From 2ea36b62d330fa13eb5e38a2399930b3e27bc00c Mon Sep 17 00:00:00 2001
From: Vivek Nayyar <vivek.of.nayyar@gmail.com>
Date: Wed, 24 Jul 2019 14:23:39 +0530
Subject: [PATCH 01/13] :recycle: added condition to check for left and right
 of nullish coalescing operator and if any is a logical expression without a
 paren then throw an error

---
 .../babel-parser/src/parser/expression.js     | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 9b48c7129e2f..88eda16283e1 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -380,6 +380,28 @@ export default class ExpressionParser extends LValParser {
 
         node.right = this.parseExprOpRightExpr(op, prec, noIn);
 
+        if (op === tt.nullishCoalescing) {
+          if (
+            left.type === "LogicalExpression" &&
+            left.operator !== "??" &&
+            !(left.extra && left.extra.parenthesized)
+          ) {
+            throw this.raise(
+              this.state.start,
+              `Wrap left hand side of the expression in parentheses`,
+            );
+          } else if (
+            node.right.type === "LogicalExpression" &&
+            node.right.operator !== "??" &&
+            !(node.right.extra && node.right.extra.parenthesized)
+          ) {
+            throw this.raise(
+              this.state.start,
+              `Wrap right hand side of the expression in parentheses.`,
+            );
+          }
+        }
+
         this.finishNode(
           node,
           op === tt.logicalOR ||

From 2ec028cf02fe7cd40534c3f822e175e2c15cbd0a Mon Sep 17 00:00:00 2001
From: Vivek Nayyar <vivek.of.nayyar@gmail.com>
Date: Fri, 26 Jul 2019 02:56:38 +0530
Subject: [PATCH 02/13] :bug: bugs fixed and test cases updated for babel
 parser

---
 .../babel-parser/src/parser/expression.js     | 16 +++-
 .../and-nullish/input.js                      |  2 +-
 .../and-nullish/output.json                   | 52 +++++------
 .../no-paren-and-nullish/input.js             |  1 +
 .../no-paren-and-nullish/options.json         |  7 ++
 .../no-paren-nullish-and/input.js             |  1 +
 .../no-paren-nullish-and/options.json         |  6 ++
 .../no-paren-nullish-or/input.js              |  1 +
 .../no-paren-nullish-or/options.json          |  6 ++
 .../no-paren-or-nullish/input.js              |  1 +
 .../no-paren-or-nullish/options.json          |  7 ++
 .../nullish-and/input.js                      |  2 +-
 .../nullish-and/output.json                   | 44 +++++-----
 .../nullish-or/input.js                       |  2 +-
 .../nullish-or/output.json                    | 86 ++++++++++---------
 .../or-nullish/input.js                       |  2 +-
 .../or-nullish/output.json                    | 52 +++++------
 17 files changed, 173 insertions(+), 115 deletions(-)
 create mode 100644 packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/input.js
 create mode 100644 packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json
 create mode 100644 packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/input.js
 create mode 100644 packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json
 create mode 100644 packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/input.js
 create mode 100644 packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json
 create mode 100644 packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/input.js
 create mode 100644 packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 88eda16283e1..bf10f1555d67 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -380,6 +380,18 @@ export default class ExpressionParser extends LValParser {
 
         node.right = this.parseExprOpRightExpr(op, prec, noIn);
 
+        if (op === tt.logicalOR) {
+          if (
+            left.type === "LogicalExpression" &&
+            left.operator === "??" &&
+            !(left.extra && left.extra.parenthesized)
+          ) {
+            throw this.raise(
+              left.start,
+              `Wrap left hand side of the expression in parentheses`,
+            );
+          }
+        }
         if (op === tt.nullishCoalescing) {
           if (
             left.type === "LogicalExpression" &&
@@ -387,7 +399,7 @@ export default class ExpressionParser extends LValParser {
             !(left.extra && left.extra.parenthesized)
           ) {
             throw this.raise(
-              this.state.start,
+              left.start,
               `Wrap left hand side of the expression in parentheses`,
             );
           } else if (
@@ -396,7 +408,7 @@ export default class ExpressionParser extends LValParser {
             !(node.right.extra && node.right.extra.parenthesized)
           ) {
             throw this.raise(
-              this.state.start,
+              node.right.start,
               `Wrap right hand side of the expression in parentheses.`,
             );
           }
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/and-nullish/input.js b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/and-nullish/input.js
index 2b0c8c8ff80a..4080eadc3962 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/and-nullish/input.js
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/and-nullish/input.js
@@ -1 +1 @@
-a && b ?? c;
+(a && b) ?? c;
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/and-nullish/output.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/and-nullish/output.json
index 779d2ccfbcc8..31a372d44df5 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/and-nullish/output.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/and-nullish/output.json
@@ -1,7 +1,7 @@
 {
   "type": "File",
   "start": 0,
-  "end": 12,
+  "end": 14,
   "loc": {
     "start": {
       "line": 1,
@@ -9,13 +9,13 @@
     },
     "end": {
       "line": 1,
-      "column": 12
+      "column": 14
     }
   },
   "program": {
     "type": "Program",
     "start": 0,
-    "end": 12,
+    "end": 14,
     "loc": {
       "start": {
         "line": 1,
@@ -23,7 +23,7 @@
       },
       "end": {
         "line": 1,
-        "column": 12
+        "column": 14
       }
     },
     "sourceType": "script",
@@ -32,7 +32,7 @@
       {
         "type": "ExpressionStatement",
         "start": 0,
-        "end": 12,
+        "end": 14,
         "loc": {
           "start": {
             "line": 1,
@@ -40,13 +40,13 @@
           },
           "end": {
             "line": 1,
-            "column": 12
+            "column": 14
           }
         },
         "expression": {
           "type": "LogicalExpression",
           "start": 0,
-          "end": 11,
+          "end": 13,
           "loc": {
             "start": {
               "line": 1,
@@ -54,35 +54,35 @@
             },
             "end": {
               "line": 1,
-              "column": 11
+              "column": 13
             }
           },
           "left": {
             "type": "LogicalExpression",
-            "start": 0,
-            "end": 6,
+            "start": 1,
+            "end": 7,
             "loc": {
               "start": {
                 "line": 1,
-                "column": 0
+                "column": 1
               },
               "end": {
                 "line": 1,
-                "column": 6
+                "column": 7
               }
             },
             "left": {
               "type": "Identifier",
-              "start": 0,
-              "end": 1,
+              "start": 1,
+              "end": 2,
               "loc": {
                 "start": {
                   "line": 1,
-                  "column": 0
+                  "column": 1
                 },
                 "end": {
                   "line": 1,
-                  "column": 1
+                  "column": 2
                 },
                 "identifierName": "a"
               },
@@ -91,35 +91,39 @@
             "operator": "&&",
             "right": {
               "type": "Identifier",
-              "start": 5,
-              "end": 6,
+              "start": 6,
+              "end": 7,
               "loc": {
                 "start": {
                   "line": 1,
-                  "column": 5
+                  "column": 6
                 },
                 "end": {
                   "line": 1,
-                  "column": 6
+                  "column": 7
                 },
                 "identifierName": "b"
               },
               "name": "b"
+            },
+            "extra": {
+              "parenthesized": true,
+              "parenStart": 0
             }
           },
           "operator": "??",
           "right": {
             "type": "Identifier",
-            "start": 10,
-            "end": 11,
+            "start": 12,
+            "end": 13,
             "loc": {
               "start": {
                 "line": 1,
-                "column": 10
+                "column": 12
               },
               "end": {
                 "line": 1,
-                "column": 11
+                "column": 13
               },
               "identifierName": "c"
             },
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/input.js b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/input.js
new file mode 100644
index 000000000000..650d93b39a30
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/input.js
@@ -0,0 +1 @@
+c && d ?? e;
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json
new file mode 100644
index 000000000000..88e9c69ae088
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json
@@ -0,0 +1,7 @@
+{
+  "plugins": [
+    "nullishCoalescingOperator",
+    "estree"
+  ],
+  "throws": "Wrap left hand side of the expression in parentheses (1:0)"
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/input.js b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/input.js
new file mode 100644
index 000000000000..b8805af4953d
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/input.js
@@ -0,0 +1 @@
+a ?? b && c;
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json
new file mode 100644
index 000000000000..286f453dbe79
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json
@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    "nullishCoalescingOperator"
+  ],
+  "throws": "Wrap right hand side of the expression in parentheses. (1:5)"
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/input.js b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/input.js
new file mode 100644
index 000000000000..1fd223be11f9
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/input.js
@@ -0,0 +1 @@
+e ?? f ?? g || h;
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json
new file mode 100644
index 000000000000..2b97cbee3275
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json
@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    "nullishCoalescingOperator"
+  ],
+  "throws": "Wrap left hand side of the expression in parentheses (1:0)"
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/input.js b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/input.js
new file mode 100644
index 000000000000..5647ff20498f
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/input.js
@@ -0,0 +1 @@
+h || i ?? j;
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json
new file mode 100644
index 000000000000..88e9c69ae088
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json
@@ -0,0 +1,7 @@
+{
+  "plugins": [
+    "nullishCoalescingOperator",
+    "estree"
+  ],
+  "throws": "Wrap left hand side of the expression in parentheses (1:0)"
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-and/input.js b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-and/input.js
index b8805af4953d..886259bfb68d 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-and/input.js
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-and/input.js
@@ -1 +1 @@
-a ?? b && c;
+a ?? (b && c);
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-and/output.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-and/output.json
index 2e4c3bf5553f..b01e3ccaf935 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-and/output.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-and/output.json
@@ -1,7 +1,7 @@
 {
   "type": "File",
   "start": 0,
-  "end": 12,
+  "end": 14,
   "loc": {
     "start": {
       "line": 1,
@@ -9,13 +9,13 @@
     },
     "end": {
       "line": 1,
-      "column": 12
+      "column": 14
     }
   },
   "program": {
     "type": "Program",
     "start": 0,
-    "end": 12,
+    "end": 14,
     "loc": {
       "start": {
         "line": 1,
@@ -23,7 +23,7 @@
       },
       "end": {
         "line": 1,
-        "column": 12
+        "column": 14
       }
     },
     "sourceType": "script",
@@ -32,7 +32,7 @@
       {
         "type": "ExpressionStatement",
         "start": 0,
-        "end": 12,
+        "end": 14,
         "loc": {
           "start": {
             "line": 1,
@@ -40,13 +40,13 @@
           },
           "end": {
             "line": 1,
-            "column": 12
+            "column": 14
           }
         },
         "expression": {
           "type": "LogicalExpression",
           "start": 0,
-          "end": 11,
+          "end": 13,
           "loc": {
             "start": {
               "line": 1,
@@ -54,7 +54,7 @@
             },
             "end": {
               "line": 1,
-              "column": 11
+              "column": 13
             }
           },
           "left": {
@@ -77,30 +77,30 @@
           "operator": "??",
           "right": {
             "type": "LogicalExpression",
-            "start": 5,
-            "end": 11,
+            "start": 6,
+            "end": 12,
             "loc": {
               "start": {
                 "line": 1,
-                "column": 5
+                "column": 6
               },
               "end": {
                 "line": 1,
-                "column": 11
+                "column": 12
               }
             },
             "left": {
               "type": "Identifier",
-              "start": 5,
-              "end": 6,
+              "start": 6,
+              "end": 7,
               "loc": {
                 "start": {
                   "line": 1,
-                  "column": 5
+                  "column": 6
                 },
                 "end": {
                   "line": 1,
-                  "column": 6
+                  "column": 7
                 },
                 "identifierName": "b"
               },
@@ -109,20 +109,24 @@
             "operator": "&&",
             "right": {
               "type": "Identifier",
-              "start": 10,
-              "end": 11,
+              "start": 11,
+              "end": 12,
               "loc": {
                 "start": {
                   "line": 1,
-                  "column": 10
+                  "column": 11
                 },
                 "end": {
                   "line": 1,
-                  "column": 11
+                  "column": 12
                 },
                 "identifierName": "c"
               },
               "name": "c"
+            },
+            "extra": {
+              "parenthesized": true,
+              "parenStart": 5
             }
           }
         }
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-or/input.js b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-or/input.js
index 40ec9c39d17f..12162ba162d9 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-or/input.js
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-or/input.js
@@ -1 +1 @@
-a ?? b || c;
+a ?? (b || c);
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-or/output.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-or/output.json
index 5ab0fcc1a530..6947e6097892 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-or/output.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/nullish-or/output.json
@@ -1,7 +1,7 @@
 {
   "type": "File",
   "start": 0,
-  "end": 12,
+  "end": 14,
   "loc": {
     "start": {
       "line": 1,
@@ -9,13 +9,13 @@
     },
     "end": {
       "line": 1,
-      "column": 12
+      "column": 14
     }
   },
   "program": {
     "type": "Program",
     "start": 0,
-    "end": 12,
+    "end": 14,
     "loc": {
       "start": {
         "line": 1,
@@ -23,7 +23,7 @@
       },
       "end": {
         "line": 1,
-        "column": 12
+        "column": 14
       }
     },
     "sourceType": "script",
@@ -32,7 +32,7 @@
       {
         "type": "ExpressionStatement",
         "start": 0,
-        "end": 12,
+        "end": 14,
         "loc": {
           "start": {
             "line": 1,
@@ -40,13 +40,13 @@
           },
           "end": {
             "line": 1,
-            "column": 12
+            "column": 14
           }
         },
         "expression": {
           "type": "LogicalExpression",
           "start": 0,
-          "end": 11,
+          "end": 13,
           "loc": {
             "start": {
               "line": 1,
@@ -54,76 +54,80 @@
             },
             "end": {
               "line": 1,
-              "column": 11
+              "column": 13
             }
           },
           "left": {
-            "type": "LogicalExpression",
+            "type": "Identifier",
             "start": 0,
-            "end": 6,
+            "end": 1,
             "loc": {
               "start": {
                 "line": 1,
                 "column": 0
               },
               "end": {
+                "line": 1,
+                "column": 1
+              },
+              "identifierName": "a"
+            },
+            "name": "a"
+          },
+          "operator": "??",
+          "right": {
+            "type": "LogicalExpression",
+            "start": 6,
+            "end": 12,
+            "loc": {
+              "start": {
                 "line": 1,
                 "column": 6
+              },
+              "end": {
+                "line": 1,
+                "column": 12
               }
             },
             "left": {
               "type": "Identifier",
-              "start": 0,
-              "end": 1,
+              "start": 6,
+              "end": 7,
               "loc": {
                 "start": {
                   "line": 1,
-                  "column": 0
+                  "column": 6
                 },
                 "end": {
                   "line": 1,
-                  "column": 1
+                  "column": 7
                 },
-                "identifierName": "a"
+                "identifierName": "b"
               },
-              "name": "a"
+              "name": "b"
             },
-            "operator": "??",
+            "operator": "||",
             "right": {
               "type": "Identifier",
-              "start": 5,
-              "end": 6,
+              "start": 11,
+              "end": 12,
               "loc": {
                 "start": {
                   "line": 1,
-                  "column": 5
+                  "column": 11
                 },
                 "end": {
                   "line": 1,
-                  "column": 6
+                  "column": 12
                 },
-                "identifierName": "b"
+                "identifierName": "c"
               },
-              "name": "b"
-            }
-          },
-          "operator": "||",
-          "right": {
-            "type": "Identifier",
-            "start": 10,
-            "end": 11,
-            "loc": {
-              "start": {
-                "line": 1,
-                "column": 10
-              },
-              "end": {
-                "line": 1,
-                "column": 11
-              },
-              "identifierName": "c"
+              "name": "c"
             },
-            "name": "c"
+            "extra": {
+              "parenthesized": true,
+              "parenStart": 5
+            }
           }
         }
       }
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/or-nullish/input.js b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/or-nullish/input.js
index b74eae4c99e2..a8204525df1a 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/or-nullish/input.js
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/or-nullish/input.js
@@ -1 +1 @@
-a || b ?? c;
+(a || b) ?? c;
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/or-nullish/output.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/or-nullish/output.json
index 0db4055d3a89..f2e2798e4046 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/or-nullish/output.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/or-nullish/output.json
@@ -1,7 +1,7 @@
 {
   "type": "File",
   "start": 0,
-  "end": 12,
+  "end": 14,
   "loc": {
     "start": {
       "line": 1,
@@ -9,13 +9,13 @@
     },
     "end": {
       "line": 1,
-      "column": 12
+      "column": 14
     }
   },
   "program": {
     "type": "Program",
     "start": 0,
-    "end": 12,
+    "end": 14,
     "loc": {
       "start": {
         "line": 1,
@@ -23,7 +23,7 @@
       },
       "end": {
         "line": 1,
-        "column": 12
+        "column": 14
       }
     },
     "sourceType": "script",
@@ -32,7 +32,7 @@
       {
         "type": "ExpressionStatement",
         "start": 0,
-        "end": 12,
+        "end": 14,
         "loc": {
           "start": {
             "line": 1,
@@ -40,13 +40,13 @@
           },
           "end": {
             "line": 1,
-            "column": 12
+            "column": 14
           }
         },
         "expression": {
           "type": "LogicalExpression",
           "start": 0,
-          "end": 11,
+          "end": 13,
           "loc": {
             "start": {
               "line": 1,
@@ -54,35 +54,35 @@
             },
             "end": {
               "line": 1,
-              "column": 11
+              "column": 13
             }
           },
           "left": {
             "type": "LogicalExpression",
-            "start": 0,
-            "end": 6,
+            "start": 1,
+            "end": 7,
             "loc": {
               "start": {
                 "line": 1,
-                "column": 0
+                "column": 1
               },
               "end": {
                 "line": 1,
-                "column": 6
+                "column": 7
               }
             },
             "left": {
               "type": "Identifier",
-              "start": 0,
-              "end": 1,
+              "start": 1,
+              "end": 2,
               "loc": {
                 "start": {
                   "line": 1,
-                  "column": 0
+                  "column": 1
                 },
                 "end": {
                   "line": 1,
-                  "column": 1
+                  "column": 2
                 },
                 "identifierName": "a"
               },
@@ -91,35 +91,39 @@
             "operator": "||",
             "right": {
               "type": "Identifier",
-              "start": 5,
-              "end": 6,
+              "start": 6,
+              "end": 7,
               "loc": {
                 "start": {
                   "line": 1,
-                  "column": 5
+                  "column": 6
                 },
                 "end": {
                   "line": 1,
-                  "column": 6
+                  "column": 7
                 },
                 "identifierName": "b"
               },
               "name": "b"
+            },
+            "extra": {
+              "parenthesized": true,
+              "parenStart": 0
             }
           },
           "operator": "??",
           "right": {
             "type": "Identifier",
-            "start": 10,
-            "end": 11,
+            "start": 12,
+            "end": 13,
             "loc": {
               "start": {
                 "line": 1,
-                "column": 10
+                "column": 12
               },
               "end": {
                 "line": 1,
-                "column": 11
+                "column": 13
               },
               "identifierName": "c"
             },

From 82a6ac2ff04b0dbca0d88bf8a1b4b436148b3ec8 Mon Sep 17 00:00:00 2001
From: Vivek Nayyar <vivek.of.nayyar@gmail.com>
Date: Fri, 26 Jul 2019 03:02:31 +0530
Subject: [PATCH 03/13] :recycle: code comments added

---
 packages/babel-parser/src/parser/expression.js | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index bf10f1555d67..9a6e6fca1f80 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -380,6 +380,14 @@ export default class ExpressionParser extends LValParser {
 
         node.right = this.parseExprOpRightExpr(op, prec, noIn);
 
+        /* this check is needed because for operations like
+         * a ?? b || c
+         * a ?? b => This is considered as a logical expression in the ast tree
+         * c => Identifier
+         * so we need to check, only for || cases that if left is logical expression without paren
+         * then raise an error
+         */
+
         if (op === tt.logicalOR) {
           if (
             left.type === "LogicalExpression" &&
@@ -392,6 +400,16 @@ export default class ExpressionParser extends LValParser {
             );
           }
         }
+        /* this check is for all && and ?? operators
+         * a ?? b && c for this example
+         * b && c => This is considered as a logical expression in the ast tree
+         * a => Identifier
+         * so for ?? operator we need to check in this case the right expression
+         * second case a && b ?? c
+         * here a && b => This is considered as a logical expression in the ast tree
+         * c => identifer
+         * so now here for ?? operator we need to check the left expression
+         */
         if (op === tt.nullishCoalescing) {
           if (
             left.type === "LogicalExpression" &&

From 823d998c5983fa7301d356d317f0aac35552bbfe Mon Sep 17 00:00:00 2001
From: Vivek Nayyar <vivek.of.nayyar@gmail.com>
Date: Fri, 26 Jul 2019 03:18:42 +0530
Subject: [PATCH 04/13] :bug: spell error rectified

---
 packages/babel-parser/src/parser/expression.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 9a6e6fca1f80..27c0992f1a28 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -396,7 +396,7 @@ export default class ExpressionParser extends LValParser {
           ) {
             throw this.raise(
               left.start,
-              `Wrap left hand side of the expression in parentheses`,
+              `Wrap left hand side of the expression in parenthesis`,
             );
           }
         }
@@ -418,7 +418,7 @@ export default class ExpressionParser extends LValParser {
           ) {
             throw this.raise(
               left.start,
-              `Wrap left hand side of the expression in parentheses`,
+              `Wrap left hand side of the expression in parenthesis`,
             );
           } else if (
             node.right.type === "LogicalExpression" &&
@@ -427,7 +427,7 @@ export default class ExpressionParser extends LValParser {
           ) {
             throw this.raise(
               node.right.start,
-              `Wrap right hand side of the expression in parentheses.`,
+              `Wrap right hand side of the expression in parenthesis.`,
             );
           }
         }

From a7037dd5902e6e58311d8d35cc70586df5437455 Mon Sep 17 00:00:00 2001
From: Vivek Nayyar <vivek.of.nayyar@gmail.com>
Date: Fri, 26 Jul 2019 03:31:48 +0530
Subject: [PATCH 05/13] :recycle: failing test updated

---
 .../no-paren-and-nullish/options.json                    | 9 +++------
 .../no-paren-nullish-and/options.json                    | 8 +++-----
 .../no-paren-nullish-or/options.json                     | 8 +++-----
 .../no-paren-or-nullish/options.json                     | 9 +++------
 4 files changed, 12 insertions(+), 22 deletions(-)

diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json
index 88e9c69ae088..68a4874b0762 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json
@@ -1,7 +1,4 @@
 {
-  "plugins": [
-    "nullishCoalescingOperator",
-    "estree"
-  ],
-  "throws": "Wrap left hand side of the expression in parentheses (1:0)"
-}
\ No newline at end of file
+  "plugins": ["nullishCoalescingOperator", "estree"],
+  "throws": "Wrap left hand side of the expression in parenthesis (1:0)"
+}
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json
index 286f453dbe79..04dafdc66f9d 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json
@@ -1,6 +1,4 @@
 {
-  "plugins": [
-    "nullishCoalescingOperator"
-  ],
-  "throws": "Wrap right hand side of the expression in parentheses. (1:5)"
-}
\ No newline at end of file
+  "plugins": ["nullishCoalescingOperator"],
+  "throws": "Wrap right hand side of the expression in parenthesis. (1:5)"
+}
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json
index 2b97cbee3275..d20df430eb8a 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json
@@ -1,6 +1,4 @@
 {
-  "plugins": [
-    "nullishCoalescingOperator"
-  ],
-  "throws": "Wrap left hand side of the expression in parentheses (1:0)"
-}
\ No newline at end of file
+  "plugins": ["nullishCoalescingOperator"],
+  "throws": "Wrap left hand side of the expression in parenthesis (1:0)"
+}
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json
index 88e9c69ae088..68a4874b0762 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json
@@ -1,7 +1,4 @@
 {
-  "plugins": [
-    "nullishCoalescingOperator",
-    "estree"
-  ],
-  "throws": "Wrap left hand side of the expression in parentheses (1:0)"
-}
\ No newline at end of file
+  "plugins": ["nullishCoalescingOperator", "estree"],
+  "throws": "Wrap left hand side of the expression in parenthesis (1:0)"
+}

From 0fb1916a0622c5612aca2e66e4a663e87c5c52ad Mon Sep 17 00:00:00 2001
From: Vivek Nayyar <vivek.of.nayyar@gmail.com>
Date: Fri, 26 Jul 2019 03:37:10 +0530
Subject: [PATCH 06/13] :bug: push tests after make build

---
 .../no-paren-and-nullish/options.json                      | 7 +++++--
 .../no-paren-nullish-and/options.json                      | 6 ++++--
 .../no-paren-nullish-or/options.json                       | 6 ++++--
 .../no-paren-or-nullish/options.json                       | 7 +++++--
 4 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json
index 68a4874b0762..af16c19bb8f9 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json
@@ -1,4 +1,7 @@
 {
-  "plugins": ["nullishCoalescingOperator", "estree"],
+  "plugins": [
+    "nullishCoalescingOperator",
+    "estree"
+  ],
   "throws": "Wrap left hand side of the expression in parenthesis (1:0)"
-}
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json
index 04dafdc66f9d..426a105218d2 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json
@@ -1,4 +1,6 @@
 {
-  "plugins": ["nullishCoalescingOperator"],
+  "plugins": [
+    "nullishCoalescingOperator"
+  ],
   "throws": "Wrap right hand side of the expression in parenthesis. (1:5)"
-}
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json
index d20df430eb8a..5aa26c43ef10 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json
@@ -1,4 +1,6 @@
 {
-  "plugins": ["nullishCoalescingOperator"],
+  "plugins": [
+    "nullishCoalescingOperator"
+  ],
   "throws": "Wrap left hand side of the expression in parenthesis (1:0)"
-}
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json
index 68a4874b0762..af16c19bb8f9 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json
@@ -1,4 +1,7 @@
 {
-  "plugins": ["nullishCoalescingOperator", "estree"],
+  "plugins": [
+    "nullishCoalescingOperator",
+    "estree"
+  ],
   "throws": "Wrap left hand side of the expression in parenthesis (1:0)"
-}
+}
\ No newline at end of file

From 3260bef0dfaa38c0b7270b60d3b5425f30e26bc1 Mon Sep 17 00:00:00 2001
From: Justin Ridgewell <justin@ridgewell.name>
Date: Thu, 25 Jul 2019 23:16:37 -0400
Subject: [PATCH 07/13] Skip nullish-coalescing flow precedence tests

They're now incorrect
---
 scripts/tests/flow/flow_tests_whitelist.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/scripts/tests/flow/flow_tests_whitelist.txt b/scripts/tests/flow/flow_tests_whitelist.txt
index 7549e6a49ae1..43f45ad565ad 100644
--- a/scripts/tests/flow/flow_tests_whitelist.txt
+++ b/scripts/tests/flow/flow_tests_whitelist.txt
@@ -29,3 +29,5 @@ class_method_kinds/polymorphic_getter.js
 ES6/modules/migrated_0020.js
 export_import_reserved_words/migrated_0003.js
 export_statements/export_trailing_comma.js
+nullish_coalescing/precedence_and.js
+nullish_coalescing/precedence_or.js

From 6a0de8b84068c81a73c1147ab51310b4d3ee1b2e Mon Sep 17 00:00:00 2001
From: Vivek Nayyar <vivek.of.nayyar@gmail.com>
Date: Fri, 26 Jul 2019 18:56:27 +0530
Subject: [PATCH 08/13] :recycle: error message updated, binop priority of
 other logical operators +1 from ?? and

---
 .../babel-parser/src/parser/expression.js     | 31 ++------
 packages/babel-parser/src/tokenizer/types.js  | 26 +++----
 .../core/opts/tokens-true/output.json         |  2 +-
 .../no-paren-and-nullish/options.json         |  2 +-
 .../no-paren-nullish-and/options.json         |  2 +-
 .../no-paren-nullish-or/options.json          |  2 +-
 .../no-paren-or-nullish/options.json          |  2 +-
 .../fixtures/typescript/cast/as/output.json   | 74 +++++++++----------
 8 files changed, 61 insertions(+), 80 deletions(-)

diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 27c0992f1a28..9aeaa5b26d9d 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -380,35 +380,16 @@ export default class ExpressionParser extends LValParser {
 
         node.right = this.parseExprOpRightExpr(op, prec, noIn);
 
-        /* this check is needed because for operations like
-         * a ?? b || c
-         * a ?? b => This is considered as a logical expression in the ast tree
-         * c => Identifier
-         * so we need to check, only for || cases that if left is logical expression without paren
-         * then raise an error
-         */
-
-        if (op === tt.logicalOR) {
-          if (
-            left.type === "LogicalExpression" &&
-            left.operator === "??" &&
-            !(left.extra && left.extra.parenthesized)
-          ) {
-            throw this.raise(
-              left.start,
-              `Wrap left hand side of the expression in parenthesis`,
-            );
-          }
-        }
-        /* this check is for all && and ?? operators
+        /* this check is for all ?? operators
          * a ?? b && c for this example
          * b && c => This is considered as a logical expression in the ast tree
          * a => Identifier
-         * so for ?? operator we need to check in this case the right expression
+         * so for ?? operator we need to check in this case the right expression to have parenthesis
          * second case a && b ?? c
          * here a && b => This is considered as a logical expression in the ast tree
          * c => identifer
-         * so now here for ?? operator we need to check the left expression
+         * so now here for ?? operator we need to check the left expression to have parenthesis
+         * if the parenthesis is missing we raise an error and throw it
          */
         if (op === tt.nullishCoalescing) {
           if (
@@ -418,7 +399,7 @@ export default class ExpressionParser extends LValParser {
           ) {
             throw this.raise(
               left.start,
-              `Wrap left hand side of the expression in parenthesis`,
+              `Nullish coalescing operator(??) requires parens when mixing with logical operators`,
             );
           } else if (
             node.right.type === "LogicalExpression" &&
@@ -427,7 +408,7 @@ export default class ExpressionParser extends LValParser {
           ) {
             throw this.raise(
               node.right.start,
-              `Wrap right hand side of the expression in parenthesis.`,
+              `Nullish coalescing operator(??) requires parens when mixing with logical operators`,
             );
           }
         }
diff --git a/packages/babel-parser/src/tokenizer/types.js b/packages/babel-parser/src/tokenizer/types.js
index 34fd891c9256..7a559a758ed2 100644
--- a/packages/babel-parser/src/tokenizer/types.js
+++ b/packages/babel-parser/src/tokenizer/types.js
@@ -139,21 +139,21 @@ export const types: { [name: string]: TokenType } = {
   tilde: new TokenType("~", { beforeExpr, prefix, startsExpr }),
   pipeline: createBinop("|>", 0),
   nullishCoalescing: createBinop("??", 1),
-  logicalOR: createBinop("||", 1),
-  logicalAND: createBinop("&&", 2),
-  bitwiseOR: createBinop("|", 3),
-  bitwiseXOR: createBinop("^", 4),
-  bitwiseAND: createBinop("&", 5),
-  equality: createBinop("==/!=/===/!==", 6),
-  relational: createBinop("</>/<=/>=", 7),
-  bitShift: createBinop("<</>>/>>>", 8),
-  plusMin: new TokenType("+/-", { beforeExpr, binop: 9, prefix, startsExpr }),
-  modulo: createBinop("%", 10),
-  star: createBinop("*", 10),
-  slash: createBinop("/", 10),
+  logicalOR: createBinop("||", 2),
+  logicalAND: createBinop("&&", 3),
+  bitwiseOR: createBinop("|", 4),
+  bitwiseXOR: createBinop("^", 5),
+  bitwiseAND: createBinop("&", 6),
+  equality: createBinop("==/!=/===/!==", 7),
+  relational: createBinop("</>/<=/>=", 8),
+  bitShift: createBinop("<</>>/>>>", 9),
+  plusMin: new TokenType("+/-", { beforeExpr, binop: 10, prefix, startsExpr }),
+  modulo: createBinop("%", 11),
+  star: createBinop("*", 11),
+  slash: createBinop("/", 11),
   exponent: new TokenType("**", {
     beforeExpr,
-    binop: 11,
+    binop: 12,
     rightAssociative: true,
   }),
 
diff --git a/packages/babel-parser/test/fixtures/core/opts/tokens-true/output.json b/packages/babel-parser/test/fixtures/core/opts/tokens-true/output.json
index 47117344de0f..a21bf5e27309 100644
--- a/packages/babel-parser/test/fixtures/core/opts/tokens-true/output.json
+++ b/packages/babel-parser/test/fixtures/core/opts/tokens-true/output.json
@@ -457,7 +457,7 @@
         "isAssign": false,
         "prefix": true,
         "postfix": false,
-        "binop": 9,
+        "binop": 10,
         "updateContext": null
       },
       "value": "+",
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json
index af16c19bb8f9..b79520d826a2 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-and-nullish/options.json
@@ -3,5 +3,5 @@
     "nullishCoalescingOperator",
     "estree"
   ],
-  "throws": "Wrap left hand side of the expression in parenthesis (1:0)"
+  "throws": "Nullish coalescing operator(??) requires parens when mixing with logical operators (1:0)"
 }
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json
index 426a105218d2..e95e6eb0b428 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-and/options.json
@@ -2,5 +2,5 @@
   "plugins": [
     "nullishCoalescingOperator"
   ],
-  "throws": "Wrap right hand side of the expression in parenthesis. (1:5)"
+  "throws": "Nullish coalescing operator(??) requires parens when mixing with logical operators (1:5)"
 }
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json
index 5aa26c43ef10..dc240a52b3ad 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-nullish-or/options.json
@@ -2,5 +2,5 @@
   "plugins": [
     "nullishCoalescingOperator"
   ],
-  "throws": "Wrap left hand side of the expression in parenthesis (1:0)"
+  "throws": "Nullish coalescing operator(??) requires parens when mixing with logical operators (1:10)"
 }
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json
index af16c19bb8f9..b79520d826a2 100644
--- a/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/nullish-coalescing-operator/no-paren-or-nullish/options.json
@@ -3,5 +3,5 @@
     "nullishCoalescingOperator",
     "estree"
   ],
-  "throws": "Wrap left hand side of the expression in parenthesis (1:0)"
+  "throws": "Nullish coalescing operator(??) requires parens when mixing with logical operators (1:0)"
 }
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/typescript/cast/as/output.json b/packages/babel-parser/test/fixtures/typescript/cast/as/output.json
index a83b677640f6..299dbc75a813 100644
--- a/packages/babel-parser/test/fixtures/typescript/cast/as/output.json
+++ b/packages/babel-parser/test/fixtures/typescript/cast/as/output.json
@@ -236,7 +236,7 @@
           }
         },
         "expression": {
-          "type": "BinaryExpression",
+          "type": "TSAsExpression",
           "start": 49,
           "end": 66,
           "loc": {
@@ -249,10 +249,10 @@
               "column": 17
             }
           },
-          "left": {
-            "type": "Identifier",
+          "expression": {
+            "type": "BinaryExpression",
             "start": 49,
-            "end": 50,
+            "end": 56,
             "loc": {
               "start": {
                 "line": 3,
@@ -260,28 +260,28 @@
               },
               "end": {
                 "line": 3,
-                "column": 1
-              },
-              "identifierName": "x"
+                "column": 7
+              }
             },
-            "name": "x"
-          },
-          "operator": "===",
-          "right": {
-            "type": "TSAsExpression",
-            "start": 55,
-            "end": 66,
-            "loc": {
-              "start": {
-                "line": 3,
-                "column": 6
+            "left": {
+              "type": "Identifier",
+              "start": 49,
+              "end": 50,
+              "loc": {
+                "start": {
+                  "line": 3,
+                  "column": 0
+                },
+                "end": {
+                  "line": 3,
+                  "column": 1
+                },
+                "identifierName": "x"
               },
-              "end": {
-                "line": 3,
-                "column": 17
-              }
+              "name": "x"
             },
-            "expression": {
+            "operator": "===",
+            "right": {
               "type": "NumericLiteral",
               "start": 55,
               "end": 56,
@@ -300,20 +300,20 @@
                 "raw": "1"
               },
               "value": 1
-            },
-            "typeAnnotation": {
-              "type": "TSNumberKeyword",
-              "start": 60,
-              "end": 66,
-              "loc": {
-                "start": {
-                  "line": 3,
-                  "column": 11
-                },
-                "end": {
-                  "line": 3,
-                  "column": 17
-                }
+            }
+          },
+          "typeAnnotation": {
+            "type": "TSNumberKeyword",
+            "start": 60,
+            "end": 66,
+            "loc": {
+              "start": {
+                "line": 3,
+                "column": 11
+              },
+              "end": {
+                "line": 3,
+                "column": 17
               }
             }
           }

From d9ea03c8106c2cef7726255a99e587dfab904174 Mon Sep 17 00:00:00 2001
From: Vivek Nayyar <vivek.of.nayyar@gmail.com>
Date: Sat, 27 Jul 2019 01:27:43 +0530
Subject: [PATCH 09/13] :recycle: increaed the binOp for in and instanceOf,
 added logic to print the brackets in an ?? && || expression, test cases added

---
 .../src/generators/expressions.js             |  6 ++---
 packages/babel-generator/src/node/index.js    | 12 ++++++++++
 .../fixtures/types/LogicalExpression/input.js |  3 ++-
 .../types/LogicalExpression/options.json      |  3 +++
 .../types/LogicalExpression/output.js         |  4 +++-
 packages/babel-generator/test/index.js        | 23 +++++++++++++++++++
 packages/babel-parser/src/tokenizer/types.js  |  4 ++--
 7 files changed, 47 insertions(+), 8 deletions(-)
 create mode 100644 packages/babel-generator/test/fixtures/types/LogicalExpression/options.json

diff --git a/packages/babel-generator/src/generators/expressions.js b/packages/babel-generator/src/generators/expressions.js
index 4f9a525bd05e..4ba6dd7002fd 100644
--- a/packages/babel-generator/src/generators/expressions.js
+++ b/packages/babel-generator/src/generators/expressions.js
@@ -227,10 +227,8 @@ export function BindExpression(node: Object) {
   this.print(node.callee, node);
 }
 
-export {
-  AssignmentExpression as BinaryExpression,
-  AssignmentExpression as LogicalExpression,
-};
+export { AssignmentExpression as BinaryExpression };
+export { AssignmentExpression as LogicalExpression };
 
 export function MemberExpression(node: Object) {
   this.print(node.object, node);
diff --git a/packages/babel-generator/src/node/index.js b/packages/babel-generator/src/node/index.js
index 394e63b5cbdd..f9d337351ce8 100644
--- a/packages/babel-generator/src/node/index.js
+++ b/packages/babel-generator/src/node/index.js
@@ -96,6 +96,18 @@ export function needsParens(node, parent, printStack) {
   if (t.isNewExpression(parent) && parent.callee === node) {
     if (isOrHasCallExpression(node)) return true;
   }
+  /* this check if for NullishCoalescing with LogicalOperators liks && and ||
+   * For example when someone creates an ast programmaticaly like this
+   * t.logicalExpression(
+   * "??",
+   *  t.logicalExpression("||", t.identifier("a"), t.identifier("b")),
+   *  t.identifier("c"),
+   *  );
+   * In the above case we should that AST is equivalent to writing a || b ?? c
+   * This is incorrect because NullishCoalescing when used with LogicalExpressions should have parenthesis
+   * The correct syntax is (a || b) ?? c, that is why we need parens in this case
+   */
+  if (t.isLogicalExpression(node) && parent.operator === "??") return true;
 
   return find(expandedParens, node, parent, printStack);
 }
diff --git a/packages/babel-generator/test/fixtures/types/LogicalExpression/input.js b/packages/babel-generator/test/fixtures/types/LogicalExpression/input.js
index 08cae4f71732..3ff8c4d4040e 100644
--- a/packages/babel-generator/test/fixtures/types/LogicalExpression/input.js
+++ b/packages/babel-generator/test/fixtures/types/LogicalExpression/input.js
@@ -1,4 +1,5 @@
 foo ||bar;
 (x => x)|| bar;
 (function a(x){return x;})|| 2;
-0||(function(){return alpha;});
\ No newline at end of file
+0||(function(){return alpha;});
+a ?? (b || c);
diff --git a/packages/babel-generator/test/fixtures/types/LogicalExpression/options.json b/packages/babel-generator/test/fixtures/types/LogicalExpression/options.json
new file mode 100644
index 000000000000..1bb4736991a4
--- /dev/null
+++ b/packages/babel-generator/test/fixtures/types/LogicalExpression/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": ["nullishCoalescingOperator"]
+}
diff --git a/packages/babel-generator/test/fixtures/types/LogicalExpression/output.js b/packages/babel-generator/test/fixtures/types/LogicalExpression/output.js
index a27aa9ac1833..994dc9ec1b59 100644
--- a/packages/babel-generator/test/fixtures/types/LogicalExpression/output.js
+++ b/packages/babel-generator/test/fixtures/types/LogicalExpression/output.js
@@ -7,4 +7,6 @@ foo || bar;
 
 0 || function () {
   return alpha;
-};
\ No newline at end of file
+};
+
+a ?? (b || c);
diff --git a/packages/babel-generator/test/index.js b/packages/babel-generator/test/index.js
index 80bee85f9eaf..e90754cc4d4a 100644
--- a/packages/babel-generator/test/index.js
+++ b/packages/babel-generator/test/index.js
@@ -298,6 +298,29 @@ describe("generation", function() {
 });
 
 describe("programmatic generation", function() {
+  it("should add parenthesis when NullishCoalescing is used along with ||", function() {
+    // https://github.com/babel/babel/issues/10260
+    const nullishCoalesc = t.logicalExpression(
+      "??",
+      t.logicalExpression("||", t.identifier("a"), t.identifier("b")),
+      t.identifier("c"),
+    );
+    const output = generate(nullishCoalesc).code;
+    expect(output).toBe(`(a || b) ?? c`);
+  });
+  it("should add parenthesis when NullishCoalesing is used with &&", function() {
+    const nullishCoalesc = t.logicalExpression(
+      "??",
+      t.identifier("a"),
+      t.logicalExpression(
+        "&&",
+        t.identifier("b"),
+        t.logicalExpression("&&", t.identifier("c"), t.identifier("d")),
+      ),
+    );
+    const output = generate(nullishCoalesc).code;
+    expect(output).toBe(`a ?? (b && c && d)`);
+  });
   it("numeric member expression", function() {
     // Should not generate `0.foo`
     const mem = t.memberExpression(
diff --git a/packages/babel-parser/src/tokenizer/types.js b/packages/babel-parser/src/tokenizer/types.js
index 7a559a758ed2..47b4ced9f14e 100644
--- a/packages/babel-parser/src/tokenizer/types.js
+++ b/packages/babel-parser/src/tokenizer/types.js
@@ -188,8 +188,8 @@ export const types: { [name: string]: TokenType } = {
   _null: createKeyword("null", { startsExpr }),
   _true: createKeyword("true", { startsExpr }),
   _false: createKeyword("false", { startsExpr }),
-  _in: createKeyword("in", { beforeExpr, binop: 7 }),
-  _instanceof: createKeyword("instanceof", { beforeExpr, binop: 7 }),
+  _in: createKeyword("in", { beforeExpr, binop: 8 }),
+  _instanceof: createKeyword("instanceof", { beforeExpr, binop: 8 }),
   _typeof: createKeyword("typeof", { beforeExpr, prefix, startsExpr }),
   _void: createKeyword("void", { beforeExpr, prefix, startsExpr }),
   _delete: createKeyword("delete", { beforeExpr, prefix, startsExpr }),

From 6918e86d4136dac063017b293415b73094b94cce Mon Sep 17 00:00:00 2001
From: Vivek Nayyar <vivek.of.nayyar@gmail.com>
Date: Sat, 27 Jul 2019 01:37:47 +0530
Subject: [PATCH 10/13] :bug: failing test fixed and comments updated

---
 .../src/generators/expressions.js             |  6 +-
 packages/babel-generator/src/node/index.js    |  6 +-
 .../fixtures/typescript/cast/as/output.json   | 74 +++++++++----------
 3 files changed, 44 insertions(+), 42 deletions(-)

diff --git a/packages/babel-generator/src/generators/expressions.js b/packages/babel-generator/src/generators/expressions.js
index 4ba6dd7002fd..4f9a525bd05e 100644
--- a/packages/babel-generator/src/generators/expressions.js
+++ b/packages/babel-generator/src/generators/expressions.js
@@ -227,8 +227,10 @@ export function BindExpression(node: Object) {
   this.print(node.callee, node);
 }
 
-export { AssignmentExpression as BinaryExpression };
-export { AssignmentExpression as LogicalExpression };
+export {
+  AssignmentExpression as BinaryExpression,
+  AssignmentExpression as LogicalExpression,
+};
 
 export function MemberExpression(node: Object) {
   this.print(node.object, node);
diff --git a/packages/babel-generator/src/node/index.js b/packages/babel-generator/src/node/index.js
index f9d337351ce8..010bca8e5ade 100644
--- a/packages/babel-generator/src/node/index.js
+++ b/packages/babel-generator/src/node/index.js
@@ -96,16 +96,16 @@ export function needsParens(node, parent, printStack) {
   if (t.isNewExpression(parent) && parent.callee === node) {
     if (isOrHasCallExpression(node)) return true;
   }
-  /* this check if for NullishCoalescing with LogicalOperators liks && and ||
+  /* this check is for NullishCoalescing being used with LogicalOperators like && and ||
    * For example when someone creates an ast programmaticaly like this
    * t.logicalExpression(
    * "??",
    *  t.logicalExpression("||", t.identifier("a"), t.identifier("b")),
    *  t.identifier("c"),
    *  );
-   * In the above case we should that AST is equivalent to writing a || b ?? c
+   * In the example above the AST is equivalent to writing a || b ?? c
    * This is incorrect because NullishCoalescing when used with LogicalExpressions should have parenthesis
-   * The correct syntax is (a || b) ?? c, that is why we need parens in this case
+   * The correct syntax is (a || b) ?? c, that is why we need parenthesis in this case
    */
   if (t.isLogicalExpression(node) && parent.operator === "??") return true;
 
diff --git a/packages/babel-parser/test/fixtures/typescript/cast/as/output.json b/packages/babel-parser/test/fixtures/typescript/cast/as/output.json
index 299dbc75a813..a83b677640f6 100644
--- a/packages/babel-parser/test/fixtures/typescript/cast/as/output.json
+++ b/packages/babel-parser/test/fixtures/typescript/cast/as/output.json
@@ -236,7 +236,7 @@
           }
         },
         "expression": {
-          "type": "TSAsExpression",
+          "type": "BinaryExpression",
           "start": 49,
           "end": 66,
           "loc": {
@@ -249,10 +249,10 @@
               "column": 17
             }
           },
-          "expression": {
-            "type": "BinaryExpression",
+          "left": {
+            "type": "Identifier",
             "start": 49,
-            "end": 56,
+            "end": 50,
             "loc": {
               "start": {
                 "line": 3,
@@ -260,28 +260,28 @@
               },
               "end": {
                 "line": 3,
-                "column": 7
-              }
+                "column": 1
+              },
+              "identifierName": "x"
             },
-            "left": {
-              "type": "Identifier",
-              "start": 49,
-              "end": 50,
-              "loc": {
-                "start": {
-                  "line": 3,
-                  "column": 0
-                },
-                "end": {
-                  "line": 3,
-                  "column": 1
-                },
-                "identifierName": "x"
+            "name": "x"
+          },
+          "operator": "===",
+          "right": {
+            "type": "TSAsExpression",
+            "start": 55,
+            "end": 66,
+            "loc": {
+              "start": {
+                "line": 3,
+                "column": 6
               },
-              "name": "x"
+              "end": {
+                "line": 3,
+                "column": 17
+              }
             },
-            "operator": "===",
-            "right": {
+            "expression": {
               "type": "NumericLiteral",
               "start": 55,
               "end": 56,
@@ -300,20 +300,20 @@
                 "raw": "1"
               },
               "value": 1
-            }
-          },
-          "typeAnnotation": {
-            "type": "TSNumberKeyword",
-            "start": 60,
-            "end": 66,
-            "loc": {
-              "start": {
-                "line": 3,
-                "column": 11
-              },
-              "end": {
-                "line": 3,
-                "column": 17
+            },
+            "typeAnnotation": {
+              "type": "TSNumberKeyword",
+              "start": 60,
+              "end": 66,
+              "loc": {
+                "start": {
+                  "line": 3,
+                  "column": 11
+                },
+                "end": {
+                  "line": 3,
+                  "column": 17
+                }
               }
             }
           }

From 417cd403312f86287401824e83cb096441650d54 Mon Sep 17 00:00:00 2001
From: Vivek Nayyar <vivek.of.nayyar@gmail.com>
Date: Sat, 27 Jul 2019 02:25:40 +0530
Subject: [PATCH 11/13] :recycle: new lines added between tests

---
 packages/babel-generator/src/node/index.js | 1 +
 packages/babel-generator/test/index.js     | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/packages/babel-generator/src/node/index.js b/packages/babel-generator/src/node/index.js
index 010bca8e5ade..faf700dc681b 100644
--- a/packages/babel-generator/src/node/index.js
+++ b/packages/babel-generator/src/node/index.js
@@ -96,6 +96,7 @@ export function needsParens(node, parent, printStack) {
   if (t.isNewExpression(parent) && parent.callee === node) {
     if (isOrHasCallExpression(node)) return true;
   }
+
   /* this check is for NullishCoalescing being used with LogicalOperators like && and ||
    * For example when someone creates an ast programmaticaly like this
    * t.logicalExpression(
diff --git a/packages/babel-generator/test/index.js b/packages/babel-generator/test/index.js
index e90754cc4d4a..826610d2b85d 100644
--- a/packages/babel-generator/test/index.js
+++ b/packages/babel-generator/test/index.js
@@ -308,6 +308,7 @@ describe("programmatic generation", function() {
     const output = generate(nullishCoalesc).code;
     expect(output).toBe(`(a || b) ?? c`);
   });
+
   it("should add parenthesis when NullishCoalesing is used with &&", function() {
     const nullishCoalesc = t.logicalExpression(
       "??",
@@ -321,6 +322,7 @@ describe("programmatic generation", function() {
     const output = generate(nullishCoalesc).code;
     expect(output).toBe(`a ?? (b && c && d)`);
   });
+
   it("numeric member expression", function() {
     // Should not generate `0.foo`
     const mem = t.memberExpression(

From 4a2d372e4ca1a6ca08cd4ec7f81fb0235ae5e02c Mon Sep 17 00:00:00 2001
From: Vivek Nayyar <vivek.of.nayyar@gmail.com>
Date: Sat, 27 Jul 2019 02:26:18 +0530
Subject: [PATCH 12/13] :recycle: basic tests for checking the binOp of
 instanceOf, in and relational operators to be equal added

---
 packages/babel-parser/test/unit/tokenizer/types.js | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 packages/babel-parser/test/unit/tokenizer/types.js

diff --git a/packages/babel-parser/test/unit/tokenizer/types.js b/packages/babel-parser/test/unit/tokenizer/types.js
new file mode 100644
index 000000000000..e9f67c6f81ff
--- /dev/null
+++ b/packages/babel-parser/test/unit/tokenizer/types.js
@@ -0,0 +1,13 @@
+import { types } from "../../../src/tokenizer/types";
+
+describe("token types", () => {
+  it("should check if the binOp for relational === in", () => {
+    expect(types.relational.binop).toEqual(types._in.binop);
+  });
+  it("should check if the binOp for relational === instanceOf", () => {
+    expect(types.relational.binop).toEqual(types._instanceof.binop);
+  });
+  it("should check if the binOp for in === instanceOf", () => {
+    expect(types._in.binop).toEqual(types._instanceof.binop);
+  });
+});

From 40eb40e34b689096d6a5921c63577904a187d4be Mon Sep 17 00:00:00 2001
From: Vivek Nayyar <vivek.of.nayyar@gmail.com>
Date: Sat, 27 Jul 2019 02:51:31 +0530
Subject: [PATCH 13/13] :recycle: new lines added in between tests

---
 packages/babel-parser/test/unit/tokenizer/types.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/packages/babel-parser/test/unit/tokenizer/types.js b/packages/babel-parser/test/unit/tokenizer/types.js
index e9f67c6f81ff..64a69051963b 100644
--- a/packages/babel-parser/test/unit/tokenizer/types.js
+++ b/packages/babel-parser/test/unit/tokenizer/types.js
@@ -4,9 +4,11 @@ describe("token types", () => {
   it("should check if the binOp for relational === in", () => {
     expect(types.relational.binop).toEqual(types._in.binop);
   });
+
   it("should check if the binOp for relational === instanceOf", () => {
     expect(types.relational.binop).toEqual(types._instanceof.binop);
   });
+
   it("should check if the binOp for in === instanceOf", () => {
     expect(types._in.binop).toEqual(types._instanceof.binop);
   });