Infer type of match guard

4 files changed, 35 insertions, 15 deletions

diff --git a/crates/ra_hir/src/expr.rs b/crates/ra_hir/src/expr.rs
index 60d997bbe..b01d53e5c 100644
--- a/crates/ra_hir/src/expr.rs
+++ b/crates/ra_hir/src/expr.rs
@@ -215,7 +215,7 @@ pub use ra_syntax::ast::BinOp as BinaryOp;
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct MatchArm {
     pub pats: Vec<PatId>,
-    // guard: Option<ExprId>, // TODO
+    pub guard: Option<ExprId>,
     pub expr: ExprId,
 }
 
@@ -511,10 +511,12 @@ impl ExprCollector {
                         MatchArm {
                             pats: vec![pat],
                             expr: then_branch,
+                            guard: None,
                         },
                         MatchArm {
                             pats: vec![placeholder_pat],
                             expr: else_branch,
+                            guard: None,
                         },
                     ];
                     self.alloc_expr(
@@ -613,6 +615,10 @@ impl ExprCollector {
                         .map(|arm| MatchArm {
                             pats: arm.pats().map(|p| self.collect_pat(p)).collect(),
                             expr: self.collect_expr_opt(arm.expr()),
+                            guard: arm.guard().map(|guard| {
+                                let e = guard.expr().expect("every guard should have an expr");
+                                self.collect_expr(e)
+                            }),
                         })
                         .collect()
                 } else {
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index 31ea45706..e2c7884b5 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -1395,7 +1395,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     for &pat in &arm.pats {
                         let _pat_ty = self.infer_pat(pat, &input_ty);
                     }
-                    // TODO type the guard
+                    if let Some(guard_expr) = arm.guard {
+                        self.infer_expr(guard_expr, &Expectation::has_type(Ty::Bool));
+                    }
                     self.infer_expr(arm.expr, &expected);
                 }
 
@@ -1468,9 +1470,17 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 cast_ty
             }
             Expr::Ref { expr, mutability } => {
-                // TODO pass the expectation down
-                let inner_ty = self.infer_expr(*expr, &Expectation::none());
+                let expectation = if let Ty::Ref(ref subty, expected_mutability) = expected.ty {
+                    if expected_mutability == Mutability::Mut && *mutability == Mutability::Shared {
+                        // TODO: throw type error - expected mut reference but found shared ref,
+                        // which cannot be coerced
+                    }
+                    Expectation::has_type((**subty).clone())
+                } else {
+                    Expectation::none()
+                };
                 // TODO reference coercions etc.
+                let inner_ty = self.infer_expr(*expr, &expectation);
                 Ty::Ref(Arc::new(inner_ty), *mutability)
             }
             Expr::UnaryOp { expr, op } => {
diff --git a/crates/ra_hir/src/ty/snapshots/tests__infer_adt_pattern.snap b/crates/ra_hir/src/ty/snapshots/tests__infer_adt_pattern.snap
index 2719f592e..48c83cbb2 100644
--- a/crates/ra_hir/src/ty/snapshots/tests__infer_adt_pattern.snap
+++ b/crates/ra_hir/src/ty/snapshots/tests__infer_adt_pattern.snap
@@ -1,10 +1,10 @@
 ---
-created: "2019-01-22T14:44:59.880187500+00:00"
-creator: insta@0.4.0
+created: "2019-01-28T21:58:55.559331849+00:00"
+creator: insta@0.5.2
 expression: "&result"
-source: "crates\\ra_hir\\src\\ty\\tests.rs"
+source: crates/ra_hir/src/ty/tests.rs
 ---
-[68; 262) '{     ...  d; }': ()
+[68; 289) '{     ...  d; }': ()
 [78; 79) 'e': E
 [82; 95) 'E::A { x: 3 }': E
 [92; 93) '3': usize
@@ -15,15 +15,18 @@ source: "crates\\ra_hir\\src\\ty\\tests.rs"
 [129; 148) 'E::A {..._var }': E
 [139; 146) 'new_var': usize
 [151; 152) 'e': E
-[159; 218) 'match ...     }': usize
+[159; 245) 'match ...     }': usize
 [165; 166) 'e': E
 [177; 187) 'E::A { x }': E
 [184; 185) 'x': usize
 [191; 192) 'x': usize
 [202; 206) 'E::B': E
-[210; 211) '1': usize
-[229; 248) 'ref d ...{ .. }': &E
-[237; 248) 'E::A { .. }': E
-[251; 252) 'e': E
-[258; 259) 'd': &E
+[210; 213) 'foo': bool
+[217; 218) '1': usize
+[228; 232) 'E::B': E
+[236; 238) '10': usize
+[256; 275) 'ref d ...{ .. }': &E
+[264; 275) 'E::A { .. }': E
+[278; 279) 'e': E
+[285; 286) 'd': &E
 
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index f74d6f5ea..8aa188059 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -421,7 +421,8 @@ fn test() {
 
     match e {
         E::A { x } => x,
-        E::B => 1,
+        E::B if foo => 1,
+        E::B => 10,
     };
 
     let ref d @ E::A { .. } = e;