3 files changed, 304 insertions, 85 deletions

diff --git a/crates/hir_ty/src/diagnostics/match_check.rs b/crates/hir_ty/src/diagnostics/match_check.rs
index 5bd03f2ac..62c329731 100644
--- a/crates/hir_ty/src/diagnostics/match_check.rs
+++ b/crates/hir_ty/src/diagnostics/match_check.rs
@@ -216,14 +216,14 @@
 //!   U(P, p) := U(P, (r_1, p_2, .., p_n))
 //!            || U(P, (r_2, p_2, .., p_n))
 //!   ```
-use std::sync::Arc;
+use std::{iter, sync::Arc};
 
 use arena::Idx;
 use hir_def::{
     adt::VariantData,
     body::Body,
     expr::{Expr, Literal, Pat, PatId},
-    AdtId, EnumVariantId, VariantId,
+    AdtId, EnumVariantId, StructId, VariantId,
 };
 use smallvec::{smallvec, SmallVec};
 
@@ -366,16 +366,17 @@ impl PatStack {
 
         let head_pat = head.as_pat(cx);
         let result = match (head_pat, constructor) {
-            (Pat::Tuple { args: ref pat_ids, ellipsis }, Constructor::Tuple { arity: _ }) => {
-                if ellipsis.is_some() {
-                    // If there are ellipsis here, we should add the correct number of
-                    // Pat::Wild patterns to `pat_ids`. We should be able to use the
-                    // constructors arity for this, but at the time of writing we aren't
-                    // correctly calculating this arity when ellipsis are present.
-                    return Err(MatchCheckErr::NotImplemented);
+            (Pat::Tuple { args: pat_ids, ellipsis }, &Constructor::Tuple { arity }) => {
+                if let Some(ellipsis) = ellipsis {
+                    let (pre, post) = pat_ids.split_at(ellipsis);
+                    let n_wild_pats = arity.saturating_sub(pat_ids.len());
+                    let pre_iter = pre.iter().map(Into::into);
+                    let wildcards = iter::repeat(PatIdOrWild::Wild).take(n_wild_pats);
+                    let post_iter = post.iter().map(Into::into);
+                    Some(self.replace_head_with(pre_iter.chain(wildcards).chain(post_iter)))
+                } else {
+                    Some(self.replace_head_with(pat_ids.iter()))
                 }
-
-                Some(self.replace_head_with(pat_ids.iter()))
             }
             (Pat::Lit(lit_expr), Constructor::Bool(constructor_val)) => {
                 match cx.body.exprs[lit_expr] {
@@ -390,21 +391,28 @@ impl PatStack {
                 }
             }
             (Pat::Wild, constructor) => Some(self.expand_wildcard(cx, constructor)?),
-            (Pat::Path(_), Constructor::Enum(constructor)) => {
+            (Pat::Path(_), constructor) => {
                 // unit enum variants become `Pat::Path`
                 let pat_id = head.as_id().expect("we know this isn't a wild");
-                if !enum_variant_matches(cx, pat_id, *constructor) {
+                let variant_id: VariantId = match constructor {
+                    &Constructor::Enum(e) => e.into(),
+                    &Constructor::Struct(s) => s.into(),
+                    _ => return Err(MatchCheckErr::NotImplemented),
+                };
+                if Some(variant_id) != cx.infer.variant_resolution_for_pat(pat_id) {
                     None
                 } else {
                     Some(self.to_tail())
                 }
             }
-            (
-                Pat::TupleStruct { args: ref pat_ids, ellipsis, .. },
-                Constructor::Enum(enum_constructor),
-            ) => {
+            (Pat::TupleStruct { args: ref pat_ids, ellipsis, .. }, constructor) => {
                 let pat_id = head.as_id().expect("we know this isn't a wild");
-                if !enum_variant_matches(cx, pat_id, *enum_constructor) {
+                let variant_id: VariantId = match constructor {
+                    &Constructor::Enum(e) => e.into(),
+                    &Constructor::Struct(s) => s.into(),
+                    _ => return Err(MatchCheckErr::MalformedMatchArm),
+                };
+                if Some(variant_id) != cx.infer.variant_resolution_for_pat(pat_id) {
                     None
                 } else {
                     let constructor_arity = constructor.arity(cx)?;
@@ -442,12 +450,22 @@ impl PatStack {
                     }
                 }
             }
-            (Pat::Record { args: ref arg_patterns, .. }, Constructor::Enum(e)) => {
+            (Pat::Record { args: ref arg_patterns, .. }, constructor) => {
                 let pat_id = head.as_id().expect("we know this isn't a wild");
-                if !enum_variant_matches(cx, pat_id, *e) {
+                let (variant_id, variant_data) = match constructor {
+                    &Constructor::Enum(e) => (
+                        e.into(),
+                        cx.db.enum_data(e.parent).variants[e.local_id].variant_data.clone(),
+                    ),
+                    &Constructor::Struct(s) => {
+                        (s.into(), cx.db.struct_data(s).variant_data.clone())
+                    }
+                    _ => return Err(MatchCheckErr::MalformedMatchArm),
+                };
+                if Some(variant_id) != cx.infer.variant_resolution_for_pat(pat_id) {
                     None
                 } else {
-                    match cx.db.enum_data(e.parent).variants[e.local_id].variant_data.as_ref() {
+                    match variant_data.as_ref() {
                         VariantData::Record(struct_field_arena) => {
                             // Here we treat any missing fields in the record as the wild pattern, as
                             // if the record has ellipsis. We want to do this here even if the
@@ -726,6 +744,7 @@ enum Constructor {
     Bool(bool),
     Tuple { arity: usize },
     Enum(EnumVariantId),
+    Struct(StructId),
 }
 
 impl Constructor {
@@ -740,6 +759,11 @@ impl Constructor {
                     VariantData::Unit => 0,
                 }
             }
+            &Constructor::Struct(s) => match cx.db.struct_data(s).variant_data.as_ref() {
+                VariantData::Tuple(struct_field_data) => struct_field_data.len(),
+                VariantData::Record(struct_field_data) => struct_field_data.len(),
+                VariantData::Unit => 0,
+            },
         };
 
         Ok(arity)
@@ -748,7 +772,7 @@ impl Constructor {
     fn all_constructors(&self, cx: &MatchCheckCtx) -> Vec<Constructor> {
         match self {
             Constructor::Bool(_) => vec![Constructor::Bool(true), Constructor::Bool(false)],
-            Constructor::Tuple { .. } => vec![*self],
+            Constructor::Tuple { .. } | Constructor::Struct(_) => vec![*self],
             Constructor::Enum(e) => cx
                 .db
                 .enum_data(e.parent)
@@ -767,10 +791,11 @@ impl Constructor {
 fn pat_constructor(cx: &MatchCheckCtx, pat: PatIdOrWild) -> MatchCheckResult<Option<Constructor>> {
     let res = match pat.as_pat(cx) {
         Pat::Wild => None,
-        // FIXME somehow create the Tuple constructor with the proper arity. If there are
-        // ellipsis, the arity is not equal to the number of patterns.
-        Pat::Tuple { args: pats, ellipsis } if ellipsis.is_none() => {
-            Some(Constructor::Tuple { arity: pats.len() })
+        Pat::Tuple { .. } => {
+            let pat_id = pat.as_id().expect("we already know this pattern is not a wild");
+            Some(Constructor::Tuple {
+                arity: cx.infer.type_of_pat[pat_id].as_tuple().ok_or(MatchCheckErr::Unknown)?.len(),
+            })
         }
         Pat::Lit(lit_expr) => match cx.body.exprs[lit_expr] {
             Expr::Literal(Literal::Bool(val)) => Some(Constructor::Bool(val)),
@@ -784,6 +809,7 @@ fn pat_constructor(cx: &MatchCheckCtx, pat: PatIdOrWild) -> MatchCheckResult<Opt
                 VariantId::EnumVariantId(enum_variant_id) => {
                     Some(Constructor::Enum(enum_variant_id))
                 }
+                VariantId::StructId(struct_id) => Some(Constructor::Struct(struct_id)),
                 _ => return Err(MatchCheckErr::NotImplemented),
             }
         }
@@ -828,13 +854,13 @@ fn all_constructors_covered(
 
             false
         }),
+        &Constructor::Struct(s) => used_constructors.iter().any(|constructor| match constructor {
+            &Constructor::Struct(sid) => sid == s,
+            _ => false,
+        }),
     }
 }
 
-fn enum_variant_matches(cx: &MatchCheckCtx, pat_id: PatId, enum_variant_id: EnumVariantId) -> bool {
-    Some(enum_variant_id.into()) == cx.infer.variant_resolution_for_pat(pat_id)
-}
-
 #[cfg(test)]
 mod tests {
     use crate::diagnostics::tests::check_diagnostics;
@@ -846,8 +872,8 @@ mod tests {
 fn main() {
     match () { }
         //^^ Missing match arm
-   match (()) { }
-       //^^^^ Missing match arm
+    match (()) { }
+        //^^^^ Missing match arm
 
     match () { _ => (), }
     match () { () => (), }
@@ -1352,6 +1378,123 @@ fn main() {
         );
     }
 
+    #[test]
+    fn tuple_of_bools_with_ellipsis_at_end_missing_arm() {
+        check_diagnostics(
+            r#"
+fn main() {
+    match (false, true, false) {
+        //^^^^^^^^^^^^^^^^^^^^ Missing match arm
+        (false, ..) => (),
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn tuple_of_bools_with_ellipsis_at_beginning_missing_arm() {
+        check_diagnostics(
+            r#"
+fn main() {
+    match (false, true, false) {
+        //^^^^^^^^^^^^^^^^^^^^ Missing match arm
+        (.., false) => (),
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn tuple_of_bools_with_ellipsis_in_middle_missing_arm() {
+        check_diagnostics(
+            r#"
+fn main() {
+    match (false, true, false) {
+        //^^^^^^^^^^^^^^^^^^^^ Missing match arm
+        (true, .., false) => (),
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn record_struct() {
+        check_diagnostics(
+            r#"struct Foo { a: bool }
+fn main(f: Foo) {
+    match f {}
+        //^ Missing match arm
+    match f { Foo { a: true } => () }
+        //^ Missing match arm
+    match &f { Foo { a: true } => () }
+        //^^ Missing match arm
+    match f { Foo { a: _ } => () }
+    match f {
+        Foo { a: true } => (),
+        Foo { a: false } => (),
+    }
+    match &f {
+        Foo { a: true } => (),
+        Foo { a: false } => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn tuple_struct() {
+        check_diagnostics(
+            r#"struct Foo(bool);
+fn main(f: Foo) {
+    match f {}
+        //^ Missing match arm
+    match f { Foo(true) => () }
+        //^ Missing match arm
+    match f {
+        Foo(true) => (),
+        Foo(false) => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn unit_struct() {
+        check_diagnostics(
+            r#"struct Foo;
+fn main(f: Foo) {
+    match f {}
+        //^ Missing match arm
+    match f { Foo => () }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn record_struct_ellipsis() {
+        check_diagnostics(
+            r#"struct Foo { foo: bool, bar: bool }
+fn main(f: Foo) {
+    match f { Foo { foo: true, .. } => () }
+        //^ Missing match arm
+    match f {
+        //^ Missing match arm
+        Foo { foo: true, .. } => (),
+        Foo { bar: false, .. } => ()
+    }
+    match f { Foo { .. } => () }
+    match f {
+        Foo { foo: true, .. } => (),
+        Foo { foo: false, .. } => ()
+    }
+}
+"#,
+        );
+    }
+
     mod false_negatives {
         //! The implementation of match checking here is a work in progress. As we roll this out, we
         //! prefer false negatives to false positives (ideally there would be no false positives). This
@@ -1393,46 +1536,5 @@ fn main() {
 "#,
             );
         }
-
-        #[test]
-        fn tuple_of_bools_with_ellipsis_at_end_missing_arm() {
-            // We don't currently handle tuple patterns with ellipsis.
-            check_diagnostics(
-                r#"
-fn main() {
-    match (false, true, false) {
-        (false, ..) => (),
-    }
-}
-"#,
-            );
-        }
-
-        #[test]
-        fn tuple_of_bools_with_ellipsis_at_beginning_missing_arm() {
-            // We don't currently handle tuple patterns with ellipsis.
-            check_diagnostics(
-                r#"
-fn main() {
-    match (false, true, false) {
-        (.., false) => (),
-    }
-}
-"#,
-            );
-        }
-
-        #[test]
-        fn struct_missing_arm() {
-            // We don't currently handle structs.
-            check_diagnostics(
-                r#"
-struct Foo { a: bool }
-fn main(f: Foo) {
-    match f { Foo { a: true } => () }
-}
-"#,
-            );
-        }
     }
 }
diff --git a/crates/hir_ty/src/infer/pat.rs b/crates/hir_ty/src/infer/pat.rs
index cde2ab82b..b70ec55eb 100644
--- a/crates/hir_ty/src/infer/pat.rs
+++ b/crates/hir_ty/src/infer/pat.rs
@@ -23,6 +23,7 @@ impl<'a> InferenceContext<'a> {
         expected: &Ty,
         default_bm: BindingMode,
         id: PatId,
+        ellipsis: Option<usize>,
     ) -> Ty {
         let (ty, def) = self.resolve_variant(path);
         let var_data = def.map(|it| variant_data(self.db.upcast(), it));
@@ -34,8 +35,15 @@ impl<'a> InferenceContext<'a> {
         let substs = ty.substs().unwrap_or_else(Substs::empty);
 
         let field_tys = def.map(|it| self.db.field_types(it)).unwrap_or_default();
+        let (pre, post) = match ellipsis {
+            Some(idx) => subpats.split_at(idx),
+            None => (&subpats[..], &[][..]),
+        };
+        let post_idx_offset = field_tys.iter().count() - post.len();
 
-        for (i, &subpat) in subpats.iter().enumerate() {
+        let pre_iter = pre.iter().enumerate();
+        let post_iter = (post_idx_offset..).zip(post.iter());
+        for (i, &subpat) in pre_iter.chain(post_iter) {
             let expected_ty = var_data
                 .as_ref()
                 .and_then(|d| d.field(&Name::new_tuple_field(i)))
@@ -111,20 +119,29 @@ impl<'a> InferenceContext<'a> {
         let expected = expected;
 
         let ty = match &body[pat] {
-            Pat::Tuple { ref args, .. } => {
+            &Pat::Tuple { ref args, ellipsis } => {
                 let expectations = match expected.as_tuple() {
                     Some(parameters) => &*parameters.0,
                     _ => &[],
                 };
-                let expectations_iter = expectations.iter().chain(repeat(&Ty::Unknown));
 
-                let inner_tys = args
-                    .iter()
-                    .zip(expectations_iter)
-                    .map(|(&pat, ty)| self.infer_pat(pat, ty, default_bm))
-                    .collect();
+                let (pre, post) = match ellipsis {
+                    Some(idx) => args.split_at(idx),
+                    None => (&args[..], &[][..]),
+                };
+                let n_uncovered_patterns = expectations.len().saturating_sub(args.len());
+                let mut expectations_iter = expectations.iter().chain(repeat(&Ty::Unknown));
+                let mut infer_pat = |(&pat, ty)| self.infer_pat(pat, ty, default_bm);
+
+                let mut inner_tys = Vec::with_capacity(n_uncovered_patterns + args.len());
+                inner_tys.extend(pre.iter().zip(expectations_iter.by_ref()).map(&mut infer_pat));
+                inner_tys.extend(expectations_iter.by_ref().take(n_uncovered_patterns).cloned());
+                inner_tys.extend(post.iter().zip(expectations_iter).map(infer_pat));
 
-                Ty::apply(TypeCtor::Tuple { cardinality: args.len() as u16 }, Substs(inner_tys))
+                Ty::apply(
+                    TypeCtor::Tuple { cardinality: inner_tys.len() as u16 },
+                    Substs(inner_tys.into()),
+                )
             }
             Pat::Or(ref pats) => {
                 if let Some((first_pat, rest)) = pats.split_first() {
@@ -150,9 +167,14 @@ impl<'a> InferenceContext<'a> {
                 let subty = self.infer_pat(*pat, expectation, default_bm);
                 Ty::apply_one(TypeCtor::Ref(*mutability), subty)
             }
-            Pat::TupleStruct { path: p, args: subpats, .. } => {
-                self.infer_tuple_struct_pat(p.as_ref(), subpats, expected, default_bm, pat)
-            }
+            Pat::TupleStruct { path: p, args: subpats, ellipsis } => self.infer_tuple_struct_pat(
+                p.as_ref(),
+                subpats,
+                expected,
+                default_bm,
+                pat,
+                *ellipsis,
+            ),
             Pat::Record { path: p, args: fields, ellipsis: _ } => {
                 self.infer_record_pat(p.as_ref(), fields, expected, default_bm, pat)
             }
diff --git a/crates/hir_ty/src/tests/patterns.rs b/crates/hir_ty/src/tests/patterns.rs
index 6a965ac4f..5a5f48fd0 100644
--- a/crates/hir_ty/src/tests/patterns.rs
+++ b/crates/hir_ty/src/tests/patterns.rs
@@ -679,3 +679,98 @@ fn box_pattern() {
         "#]],
     );
 }
+
+#[test]
+fn tuple_ellipsis_pattern() {
+    check_infer(
+        r#"
+fn foo(tuple: (u8, i16, f32)) {
+    match tuple {
+        (.., b, c) => {},
+        (a, .., c) => {},
+        (a, b, ..) => {},
+        (a, b) => {/*too short*/}
+        (a, b, c, d) => {/*too long*/}
+        _ => {}
+    }
+}"#,
+        expect![[r#"
+            7..12 'tuple': (u8, i16, f32)
+            30..224 '{     ...   } }': ()
+            36..222 'match ...     }': ()
+            42..47 'tuple': (u8, i16, f32)
+            58..68 '(.., b, c)': (u8, i16, f32)
+            63..64 'b': i16
+            66..67 'c': f32
+            72..74 '{}': ()
+            84..94 '(a, .., c)': (u8, i16, f32)
+            85..86 'a': u8
+            92..93 'c': f32
+            98..100 '{}': ()
+            110..120 '(a, b, ..)': (u8, i16, f32)
+            111..112 'a': u8
+            114..115 'b': i16
+            124..126 '{}': ()
+            136..142 '(a, b)': (u8, i16, f32)
+            137..138 'a': u8
+            140..141 'b': i16
+            146..161 '{/*too short*/}': ()
+            170..182 '(a, b, c, d)': (u8, i16, f32, {unknown})
+            171..172 'a': u8
+            174..175 'b': i16
+            177..178 'c': f32
+            180..181 'd': {unknown}
+            186..200 '{/*too long*/}': ()
+            209..210 '_': (u8, i16, f32)
+            214..216 '{}': ()
+        "#]],
+    );
+}
+
+#[test]
+fn tuple_struct_ellipsis_pattern() {
+    check_infer(
+        r#"
+struct Tuple(u8, i16, f32);
+fn foo(tuple: Tuple) {
+    match tuple {
+        Tuple(.., b, c) => {},
+        Tuple(a, .., c) => {},
+        Tuple(a, b, ..) => {},
+        Tuple(a, b) => {/*too short*/}
+        Tuple(a, b, c, d) => {/*too long*/}
+        _ => {}
+    }
+}"#,
+        expect![[r#"
+            35..40 'tuple': Tuple
+            49..268 '{     ...   } }': ()
+            55..266 'match ...     }': ()
+            61..66 'tuple': Tuple
+            77..92 'Tuple(.., b, c)': Tuple
+            87..88 'b': i16
+            90..91 'c': f32
+            96..98 '{}': ()
+            108..123 'Tuple(a, .., c)': Tuple
+            114..115 'a': u8
+            121..122 'c': f32
+            127..129 '{}': ()
+            139..154 'Tuple(a, b, ..)': Tuple
+            145..146 'a': u8
+            148..149 'b': i16
+            158..160 '{}': ()
+            170..181 'Tuple(a, b)': Tuple
+            176..177 'a': u8
+            179..180 'b': i16
+            185..200 '{/*too short*/}': ()
+            209..226 'Tuple(... c, d)': Tuple
+            215..216 'a': u8
+            218..219 'b': i16
+            221..222 'c': f32
+            224..225 'd': {unknown}
+            230..244 '{/*too long*/}': ()
+            253..254 '_': Tuple
+            258..260 '{}': ()
+        "#]],
+    );
+}