3 files changed, 71 insertions, 2 deletions

diff --git a/crates/ra_db/src/fixture.rs b/crates/ra_db/src/fixture.rs
index 7f43c2971..3dc86ca2d 100644
--- a/crates/ra_db/src/fixture.rs
+++ b/crates/ra_db/src/fixture.rs
@@ -61,7 +61,14 @@ fn with_single_file(db: &mut dyn SourceDatabaseExt, ra_fixture: &str) -> FileId
         };
 
         let mut crate_graph = CrateGraph::default();
-        crate_graph.add_crate_root(file_id, meta.edition, meta.krate, meta.cfg, meta.env);
+        crate_graph.add_crate_root(
+            file_id,
+            meta.edition,
+            meta.krate,
+            meta.cfg,
+            meta.env,
+            Default::default(),
+        );
         crate_graph
     } else {
         let mut crate_graph = CrateGraph::default();
@@ -71,6 +78,7 @@ fn with_single_file(db: &mut dyn SourceDatabaseExt, ra_fixture: &str) -> FileId
             None,
             CfgOptions::default(),
             Env::default(),
+            Default::default(),
         );
         crate_graph
     };
@@ -119,6 +127,7 @@ fn with_files(db: &mut dyn SourceDatabaseExt, fixture: &str) -> Option<FilePosit
                 Some(krate.clone()),
                 meta.cfg,
                 meta.env,
+                Default::default(),
             );
             let prev = crates.insert(krate.clone(), crate_id);
             assert!(prev.is_none());
@@ -155,6 +164,7 @@ fn with_files(db: &mut dyn SourceDatabaseExt, fixture: &str) -> Option<FilePosit
             None,
             CfgOptions::default(),
             Env::default(),
+            Default::default(),
         );
     } else {
         for (from, to) in crate_deps {
diff --git a/crates/ra_db/src/input.rs b/crates/ra_db/src/input.rs
index 1a1c64202..06d40db96 100644
--- a/crates/ra_db/src/input.rs
+++ b/crates/ra_db/src/input.rs
@@ -113,6 +113,7 @@ pub struct CrateData {
     pub display_name: Option<String>,
     pub cfg_options: CfgOptions,
     pub env: Env,
+    pub extern_source: ExternSource,
     pub dependencies: Vec<Dependency>,
 }
 
@@ -122,11 +123,22 @@ pub enum Edition {
     Edition2015,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct ExternSourceId(pub u32);
+
 #[derive(Default, Debug, Clone, PartialEq, Eq)]
 pub struct Env {
     entries: FxHashMap<String, String>,
 }
 
+// FIXME: Redesign vfs for solve the following limitation ?
+// Note: Some env variables (e.g. OUT_DIR) are located outside of the
+// crate. We store a map to allow remap it to ExternSourceId
+#[derive(Default, Debug, Clone, PartialEq, Eq)]
+pub struct ExternSource {
+    extern_paths: FxHashMap<String, ExternSourceId>,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Dependency {
     pub crate_id: CrateId,
@@ -141,6 +153,7 @@ impl CrateGraph {
         display_name: Option<String>,
         cfg_options: CfgOptions,
         env: Env,
+        extern_source: ExternSource,
     ) -> CrateId {
         let data = CrateData {
             root_file_id: file_id,
@@ -148,6 +161,7 @@ impl CrateGraph {
             display_name,
             cfg_options,
             env,
+            extern_source,
             dependencies: Vec::new(),
         };
         let crate_id = CrateId(self.arena.len() as u32);
@@ -271,6 +285,27 @@ impl Env {
     }
 }
 
+impl ExternSource {
+    pub fn extern_path(&self, path: &str) -> Option<(ExternSourceId, RelativePathBuf)> {
+        self.extern_paths.iter().find_map(|(root_path, id)| {
+            if path.starts_with(root_path) {
+                let mut rel_path = &path[root_path.len()..];
+                if rel_path.starts_with("/") {
+                    rel_path = &rel_path[1..];
+                }
+                let rel_path = RelativePathBuf::from_path(rel_path).ok()?;
+                Some((id.clone(), rel_path))
+            } else {
+                None
+            }
+        })
+    }
+
+    pub fn set_extern_path(&mut self, root_path: &str, root: ExternSourceId) {
+        self.extern_paths.insert(root_path.to_owned(), root);
+    }
+}
+
 #[derive(Debug)]
 pub struct ParseEditionError {
     invalid_input: String,
@@ -300,6 +335,7 @@ mod tests {
             None,
             CfgOptions::default(),
             Env::default(),
+            Default::default(),
         );
         let crate2 = graph.add_crate_root(
             FileId(2u32),
@@ -307,6 +343,7 @@ mod tests {
             None,
             CfgOptions::default(),
             Env::default(),
+            Default::default(),
         );
         let crate3 = graph.add_crate_root(
             FileId(3u32),
@@ -314,6 +351,7 @@ mod tests {
             None,
             CfgOptions::default(),
             Env::default(),
+            Default::default(),
         );
         assert!(graph.add_dep(crate1, CrateName::new("crate2").unwrap(), crate2).is_ok());
         assert!(graph.add_dep(crate2, CrateName::new("crate3").unwrap(), crate3).is_ok());
@@ -329,6 +367,7 @@ mod tests {
             None,
             CfgOptions::default(),
             Env::default(),
+            Default::default(),
         );
         let crate2 = graph.add_crate_root(
             FileId(2u32),
@@ -336,6 +375,7 @@ mod tests {
             None,
             CfgOptions::default(),
             Env::default(),
+            Default::default(),
         );
         let crate3 = graph.add_crate_root(
             FileId(3u32),
@@ -343,6 +383,7 @@ mod tests {
             None,
             CfgOptions::default(),
             Env::default(),
+            Default::default(),
         );
         assert!(graph.add_dep(crate1, CrateName::new("crate2").unwrap(), crate2).is_ok());
         assert!(graph.add_dep(crate2, CrateName::new("crate3").unwrap(), crate3).is_ok());
@@ -357,6 +398,7 @@ mod tests {
             None,
             CfgOptions::default(),
             Env::default(),
+            Default::default(),
         );
         let crate2 = graph.add_crate_root(
             FileId(2u32),
@@ -364,6 +406,7 @@ mod tests {
             None,
             CfgOptions::default(),
             Env::default(),
+            Default::default(),
         );
         assert!(graph
             .add_dep(crate1, CrateName::normalize_dashes("crate-name-with-dashes"), crate2)
diff --git a/crates/ra_db/src/lib.rs b/crates/ra_db/src/lib.rs
index fb002d717..d500d5e85 100644
--- a/crates/ra_db/src/lib.rs
+++ b/crates/ra_db/src/lib.rs
@@ -11,7 +11,8 @@ use ra_syntax::{ast, Parse, SourceFile, TextRange, TextUnit};
 pub use crate::{
     cancellation::Canceled,
     input::{
-        CrateGraph, CrateId, CrateName, Dependency, Edition, Env, FileId, SourceRoot, SourceRootId,
+        CrateGraph, CrateId, CrateName, Dependency, Edition, Env, ExternSource, ExternSourceId,
+        FileId, SourceRoot, SourceRootId,
     },
 };
 pub use relative_path::{RelativePath, RelativePathBuf};
@@ -87,6 +88,12 @@ pub trait FileLoader {
     fn resolve_relative_path(&self, anchor: FileId, relative_path: &RelativePath)
         -> Option<FileId>;
     fn relevant_crates(&self, file_id: FileId) -> Arc<Vec<CrateId>>;
+
+    fn resolve_extern_path(
+        &self,
+        extern_id: ExternSourceId,
+        relative_path: &RelativePath,
+    ) -> Option<FileId>;
 }
 
 /// Database which stores all significant input facts: source code and project
@@ -164,4 +171,13 @@ impl<T: SourceDatabaseExt> FileLoader for FileLoaderDelegate<&'_ T> {
         let source_root = self.0.file_source_root(file_id);
         self.0.source_root_crates(source_root)
     }
+
+    fn resolve_extern_path(
+        &self,
+        extern_id: ExternSourceId,
+        relative_path: &RelativePath,
+    ) -> Option<FileId> {
+        let source_root = self.0.source_root(SourceRootId(extern_id.0));
+        source_root.file_by_relative_path(&relative_path)
+    }
 }