5 files changed, 78 insertions, 21 deletions

diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index 12399c6ac..99c247a0b 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -551,6 +551,14 @@ impl DefWithBody {
             DefWithBody::Static(s) => s.resolver(db),
         }
     }
+
+    pub(crate) fn krate(self, db: &impl HirDatabase) -> Option<Crate> {
+        match self {
+            DefWithBody::Const(c) => c.krate(db),
+            DefWithBody::Function(f) => f.krate(db),
+            DefWithBody::Static(s) => s.krate(db),
+        }
+    }
 }
 
 pub trait HasBody: Copy {
@@ -671,6 +679,10 @@ impl Function {
         self.id.module(db)
     }
 
+    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
+        self.module(db).krate(db)
+    }
+
     pub fn name(self, db: &impl HirDatabase) -> Name {
         self.data(db).name.clone()
     }
@@ -745,6 +757,10 @@ impl Const {
         self.id.module(db)
     }
 
+    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
+        self.module(db).krate(db)
+    }
+
     pub fn data(self, db: &impl HirDatabase) -> Arc<ConstData> {
         db.const_data(self)
     }
@@ -824,6 +840,10 @@ impl Static {
         self.id.module(db)
     }
 
+    pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
+        self.module(db).krate(db)
+    }
+
     pub fn data(self, db: &impl HirDatabase) -> Arc<ConstData> {
         db.static_data(self)
     }
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index 36bfb10ce..e6ecbe1ea 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -16,7 +16,10 @@ use std::ops::Deref;
 use std::sync::Arc;
 use std::{fmt, mem};
 
-use crate::{db::HirDatabase, type_ref::Mutability, Adt, GenericParams, Name, Trait, TypeAlias};
+use crate::{
+    db::HirDatabase, expr::ExprId, type_ref::Mutability, Adt, DefWithBody, GenericParams, Name,
+    Trait, TypeAlias,
+};
 use display::{HirDisplay, HirFormatter};
 
 pub(crate) use autoderef::autoderef;
@@ -100,6 +103,12 @@ pub enum TypeCtor {
     /// couldn't find a better representation.  In that case, we generate
     /// an **application type** like `(Iterator::Item)<T>`.
     AssociatedType(TypeAlias),
+
+    /// The type of a specific closure.
+    ///
+    /// The closure signature is stored in a `FnPtr` type in the first type
+    /// parameter.
+    Closure { def: DefWithBody, expr: ExprId },
 }
 
 /// A nominal type with (maybe 0) type parameters. This might be a primitive
@@ -481,6 +490,10 @@ impl Ty {
                     let sig = db.callable_item_signature(def);
                     Some(sig.subst(&a_ty.parameters))
                 }
+                TypeCtor::Closure { .. } => {
+                    let sig_param = &a_ty.parameters[0];
+                    sig_param.callable_sig(db)
+                }
                 _ => None,
             },
             _ => None,
@@ -720,6 +733,14 @@ impl HirDisplay for ApplicationTy {
                     write!(f, ">")?;
                 }
             }
+            TypeCtor::Closure { .. } => {
+                let sig = self.parameters[0]
+                    .callable_sig(f.db)
+                    .expect("first closure parameter should contain signature");
+                write!(f, "|")?;
+                f.write_joined(sig.params(), ", ")?;
+                write!(f, "| -> {}", sig.ret().display(f.db))?;
+            }
         }
         Ok(())
     }
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index 81a8623bf..c04f2a0c4 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -885,18 +885,32 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             Expr::Lambda { body, args, arg_types } => {
                 assert_eq!(args.len(), arg_types.len());
 
+                let mut sig_tys = Vec::new();
+
                 for (arg_pat, arg_type) in args.iter().zip(arg_types.iter()) {
                     let expected = if let Some(type_ref) = arg_type {
                         self.make_ty(type_ref)
                     } else {
                         Ty::Unknown
                     };
-                    self.infer_pat(*arg_pat, &expected, BindingMode::default());
+                    let arg_ty = self.infer_pat(*arg_pat, &expected, BindingMode::default());
+                    sig_tys.push(arg_ty);
                 }
 
-                // FIXME: infer lambda type etc.
-                let _body_ty = self.infer_expr(*body, &Expectation::none());
-                Ty::Unknown
+                // add return type
+                let ret_ty = self.new_type_var();
+                sig_tys.push(ret_ty.clone());
+                let sig_ty = Ty::apply(
+                    TypeCtor::FnPtr { num_args: sig_tys.len() as u16 - 1 },
+                    sig_tys.into(),
+                );
+                let closure_ty = Ty::apply_one(
+                    TypeCtor::Closure { def: self.body.owner(), expr: tgt_expr },
+                    sig_ty,
+                );
+
+                self.infer_expr(*body, &Expectation::has_type(ret_ty));
+                closure_ty
             }
             Expr::Call { callee, args } => {
                 let callee_ty = self.infer_expr(*callee, &Expectation::none());
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index 3ac1fbdd5..eb8770ec4 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -1077,7 +1077,6 @@ fn test(x: &i32) {
 }
 "#),
         @r###"
-
     [9; 10) 'x': &i32
     [18; 369) '{     ...o_x; }': ()
     [28; 29) 'y': &i32
@@ -1107,8 +1106,8 @@ fn test(x: &i32) {
     [177; 205) '{     ...     }': ()
     [191; 192) 'h': {unknown}
     [195; 198) 'val': {unknown}
-    [215; 221) 'lambda': {unknown}
-    [224; 256) '|a: u6...b; c }': {unknown}
+    [215; 221) 'lambda': |u64, u64, i32| -> i32
+    [224; 256) '|a: u6...b; c }': |u64, u64, i32| -> i32
     [225; 226) 'a': u64
     [233; 234) 'b': u64
     [236; 237) 'c': i32
@@ -2836,12 +2835,11 @@ fn test() -> u64 {
 }
 "#),
         @r###"
-
     [44; 102) '{     ...0(2) }': u64
     [54; 55) 'a': S
     [58; 59) 'S': S(fn(u32) -> u64) -> S
     [58; 68) 'S(|i| 2*i)': S
-    [60; 67) '|i| 2*i': fn(u32) -> u64
+    [60; 67) '|i| 2*i': |i32| -> i32
     [61; 62) 'i': i32
     [64; 65) '2': i32
     [64; 67) '2*i': i32
@@ -4019,20 +4017,20 @@ fn test() {
     [188; 192) '1i32': i32
     [199; 200) 'x': Option<i32>
     [199; 215) 'x.map(...v + 1)': {unknown}
-    [205; 214) '|v| v + 1': {unknown}
+    [205; 214) '|v| v + 1': |{unknown}| -> i32
     [206; 207) 'v': {unknown}
     [209; 210) 'v': {unknown}
     [209; 214) 'v + 1': i32
     [213; 214) '1': i32
     [221; 222) 'x': Option<i32>
     [221; 237) 'x.map(... 1u64)': {unknown}
-    [227; 236) '|_v| 1u64': {unknown}
+    [227; 236) '|_v| 1u64': |{unknown}| -> u64
     [228; 230) '_v': {unknown}
     [232; 236) '1u64': u64
     [247; 248) 'y': Option<i64>
     [264; 265) 'x': Option<i32>
     [264; 277) 'x.map(|_v| 1)': Option<i64>
-    [270; 276) '|_v| 1': {unknown}
+    [270; 276) '|_v| 1': |{unknown}| -> i32
     [271; 273) '_v': {unknown}
     [275; 276) '1': i32
     "###
@@ -4060,17 +4058,17 @@ fn test<F: FnOnce(u32) -> u64>(f: F) {
     [85; 86) 'f': F
     [85; 89) 'f(1)': {unknown}
     [87; 88) '1': i32
-    [99; 100) 'g': {unknown}
-    [103; 112) '|v| v + 1': {unknown}
-    [104; 105) 'v': {unknown}
-    [107; 108) 'v': {unknown}
+    [99; 100) 'g': |u64| -> i32
+    [103; 112) '|v| v + 1': |u64| -> i32
+    [104; 105) 'v': u64
+    [107; 108) 'v': u64
     [107; 112) 'v + 1': i32
     [111; 112) '1': i32
-    [118; 119) 'g': {unknown}
-    [118; 125) 'g(1u64)': {unknown}
+    [118; 119) 'g': |u64| -> i32
+    [118; 125) 'g(1u64)': i32
     [120; 124) '1u64': u64
-    [135; 136) 'h': {unknown}
-    [139; 152) '|v| 1u128 + v': {unknown}
+    [135; 136) 'h': |u128| -> u128
+    [139; 152) '|v| 1u128 + v': |u128| -> u128
     [140; 141) 'v': u128
     [143; 148) '1u128': u128
     [143; 152) '1u128 + v': u128
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index 462156021..34e623931 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -571,6 +571,10 @@ pub(crate) fn struct_datum_query(
                 type_alias.krate(db) != Some(krate),
             )
         }
+        TypeCtor::Closure { def, .. } => {
+            let upstream = def.krate(db) != Some(krate);
+            (1, vec![], upstream)
+        }
     };
     let flags = chalk_rust_ir::StructFlags {
         upstream,