3 files changed, 65 insertions, 19 deletions

diff --git a/crates/ra_hir/src/ty/display.rs b/crates/ra_hir/src/ty/display.rs
new file mode 100644
index 000000000..63ec9d7e1
--- /dev/null
+++ b/crates/ra_hir/src/ty/display.rs
@@ -0,0 +1,56 @@
+use std::fmt;
+
+use crate::db::HirDatabase;
+
+pub struct HirFormatter<'a, 'b, DB> {
+    pub db: &'a DB,
+    fmt: &'a mut fmt::Formatter<'b>,
+}
+
+pub trait HirDisplay {
+    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result;
+    fn display<'a, DB>(&'a self, db: &'a DB) -> HirDisplayWrapper<'a, DB, Self>
+    where
+        Self: Sized,
+    {
+        HirDisplayWrapper(db, self)
+    }
+}
+
+impl<'a, 'b, DB> HirFormatter<'a, 'b, DB>
+where
+    DB: HirDatabase,
+{
+    pub fn write_joined<T: HirDisplay>(
+        &mut self,
+        iter: impl IntoIterator<Item = T>,
+        sep: &str,
+    ) -> fmt::Result {
+        let mut first = true;
+        for e in iter {
+            if !first {
+                write!(self, "{}", sep)?;
+            }
+            first = false;
+            e.hir_fmt(self)?;
+        }
+        Ok(())
+    }
+
+    /// This allows using the `write!` macro directly with a `HirFormatter`.
+    pub fn write_fmt(&mut self, args: fmt::Arguments) -> fmt::Result {
+        fmt::write(self.fmt, args)
+    }
+}
+
+pub struct HirDisplayWrapper<'a, DB, T>(&'a DB, &'a T);
+
+impl<'a, DB, T> fmt::Display for HirDisplayWrapper<'a, DB, T>
+where
+    DB: HirDatabase,
+    T: HirDisplay,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.1.hir_fmt(&mut HirFormatter { db: self.0, fmt: f })
+    }
+}
diff --git a/crates/ra_hir/src/ty/lower.rs b/crates/ra_hir/src/ty/lower.rs
index f4e055feb..ee4508bb2 100644
--- a/crates/ra_hir/src/ty/lower.rs
+++ b/crates/ra_hir/src/ty/lower.rs
@@ -9,7 +9,7 @@
 use std::sync::Arc;
 
 use crate::{
-    Function, Struct, StructField, Enum, EnumVariant, Path, Name,
+    Function, Struct, StructField, Enum, EnumVariant, Path,
     ModuleDef, TypeAlias,
     Const, Static,
     HirDatabase,
@@ -232,13 +232,12 @@ fn type_for_fn(db: &impl HirDatabase, def: Function) -> Ty {
     let signature = def.signature(db);
     let resolver = def.resolver(db);
     let generics = def.generic_params(db);
-    let name = def.name(db);
     let input =
         signature.params().iter().map(|tr| Ty::from_hir(db, &resolver, tr)).collect::<Vec<_>>();
     let output = Ty::from_hir(db, &resolver, signature.ret_type());
     let sig = Arc::new(FnSig { input, output });
     let substs = make_substs(&generics);
-    Ty::FnDef { def: def.into(), sig, name, substs }
+    Ty::FnDef { def: def.into(), sig, substs }
 }
 
 /// Build the declared type of a const.
@@ -266,7 +265,6 @@ fn type_for_struct_constructor(db: &impl HirDatabase, def: Struct) -> Ty {
     };
     let resolver = def.resolver(db);
     let generics = def.generic_params(db);
-    let name = def.name(db).unwrap_or_else(Name::missing);
     let input = fields
         .iter()
         .map(|(_, field)| Ty::from_hir(db, &resolver, &field.type_ref))
@@ -274,7 +272,7 @@ fn type_for_struct_constructor(db: &impl HirDatabase, def: Struct) -> Ty {
     let output = type_for_struct(db, def);
     let sig = Arc::new(FnSig { input, output });
     let substs = make_substs(&generics);
-    Ty::FnDef { def: def.into(), sig, name, substs }
+    Ty::FnDef { def: def.into(), sig, substs }
 }
 
 /// Build the type of a tuple enum variant constructor.
@@ -286,7 +284,6 @@ fn type_for_enum_variant_constructor(db: &impl HirDatabase, def: EnumVariant) ->
     };
     let resolver = def.parent_enum(db).resolver(db);
     let generics = def.parent_enum(db).generic_params(db);
-    let name = def.name(db).unwrap_or_else(Name::missing);
     let input = fields
         .iter()
         .map(|(_, field)| Ty::from_hir(db, &resolver, &field.type_ref))
@@ -294,7 +291,7 @@ fn type_for_enum_variant_constructor(db: &impl HirDatabase, def: EnumVariant) ->
     let substs = make_substs(&generics);
     let output = type_for_enum(db, def.parent_enum(db)).subst(&substs);
     let sig = Arc::new(FnSig { input, output });
-    Ty::FnDef { def: def.into(), sig, name, substs }
+    Ty::FnDef { def: def.into(), sig, substs }
 }
 
 fn make_substs(generics: &GenericParams) -> Substs {
@@ -310,20 +307,12 @@ fn make_substs(generics: &GenericParams) -> Substs {
 
 fn type_for_struct(db: &impl HirDatabase, s: Struct) -> Ty {
     let generics = s.generic_params(db);
-    Ty::Adt {
-        def_id: s.into(),
-        name: s.name(db).unwrap_or_else(Name::missing),
-        substs: make_substs(&generics),
-    }
+    Ty::Adt { def_id: s.into(), substs: make_substs(&generics) }
 }
 
 fn type_for_enum(db: &impl HirDatabase, s: Enum) -> Ty {
     let generics = s.generic_params(db);
-    Ty::Adt {
-        def_id: s.into(),
-        name: s.name(db).unwrap_or_else(Name::missing),
-        substs: make_substs(&generics),
-    }
+    Ty::Adt { def_id: s.into(), substs: make_substs(&generics) }
 }
 
 fn type_for_type_alias(db: &impl HirDatabase, t: TypeAlias) -> Ty {
diff --git a/crates/ra_hir/src/ty/tests.rs b/crates/ra_hir/src/ty/tests.rs
index c7d409e6d..acae71c26 100644
--- a/crates/ra_hir/src/ty/tests.rs
+++ b/crates/ra_hir/src/ty/tests.rs
@@ -10,6 +10,7 @@ use test_utils::covers;
 use crate::{
     source_binder,
     mock::MockDatabase,
+    ty::display::HirDisplay,
 };
 
 // These tests compare the inference results for all expressions in a file
@@ -2142,7 +2143,7 @@ fn type_at_pos(db: &MockDatabase, pos: FilePosition) -> String {
     let node = algo::find_node_at_offset::<ast::Expr>(syntax.syntax(), pos.offset).unwrap();
     let expr = body_source_map.node_expr(node).unwrap();
     let ty = &inference_result[expr];
-    ty.to_string()
+    ty.display(db).to_string()
 }
 
 fn infer(content: &str) -> String {
@@ -2178,7 +2179,7 @@ fn infer(content: &str) -> String {
                 "{} '{}': {}\n",
                 syntax_ptr.range(),
                 ellipsize(node.text().to_string().replace("\n", " "), 15),
-                ty
+                ty.display(&db)
             )
             .unwrap();
         }