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, 2 insertions, 2 deletions

diff --git a/crates/ra_ide_api/tests/test/main.rs b/crates/ra_ide_api/tests/test/main.rs
index 4cf842452..0526f7584 100644
--- a/crates/ra_ide_api/tests/test/main.rs
+++ b/crates/ra_ide_api/tests/test/main.rs
@@ -1,7 +1,7 @@
 use insta::assert_debug_snapshot_matches;
 use ra_ide_api::{
     mock_analysis::{single_file, single_file_with_position, MockAnalysis},
-    AnalysisChange, CrateGraph, FileId, Query, NavigationTarget,
+    AnalysisChange, CrateGraph, Edition::Edition2018, FileId, Query, NavigationTarget
 };
 use ra_syntax::{TextRange, SmolStr};
 
@@ -36,7 +36,7 @@ fn test_resolve_crate_root() {
     assert!(host.analysis().crate_for(mod_file).unwrap().is_empty());
 
     let mut crate_graph = CrateGraph::default();
-    let crate_id = crate_graph.add_crate_root(root_file);
+    let crate_id = crate_graph.add_crate_root(root_file, Edition2018);
     let mut change = AnalysisChange::new();
     change.set_crate_graph(crate_graph);
     host.apply_change(change);