Merge #1733

1733: Parse arbitrarily complex `box` patterns. r=matklad a=ecstatic-morse

This fully resolves the pattern part of #1412 by enabling the parsing of complex `box` patterns such as:

```rust
let box Struct { box i, j: box Inner(box &x) } = todo!();
```

This introduces a new `ast::BoxPat` (in the mold of `ast::RefPat`) that gets translated to `hir::Pat::Missing`.

Co-authored-by: Dylan MacKenzie <[email protected]>

1 files changed, 3 insertions, 0 deletions

diff --git a/crates/ra_syntax/src/grammar.ron b/crates/ra_syntax/src/grammar.ron
index 4659192cd..1836862fe 100644
--- a/crates/ra_syntax/src/grammar.ron
+++ b/crates/ra_syntax/src/grammar.ron
@@ -158,6 +158,7 @@ Grammar(
         "DYN_TRAIT_TYPE",
 
         "REF_PAT",
+        "BOX_PAT",
         "BIND_PAT",
         "PLACEHOLDER_PAT",
         "PATH_PAT",
@@ -523,6 +524,7 @@ Grammar(
         ),
 
         "RefPat": ( options: [ "Pat" ]),
+        "BoxPat": ( options: [ "Pat" ]),
         "BindPat": (
             options: [ "Pat" ],
             traits: ["NameOwner"]
@@ -552,6 +554,7 @@ Grammar(
         "Pat": (
             enum: [
                 "RefPat",
+                "BoxPat",
                 "BindPat",
                 "PlaceholderPat",
                 "PathPat",