Improve completion of cfg attributes

The completion of cfg will look at the enabled cfg keys when
performing completion.

It will also look crate features when completing a feature cfg
option. A fixed list of known values for some cfg options are
provided.

For unknown keys it will look at the enabled values for that cfg key,
which means that completion will only show enabled options for those.

2 files changed, 15 insertions, 0 deletions

diff --git a/crates/base_db/src/fixture.rs b/crates/base_db/src/fixture.rs
index 6ce377710..6d3b1266e 100644
--- a/crates/base_db/src/fixture.rs
+++ b/crates/base_db/src/fixture.rs
@@ -131,6 +131,7 @@ impl ChangeFixture {
                     meta.cfg,
                     meta.env,
                     Default::default(),
+                    Default::default(),
                 );
                 let prev = crates.insert(crate_name.clone(), crate_id);
                 assert!(prev.is_none());
@@ -160,6 +161,7 @@ impl ChangeFixture {
                 default_cfg,
                 Env::default(),
                 Default::default(),
+                Default::default(),
             );
         } else {
             for (from, to) in crate_deps {
diff --git a/crates/base_db/src/input.rs b/crates/base_db/src/input.rs
index 23cb0c839..d99388f71 100644
--- a/crates/base_db/src/input.rs
+++ b/crates/base_db/src/input.rs
@@ -192,6 +192,7 @@ pub struct CrateData {
     pub env: Env,
     pub dependencies: Vec<Dependency>,
     pub proc_macro: Vec<ProcMacro>,
+    pub features: FxHashMap<String, Vec<String>>,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -221,6 +222,7 @@ impl CrateGraph {
         cfg_options: CfgOptions,
         env: Env,
         proc_macro: Vec<ProcMacro>,
+        features: FxHashMap<String, Vec<String>>,
     ) -> CrateId {
         let data = CrateData {
             root_file_id: file_id,
@@ -230,6 +232,7 @@ impl CrateGraph {
             env,
             proc_macro,
             dependencies: Vec::new(),
+            features,
         };
         let crate_id = CrateId(self.arena.len() as u32);
         let prev = self.arena.insert(crate_id, data);
@@ -506,6 +509,7 @@ mod tests {
             CfgOptions::default(),
             Env::default(),
             Default::default(),
+            Default::default(),
         );
         let crate2 = graph.add_crate_root(
             FileId(2u32),
@@ -514,6 +518,7 @@ mod tests {
             CfgOptions::default(),
             Env::default(),
             Default::default(),
+            Default::default(),
         );
         let crate3 = graph.add_crate_root(
             FileId(3u32),
@@ -522,6 +527,7 @@ mod tests {
             CfgOptions::default(),
             Env::default(),
             Default::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());
@@ -538,6 +544,7 @@ mod tests {
             CfgOptions::default(),
             Env::default(),
             Default::default(),
+            Default::default(),
         );
         let crate2 = graph.add_crate_root(
             FileId(2u32),
@@ -546,6 +553,7 @@ mod tests {
             CfgOptions::default(),
             Env::default(),
             Default::default(),
+            Default::default(),
         );
         assert!(graph.add_dep(crate1, CrateName::new("crate2").unwrap(), crate2).is_ok());
         assert!(graph.add_dep(crate2, CrateName::new("crate2").unwrap(), crate2).is_err());
@@ -561,6 +569,7 @@ mod tests {
             CfgOptions::default(),
             Env::default(),
             Default::default(),
+            Default::default(),
         );
         let crate2 = graph.add_crate_root(
             FileId(2u32),
@@ -569,6 +578,7 @@ mod tests {
             CfgOptions::default(),
             Env::default(),
             Default::default(),
+            Default::default(),
         );
         let crate3 = graph.add_crate_root(
             FileId(3u32),
@@ -577,6 +587,7 @@ mod tests {
             CfgOptions::default(),
             Env::default(),
             Default::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());
@@ -592,6 +603,7 @@ mod tests {
             CfgOptions::default(),
             Env::default(),
             Default::default(),
+            Default::default(),
         );
         let crate2 = graph.add_crate_root(
             FileId(2u32),
@@ -600,6 +612,7 @@ mod tests {
             CfgOptions::default(),
             Env::default(),
             Default::default(),
+            Default::default(),
         );
         assert!(graph
             .add_dep(crate1, CrateName::normalize_dashes("crate-name-with-dashes"), crate2)