From ab7d1231ad6bab4e13199038c58e7ea3ae1e9e27 Mon Sep 17 00:00:00 2001
From: Justin Ridgewell <justin@ridgewell.name>
Date: Sun, 25 Mar 2018 22:47:48 +0100
Subject: [PATCH] Fix flow errors with Logical Assignment Operators (#7629)

* Fix flow errors with logical assignment

* Fix column numbers
---
 packages/babylon/src/parser/expression.js     | 25 +++++++++++++++----
 packages/babylon/src/tokenizer/index.js       | 21 ++++++----------
 .../pipeline-operator/no-plugin/options.json  |  2 +-
 3 files changed, 28 insertions(+), 20 deletions(-)

diff --git a/packages/babylon/src/parser/expression.js b/packages/babylon/src/parser/expression.js
index 75178532ea..1abe3905a3 100644
--- a/packages/babylon/src/parser/expression.js
+++ b/packages/babylon/src/parser/expression.js
@@ -151,7 +151,16 @@ export default class ExpressionParser extends LValParser {
     }
     if (this.state.type.isAssign) {
       const node = this.startNodeAt(startPos, startLoc);
-      node.operator = this.state.value;
+      const operator = this.state.value;
+      node.operator = operator;
+
+      if (operator === "??=") {
+        this.expectPlugin("nullishCoalescingOperator");
+        this.expectPlugin("logicalAssignment");
+      }
+      if (operator === "||=" || operator === "&&=") {
+        this.expectPlugin("logicalAssignment");
+      }
       node.left = this.match(tt.eq)
         ? this.toAssignable(left, undefined, "assignment expression")
         : left;
@@ -271,11 +280,12 @@ export default class ExpressionParser extends LValParser {
     if (prec != null && (!noIn || !this.match(tt._in))) {
       if (prec > minPrec) {
         const node = this.startNodeAt(leftStartPos, leftStartLoc);
+        const operator = this.state.value;
         node.left = left;
-        node.operator = this.state.value;
+        node.operator = operator;
 
         if (
-          node.operator === "**" &&
+          operator === "**" &&
           left.type === "UnaryExpression" &&
           left.extra &&
           !left.extra.parenthesizedArgument &&
@@ -288,13 +298,18 @@ export default class ExpressionParser extends LValParser {
         }
 
         const op = this.state.type;
+        if (op === tt.nullishCoalescing) {
+          this.expectPlugin("nullishCoalescingOperator");
+        } else if (op === tt.pipeline) {
+          this.expectPlugin("pipelineOperator");
+        }
+
         this.next();
 
         const startPos = this.state.start;
         const startLoc = this.state.startLoc;
 
-        if (node.operator === "|>") {
-          this.expectPlugin("pipelineOperator");
+        if (op === tt.pipeline) {
           // Support syntax such as 10 |> x => x + 1
           this.state.potentialArrowAt = startPos;
         }
diff --git a/packages/babylon/src/tokenizer/index.js b/packages/babylon/src/tokenizer/index.js
index 6a7ec8f9f4..3143a0ae43 100644
--- a/packages/babylon/src/tokenizer/index.js
+++ b/packages/babylon/src/tokenizer/index.js
@@ -464,18 +464,14 @@ export default class Tokenizer extends LocationParser {
     const next = this.input.charCodeAt(this.state.pos + 1);
 
     if (next === code) {
-      const assign =
-        this.input.charCodeAt(this.state.pos + 2) === charCodes.equalsTo;
-      if (assign) {
-        // $FlowFixMe
-        this.expectPlugin("logicalAssignment");
+      if (this.input.charCodeAt(this.state.pos + 2) === charCodes.equalsTo) {
+        this.finishOp(tt.assign, 3);
+      } else {
+        this.finishOp(
+          code === charCodes.verticalBar ? tt.logicalOR : tt.logicalAND,
+          2,
+        );
       }
-      this.finishOp(
-        assign
-          ? tt.assign
-          : code === charCodes.verticalBar ? tt.logicalOR : tt.logicalAND,
-        assign ? 3 : 2,
-      );
       return;
     }
 
@@ -607,11 +603,8 @@ export default class Tokenizer extends LocationParser {
     const next = this.input.charCodeAt(this.state.pos + 1);
     const next2 = this.input.charCodeAt(this.state.pos + 2);
     if (next === charCodes.questionMark) {
-      this.expectPlugin("nullishCoalescingOperator");
-
       if (next2 === charCodes.equalsTo) {
         // '??='
-        this.expectPlugin("logicalAssignment");
         this.finishOp(tt.assign, 3);
       } else {
         // '??'
diff --git a/packages/babylon/test/fixtures/experimental/pipeline-operator/no-plugin/options.json b/packages/babylon/test/fixtures/experimental/pipeline-operator/no-plugin/options.json
index 0a8f05f84b..5d8a6bb120 100644
--- a/packages/babylon/test/fixtures/experimental/pipeline-operator/no-plugin/options.json
+++ b/packages/babylon/test/fixtures/experimental/pipeline-operator/no-plugin/options.json
@@ -1,3 +1,3 @@
 {
-  "throws": "This experimental syntax requires enabling the parser plugin: 'pipelineOperator' (1:5)"
+  "throws": "This experimental syntax requires enabling the parser plugin: 'pipelineOperator' (1:2)"
 }