Merge #3549

3549: Implement env! macro r=matklad a=edwin0cheng

This PR implements `env!` macro by adding following things:

1. Added `additional_outdirs` settings in vscode. (naming to be bikeshed)
2. Added `ExternSourceId` which is a wrapping for SourceRootId but only used in extern sources. It is because `OUT_DIR` is not belonged to any crate and we have to access it behind an `AstDatabase`.
3. This PR does not implement the `OUT_DIR` parsing from `cargo check`. I don't have general design about this,  @kiljacken could we reuse some cargo watch code for that ?

~~Block on [#3536]~~

PS: After this PR , we (kind of) completed the `include!(concat!(env!('OUT_DIR'),  "foo.rs")` macro call combo. [Exodia Obliterate!](https://www.youtube.com/watch?v=RfqNH3FoGi0)

Co-authored-by: Edwin Cheng <[email protected]>

2 files changed, 27 insertions, 0 deletions

diff --git a/crates/ra_hir_ty/src/test_db.rs b/crates/ra_hir_ty/src/test_db.rs
index c794f7b84..0be2fea4b 100644
--- a/crates/ra_hir_ty/src/test_db.rs
+++ b/crates/ra_hir_ty/src/test_db.rs
@@ -67,6 +67,13 @@ impl FileLoader for TestDB {
     fn relevant_crates(&self, file_id: FileId) -> Arc<Vec<CrateId>> {
         FileLoaderDelegate(self).relevant_crates(file_id)
     }
+    fn resolve_extern_path(
+        &self,
+        extern_id: ra_db::ExternSourceId,
+        relative_path: &RelativePath,
+    ) -> Option<FileId> {
+        FileLoaderDelegate(self).resolve_extern_path(extern_id, relative_path)
+    }
 }
 
 impl TestDB {
diff --git a/crates/ra_hir_ty/src/tests/macros.rs b/crates/ra_hir_ty/src/tests/macros.rs
index ffa78b046..32457bbf7 100644
--- a/crates/ra_hir_ty/src/tests/macros.rs
+++ b/crates/ra_hir_ty/src/tests/macros.rs
@@ -550,6 +550,26 @@ fn main() {
 }
 
 #[test]
+fn infer_builtin_macros_env() {
+    assert_snapshot!(
+        infer(r#"
+//- /main.rs env:foo=bar
+#[rustc_builtin_macro]
+macro_rules! env {() => {}}
+
+fn main() {
+    let x = env!("foo");
+}
+"#),
+        @r###"
+    ![0; 5) '"bar"': &str
+    [88; 116) '{     ...o"); }': ()
+    [98; 99) 'x': &str
+    "###
+    );
+}
+
+#[test]
 fn infer_derive_clone_simple() {
     let (db, pos) = TestDB::with_position(
         r#"