6 files changed, 102 insertions, 39 deletions

diff --git a/crates/ra_hir_def/src/adt.rs b/crates/ra_hir_def/src/adt.rs
index 8f41e55d2..a29c4d41e 100644
--- a/crates/ra_hir_def/src/adt.rs
+++ b/crates/ra_hir_def/src/adt.rs
@@ -8,7 +8,7 @@ use ra_syntax::ast::{self, NameOwner, TypeAscriptionOwner};
 
 use crate::{
     db::DefDatabase2, type_ref::TypeRef, AstItemDef, EnumId, LocalEnumVariantId,
-    LocalStructFieldId, StructId, UnionId,
+    LocalStructFieldId, StructOrUnionId,
 };
 
 /// Note that we use `StructData` for unions as well!
@@ -49,15 +49,11 @@ pub struct StructFieldData {
 }
 
 impl StructData {
-    pub(crate) fn struct_data_query(db: &impl DefDatabase2, struct_: StructId) -> Arc<StructData> {
-        let src = struct_.source(db);
-        let name = src.ast.name().map(|n| n.as_name());
-        let variant_data = VariantData::new(src.ast.kind());
-        let variant_data = Arc::new(variant_data);
-        Arc::new(StructData { name, variant_data })
-    }
-    pub(crate) fn union_data_query(db: &impl DefDatabase2, struct_: UnionId) -> Arc<StructData> {
-        let src = struct_.source(db);
+    pub(crate) fn struct_data_query(
+        db: &impl DefDatabase2,
+        id: StructOrUnionId,
+    ) -> Arc<StructData> {
+        let src = id.source(db);
         let name = src.ast.name().map(|n| n.as_name());
         let variant_data = VariantData::new(src.ast.kind());
         let variant_data = Arc::new(variant_data);
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_hir_def/src/db.rs b/crates/ra_hir_def/src/db.rs
index a42348101..29cf71a59 100644
--- a/crates/ra_hir_def/src/db.rs
+++ b/crates/ra_hir_def/src/db.rs
@@ -11,7 +11,7 @@ use crate::{
         raw::{ImportSourceMap, RawItems},
         CrateDefMap,
     },
-    EnumId, StructId, UnionId,
+    EnumId, StructOrUnionId,
 };
 
 #[salsa::query_group(InternDatabaseStorage)]
@@ -19,9 +19,8 @@ pub trait InternDatabase: SourceDatabase {
     #[salsa::interned]
     fn intern_function(&self, loc: crate::ItemLoc<ast::FnDef>) -> crate::FunctionId;
     #[salsa::interned]
-    fn intern_struct(&self, loc: crate::ItemLoc<ast::StructDef>) -> crate::StructId;
-    #[salsa::interned]
-    fn intern_union(&self, loc: crate::ItemLoc<ast::StructDef>) -> crate::UnionId;
+    fn intern_struct_or_union(&self, loc: crate::ItemLoc<ast::StructDef>)
+        -> crate::StructOrUnionId;
     #[salsa::interned]
     fn intern_enum(&self, loc: crate::ItemLoc<ast::EnumDef>) -> crate::EnumId;
     #[salsa::interned]
@@ -49,10 +48,7 @@ pub trait DefDatabase2: InternDatabase + AstDatabase {
     fn crate_def_map(&self, krate: CrateId) -> Arc<CrateDefMap>;
 
     #[salsa::invoke(StructData::struct_data_query)]
-    fn struct_data(&self, s: StructId) -> Arc<StructData>;
-
-    #[salsa::invoke(StructData::union_data_query)]
-    fn union_data(&self, s: UnionId) -> Arc<StructData>;
+    fn struct_data(&self, id: StructOrUnionId) -> Arc<StructData>;
 
     #[salsa::invoke(EnumData::enum_data_query)]
     fn enum_data(&self, e: EnumId) -> Arc<EnumData>;
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
index 63ed2a098..239317efe 100644
--- a/crates/ra_hir_def/src/lib.rs
+++ b/crates/ra_hir_def/src/lib.rs
@@ -205,26 +205,30 @@ impl AstItemDef<ast::FnDef> for FunctionId {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct StructId(salsa::InternId);
-impl_intern_key!(StructId);
-impl AstItemDef<ast::StructDef> for StructId {
+pub struct StructOrUnionId(salsa::InternId);
+impl_intern_key!(StructOrUnionId);
+impl AstItemDef<ast::StructDef> for StructOrUnionId {
     fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StructDef>) -> Self {
-        db.intern_struct(loc)
+        db.intern_struct_or_union(loc)
     }
     fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StructDef> {
-        db.lookup_intern_struct(self)
+        db.lookup_intern_struct_or_union(self)
     }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct UnionId(salsa::InternId);
-impl_intern_key!(UnionId);
-impl AstItemDef<ast::StructDef> for UnionId {
-    fn intern(db: &impl InternDatabase, loc: ItemLoc<ast::StructDef>) -> Self {
-        db.intern_union(loc)
+pub struct StructId(pub StructOrUnionId);
+impl From<StructId> for StructOrUnionId {
+    fn from(id: StructId) -> StructOrUnionId {
+        id.0
     }
-    fn lookup_intern(self, db: &impl InternDatabase) -> ItemLoc<ast::StructDef> {
-        db.lookup_intern_union(self)
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct UnionId(pub StructOrUnionId);
+impl From<UnionId> for StructOrUnionId {
+    fn from(id: UnionId) -> StructOrUnionId {
+        id.0
     }
 }
 
diff --git a/crates/ra_hir_def/src/nameres/collector.rs b/crates/ra_hir_def/src/nameres/collector.rs
index 30664278e..37d0f3093 100644
--- a/crates/ra_hir_def/src/nameres/collector.rs
+++ b/crates/ra_hir_def/src/nameres/collector.rs
@@ -20,7 +20,8 @@ use crate::{
     },
     path::{Path, PathKind},
     AdtId, AstId, AstItemDef, ConstId, CrateModuleId, EnumId, EnumVariantId, FunctionId,
-    LocationCtx, ModuleDefId, ModuleId, StaticId, StructId, TraitId, TypeAliasId, UnionId,
+    LocationCtx, ModuleDefId, ModuleId, StaticId, StructId, StructOrUnionId, TraitId, TypeAliasId,
+    UnionId,
 };
 
 pub(super) fn collect_defs(db: &impl DefDatabase2, mut def_map: CrateDefMap) -> CrateDefMap {
@@ -36,11 +37,12 @@ pub(super) fn collect_defs(db: &impl DefDatabase2, mut def_map: CrateDefMap) ->
         );
 
         // look for the prelude
-        if def_map.prelude.is_none() {
-            let map = db.crate_def_map(dep.crate_id);
-            if map.prelude.is_some() {
-                def_map.prelude = map.prelude;
-            }
+        // If the dependency defines a prelude, we overwrite an already defined
+        // prelude. This is necessary to import the "std" prelude if a crate
+        // depends on both "core" and "std".
+        let dep_def_map = db.crate_def_map(dep.crate_id);
+        if dep_def_map.prelude.is_some() {
+            def_map.prelude = dep_def_map.prelude;
         }
     }
 
@@ -665,12 +667,14 @@ where
                 PerNs::values(FunctionId::from_ast_id(ctx, ast_id).into())
             }
             raw::DefKind::Struct(ast_id) => {
-                let s = StructId::from_ast_id(ctx, ast_id).into();
+                let id = StructOrUnionId::from_ast_id(ctx, ast_id).into();
+                let s = StructId(id).into();
                 PerNs::both(s, s)
             }
             raw::DefKind::Union(ast_id) => {
-                let s = UnionId::from_ast_id(ctx, ast_id).into();
-                PerNs::both(s, s)
+                let id = StructOrUnionId::from_ast_id(ctx, ast_id).into();
+                let u = UnionId(id).into();
+                PerNs::both(u, u)
             }
             raw::DefKind::Enum(ast_id) => PerNs::types(EnumId::from_ast_id(ctx, ast_id).into()),
             raw::DefKind::Const(ast_id) => PerNs::values(ConstId::from_ast_id(ctx, ast_id).into()),
diff --git a/crates/ra_hir_def/src/nameres/tests.rs b/crates/ra_hir_def/src/nameres/tests.rs
index 52bd0aa91..256f7d4be 100644
--- a/crates/ra_hir_def/src/nameres/tests.rs
+++ b/crates/ra_hir_def/src/nameres/tests.rs
@@ -464,6 +464,37 @@ fn values_dont_shadow_extern_crates() {
 }
 
 #[test]
+fn std_prelude_takes_precedence_above_core_prelude() {
+    let map = def_map(
+        r#"
+        //- /main.rs crate:main deps:core,std
+        use {Foo, Bar};
+
+        //- /std.rs crate:std deps:core
+        #[prelude_import]
+        pub use self::prelude::*;
+        mod prelude {
+            pub struct Foo;
+            pub use core::prelude::Bar;
+        }
+
+        //- /core.rs crate:core
+        #[prelude_import]
+        pub use self::prelude::*;
+        mod prelude {
+            pub struct Bar;
+        }
+        "#,
+    );
+
+    assert_snapshot!(map, @r###"
+        ⋮crate
+        ⋮Bar: t v
+        ⋮Foo: t v
+    "###);
+}
+
+#[test]
 fn cfg_not_test() {
     let map = def_map(
         r#"