From c2d303f8be84731292908fb4a0552feeb59d139a Mon Sep 17 00:00:00 2001
From: Daniel Tschinder <daniel@tschinder.de>
Date: Thu, 16 May 2019 02:31:21 -0700
Subject: [PATCH] Do not use lookahead when parsing declare module or declare
 module.exports in flow (#9985)

* Do not use lookahead when parsing declare module or declare module.exports in flow

* Improve code
---
 packages/babel-parser/src/plugins/flow.js | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/packages/babel-parser/src/plugins/flow.js b/packages/babel-parser/src/plugins/flow.js
index 9522d13725a6..b5f4cbabcfaa 100644
--- a/packages/babel-parser/src/plugins/flow.js
+++ b/packages/babel-parser/src/plugins/flow.js
@@ -239,13 +239,13 @@ export default (superClass: Class<Parser>): Class<Parser> =>
         return this.flowParseDeclareFunction(node);
       } else if (this.match(tt._var)) {
         return this.flowParseDeclareVariable(node);
-      } else if (this.isContextual("module")) {
-        if (this.lookahead().type === tt.dot) {
+      } else if (this.eatContextual("module")) {
+        if (this.match(tt.dot)) {
           return this.flowParseDeclareModuleExports(node);
         } else {
           if (insideModule) {
             this.unexpected(
-              null,
+              this.state.lastTokStart,
               "`declare module` cannot be used inside another `declare module`",
             );
           }
@@ -276,8 +276,6 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     }
 
     flowParseDeclareModule(node: N.FlowDeclareModule): N.FlowDeclareModule {
-      this.next();
-
       this.scope.enter(SCOPE_OTHER);
 
       if (this.match(tt.string)) {
@@ -422,8 +420,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     flowParseDeclareModuleExports(
       node: N.FlowDeclareModuleExports,
     ): N.FlowDeclareModuleExports {
-      this.expectContextual("module");
-      this.expect(tt.dot);
+      this.next();
       this.expectContextual("exports");
       node.typeAnnotation = this.flowParseTypeAnnotation();
       this.semicolon();