2 files changed, 34 insertions, 6 deletions

diff --git a/crates/ra_hir_def/src/builtin_type.rs b/crates/ra_hir_def/src/builtin_type.rs
index 12929caa9..2ec0c83fe 100644
--- a/crates/ra_hir_def/src/builtin_type.rs
+++ b/crates/ra_hir_def/src/builtin_type.rs
@@ -3,6 +3,8 @@
 //! A peculiarity of built-in types is that they are always available and are
 //! not associated with any particular crate.
 
+use std::fmt;
+
 use hir_expand::name::{self, Name};
 
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
@@ -61,3 +63,33 @@ impl BuiltinType {
         (name::F64, BuiltinType::Float { bitness: FloatBitness::X64 }),
     ];
 }
+
+impl fmt::Display for BuiltinType {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let type_name = match self {
+            BuiltinType::Char => "char",
+            BuiltinType::Bool => "bool",
+            BuiltinType::Str => "str",
+            BuiltinType::Int { signedness, bitness } => match (signedness, bitness) {
+                (Signedness::Signed, IntBitness::Xsize) => "isize",
+                (Signedness::Signed, IntBitness::X8) => "i8",
+                (Signedness::Signed, IntBitness::X16) => "i16",
+                (Signedness::Signed, IntBitness::X32) => "i32",
+                (Signedness::Signed, IntBitness::X64) => "i64",
+                (Signedness::Signed, IntBitness::X128) => "i128",
+
+                (Signedness::Unsigned, IntBitness::Xsize) => "usize",
+                (Signedness::Unsigned, IntBitness::X8) => "u8",
+                (Signedness::Unsigned, IntBitness::X16) => "u16",
+                (Signedness::Unsigned, IntBitness::X32) => "u32",
+                (Signedness::Unsigned, IntBitness::X64) => "u64",
+                (Signedness::Unsigned, IntBitness::X128) => "u128",
+            },
+            BuiltinType::Float { bitness } => match bitness {
+                FloatBitness::X32 => "f32",
+                FloatBitness::X64 => "f64",
+            },
+        };
+        f.write_str(type_name)
+    }
+}
diff --git a/crates/ra_ide_api/src/hover.rs b/crates/ra_ide_api/src/hover.rs
index 244c65814..cc41390b2 100644
--- a/crates/ra_ide_api/src/hover.rs
+++ b/crates/ra_ide_api/src/hover.rs
@@ -1,6 +1,6 @@
 //! FIXME: write short doc here
 
-use hir::{Adt, BuiltinType, HasSource, HirDisplay};
+use hir::{Adt, HasSource, HirDisplay};
 use ra_db::SourceDatabase;
 use ra_syntax::{
     algo::{ancestors_at_offset, find_covering_element, find_node_at_offset},
@@ -132,11 +132,7 @@ pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeIn
                 hir::ModuleDef::Static(it) => res.extend(from_def_source(db, it)),
                 hir::ModuleDef::Trait(it) => res.extend(from_def_source(db, it)),
                 hir::ModuleDef::TypeAlias(it) => res.extend(from_def_source(db, it)),
-                hir::ModuleDef::BuiltinType(it) => {
-                    if let Some(b) = BuiltinType::ALL.iter().find(|(_, ty)| *ty == it) {
-                        res.extend(Some(b.0.to_string()))
-                    }
-                }
+                hir::ModuleDef::BuiltinType(it) => res.extend(Some(it.to_string())),
             },
             Some(SelfType(ty)) => {
                 if let Some((adt_def, _)) = ty.as_adt() {