Parse range patterns in let statement with type annotation

Author: lowr

crates/parser/src/grammar/patterns.rs

@@ -103,6 +103,8 @@ fn pattern_single_r(p: &mut Parser<'_>, recovery_set: TokenSet) {
                 //       ^
                 // `let 0 .. =`
                 //           ^
+                // `let 0..: _ =`
+                //         ^
                 // (1.., _)
                 //     ^
                 // `Some(0 .. )`
@@ -111,9 +113,12 @@ fn pattern_single_r(p: &mut Parser<'_>, recovery_set: TokenSet) {
                 //             ^
                 // `[0..]`
                 //      ^
-                if p.at(T![=]) | p.at(T![')']) | p.at(T![,]) | p.at(T!['}']) | p.at(T![']']) {
+                if matches!(p.current(), T![=] | T![,] | T![:] | T![')'] | T!['}'] | T![']']) {
                     // test half_open_range_pat
-                    // fn f() { let 0 .. = 1u32; }
+                    // fn f() {
+                    //     let 0 .. = 1u32;
+                    //     let 0..: _ = 1u32;
+                    // }
                 } else {
                     atom_pat(p, recovery_set);
                 }

crates/parser/test_data/parser/inline/ok/0166_half_open_range_pat.rast

@@ -11,7 +11,7 @@ SOURCE_FILE
     BLOCK_EXPR
       STMT_LIST
         L_CURLY "{"
-        WHITESPACE " "
+        WHITESPACE "\n    "
         LET_STMT
           LET_KW "let"
           WHITESPACE " "
@@ -27,6 +27,25 @@ SOURCE_FILE
           LITERAL
             INT_NUMBER "1u32"
           SEMICOLON ";"
-        WHITESPACE " "
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          RANGE_PAT
+            LITERAL_PAT
+              LITERAL
+                INT_NUMBER "0"
+            DOT2 ".."
+          COLON ":"
+          WHITESPACE " "
+          INFER_TYPE
+            UNDERSCORE "_"
+          WHITESPACE " "
+          EQ "="
+          WHITESPACE " "
+          LITERAL
+            INT_NUMBER "1u32"
+          SEMICOLON ";"
+        WHITESPACE "\n"
         R_CURLY "}"
   WHITESPACE "\n"

crates/parser/test_data/parser/inline/ok/0166_half_open_range_pat.rs

@@ -1 +1,4 @@
-fn f() { let 0 .. = 1u32; }
+fn f() {
+    let 0 .. = 1u32;
+    let 0..: _ = 1u32;
+}