struct field to a different name instead: `f: other_f` + /// ``` + parent_pat: Option<&'tcx Pat<'tcx>>, } impl<'tcx> FnCtxt<'_, 'tcx> { @@ -120,7 +136,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { span: Option, origin_expr: bool, ) { - self.check_pat(pat, expected, INITIAL_BM, TopInfo { expected, origin_expr, span }); + let info = TopInfo { expected, origin_expr, span, parent_pat: None }; + self.check_pat(pat, expected, INITIAL_BM, info); } /// Type check the given `pat` against the `expected` type @@ -161,8 +178,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { self.check_pat_struct(pat, qpath, fields, etc, expected, def_bm, ti) } PatKind::Or(pats) => { + let parent_pat = Some(pat); for pat in pats { - self.check_pat(pat, expected, def_bm, ti); + self.check_pat(pat, expected, def_bm, TopInfo { parent_pat, ..ti }); } expected } @@ -501,7 +519,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { fn check_pat_ident( &self, - pat: &Pat<'_>, + pat: &'tcx Pat<'tcx>, ba: hir::BindingAnnotation, var_id: HirId, sub: Option<&'tcx Pat<'tcx>>, @@ -546,7 +564,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } if let Some(p) = sub { - self.check_pat(&p, expected, def_bm, ti); + self.check_pat(&p, expected, def_bm, TopInfo { parent_pat: Some(&pat), ..ti }); } local_ty @@ -647,6 +665,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { variant_ty } else { for field in fields { + let ti = TopInfo { parent_pat: Some(&pat), ..ti }; self.check_pat(&field.pat, self.tcx.types.err, def_bm, ti); } return self.tcx.types.err; @@ -656,9 +675,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { self.demand_eqtype_pat(pat.span, expected, pat_ty, ti); // Type-check subpatterns. - if self - .check_struct_pat_fields(pat_ty, pat.hir_id, pat.span, variant, fields, etc, def_bm, ti) - { + if self.check_struct_pat_fields(pat_ty, &pat, variant, fields, etc, def_bm, ti) { pat_ty } else { self.tcx.types.err @@ -696,18 +713,56 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } // Type-check the path. - let pat_ty = self.instantiate_value_path(segments, opt_ty, res, pat.span, pat.hir_id).0; - if let Some(mut err) = + let (pat_ty, pat_res) = + self.instantiate_value_path(segments, opt_ty, res, pat.span, pat.hir_id); + if let Some(err) = self.demand_suptype_with_origin(&self.pattern_cause(ti, pat.span), expected, pat_ty) { - err.emit(); + self.emit_bad_pat_path(err, pat.span, res, pat_res, segments, ti.parent_pat); } pat_ty } + fn emit_bad_pat_path( + &self, + mut e: DiagnosticBuilder<'_>, + pat_span: Span, + res: Res, + pat_res: Res, + segments: &'b [hir::PathSegment<'b>], + parent_pat: Option<&Pat<'_>>, + ) { + if let Some(span) = self.tcx.hir().res_span(pat_res) { + e.span_label(span, &format!("{} defined here", res.descr())); + if let [hir::PathSegment { ident, .. }] = &*segments { + e.span_label( + pat_span, + &format!( + "`{}` is interpreted as {} {}, not a new binding", + ident, + res.article(), + res.descr(), + ), + ); + let (msg, sugg) = match parent_pat { + Some(Pat { kind: hir::PatKind::Struct(..), .. }) => ( + "bind the struct field to a different name instead", + format!("{}: other_{}", ident, ident.as_str().to_lowercase()), + ), + _ => ( + "introduce a new binding instead", + format!("other_{}", ident.as_str().to_lowercase()), + ), + }; + e.span_suggestion(ident.span, msg, sugg, Applicability::HasPlaceholders); + } + } + e.emit(); + } + fn check_pat_tuple_struct( &self, - pat: &Pat<'_>, + pat: &'tcx Pat<'tcx>, qpath: &hir::QPath<'_>, subpats: &'tcx [&'tcx Pat<'tcx>], ddpos: Option, @@ -717,8 +772,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { ) -> Ty<'tcx> { let tcx = self.tcx; let on_error = || { + let parent_pat = Some(pat); for pat in subpats { - self.check_pat(&pat, tcx.types.err, def_bm, ti); + self.check_pat(&pat, tcx.types.err, def_bm, TopInfo { parent_pat, ..ti }); } }; let report_unexpected_res = |res: Res| { @@ -793,7 +849,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { }; for (i, subpat) in subpats.iter().enumerate_and_adjust(variant.fields.len(), ddpos) { let field_ty = self.field_ty(subpat.span, &variant.fields[i], substs); - self.check_pat(&subpat, field_ty, def_bm, ti); + self.check_pat(&subpat, field_ty, def_bm, TopInfo { parent_pat: Some(&pat), ..ti }); self.tcx.check_stability(variant.fields[i].did, Some(pat.hir_id), subpat.span); } @@ -938,8 +994,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { fn check_struct_pat_fields( &self, adt_ty: Ty<'tcx>, - pat_id: HirId, - span: Span, + pat: &'tcx Pat<'tcx>, variant: &'tcx ty::VariantDef, fields: &'tcx [hir::FieldPat<'tcx>], etc: bool, @@ -950,7 +1005,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let (substs, adt) = match adt_ty.kind { ty::Adt(adt, substs) => (substs, adt), - _ => span_bug!(span, "struct pattern is not an ADT"), + _ => span_bug!(pat.span, "struct pattern is not an ADT"), }; let kind_name = adt.variant_descr(); @@ -983,7 +1038,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { .get(&ident) .map(|(i, f)| { self.write_field_index(field.hir_id, *i); - self.tcx.check_stability(f.did, Some(pat_id), span); + self.tcx.check_stability(f.did, Some(pat.hir_id), span); self.field_ty(span, f, substs) }) .unwrap_or_else(|| { @@ -994,7 +1049,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } }; - self.check_pat(&field.pat, field_ty, def_bm, ti); + self.check_pat(&field.pat, field_ty, def_bm, TopInfo { parent_pat: Some(&pat), ..ti }); } let mut unmentioned_fields = variant @@ -1017,7 +1072,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { if variant.is_field_list_non_exhaustive() && !adt.did.is_local() && !etc { struct_span_err!( tcx.sess, - span, + pat.span, E0638, "`..` required with {} marked as non-exhaustive", kind_name @@ -1029,14 +1084,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { if kind_name == "union" { if fields.len() != 1 { tcx.sess - .struct_span_err(span, "union patterns should have exactly one field") + .struct_span_err(pat.span, "union patterns should have exactly one field") .emit(); } if etc { - tcx.sess.struct_span_err(span, "`..` cannot be used in union patterns").emit(); + tcx.sess.struct_span_err(pat.span, "`..` cannot be used in union patterns").emit(); } } else if !etc && !unmentioned_fields.is_empty() { - self.error_unmentioned_fields(span, &unmentioned_fields, variant); + self.error_unmentioned_fields(pat.span, &unmentioned_fields, variant); } no_field_errors } @@ -1196,7 +1251,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { fn check_pat_ref( &self, - pat: &Pat<'_>, + pat: &'tcx Pat<'tcx>, inner: &'tcx Pat<'tcx>, mutbl: hir::Mutability, expected: Ty<'tcx>, @@ -1236,7 +1291,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } else { (tcx.types.err, tcx.types.err) }; - self.check_pat(&inner, inner_ty, def_bm, ti); + self.check_pat(&inner, inner_ty, def_bm, TopInfo { parent_pat: Some(&pat), ..ti }); rptr_ty } diff --git a/src/test/ui/blind/blind-item-block-middle.stderr b/src/test/ui/blind/blind-item-block-middle.stderr index 264e7fc8e73a2..d8d15615d7c33 100644 --- a/src/test/ui/blind/blind-item-block-middle.stderr +++ b/src/test/ui/blind/blind-item-block-middle.stderr @@ -1,8 +1,15 @@ error[E0308]: mismatched types --> $DIR/blind-item-block-middle.rs:6:9 | +LL | mod foo { pub struct bar; } + | --------------- unit struct defined here +... LL | let bar = 5; - | ^^^ expected integer, found struct `foo::bar` + | ^^^ + | | + | expected integer, found struct `foo::bar` + | `bar` is interpreted as a unit struct, not a new binding + | help: introduce a new binding instead: `other_bar` error: aborting due to previous error diff --git a/src/test/ui/issues/issue-33504.stderr b/src/test/ui/issues/issue-33504.stderr index 522df6a07c2c6..1e61178f42edb 100644 --- a/src/test/ui/issues/issue-33504.stderr +++ b/src/test/ui/issues/issue-33504.stderr @@ -1,8 +1,15 @@ error[E0308]: mismatched types --> $DIR/issue-33504.rs:7:13 | +LL | struct Test; + | ------------ unit struct defined here +... LL | let Test = 1; - | ^^^^ expected integer, found struct `Test` + | ^^^^ + | | + | expected integer, found struct `Test` + | `Test` is interpreted as a unit struct, not a new binding + | help: introduce a new binding instead: `other_test` error: aborting due to previous error diff --git a/src/test/ui/issues/issue-4968.stderr b/src/test/ui/issues/issue-4968.stderr index 35435d0e61819..5451cf423559e 100644 --- a/src/test/ui/issues/issue-4968.stderr +++ b/src/test/ui/issues/issue-4968.stderr @@ -1,8 +1,15 @@ error[E0308]: mismatched types --> $DIR/issue-4968.rs:5:16 | +LL | const A: (isize,isize) = (4,2); + | ------------------------------- constant defined here +LL | fn main() { LL | match 42 { A => () } - | ^ expected integer, found tuple + | ^ + | | + | expected integer, found tuple + | `A` is interpreted as a constant, not a new binding + | help: introduce a new binding instead: `other_a` | = note: expected type `{integer}` found tuple `(isize, isize)` diff --git a/src/test/ui/issues/issue-5100.stderr b/src/test/ui/issues/issue-5100.stderr index c81d6dcaf0217..a89980964ca0a 100644 --- a/src/test/ui/issues/issue-5100.stderr +++ b/src/test/ui/issues/issue-5100.stderr @@ -1,6 +1,9 @@ error[E0308]: mismatched types --> $DIR/issue-5100.rs:8:9 | +LL | enum A { B, C } + | - unit variant defined here +... LL | match (true, false) { | ------------- this expression has type `(bool, bool)` LL | A::B => (), diff --git a/src/test/ui/issues/issue-7867.stderr b/src/test/ui/issues/issue-7867.stderr index 4a29464aebd2b..0d3121d60455d 100644 --- a/src/test/ui/issues/issue-7867.stderr +++ b/src/test/ui/issues/issue-7867.stderr @@ -1,6 +1,9 @@ error[E0308]: mismatched types --> $DIR/issue-7867.rs:7:9 | +LL | enum A { B, C } + | - unit variant defined here +... LL | match (true, false) { | ------------- this expression has type `(bool, bool)` LL | A::B => (), diff --git a/src/test/ui/match/match-tag-nullary.stderr b/src/test/ui/match/match-tag-nullary.stderr index 3703a59edb836..723c7fa92b10d 100644 --- a/src/test/ui/match/match-tag-nullary.stderr +++ b/src/test/ui/match/match-tag-nullary.stderr @@ -1,6 +1,9 @@ error[E0308]: mismatched types --> $DIR/match-tag-nullary.rs:4:40 | +LL | enum B { B } + | - unit variant defined here +LL | LL | fn main() { let x: A = A::A; match x { B::B => { } } } | - ^^^^ expected enum `A`, found enum `B` | | diff --git a/src/test/ui/rfc-2005-default-binding-mode/const.stderr b/src/test/ui/rfc-2005-default-binding-mode/const.stderr index 27efd450b9471..10d30ec1a1b18 100644 --- a/src/test/ui/rfc-2005-default-binding-mode/const.stderr +++ b/src/test/ui/rfc-2005-default-binding-mode/const.stderr @@ -1,10 +1,17 @@ error[E0308]: mismatched types --> $DIR/const.rs:14:9 | +LL | const FOO: Foo = Foo{bar: 5}; + | ----------------------------- constant defined here +... LL | match &f { | -- this expression has type `&Foo` LL | FOO => {}, - | ^^^ expected `&Foo`, found struct `Foo` + | ^^^ + | | + | expected `&Foo`, found struct `Foo` + | `FOO` is interpreted as a constant, not a new binding + | help: introduce a new binding instead: `other_foo` error: aborting due to previous error diff --git a/src/test/ui/suggestions/const-in-struct-pat.rs b/src/test/ui/suggestions/const-in-struct-pat.rs new file mode 100644 index 0000000000000..1cbba935402a9 --- /dev/null +++ b/src/test/ui/suggestions/const-in-struct-pat.rs @@ -0,0 +1,11 @@ +#[allow(non_camel_case_types)] +struct foo; +struct Thing { + foo: String, +} + +fn example(t: Thing) { + let Thing { foo } = t; //~ ERROR mismatched types +} + +fn main() {} diff --git a/src/test/ui/suggestions/const-in-struct-pat.stderr b/src/test/ui/suggestions/const-in-struct-pat.stderr new file mode 100644 index 0000000000000..0a010dcab4c26 --- /dev/null +++ b/src/test/ui/suggestions/const-in-struct-pat.stderr @@ -0,0 +1,16 @@ +error[E0308]: mismatched types + --> $DIR/const-in-struct-pat.rs:8:17 + | +LL | struct foo; + | ----------- unit struct defined here +... +LL | let Thing { foo } = t; + | ^^^ - this expression has type `Thing` + | | + | expected struct `std::string::String`, found struct `foo` + | `foo` is interpreted as a unit struct, not a new binding + | help: bind the struct field to a different name instead: `foo: other_foo` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0308`.