Parse using[foo] as computed member expression

packages/babel-parser/src/parser/statement.ts

@@ -498,14 +498,24 @@ export default abstract class StatementParser extends ExpressionParser {
           node as Undone<N.VariableDeclaration>,
           "using",
         );
-      case tt._let:
-        if (
-          this.state.containsEsc ||
-          !allowDeclaration ||
-          !this.hasFollowingBindingAtom()
-        ) {
+      case tt._let: {
+        if (this.state.containsEsc) {
           break;
         }
+        // `let [` is an explicit negative lookahead for
+        // ExpressionStatement, so special-case it first.
+        const next = this.nextTokenStart();
+        const nextCh = this.codePointAtPos(next);
+        if (nextCh !== charCodes.leftSquareBracket) {
+          if (!allowDeclaration) break;
+          if (
+            !this.chStartsBindingIdentifier(nextCh, next) &&
+            nextCh !== charCodes.leftCurlyBrace
+          ) {
+            break;
+          }
+        }
+      }
       // fall through
       case tt._const: {
         if (!allowDeclaration) {

packages/babel-parser/test/fixtures/es2015/let/let-array-with-newline/input.js

@@ -0,0 +1,3 @@
+do let
+[x] = 0
+while (false);

packages/babel-parser/test/fixtures/es2015/let/let-array-with-newline/output.json

@@ -0,0 +1,56 @@
+{
+  "type": "File",
+  "start":0,"end":29,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":3,"column":14,"index":29}},
+  "errors": [
+    "SyntaxError: Lexical declaration cannot appear in a single-statement context. (1:3)"
+  ],
+  "program": {
+    "type": "Program",
+    "start":0,"end":29,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":3,"column":14,"index":29}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "DoWhileStatement",
+        "start":0,"end":29,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":3,"column":14,"index":29}},
+        "body": {
+          "type": "VariableDeclaration",
+          "start":3,"end":14,"loc":{"start":{"line":1,"column":3,"index":3},"end":{"line":2,"column":7,"index":14}},
+          "declarations": [
+            {
+              "type": "VariableDeclarator",
+              "start":7,"end":14,"loc":{"start":{"line":2,"column":0,"index":7},"end":{"line":2,"column":7,"index":14}},
+              "id": {
+                "type": "ArrayPattern",
+                "start":7,"end":10,"loc":{"start":{"line":2,"column":0,"index":7},"end":{"line":2,"column":3,"index":10}},
+                "elements": [
+                  {
+                    "type": "Identifier",
+                    "start":8,"end":9,"loc":{"start":{"line":2,"column":1,"index":8},"end":{"line":2,"column":2,"index":9},"identifierName":"x"},
+                    "name": "x"
+                  }
+                ]
+              },
+              "init": {
+                "type": "NumericLiteral",
+                "start":13,"end":14,"loc":{"start":{"line":2,"column":6,"index":13},"end":{"line":2,"column":7,"index":14}},
+                "extra": {
+                  "rawValue": 0,
+                  "raw": "0"
+                },
+                "value": 0
+              }
+            }
+          ],
+          "kind": "let"
+        },
+        "test": {
+          "type": "BooleanLiteral",
+          "start":22,"end":27,"loc":{"start":{"line":3,"column":7,"index":22},"end":{"line":3,"column":12,"index":27}},
+          "value": false
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babel-parser/test/fixtures/es2015/let/let-with-linebreak-and-escaped/input.js

@@ -0,0 +1,2 @@
+while (0) let
+\u0061 = 1;

packages/babel-parser/test/fixtures/es2015/let/let-with-linebreak-and-escaped/output.json

@@ -0,0 +1,58 @@
+{
+  "type": "File",
+  "start":0,"end":25,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":2,"column":11,"index":25}},
+  "program": {
+    "type": "Program",
+    "start":0,"end":25,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":2,"column":11,"index":25}},
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "WhileStatement",
+        "start":0,"end":13,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":13,"index":13}},
+        "test": {
+          "type": "NumericLiteral",
+          "start":7,"end":8,"loc":{"start":{"line":1,"column":7,"index":7},"end":{"line":1,"column":8,"index":8}},
+          "extra": {
+            "rawValue": 0,
+            "raw": "0"
+          },
+          "value": 0
+        },
+        "body": {
+          "type": "ExpressionStatement",
+          "start":10,"end":13,"loc":{"start":{"line":1,"column":10,"index":10},"end":{"line":1,"column":13,"index":13}},
+          "expression": {
+            "type": "Identifier",
+            "start":10,"end":13,"loc":{"start":{"line":1,"column":10,"index":10},"end":{"line":1,"column":13,"index":13},"identifierName":"let"},
+            "name": "let"
+          }
+        }
+      },
+      {
+        "type": "ExpressionStatement",
+        "start":14,"end":25,"loc":{"start":{"line":2,"column":0,"index":14},"end":{"line":2,"column":11,"index":25}},
+        "expression": {
+          "type": "AssignmentExpression",
+          "start":14,"end":24,"loc":{"start":{"line":2,"column":0,"index":14},"end":{"line":2,"column":10,"index":24}},
+          "operator": "=",
+          "left": {
+            "type": "Identifier",
+            "start":14,"end":20,"loc":{"start":{"line":2,"column":0,"index":14},"end":{"line":2,"column":6,"index":20},"identifierName":"a"},
+            "name": "a"
+          },
+          "right": {
+            "type": "NumericLiteral",
+            "start":23,"end":24,"loc":{"start":{"line":2,"column":9,"index":23},"end":{"line":2,"column":10,"index":24}},
+            "extra": {
+              "rawValue": 1,
+              "raw": "1"
+            },
+            "value": 1
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}