WIP: issue 1479 subslice patterns

Author: tomjakubowski

crates/ra_parser/src/grammar/patterns.rs

@@ -58,6 +58,12 @@ const PAT_RECOVERY_SET: TokenSet =
 fn atom_pat(p: &mut Parser, recovery_set: TokenSet) -> Option<CompletedMarker> {
     let la0 = p.nth(0);
     let la1 = p.nth(1);
+    if la0 == IDENT && la1 == T![..] {
+        let m = p.start();
+        p.bump();
+        p.bump();
+        return Some(m.complete(p, SUBSLICE_PAT));
+    }
     if la0 == T![ref]
         || la0 == T![mut]
         || la0 == T![box]
@@ -225,6 +231,7 @@ fn tuple_pat(p: &mut Parser) -> CompletedMarker {
 // test slice_pat
 // fn main() {
 //     let [a, b, ..] = [];
+//     let [a, b..] = [];
 // }
 fn slice_pat(p: &mut Parser) -> CompletedMarker {
     assert!(p.at(T!['[']));

crates/ra_parser/src/syntax_kind/generated.rs

@@ -165,6 +165,7 @@ pub enum SyntaxKind {
     SLICE_PAT,
     RANGE_PAT,
     LITERAL_PAT,
+    SUBSLICE_PAT,
     TUPLE_EXPR,
     ARRAY_EXPR,
     PAREN_EXPR,
@@ -632,6 +633,7 @@ impl SyntaxKind {
             SLICE_PAT => &SyntaxInfo { name: "SLICE_PAT" },
             RANGE_PAT => &SyntaxInfo { name: "RANGE_PAT" },
             LITERAL_PAT => &SyntaxInfo { name: "LITERAL_PAT" },
+            SUBSLICE_PAT => &SyntaxInfo { name: "SUBSLICE_PAT" },
             TUPLE_EXPR => &SyntaxInfo { name: "TUPLE_EXPR" },
             ARRAY_EXPR => &SyntaxInfo { name: "ARRAY_EXPR" },
             PAREN_EXPR => &SyntaxInfo { name: "PAREN_EXPR" },

crates/ra_syntax/src/grammar.ron

@@ -168,6 +168,7 @@ Grammar(
         "SLICE_PAT",
         "RANGE_PAT",
         "LITERAL_PAT",
+        "SUBSLICE_PAT",
 
         // atoms
         "TUPLE_EXPR",
@@ -686,7 +687,7 @@ Grammar(
         "LifetimeArg": (),
 
         "MacroItems": (
-            traits: [ "ModuleItemOwner", "FnDefOwner" ],            
+            traits: [ "ModuleItemOwner", "FnDefOwner" ],
         ),
 
         "MacroStmts" : (

crates/ra_syntax/tests/data/parser/inline/ok/0024_slice_pat.rs

@@ -1,3 +1,4 @@
 fn main() {
     let [a, b, ..] = [];
+    let [a, b..] = [];
 }