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]>

1 files changed, 5 insertions, 3 deletions

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);