Merge #774

774: Batch crate & command r=matklad a=flodiebold

This adds a new crate, `ra_batch`, which is intended for scenarios where you're loading a workspace once and then running some analyses using the HIR API. Also, it adds a command to `ra_cli` which uses that to type-check all crates in a workspace and print some statistics:

E.g. in rust-analyzer:
```
> $ time target/release/ra_cli analysis-stats
Database loaded, 21 roots
Crates in this dir: 28
Total modules found: 231
Total declarations: 3694
Total functions: 2408
Total expressions: 47017
Expressions of unknown type: 19826 (42%)
Expressions of partially unknown type: 4482 (9%)
target/release/ra_cli analysis-stats  3,23s user 0,60s system 100% cpu 3,821 total
```

Or in rust-lang/rust:
```
> $ time ../opensource/rust-analyzer/target/release/ra_cli analysis-stats
Database loaded, 77 roots
Crates in this dir: 130
Total modules found: 1820
Total declarations: 35038
Total functions: 25914
Total expressions: 753678
Expressions of unknown type: 337975 (44%)
Expressions of partially unknown type: 92314 (12%)
../opensource/rust-analyzer/target/release/ra_cli analysis-stats  13,45s user 2,08s system 100% cpu 15,477 total
```

~This still needs a test. Type-checking all of rust-analyzer sadly takes almost a minute when compiled in debug mode :sweat_smile: So I'll need to add something simpler (maybe just looking at a few modules).~

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

1 files changed, 5 insertions, 0 deletions

diff --git a/crates/ra_vfs/src/lib.rs b/crates/ra_vfs/src/lib.rs
index 6b4eb6842..3805be570 100644
--- a/crates/ra_vfs/src/lib.rs
+++ b/crates/ra_vfs/src/lib.rs
@@ -94,6 +94,7 @@ impl Roots {
         let mut roots = Arena::default();
         // A hack to make nesting work.
         paths.sort_by_key(|it| Reverse(it.as_os_str().len()));
+        paths.dedup();
         for (i, path) in paths.iter().enumerate() {
             let nested_roots = paths[..i]
                 .iter()
@@ -181,6 +182,10 @@ impl Vfs {
         None
     }
 
+    pub fn num_roots(&self) -> usize {
+        self.roots.len()
+    }
+
     pub fn load(&mut self, path: &Path) -> Option<VfsFile> {
         if let Some((root, rel_path, file)) = self.find_root(path) {
             return if let Some(file) = file {