Merge #1815

1815: Support correct `$crate` expansion in macros r=uHOOCCOOHu a=uHOOCCOOHu

This PR makes normal use cases of `$crate` from macros work as expected.

It makes more macros from `std` work. Type inference works well with `panic`, `unimplemented`, `format`, and maybe more.
Sadly that `vec![1, 2, 3]` still not works, but it is not longer an issue about macro.

Screenshot:
![Screenshot_20190927_022136](https://user-images.githubusercontent.com/14816024/65714465-b4568f80-e0cd-11e9-8043-dd44c2ae8040.png)




Co-authored-by: uHOOCCOOHu <[email protected]>

1 files changed, 14 insertions, 0 deletions

diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index b808a0c36..67adcfa28 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -332,6 +332,20 @@ impl CrateDefMap {
     ) -> ResolvePathResult {
         let mut segments = path.segments.iter().enumerate();
         let mut curr_per_ns: PerNs = match path.kind {
+            PathKind::DollarCrate(krate) => {
+                if krate == self.krate {
+                    tested_by!(macro_dollar_crate_self);
+                    PerNs::types(Module { krate: self.krate, module_id: self.root }.into())
+                } else {
+                    match krate.root_module(db) {
+                        Some(module) => {
+                            tested_by!(macro_dollar_crate_other);
+                            PerNs::types(module.into())
+                        }
+                        None => return ResolvePathResult::empty(ReachedFixedPoint::Yes),
+                    }
+                }
+            }
             PathKind::Crate => {
                 PerNs::types(Module { krate: self.krate, module_id: self.root }.into())
             }