10 files changed, 213 insertions, 28 deletions

diff --git a/crates/ra_db/src/input.rs b/crates/ra_db/src/input.rs
index a5f4e489f..c103503bd 100644
--- a/crates/ra_db/src/input.rs
+++ b/crates/ra_db/src/input.rs
@@ -31,9 +31,23 @@ pub struct SourceRootId(pub u32);
 
 #[derive(Default, Clone, Debug, PartialEq, Eq)]
 pub struct SourceRoot {
+    /// Sysroot or crates.io library.
+    ///
+    /// Libraries are considered mostly immutable, this assumption is used to
+    /// optimize salsa's query structure
+    pub is_library: bool,
     pub files: FxHashMap<RelativePathBuf, FileId>,
 }
 
+impl SourceRoot {
+    pub fn new() -> SourceRoot {
+        Default::default()
+    }
+    pub fn new_library() -> SourceRoot {
+        SourceRoot { is_library: true, ..SourceRoot::new() }
+    }
+}
+
 /// `CrateGraph` is a bit of information which turns a set of text files into a
 /// number of Rust crates. Each crate is defined by the `FileId` of its root module,
 /// the set of cfg flags (not yet implemented) and the set of dependencies. Note
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index 46ec136bd..e023ff25a 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -4,6 +4,7 @@
 //! and the corresponding code mostly in librustc_typeck/check/method/probe.rs.
 use std::sync::Arc;
 
+use arrayvec::ArrayVec;
 use rustc_hash::FxHashMap;
 
 use crate::{
@@ -113,19 +114,32 @@ impl CrateImplBlocks {
     }
 }
 
-fn def_crate(db: &impl HirDatabase, cur_crate: Crate, ty: &Ty) -> Option<Crate> {
+fn def_crates(db: &impl HirDatabase, cur_crate: Crate, ty: &Ty) -> Option<ArrayVec<[Crate; 2]>> {
+    // Types like slice can have inherent impls in several crates, (core and alloc).
+    // The correspoinding impls are marked with lang items, so we can use them to find the required crates.
+    macro_rules! lang_item_crate {
+        ($db:expr, $cur_crate:expr, $($name:expr),+ $(,)?) => {{
+            let mut v = ArrayVec::<[Crate; 2]>::new();
+            $(
+                v.push($db.lang_item($cur_crate, $name.into())?.krate($db)?);
+            )+
+            Some(v)
+        }};
+    }
+
     match ty {
         Ty::Apply(a_ty) => match a_ty.ctor {
-            TypeCtor::Adt(def_id) => def_id.krate(db),
-            TypeCtor::Bool => db.lang_item(cur_crate, "bool".into())?.krate(db),
-            TypeCtor::Char => db.lang_item(cur_crate, "char".into())?.krate(db),
+            TypeCtor::Adt(def_id) => Some(std::iter::once(def_id.krate(db)?).collect()),
+            TypeCtor::Bool => lang_item_crate!(db, cur_crate, "bool"),
+            TypeCtor::Char => lang_item_crate!(db, cur_crate, "char"),
             TypeCtor::Float(UncertainFloatTy::Known(f)) => {
-                db.lang_item(cur_crate, f.ty_to_string().into())?.krate(db)
+                lang_item_crate!(db, cur_crate, f.ty_to_string())
             }
             TypeCtor::Int(UncertainIntTy::Known(i)) => {
-                db.lang_item(cur_crate, i.ty_to_string().into())?.krate(db)
+                lang_item_crate!(db, cur_crate, i.ty_to_string())
             }
-            TypeCtor::Str => db.lang_item(cur_crate, "str".into())?.krate(db),
+            TypeCtor::Str => lang_item_crate!(db, cur_crate, "str"),
+            TypeCtor::Slice => lang_item_crate!(db, cur_crate, "slice_alloc", "slice"),
             _ => None,
         },
         _ => None,
@@ -218,19 +232,17 @@ fn iterate_inherent_methods<T>(
     krate: Crate,
     mut callback: impl FnMut(&Ty, Function) -> Option<T>,
 ) -> Option<T> {
-    let krate = match def_crate(db, krate, &ty.value) {
-        Some(krate) => krate,
-        None => return None,
-    };
-    let impls = db.impls_in_crate(krate);
+    for krate in def_crates(db, krate, &ty.value)? {
+        let impls = db.impls_in_crate(krate);
 
-    for impl_block in impls.lookup_impl_blocks(&ty.value) {
-        for item in impl_block.items(db) {
-            if let ImplItem::Method(f) = item {
-                let data = f.data(db);
-                if name.map_or(true, |name| data.name() == name) && data.has_self_param() {
-                    if let Some(result) = callback(&ty.value, f) {
-                        return Some(result);
+        for impl_block in impls.lookup_impl_blocks(&ty.value) {
+            for item in impl_block.items(db) {
+                if let ImplItem::Method(f) = item {
+                    let data = f.data(db);
+                    if name.map_or(true, |name| data.name() == name) && data.has_self_param() {
+                        if let Some(result) = callback(&ty.value, f) {
+                            return Some(result);
+                        }
                     }
                 }
             }
@@ -248,13 +260,14 @@ impl Ty {
         krate: Crate,
         mut callback: impl FnMut(ImplItem) -> Option<T>,
     ) -> Option<T> {
-        let krate = def_crate(db, krate, &self)?;
-        let impls = db.impls_in_crate(krate);
+        for krate in def_crates(db, krate, &self)? {
+            let impls = db.impls_in_crate(krate);
 
-        for impl_block in impls.lookup_impl_blocks(&self) {
-            for item in impl_block.items(db) {
-                if let Some(result) = callback(item) {
-                    return Some(result);
+            for impl_block in impls.lookup_impl_blocks(&self) {
+                for item in impl_block.items(db) {
+                    if let Some(result) = callback(item) {
+                        return Some(result);
+                    }
                 }
             }
         }
diff --git a/crates/ra_ide_api/src/change.rs b/crates/ra_ide_api/src/change.rs
index 895b1e966..8d9918d16 100644
--- a/crates/ra_ide_api/src/change.rs
+++ b/crates/ra_ide_api/src/change.rs
@@ -163,7 +163,8 @@ impl RootDatabase {
         if !change.new_roots.is_empty() {
             let mut local_roots = Vec::clone(&self.local_roots());
             for (root_id, is_local) in change.new_roots {
-                self.set_source_root(root_id, Default::default());
+                let root = if is_local { SourceRoot::new() } else { SourceRoot::new_library() };
+                self.set_source_root(root_id, Arc::new(root));
                 if is_local {
                     local_roots.push(root_id);
                 }
diff --git a/crates/ra_ide_api/src/completion/complete_postfix.rs b/crates/ra_ide_api/src/completion/complete_postfix.rs
index 278b1b797..e20a12e2a 100644
--- a/crates/ra_ide_api/src/completion/complete_postfix.rs
+++ b/crates/ra_ide_api/src/completion/complete_postfix.rs
@@ -51,6 +51,8 @@ pub(super) fn complete_postfix(acc: &mut Completions, ctx: &CompletionContext) {
         )
         .add_to(acc);
         postfix_snippet(ctx, "dbg", "dbg!(expr)", &format!("dbg!({})", receiver_text)).add_to(acc);
+        postfix_snippet(ctx, "box", "Box::new(expr)", &format!("Box::new({})", receiver_text))
+            .add_to(acc);
     }
 }
 
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__postfix_completion_works_for_trivial_path_expression.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__postfix_completion_works_for_trivial_path_expression.snap
index fcb292596..c1a40b7b4 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__postfix_completion_works_for_trivial_path_expression.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__postfix_completion_works_for_trivial_path_expression.snap
@@ -1,11 +1,18 @@
 ---
-created: "2019-05-23T22:23:35.118738523Z"
+created: "2019-06-23T13:01:08.775536006Z"
 creator: [email protected]
 source: crates/ra_ide_api/src/completion/completion_item.rs
 expression: kind_completions
 ---
 [
     CompletionItem {
+        label: "box",
+        source_range: [76; 76),
+        delete: [72; 76),
+        insert: "Box::new(bar)",
+        detail: "Box::new(expr)",
+    },
+    CompletionItem {
         label: "dbg",
         source_range: [76; 76),
         delete: [72; 76),
diff --git a/crates/ra_parser/src/grammar/items.rs b/crates/ra_parser/src/grammar/items.rs
index e85147e9e..424d0476d 100644
--- a/crates/ra_parser/src/grammar/items.rs
+++ b/crates/ra_parser/src/grammar/items.rs
@@ -103,7 +103,21 @@ pub(super) fn maybe_item(p: &mut Parser, m: Marker, flavor: ItemFlavor) -> Resul
         p.bump_remap(T![auto]);
         has_mods = true;
     }
-    if p.at(IDENT) && p.at_contextual_kw("default") && p.nth(1) == T![impl] {
+
+    if p.at(IDENT)
+        && p.at_contextual_kw("default")
+        && (match p.nth(1) {
+            T![impl] => true,
+            T![fn] | T![type] => {
+                if let ItemFlavor::Mod = flavor {
+                    true
+                } else {
+                    false
+                }
+            }
+            _ => false,
+        })
+    {
         p.bump_remap(T![default]);
         has_mods = true;
     }
@@ -163,12 +177,25 @@ pub(super) fn maybe_item(p: &mut Parser, m: Marker, flavor: ItemFlavor) -> Resul
         // test default_impl
         // default impl Foo {}
 
+        // test_err default_fn_type
+        // trait T {
+        //     default type T = Bar;
+        //     default fn foo() {}
+        // }
+
+        // test default_fn_type
+        // impl T for Foo {
+        //     default type T = Bar;
+        //     default fn foo() {}
+        // }
+
         // test unsafe_default_impl
         // unsafe default impl Foo {}
         T![impl] => {
             traits::impl_block(p);
             m.complete(p, IMPL_BLOCK);
         }
+
         // test existential_type
         // existential type Foo: Fn() -> usize;
         T![type] => {
diff --git a/crates/ra_syntax/tests/data/parser/inline/err/0014_default_fn_type.rs b/crates/ra_syntax/tests/data/parser/inline/err/0014_default_fn_type.rs
new file mode 100644
index 000000000..15ba8f4a8
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/inline/err/0014_default_fn_type.rs
@@ -0,0 +1,4 @@
+trait T {
+    default type T = Bar;
+    default fn foo() {}
+}
diff --git a/crates/ra_syntax/tests/data/parser/inline/err/0014_default_fn_type.txt b/crates/ra_syntax/tests/data/parser/inline/err/0014_default_fn_type.txt
new file mode 100644
index 000000000..7da4e243f
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/inline/err/0014_default_fn_type.txt
@@ -0,0 +1,58 @@
+SOURCE_FILE@[0; 62)
+  TRAIT_DEF@[0; 61)
+    TRAIT_KW@[0; 5) "trait"
+    WHITESPACE@[5; 6) " "
+    NAME@[6; 7)
+      IDENT@[6; 7) "T"
+    WHITESPACE@[7; 8) " "
+    ITEM_LIST@[8; 61)
+      L_CURLY@[8; 9) "{"
+      WHITESPACE@[9; 14) "\n    "
+      MACRO_CALL@[14; 21)
+        PATH@[14; 21)
+          PATH_SEGMENT@[14; 21)
+            NAME_REF@[14; 21)
+              IDENT@[14; 21) "default"
+      WHITESPACE@[21; 22) " "
+      TYPE_ALIAS_DEF@[22; 35)
+        TYPE_KW@[22; 26) "type"
+        WHITESPACE@[26; 27) " "
+        NAME@[27; 28)
+          IDENT@[27; 28) "T"
+        WHITESPACE@[28; 29) " "
+        EQ@[29; 30) "="
+        WHITESPACE@[30; 31) " "
+        PATH_TYPE@[31; 34)
+          PATH@[31; 34)
+            PATH_SEGMENT@[31; 34)
+              NAME_REF@[31; 34)
+                IDENT@[31; 34) "Bar"
+        SEMI@[34; 35) ";"
+      WHITESPACE@[35; 40) "\n    "
+      MACRO_CALL@[40; 47)
+        PATH@[40; 47)
+          PATH_SEGMENT@[40; 47)
+            NAME_REF@[40; 47)
+              IDENT@[40; 47) "default"
+      WHITESPACE@[47; 48) " "
+      FN_DEF@[48; 59)
+        FN_KW@[48; 50) "fn"
+        WHITESPACE@[50; 51) " "
+        NAME@[51; 54)
+          IDENT@[51; 54) "foo"
+        PARAM_LIST@[54; 56)
+          L_PAREN@[54; 55) "("
+          R_PAREN@[55; 56) ")"
+        WHITESPACE@[56; 57) " "
+        BLOCK@[57; 59)
+          L_CURLY@[57; 58) "{"
+          R_CURLY@[58; 59) "}"
+      WHITESPACE@[59; 60) "\n"
+      R_CURLY@[60; 61) "}"
+  WHITESPACE@[61; 62) "\n"
+error 21: expected EXCL
+error 21: expected `{`, `[`, `(`
+error 21: expected SEMI
+error 47: expected EXCL
+error 47: expected `{`, `[`, `(`
+error 47: expected SEMI
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0132_default_fn_type.rs b/crates/ra_syntax/tests/data/parser/inline/ok/0132_default_fn_type.rs
new file mode 100644
index 000000000..8f5d61113
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0132_default_fn_type.rs
@@ -0,0 +1,4 @@
+impl T for Foo {
+    default type T = Bar;
+    default fn foo() {}
+}
diff --git a/crates/ra_syntax/tests/data/parser/inline/ok/0132_default_fn_type.txt b/crates/ra_syntax/tests/data/parser/inline/ok/0132_default_fn_type.txt
new file mode 100644
index 000000000..384b203d3
--- /dev/null
+++ b/crates/ra_syntax/tests/data/parser/inline/ok/0132_default_fn_type.txt
@@ -0,0 +1,55 @@
+SOURCE_FILE@[0; 69)
+  IMPL_BLOCK@[0; 68)
+    IMPL_KW@[0; 4) "impl"
+    WHITESPACE@[4; 5) " "
+    PATH_TYPE@[5; 6)
+      PATH@[5; 6)
+        PATH_SEGMENT@[5; 6)
+          NAME_REF@[5; 6)
+            IDENT@[5; 6) "T"
+    WHITESPACE@[6; 7) " "
+    FOR_KW@[7; 10) "for"
+    WHITESPACE@[10; 11) " "
+    PATH_TYPE@[11; 14)
+      PATH@[11; 14)
+        PATH_SEGMENT@[11; 14)
+          NAME_REF@[11; 14)
+            IDENT@[11; 14) "Foo"
+    WHITESPACE@[14; 15) " "
+    ITEM_LIST@[15; 68)
+      L_CURLY@[15; 16) "{"
+      WHITESPACE@[16; 21) "\n    "
+      TYPE_ALIAS_DEF@[21; 42)
+        DEFAULT_KW@[21; 28) "default"
+        WHITESPACE@[28; 29) " "
+        TYPE_KW@[29; 33) "type"
+        WHITESPACE@[33; 34) " "
+        NAME@[34; 35)
+          IDENT@[34; 35) "T"
+        WHITESPACE@[35; 36) " "
+        EQ@[36; 37) "="
+        WHITESPACE@[37; 38) " "
+        PATH_TYPE@[38; 41)
+          PATH@[38; 41)
+            PATH_SEGMENT@[38; 41)
+              NAME_REF@[38; 41)
+                IDENT@[38; 41) "Bar"
+        SEMI@[41; 42) ";"
+      WHITESPACE@[42; 47) "\n    "
+      FN_DEF@[47; 66)
+        DEFAULT_KW@[47; 54) "default"
+        WHITESPACE@[54; 55) " "
+        FN_KW@[55; 57) "fn"
+        WHITESPACE@[57; 58) " "
+        NAME@[58; 61)
+          IDENT@[58; 61) "foo"
+        PARAM_LIST@[61; 63)
+          L_PAREN@[61; 62) "("
+          R_PAREN@[62; 63) ")"
+        WHITESPACE@[63; 64) " "
+        BLOCK@[64; 66)
+          L_CURLY@[64; 65) "{"
+          R_CURLY@[65; 66) "}"
+      WHITESPACE@[66; 67) "\n"
+      R_CURLY@[67; 68) "}"
+  WHITESPACE@[68; 69) "\n"