Merge #816

816: Prelude & Edition 2015 import resolution r=matklad a=flodiebold

I implemented the prelude import, but it turned out to be useless without being able to resolve any of the imports in the prelude :sweat_smile: So I had to add some edition handling and handle 2015-style imports (at least the simplified scheme proposed in rust-lang/rust#57745). So now finally `Option` resolves :smile: 

One remaining problem is that we don't actually know the edition for sysroot crates. They're currently hardcoded to 2015, but there's already a bunch of PRs upgrading the editions of various rustc crates, so we'll have to detect the edition somehow, or just change the hardcoding to 2018 later, I guess...

~Also currently missing is completion for prelude names, though that shouldn't be hard to add. And `Vec` still doesn't resolve, so I need to look into that.~

Co-authored-by: Florian Diebold <[email protected]>

2 files changed, 11 insertions, 3 deletions

diff --git a/crates/ra_project_model/src/cargo_workspace.rs b/crates/ra_project_model/src/cargo_workspace.rs
index 5866be519..81cb506b7 100644
--- a/crates/ra_project_model/src/cargo_workspace.rs
+++ b/crates/ra_project_model/src/cargo_workspace.rs
@@ -4,6 +4,7 @@ use cargo_metadata::{MetadataCommand, CargoOpt};
 use ra_arena::{Arena, RawId, impl_arena_id};
 use rustc_hash::FxHashMap;
 use failure::format_err;
+use ra_db::Edition;
 
 use crate::Result;
 
@@ -35,6 +36,7 @@ struct PackageData {
     targets: Vec<Target>,
     is_member: bool,
     dependencies: Vec<PackageDependency>,
+    edition: Edition,
 }
 
 #[derive(Debug, Clone)]
@@ -84,6 +86,9 @@ impl Package {
     pub fn root(self, ws: &CargoWorkspace) -> &Path {
         ws.packages[self].manifest.parent().unwrap()
     }
+    pub fn edition(self, ws: &CargoWorkspace) -> Edition {
+        ws.packages[self].edition
+    }
     pub fn targets<'a>(self, ws: &'a CargoWorkspace) -> impl Iterator<Item = Target> + 'a {
         ws.packages[self].targets.iter().cloned()
     }
@@ -135,6 +140,7 @@ impl CargoWorkspace {
                 manifest: meta_pkg.manifest_path.clone(),
                 targets: Vec::new(),
                 is_member,
+                edition: Edition::from_string(&meta_pkg.edition),
                 dependencies: Vec::new(),
             });
             let pkg_data = &mut packages[pkg];
diff --git a/crates/ra_project_model/src/lib.rs b/crates/ra_project_model/src/lib.rs
index 3b1e07149..1b18ac836 100644
--- a/crates/ra_project_model/src/lib.rs
+++ b/crates/ra_project_model/src/lib.rs
@@ -6,7 +6,7 @@ use std::path::{Path, PathBuf};
 use failure::bail;
 use rustc_hash::FxHashMap;
 
-use ra_db::{CrateGraph, FileId};
+use ra_db::{CrateGraph, FileId, Edition};
 
 pub use crate::{
     cargo_workspace::{CargoWorkspace, Package, Target, TargetKind},
@@ -36,7 +36,8 @@ impl ProjectWorkspace {
         let mut sysroot_crates = FxHashMap::default();
         for krate in self.sysroot.crates() {
             if let Some(file_id) = load(krate.root(&self.sysroot)) {
-                sysroot_crates.insert(krate, crate_graph.add_crate_root(file_id));
+                sysroot_crates
+                    .insert(krate, crate_graph.add_crate_root(file_id, Edition::Edition2015));
             }
         }
         for from in self.sysroot.crates() {
@@ -62,7 +63,8 @@ impl ProjectWorkspace {
             for tgt in pkg.targets(&self.cargo) {
                 let root = tgt.root(&self.cargo);
                 if let Some(file_id) = load(root) {
-                    let crate_id = crate_graph.add_crate_root(file_id);
+                    let edition = pkg.edition(&self.cargo);
+                    let crate_id = crate_graph.add_crate_root(file_id, edition);
                     if tgt.kind(&self.cargo) == TargetKind::Lib {
                         lib_tgt = Some(crate_id);
                         pkg_to_lib_crate.insert(pkg, crate_id);